@phdthesis{ZitzlerKunkel2014,
  author    = {Zitzler-Kunkel, Andr{\´e}},
  title     = {Funktionale Merocyaninfarbstoffe: Synthese, molekulare und Selbstorganisationseigenschaften sowie ihre Anwendung in der organischen Photovoltaik},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-101536},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2014},
  abstract  = {Analog zu den auf hochgeordneten Farbstoffarchitekturen in den biologischen Photosyntheseapparaten basierenden Energiekonversionssystemen sollte die exakte Einstellung zwischenmolekularer Wechselwirkungen auch in k{\"u}nstlichen Halbleitern eine entscheidende Rolle f{\"u}r die Weiterentwicklung organischer Elektronikmaterialien spielen. F{\"u}r eine derartige, pr{\"a}zise Steuerung der nanoskaligen Anordnung in organischen Materialien erscheinen Merocyaninfarbstoffe wegen ihrer hochgerichteten, dipolaren Aggregation {\"a}ußerst aussichtsreich. In diesem Zusammenhang war das Ziel der vorliegenden Arbeit die Ausnutzung funktionaler, stark selbstorganisierender Merocyanine, um eine gezielte Beeinflussung der Morphologie in der aktiven Schicht von BHJ-Solarzellen zu erreichen. Hierzu sollte zun{\"a}chst eine umfangreiche Serie komplexer Merocyanine synthetisiert und vollst{\"a}ndig charakterisiert werden. Im Folgenden wurde angestrebt, die optischen und elektrochemischen Eigenschaften der molekular gel{\"o}sten Farbstoffe zu bestimmen und f{\"u}r ausgew{\"a}hlte, geeignete Strukturen das Selbstorganisationsverhalten im Detail zu studieren. Zuletzt sollte durch eine sorgf{\"a}ltige Optimierung der Prozessierungsbedingungen ein Transfer der in L{\"o}sung gefundenen, supramolekularen Strukturen in den Blend l{\"o}sungsprozessierter BHJ-Solarzellen erreicht werden. Die organischen Elektronikbauteile wurden dabei im Arbeitskreis von Prof. Dr. Klaus Meerholz (Universit{\"a}t K{\"o}ln) gefertigt und charakterisiert. Zusammenfassend zeichnet die vorliegende Arbeit ein umfassendes Bild von der Synthese funktionaler Merocyanine, dem Studium ihrer molekularen und Selbstorganisationseigenschaften sowie ihrer Anwendung als p-Halbleitermaterialien in organischen Solarzellen. Der komplexe Molek{\"u}laufbau der dargestellten Farbstoffe f{\"u}hrte dabei zur Ausbildung verschiedener Farbstofforganisate, deren Struktur sowohl in L{\"o}sung als auch teilweise im Festk{\"o}rper aufgekl{\"a}rt werden konnte. Die erfolgreiche Implementierung von H-aggregierten Spezies der Verbindung 67b in die aktive Schicht organischer BHJ-Solarzellen resultierte in der Bildung effizienter Perkolationspfade f{\"u}r Exzitonen und freie Ladungstr{\"a}ger, wodurch diese Bauteile merklich h{\"o}here Stromdichten generieren konnten und gegen{\"u}ber Zellen ohne H-Spezies {\"u}ber 20 \% gesteigerte Effizienz aufwiesen. Diese Befunde verifizieren die postulierte Hypothese, dass eine gezielte Einstellung der zwischenmolekularen Wechselwirkungen bei organischen Halbleitern zu einer Optimierung der Funktionalit{\"a}t organischer Elektronikmaterialien beitragen kann.},
  subject      = {Merocyanine},
  language  = {de}
}
@article{ZimniakKirschnerHilpertetal.2021,
  author    = {Zimniak, Melissa and Kirschner, Luisa and Hilpert, Helen and Geiger, Nina and Danov, Olga and Oberwinkler, Heike and Steinke, Maria and Sewald, Katherina and Seibel, J{\"u}rgen and Bodem, Jochen},
  title     = {The serotonin reuptake inhibitor Fluoxetine inhibits SARS-CoV-2 in human lung tissue},
  series = {Scientific Reports},
  volume    = {11},
  journal   = {Scientific Reports},
  doi       = {10.1038/s41598-021-85049-0},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-259820},
  pages     = {5890},
  year      = {2021},
  abstract  = {To circumvent time-consuming clinical trials, testing whether existing drugs are effective inhibitors of SARS-CoV-2, has led to the discovery of Remdesivir. We decided to follow this path and screened approved medications "off-label" against SARS-CoV-2. Fluoxetine inhibited SARS-CoV-2 at a concentration of 0.8 mu g/ml significantly in these screenings, and the EC50 was determined with 387 ng/ml. Furthermore, Fluoxetine reduced viral infectivity in precision-cut human lung slices showing its activity in relevant human tissue targeted in severe infections. Fluoxetine treatment resulted in a decrease in viral protein expression. Fluoxetine is a racemate consisting of both stereoisomers, while the S-form is the dominant serotonin reuptake inhibitor. We found that both isomers show similar activity on the virus, indicating that the R-form might specifically be used for SARS-CoV-2 treatment. Fluoxetine inhibited neither Rabies virus, human respiratory syncytial virus replication nor the Human Herpesvirus 8 or Herpes simplex virus type 1 gene expression, indicating that it acts virus-specific. Moreover, since it is known that Fluoxetine inhibits cytokine release, we see the role of Fluoxetine in the treatment of SARS-CoV-2 infected patients of risk groups.},
  language  = {en}
}
@phdthesis{Zhang2012,
  author    = {Zhang, Guoliang},
  title     = {Phytochemical Research on Two Ancistrocladus Species, Semi-Synthesis of Dimeric Naphthylisoquinoline Alkaloids, and Structure Optimization of Antitumoral Naphthoquinones},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-72734},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2012},
  abstract  = {Plant-derived natural products and their analogs continue to play an important role in the discovery of new drugs for the treatment of human diseases. Potentially promising representatives of secondary metabolites are the naphthylisoquinoline alkaloids, which show a broad range of activities against protozoan pathogens, such as plasmodia, leishmania, and trypanosoma. Due to the increasing resistance of those pathogens against current therapies, highly potent novel agents are still urgently needed. Thus, it is worthy to discover new naphthylisoquinoline alkaloids hopefully with pronounced bioactivities by isolation from plants or by synthesis. The naphthylisoquinoline alkaloids are biosynthetically related to another class of plant-derived products, the naphthoquinones, some of which have been recently found to display excellent anti-multiple myeloma activities without showing any cytotoxicities on normal blood cells. Multiple myeloma still remains incurable, although remissions may be induced with co-opted therapeutic treatments. Therefore, more potent naphthoquinones are urgently required, and can be obtained by isolation from plants or by synthesis. In detail, the results in this thesis are listed as follows: 1) Isolation and characterization of naphthylisoquinoline alkaloids from the stems of a Chinese Ancistrocladus tectorius species. Nine new naphthylisoquinoline alkaloids, named ancistectorine A1 (60), N-methylancistectorine A1 (61), ancistectorine A2 (62a), 5-epi-ancistectorine A2 (62b), 4'-O-demethylancistectorine A2 (63), ancistectorine A3 (64), ancistectorine B1 (65), ancistectorine C1 (66), and 5-epi-ancistrolikokine D (67) were isolated from the Chinese A. tectorius and fully characterized by chemical, spectroscopic, and chiroptical methods. Furthermore, the in vitro anti-infectious activities of 60-62 and 63-66 have been tested. Three of the metabolites, 61, 62a, and 62b, exhibited strong antiplasmodial activities against the strain K1 of P. falciparum without showing significant cytotoxicities. With IC50 values of 0.08, 0.07, and 0.03 μM, respectively, they were 37 times more active than the standard chloroquine (IC50 = 0.26 μM). Moreover, these three compounds displayed high antiplasmodial selectivity indexes ranging from 100 to 3300. According to the TDR/WHO guidelines, they could be considered as lead compounds. In addition, seven alkaloids, 69-74 (structures not shown here), were isolated from A. tectorius that were known, but new to the plant, together with another fourteen known compounds (of these, only the structures of the three main alkaloids, 5a, 5b, and 78 are shown here), which had been previously found in the plant. The three metabolites ancistrocladine (5a), hamatine (5b), and (+)-ancistrocline (78) were found to show no or moderate activities against the MM cell lines. 2) Isolation and characterization of naphthylisoquinoline alkaloids from the root bark of a new, botanically yet undescribed Congolese Ancistrocladus species. An unprecedented dimeric Dioncophyllaceae-type naphthylisoquinoline alkaloid, jozimine A2 (84), as first recognized by G. Bauckmann from an as yet undescribed Ancistrocladus species, was purified and characterized as part of this thesis. Its full structural assignment was achieved by spectroscopic and chiroptical methods, and further confirmed by an X-ray diffraction analysis, which had never succeeded for any other dimeric naphthylisoquinoline alkaloids before. Structurally, the dimer is composed of two identical 4'-O-demethyldioncophylline A halves, coupled through a sterically hindered central axis at C-3',3'' of the two naphthalene moieties. Pharmacologically, jozimine A2 (84) showed an extraordinary antiplasmodial activity (IC50 = 1.4 nM) against the strain NF54 of P. falciparum. Beside jozimine A2 (85), another new alkaloid, 6-O-demethylancistrobrevine C (84), and four known ones, ancistrocladine (5a), hamatine (5b), ancistrobrevine C (86), and dioncophylline A (6) were isolated from the Ancistrocladus species, the latter in a large quantity (~500 mg), showing that the plant produces Ancistrocladaceae-type, mixed-Ancistrocladaceae/Dioncophyllaceae-type, and Dioncophyllaceae-type naphthyl- isoquinoline alkaloids. Remarkably, it is one of the very few plants, like A. abbreviatus, and A. barteri, that simultaneously contain typical representatives of all the above three classes of alkaloids. 3) Semi-synthesis of jozimine A2 (85), 3'-epi-85, jozimine A3 (93) and other alkaloids from dioncophylline A (6). The dimeric naphthylisoquinoline alkaloids, jozimine A2 (85) and 3'-epi-85, constitute rewarding synthetic targets for a comparative analysis of their antiplasmodial activities and for a further confirmation of the assigned absolute configurations of the isolated natural product of 85. They were semi-synthesized in a four-step reaction sequence from dioncophylline A (6) in cooperation with T. B{\"u}ttner. The key step was a biomimetic phenol-oxidative dimerization at C-3' of the N,O-dibenzylated derivative of 89 by utilizing Pb(OAc)4. This is the first time that the synthesis of such an extremely sterically hindered (four ortho-substituents) naphthylisoquinoline alkaloid - with three consecutive biaryl axes! - has been successfully achieved. A novel dimeric naphthylisoquinoline, jozimine A3 (93), bearing a 6',6''-central biaryl axis, was semi-synthesized from 5'-O-demethyldioncophylline A (90) by a similar biomimetic phenol-oxidative coupling reaction as a key step, by employing Ag2O. HPLC analysis with synthetic reference material of 3'-epi-85 and 93 for co-elution revealed that these two alkaloids clearly are not present in the crude extract of the Ancistrocladus species from which jozimine A2 (85) was isolated. This evidences that jozimine A2 (85) is very specifically biosynthesized by the plant with a high regio- and stereoslectivity. Remarkably, the two synthetic novel dimeric naphthylisoquinoline alkaloids 3'-epi-85 and 93 were found to display very good antiplasmodial activities, albeit weaker than that of the natural and semi-synthetic product 85. Additionally, the two compounds 3'-epi-85 and 93 possessed high or moderate selectivity indexes, which were much lower than that of 85. However, they can still be considered as new lead structures. Two unprecedented oxidative products of dioncophylline A, the diastereomeric dioncotetralones A (94a) and B (94b), were synthesized from dioncophylline A (6) in a one-step reaction. Remarkably, the aromatic properties in the "naphthalene" and the "isoquinoline" rings of 94a and 94b are partially lost and the "biaryl" axis has become a C,C-double bond, so that the two halves are nearly co-planar to each other, which has never been found among any natural or synthetic naphthylisoquinoline alkaloid. Their full structural characterization was accomplished by spectroscopic methods and quantum-chemical CD calculations (done by Y. Hemberger). The presumed reaction mechanism was proposed in this thesis. In addition, one of the two compounds, 94a, exhibited a highly antiplasmodial activity (IC50 = 0.09 μM) with low cytotoxicity, and thus, can be considered as a new promising lead structure. Its 2'-epi-isomer, 94b, was inactive, evidencing a significant effect of chirality on the bioactivity. Of a number of naphthylisoquinoline alkaloids tested against the multiple-myeloma cell lines, the three compounds, dioncophylline A (6), 4'-O-demethyldioncophylline A (89), and 5'-O-demethyldioncophylline A (90) showed excellent activities, even much stronger than dioncoquinones B (10), C (102), the epoxide 175, or the standard drug melphalan. 4) Isolation and characterization of bioactive naphthoquinones from cell cultures of Triphyophyllum peltatum. Three new naphthoquinones, dioncoquinones C (102), D (103), and E (104), the known 8-hydroxydroserone (105), which is new to this plant, and one new naphthol dimer, triphoquinol A (107), were isolated from cell cultures of T. peltatum in cooperation with A. Irmer. Dioncoquinone C (102) showed an excellent activity against the MM cells, very similar to that of the previously found dioncoquinone B (10), without showing any inhibitory effect on normal cells. The other three naphthoquinones, 103105, were inactive or only weakly active. 5) Establishment of a new strategy for a synthetic access to dioncoquinones B (10) and C (102) on a large scale for in vivo experiments and for the synthesis of their analogs for first SAR studies. Before the synthesis of dioncoquinone B (10) described in this thesis, two synthetic pathways had previously been established in our group. The third approach described here involved the preparation of the joint synthetic intermediate 42 with the previous two routes. The tertiary benzamide 135 was ortho-deprotonated by using s-BuLi/TMEDA, followed by transmetallation with MgBr2▪2Et2O, and reaction with 2-methylallyl bromide (139). It resulted in the formation of ortho-allyl benzamide 140, which was cyclized by using methyl lithium to afford the naphthol 42. This strategy proved to be the best among the established three approaches with regard to its very low number of steps and high yields. By starting with 136, this third strategy yielded the related bioactive natural product, dioncoquinone C (102), which was accessed by total synthesis for the first time. To identify the pharmacophore of the antitumoral naphthoquinones, a library of dioncoquinone B (10) and C (102) analogs were synthesized for in vitro testing. Among the numerous naphthoquinones tested, the synthetic 7-O-demethyldioncoquinone C (or 7-O-hydroxyldioncoquinone B) (145), constitutes another promising basic structure to develop a new anti-MM agent. Furthermore, preliminary SAR results evidence that the three hydroxy functions at C-3, C-5, and C-6 are essential for the biological properties as exemplarily shown through the compounds 10, 102, and 145. All other mixed OH/OMe- or completely OMe-substituted structures were entirely inactive. By a serendipity the expoxide 175 was found to display the best anti-MM activity of all the tested isolated metabolites from T. peltatum, the synthesized naphthoquinones, and their synthetic intermediates. Toxic effects of 175 on normal cells were not observed, in contrast to the high toxicities of all other epoxides. Thus, the anti-MM activity of 175 is of high selectivity. The preliminary SAR studies revealed that the 6-OMe group in 175 is required, thus differed with the above described naphthoquinones (where 6-OH is a requisite in 10, 102, and 145), which evidenced potentially different modes of action for these two classes of compounds. 6) The first attempted total synthesis of the new naturally occurring triphoquinone (187a), which was recently isolated from the root cultures of T. peltatum in our group. A novel naphthoquinone-naphthalene dimer, 187a (structure shown in Chapter 10), was isolated in small quantities from the root cultures of T. peltatum. Thus, its total synthesis was attempted for obtaining sufficient amounts for selected biotestings. The key step was planned to prepare the extremely sterically hindered (four ortho-substituents) binaphthalene 188 by a coupling reaction between the two 2-methylnaphthalene derivatives. Test reactions involving a system of two simplified 2-methylnaphthylboron species and 2-methylnaphthyl bromide proved the Buchwald ligand as most promising. The optimized conditions were then applied to the two true - highly oxygenated - coupling substrates, between the 2-methylnaphthylboron derivatives 210, 211, 213, or 214 and the 2-methylnaphthyl iodides (or bromides) 215 (206), 215 (206), 212 (205), or 212 (205), respectively. Unfortunately, this crucial step failed although various bases and solvent systems were tested. This could be due to the high electron density of the two coupling substrates, both bearing strongly OMOM/OMe-donating function groups. Therefore, a more powerful catalyst system or an alternative synthetic strategy must be explored for the total synthesis of 187a. 7) Phytochemical investigation of the Streptomyces strain RV-15 derived from a marine sponge. Cyclodysidins A-D (216-219), four new cyclic lipopeptides with a- and ß-amino acids, were isolated from the Streptomyces strain RV15 derived from a marine sponge by Dr. U. Abdelmohsen. Their structures were established as cyclo-(ß-AFA-Ser-Gln-Asn-Tyr-Asn-Ser-Thr) by spectroscopic analysis using 2D NMR techniques and CID-MS/MS in the course of this thesis. In conclusion, the present work contributes to the discovery of novel antiplasmodial naphthylisoquinoline alkaloids and antitumoral naphthoquinones, which will pave the way for future studies on these two classes of compounds.},
  subject      = {Ancistrocladus},
  language  = {en}
}
@article{ZhangRadackiBraunschweigetal.2021,
  author    = {Zhang, Fangyuan and Radacki, Krzysztof and Braunschweig, Holger and Lambert, Christoph and Ravat, Prince},
  title     = {Zinc-[7]helicenocyanine and its discrete π-stacked homochiral Dimer},
  series = {Angewandte Chemie International Edition},
  volume    = {60},
  journal   = {Angewandte Chemie International Edition},
  doi       = {10.1002/anie.202109380},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256534},
  pages     = {23656-23660},
  year      = {2021},
  abstract  = {In this communication, we demonstrate a novel approach to prepare a discrete dimer of chiral phthalocyanine (Pc) by exploiting the flexible molecular geometry of helicenes, which enables structural interlocking and strong aggregation tendency of Pcs. Synthesized [7]helicene-Pc hybrid molecular structure, zinc-[7]helicenocyanine (Zn-7HPc), exclusively forms a stable dimeric pair consisting of two homochiral molecules. The dimerization constants were estimated to be as high as 8.96×10\(^6\) M\(^{-1}\) and 3.42×107 M\(^{-1}\) in THF and DMSO, respectively, indicating remarkable stability of dimer. In addition, Zn\(^{-7}\)HPc exhibited chiral self-sorting behavior, which resulted in preferential formation of a homochiral dimer also in the racemic sample. Two phthalocyanine subunits in the dimeric form strongly communicate with each other as revealed by a large comproportionation constant and observation of an IV-CT band for the thermodynamically stable mixed-valence state.},
  language  = {en}
}
@article{ZhangMichailSaaletal.2019,
  author    = {Zhang, Fangyuan and Michail, Evripidis and Saal, Fridolin and Krause, Ana-Maria and Ravat, Prince},
  title     = {Stereospecific Synthesis and Photophysical Properties of Propeller-Shaped C\(_{90}\)H\(_{48}\) PAH},
  series = {Chemistry - A European Journal},
  volume    = {25},
  journal   = {Chemistry - A European Journal},
  number    = {71},
  doi       = {10.1002/chem.201904962},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-208682},
  pages     = {16241-16245},
  year      = {2019},
  abstract  = {Herein, we have synthesized an enantiomerically pure propeller-shaped PAH, C\(_{90}\)H\(_{48}\), possessing three [7]helicene and three [5]helicene subunits. This compound can be obtained in gram quantities in a straightforward manner. The photophysical and chiroptical properties were investigated using UV/Vis absorption and emission, optical rotation and circular dichroism spectroscopy, supported by DFT calculations. The nonlinear optical properties were investigated by two-photon absorption measurements using linearly and circularly polarized light. The extremely twisted structure and packing of the homochiral compound were investigated by single-crystal X-ray diffraction analysis.},
  language  = {en}
}
@article{ZahranAlbohyKhaliletal.2020,
  author    = {Zahran, Eman Maher and Albohy, Amgad and Khalil, Amira and Ibrahim, Alyaa Hatem and Ahmed, Heba Ali and El-Hossary, Ebaa M. and Bringmann, Gerhard and Abdelmohsen, Usama Ramadan},
  title     = {Bioactivity Potential of Marine Natural Products from Scleractinia-Associated Microbes and In Silico Anti-SARS-COV-2 Evaluation},
  series = {Marine Drugs},
  volume    = {18},
  journal   = {Marine Drugs},
  number    = {12},
  issn      = {1660-3397},
  doi       = {10.3390/md18120645},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-220041},
  year      = {2020},
  abstract  = {Marine organisms and their associated microbes are rich in diverse chemical leads. With the development of marine biotechnology, a considerable number of research activities are focused on marine bacteria and fungi-derived bioactive compounds. Marine bacteria and fungi are ranked on the top of the hierarchy of all organisms, as they are responsible for producing a wide range of bioactive secondary metabolites with possible pharmaceutical applications. Thus, they have the potential to provide future drugs against challenging diseases, such as cancer, a range of viral diseases, malaria, and inflammation. This review aims at describing the literature on secondary metabolites that have been obtained from Scleractinian-associated organisms including bacteria, fungi, and zooxanthellae, with full coverage of the period from 1982 to 2020, as well as illustrating their biological activities and structure activity relationship (SAR). Moreover, all these compounds were filtered based on ADME analysis to determine their physicochemical properties, and 15 compounds were selected. The selected compounds were virtually investigated for potential inhibition for SARS-CoV-2 targets using molecular docking studies. Promising potential results against SARS-CoV-2 RNA dependent RNA polymerase (RdRp) and methyltransferase (nsp16) are presented.},
  language  = {en}
}
@article{WuerthnerNoll2021,
  author    = {W{\"u}rthner, Frank and Noll, Niklas},
  title     = {A Calix[4]arene-Based Cyclic Dinuclear Ruthenium Complex for Light-Driven Catalytic Water Oxidation},
  series = {Chemistry - A European Journal},
  volume    = {27},
  journal   = {Chemistry - A European Journal},
  number    = {1},
  doi       = {10.1002/chem.202004486},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230030},
  pages     = {444-450},
  year      = {2021},
  abstract  = {A cyclic dinuclear ruthenium(bda) (bda: 2,2'-bipyridine-6,6'-dicarboxylate) complex equipped with oligo(ethylene glycol)-functionalized axial calix[4]arene ligands has been synthesized for homogenous catalytic water oxidation. This novel Ru(bda) macrocycle showed significantly increased catalytic activity in chemical and photocatalytic water oxidation compared to the archetype mononuclear reference [Ru(bda)(pic)\(_2\)]. Kinetic investigations, including kinetic isotope effect studies, disclosed a unimolecular water nucleophilic attack mechanism of this novel dinuclear water oxidation catalyst (WOC) under the involvement of the second coordination sphere. Photocatalytic water oxidation with this cyclic dinuclear Ru complex using [Ru(bpy)\(_3\)]Cl\(_2\) as a standard photosensitizer revealed a turnover frequency of 15.5 s\(^{-1}\) and a turnover number of 460. This so far highest photocatalytic performance reported for a Ru(bda) complex underlines the potential of this water-soluble WOC for artificial photosynthesis.},
  language  = {en}
}
@article{WuerthnerMezaChinchaSchindleretal.2021,
  author    = {W{\"u}rthner, Frank and Meza-Chincha, Ana-Lucia and Schindler, Dorothee and Natali, Mirco},
  title     = {Effects of Photosensitizers and Reaction Media on Light-Driven Water Oxidation with Trinuclear Ruthenium Macrocycles},
  series = {ChemPhotoChem},
  volume    = {5},
  journal   = {ChemPhotoChem},
  number    = {2},
  doi       = {10.1002/cptc.202000133},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230116},
  pages     = {173-183},
  year      = {2021},
  abstract  = {Photocatalytic water oxidation is a promising process for the production of solar fuels and the elucidation of factors that influence this process is of high significance. Thus, we have studied in detail light-driven water oxidation with a trinuclear Ru(bda) (bda: 2,2'-bipyridine-6,6'-dicarboxylate) macrocycle MC3 and its highly water soluble derivative m-CH\(_2\)NMe\(_2\)-MC3 using a series of ruthenium tris(bipyridine) complexes as photosensitizers under varied reaction conditions. Our investigations showed that the catalytic activities of these Ru macrocycles are significantly affected by the choice of photosensitizer (PS) and reaction media, in addition to buffer concentration, light intensity and concentration of the sensitizer. Our steady-state and transient spectroscopic studies revealed that the photocatalytic performance of trinuclear Ru(bda) macrocycles is not limited by their intrinsic catalytic activities but rather by the efficiency of photogeneration of oxidant PS\(^+\) and its ability to act as an oxidizing agent to the catalysts as both are strongly dependent on the choice of photosensitizer and the amount of employed organic co-solvent.},
  language  = {en}
}
@article{WaechtlerKuebelBarthelmesetal.2016,
  author    = {W{\"a}chtler, Maria and K{\"u}bel, Joachim and Barthelmes, Kevin and Winter, Andreas and Schmiedel, Alexander and Pascher, Torbj{\"o}rn and Lambert, Christoph and Schubert, Ulrich S. and Dietzek, Benjamin},
  title     = {Energy transfer and formation of long-lived \(^3\)MLCT states in multimetallic complexes with extended highly conjugated bis-terpyridyl ligands},
  series = {Physical Chemistry Chemical Physics},
  volume    = {18},
  journal   = {Physical Chemistry Chemical Physics},
  number    = {4},
  doi       = {10.1039/c5cp04447b},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-191041},
  pages     = {2350-2360},
  year      = {2016},
  abstract  = {Multimetallic complexes with extended and highly conjugated bis-2,2':6',2''-terpyridyl bridging ligands, which present building blocks for coordination polymers, are investigated with respect to their ability to act as light-harvesting antennae. The investigated species combine Ru(II)- with Os(II)- and Fe(II)-terpyridyl chromophores, the latter acting as energy sinks. Due to the extended conjugated system the ligands are able to prolong the lifetime of the \(^3\)MLCT states compared to unsubstituted terpyridyl species by delocalization and energetic stabilization of the \(^3\)MLCT states. This concept is applied for the first time to Fe(II) terpyridyl species and results in an exceptionally long lifetime of 23 ps for the Fe(II) \(^3\)MLCT state. While partial energy (>80\%) transfer is observed between the Ru(II) and Fe(II) centers with a time-constant of 15 ps, excitation energy is transferred completely from the Ru(II) to the Os(II) center within the first 200 fs after excitation.},
  language  = {en}
}
@article{WuRoldaoRauchetal.2022,
  author    = {Wu, Zhu and Roldao, Juan Carlos and Rauch, Florian and Friedrich, Alexandra and Ferger, Matthias and W{\"u}rthner, Frank and Gierschner, Johannes and Marder, Todd B.},
  title     = {Pure Boric Acid Does Not Show Room-Temperature Phosphorescence (RTP)},
  series = {Angewandte Chemie},
  volume    = {61},
  journal   = {Angewandte Chemie},
  number    = {15},
  doi       = {10.1002/anie.202200599},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318308},
  year      = {2022},
  abstract  = {Boric acid (BA) has been used as a transparent glass matrix for optical materials for over 100 years. However, recently, apparent room-temperature phosphorescence (RTP) from BA (crystalline and powder states) was reported (Zheng et al., Angew. Chem. Int. Ed. 2021, 60, 9500) when irradiated at 280 nm under ambient conditions. We suspected that RTP from their BA sample was induced by an unidentified impurity. Our experimental results show that pure BA synthesized from B(OMe)\(_{3}\) does not luminesce in the solid state when irradiated at 250-400 nm, while commercial BA indeed (faintly) luminesces. Our theoretical calculations show that neither individual BA molecules nor aggregates would absorb light at >175 nm, and we observe no absorption of solid pure BA experimentally at >200 nm. Therefore, it is not possible for pure BA to be excited at >250 nm even in the solid state. Thus, pure BA does not display RTP, whereas trace impurities can induce RTP.},
  language  = {en}
}
@article{WuDinkelbachKerneretal.2022,
  author    = {Wu, Zhu and Dinkelbach, Fabian and Kerner, Florian and Friedrich, Alexandra and Ji, Lei and Stepanenko, Vladimir and W{\"u}rthner, Frank and Marian, Christel M. and Marder, Todd B.},
  title     = {Aggregation-Induced Dual Phosphorescence from (o-Bromophenyl)-Bis(2,6-Dimethylphenyl)Borane at Room Temperature},
  series = {Chemistry—A European Journal},
  volume    = {28},
  journal   = {Chemistry—A European Journal},
  number    = {30},
  doi       = {10.1002/chem.202200525},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318297},
  year      = {2022},
  abstract  = {Designing highly efficient purely organic phosphors at room temperature remains a challenge because of fast non-radiative processes and slow intersystem crossing (ISC) rates. The majority of them emit only single component phosphorescence. Herein, we have prepared 3 isomers (o, m, p-bromophenyl)-bis(2,6-dimethylphenyl)boranes. Among the 3 isomers (o-, m- and p-BrTAB) synthesized, the ortho-one is the only one which shows dual phosphorescence, with a short lifetime of 0.8 ms and a long lifetime of 234 ms in the crystalline state at room temperature. Based on theoretical calculations and crystal structure analysis of o-BrTAB, the short lifetime component is ascribed to the T\(^M_1\) state of the monomer which emits the higher energy phosphorescence. The long-lived, lower energy phosphorescence emission is attributed to the T\(^A_1\) state of an aggregate, with multiple intermolecular interactions existing in crystalline o-BrTAB inhibiting nonradiative decay and stabilizing the triplet states efficiently.},
  language  = {en}
}
@article{WortmannSalehEngelsPeyerimhoff1994,
  author    = {Wortmann-Saleh, D. and Engels, Bernd and Peyerimhoff, S. D.},
  title     = {Theoretical Study of the Reaction O(\(^3\)P) + C\(_2\)H\(_4\) and comparison with the \(^3\)CH\(_3\) + C\(_2\)H\(_4\) Reaction},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59076},
  year      = {1994},
  abstract  = {The minimum energy path for the reaction O(\(^3\)P\(_g\)) + C\(_2\)H\(_4\)(\(^1\)A\(_g\)) has been calculated by optimizing all relevant geometrical parameters along the approach of oxygen to ethene. A barrier of 4.7 kcal/mol in the \(^3\)A"( ... 9a'\(^2\)- 10a'3a") potential energy surface and an energy difference of 14.4 kcal/mol between the product and the fragments is found at the multireference-configuration interaction level. The corresponding values at the lower-level treatment CASSCF are 9 kcal/mol for the barrier and 9 kcal/mol for the depth of the potential; this shows the importance of inclusion of electron correlation. The barrier for CH\(_2\) rotation for the lowestenergy structure (asymmetric OC\(_2\)H\(_4\)) is around 5 kcal/mol. The energy gap to the first excited state \(^3\)A'( ... 9a'l0a'3a'12) is found tobe 3.6 kcal/mol in MRD-CI calculations at the ground-state minimum. Comparison with \(^3\)CH\(_2\) + C\(_2\)H\(_4\) shows that in this system the lowest-energy surface is \(^3\)A', i.e., the state which is the excited state in 0 + C\(_2\)H\(_4\). This difference in energy ordering of \(^3\)A' and \(^3\)A" states results from the fact that the p\(_x\), p\(_y\), p\(_z\) degeneracy of oxygen orbitals is lifted in \(^3\)CH\(_2\)leading to b\(_1\), b\(_2\). and a\(_1\) MOs whereby the lowest b\(_2\) (a") remains doubly occupied; as a consequence, the reaction pattem between the oxygen and \(^3\)CH\(_2\) approach is different, which is also quite apparent in the calculated charge transfer.},
  subject      = {Organische Chemie},
  language  = {en}
}
@article{WolterAizezersFenneletal.2012,
  author    = {Wolter, Steffen and Aizezers, Janis and Fennel, Franziska and Seidel, Marcus and W{\"u}rthner, Frank and K{\"u}hn, Oliver and Lochbrunner, Stefan},
  title     = {Size-dependent exciton dynamics in one-dimensional perylene bisimide aggregates},
  series = {New Journal of Physics},
  volume    = {14},
  journal   = {New Journal of Physics},
  number    = {105027},
  doi       = {10.1088/1367-2630/14/10/105027},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-135190},
  year      = {2012},
  abstract  = {The size-dependent exciton dynamics of one-dimensional aggregates of substituted perylene bisimides are studied by ultrafast transient absorption spectroscopy and kinetic Monte-Carlo simulations as a function of the excitation density and the temperature in the range of 25-90 degrees C. For low temperatures, the aggregates can be treated as infinite chains and the dynamics is dominated by diffusion-driven exciton-exciton annihilation. With increasing temperature the aggregates dissociate into small fragments consisting of very few monomers. This scenario is also supported by the time-dependent anisotropy deduced from polarization-dependent experiments.},
  language  = {en}
}
@phdthesis{Wolf2021,
  author    = {Wolf, Natalia},
  title     = {Synthese multifunktionaler Farbstoffe und Linker zur Visualisierung biologischer Strukturen},
  doi       = {10.25972/OPUS-20531},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-205312},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Durch stetige Entwicklung der Mikroskopiemethoden in den letzten Jahrzehnten ist es nun m{\"o}glich Strukturen und Abl{\"a}ufe in biologischen Systemen detaillierter darzustellen als mit der von Abbe entdeckten maximalen Aufl{\"o}sungsgrenze. Oft werden dabei Fluoreszenzmarker benutzt, welche die unsichtbare Welt der Mikrobiologie und deren biochemische Prozesse illuminieren. Diese werden entweder durch Expression, wie z.B. das gr{\"u}n fluoreszierende Protein (GFP), in das zu untersuchende Objekt eingebracht oder durch klassische Markierungsmethoden mithilfe von fluoreszierenden Immunkonjugaten installiert. Jedoch gewinnt eine alternative Strategie, die von der interdisziplin{\"a}ren Zusammenarbeit zwischen Chemikern, Physikern und Biologen profitiert, immer mehr an Bedeutung - die bioorthogonale Click-Chemie. Sie erm{\"o}glicht eine effiziente Fluoreszenzmarkierung der biologischen Strukturen unter minimalem Eingriff in die Abl{\"a}ufe der Zelle. Dazu m{\"u}ssen allerdings sowohl Farbstoffe als auch die biologisch aktiven Substanzen chemisch modifiziert werden, da nur dadurch die Bioorthogonalit{\"a}t gew{\"a}hrleistet werden kann. Mittlerweile existiert eine breite Palette an fluoreszierenden Farbstoffen, die das komplette sichtbare Spektrum abdecken und sich f{\"u}r diverse Mikroskopiemethoden eignen. Allerdings gibt es zwei Farbstoffklassen, die sich aus der gesamten F{\"u}lle abheben und sich f{\"u}r hochaufl{\"o}sende bildgebende Experimente auf Einzelmolek{\"u}lebene eignen. Zum einen ist es die Farbstofffamilie der Cyanine und insbesondere der wasserl{\"o}slichen Pentamethincyanine, die reversibel und kontrolliert zum Photoschalten animiert werden k{\"o}nnen und in der stochastisch optischen Rekonstruktionsmikroskopie Anwendung finden. Zum anderen ist es die Gruppe, der Rhodamine und Fluoresceine, die zu Xanthenfarbstoffen geh{\"o}ren und sich durch gute photophysikalische Eigenschaften auszeichnen. Trotz der Beliebtheit stellt ihre Darstellung immer noch eine Herausforderung dar und limitiert deren Einsatz. Deshalb war es notwendig im Rahmen der vorliegenden Arbeit M{\"o}glichkeiten zur Syntheseoptimierung beider Farbstoffklassen zu finden, damit diese im Folgenden weiterentwickelt und an die biologische Fragestellung angepasst werden k{\"o}nnen. Die Arbeit unterteilt sich deshalb in Relation an die oben genannten Farbstoffklassen in zwei Bereiche. Im ersten Teil wurden Projekte basierend auf den wasserl{\"o}slichen Pentamethincyaninen behandelt. Im zweiten Teil besch{\"a}ftigte sich die Arbeit mit Projekten, die auf Xanthen-Farbstoffen aufbauen.},
  subject      = {Farbstoff},
  language  = {de}
}
@phdthesis{Wohlfarth2002,
  author    = {Wohlfarth, Michael},
  title     = {Die Aufkl{\"a}rung der Biogenese strukturell ungew{\"o}hnlicher Alkaloide aus Triphyophyllum (Dioncophyllaceae) und Antidesma (Euphorbiaceae) und Entwicklung und Einsatz der "Triade" zur phytochemischen Online-Analytik: HPLC-MS/MS, HPLC-NMR und HPLC-CD},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-298},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2002},
  abstract  = {Tropische Pflanzen gelten als wertvolle Quellen biologisch aktiver Sekund{\"a}rmetaboliten. Im Rahmen dieser Dissertation wurden mehrere tropische Arten unter verschiedenen naturstoffchemischen Gesichtspunkten bearbeitet. Einen Schwerpunkt bildeten die tropischen Lianenfamilien der Ancistrocladaceen und Dioncophyllaceen. Diese produzieren die Naphthylisochinolin-Alkaloide, Biarylnaturstoffe mit faszinierenden strukturellen und pharmakologischen Eigenschaften. In dieser Arbeit wurde die Biogenese der Naphthylisochinolinalkaloide am Beispiel von Dioncophyllin A aus Triphyophyllum peltatum mittels Verf{\"u}tterung von [13C2]-Acetat untersucht. 13C-NMR-Experimente offenbarten einen Einbau von diskreten [13C2]-Einheiten im ganzen Kohlenstoffger{\"u}st. Damit sind die Naphthylisochinolin-Alkaloide die ersten bekannten Tetrahydroisochinolin-Alkaloide mit einem polyketidischen Ursprung. Als weiteres Forschungsobjekt diente das strukturell und biogenetisch hochinteressante Pyridon-Alkaloid Antidesmon aus Antidesma membranaceum. Untersuchungen zur Biogenese f{\"u}hrten zur Entdeckung eines neuen Biogeneseweges. Antidesmon wird ebenfalls aus einer Polyketid-Vorstufe gebildet. {\"U}berraschenderweise dient Glycin als Vorstufe f{\"u}r einen C2N-Baustein. Im analytischen Bereich standen der Einsatz und die methodische Verbesserung der online-"Triade" HPLC-MS/MS, HPLC-NMR und HPLC-CD im Vordergrund. Diese neuen Techniken dienten im Anschluß der phytochemischen Untersuchung verschiedener Pflanzenextrakte. Nach der erstmaligen online-Analyse von Ancistrocladus griffithii wurden drei neue Alkaloide, Ancistrogriffin A, B und C, detektiert und strukturell aufgekl{\"a}rt. Weiterhin wurde das erste dimere Naphthylisochinolin-Alkaloid aus einer asiatischen Ancistrocladus-Spezies, Ancistrogriffithin A, detektiert und vor seiner Isolierung strukturell mit online-Methoden aufgekl{\"a}rt.},
  subject      = {Triphyophyllum peltatum},
  language  = {de}
}
@phdthesis{Witterauf2015,
  author    = {Witterauf, Franziska},
  title     = {Ein neues Pro-Prodrug-Konzept zur Synthese antitumoraler Wirkstoffe sowie N,C- und C,C-verkn{\"u}pfter dimerer und trimerer Porphyrine},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-124922},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2015},
  abstract  = {Seit Anfang des 20. Jahrhunderts ist die Krankheit Krebs die zweith{\"a}ufigste Todesursache. Die immer besser werdende Diagnostik zur Fr{\"u}herkennung von Krebserkrankungen bringt zudem mit sich, dass eine steigende Anzahl an Krankheitsf{\"a}llen bekannt wird; gleichzeitig hat eine sichere Erkennung im Fr{\"u}hstadium einen hohen Stellenwert, da nur so fr{\"u}hzeitig therapeutische Maßnahmen ergriffen werden k{\"o}nnen. Obwohl zur kurativen oder zur palliativen Behandlung schon lange viele ausgereifte Therapiemethoden und -konzepte erfolgreich angewendet werden, sind bis heute viele Krebserkrankungen noch immer unheilbar und es gibt bislang in vielen F{\"a}llen noch keine potenten Arzneistoffe f{\"u}r eine wirkungsvolle Therapie. Die Suche nach neuen Wirkstoffen ist daher ein Schwerpunkt aktueller Forschung. Auch unsere Arbeitsgruppe besch{\"a}ftigt sich mit dieser Thematik und hat in Zusammenarbeit mit dem Universit{\"a}tsklinikum W{\"u}rzburg ein neuartiges Pro-Prodrug- Konzept f{\"u}r antitumorale Wirkstoffe entwickelt. Daher war es ein Ziel der vorliegenden Arbeit, aufbauend auf medizinischen und biochemischen Vorarbeiten, eine Leitstruktur f{\"u}r antitumorale Wirkstoffe zu erarbeiten, die auf dem hier vorgestellten Pro-Prodrug-Konzept basiert, und eine entsprechende Syntheseroute zur Gewinnung erster Fluoreszenz-markierter Pro-Prodrug-Modellverbindungen zu etablieren. Eine andere interessante Substanzklasse, die nicht nur aufgrund ihrer Wirkeigenschaften als Photosensibilisatoren in der photodynamischen Therapie bereits Gegenstand intensiver Forschung ist, sondern auch in weiteren Bereichen der angewandten Chemie, wie beispielsweise in der metallorganischen Katalyse oder in den Materialwissenschaften Anwendung findet, sind die Porphyrine. Neben den achiralen Vertretern finden die chiralen Porphyrinoide Anwendung in der chiralen Erkennung oder in der asymmetrischen Synthese. Auf dem Gebiet der Porphyrine war das Ziel der vorliegenden Arbeit die gezielte Synthese N,C- und C,C-verkn{\"u}pfter dimerer und trimerer Porphyrine, einhergehend mit intensiven Untersuchungen der Reaktivit{\"a}t der verwendeten Bausteine, des Reaktionsmechanismus und der hohen Regioselektivit{\"a}t. Da einige der synthetisierten Substanzen Axial- oder Helikalchiralit{\"a}t aufweisen, wurden diese durch HPLC-CD eingehend auf ihre chiroptischen Eigenschaften untersucht.},
  subject      = {Porphyrine},
  language  = {de}
}
@article{WissingKauppBoersmaetal.1994,
  author    = {Wissing, Elmo and Kaupp, Martin and Boersma, Jaap and Spek, Anthony L. and Koten, Gerard van},
  title     = {Alkylation Reactions of Dialkylzinc Compounds with 1,4- Diaza- 1,3-butadienes: Cationic and radical Anionic Organozinc Intermediates. Molecular Structure of the Cationic Organozinc Species [MeZn(t-BuN=CHCH=N-t-Bu)]O\(_3\)SCF\(_3\) and Me\(_2\)Zn(bpy)(bpy = 2,2' -Bipyridine)},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-60008},
  year      = {1994},
  abstract  = {No abstract available},
  subject      = {Anorganische Chemie},
  language  = {en}
}
@phdthesis{Wissel2004,
  author    = {Wissel, Kathrin},
  title     = {Untersuchungen zur Typ-, Regio- und Stereoselektivit{\"a}t bei Norrish-Typ-II-Yang-Cyclisierungen und Di-Pi-Methan-Umlagerungen in organisierten Medien},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-8935},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {Gegenstand der vorliegenden Arbeit ist die Untersuchung der Typ-, Regio- und Stereoselektivit{\"a}t photochemischer Reaktionen in organisierten Medien. Es wird anhand ausgew{\"a}hlter Beispiele gezeigt, daß bei der Festk{\"o}rperbestrahlung von kronenetherverkn{\"u}pften Substraten sowie von photoaktiven Verbindungen, die mit Polyaminos{\"a}uren, Cyclodextrinen oder Zeolithen assoziiert sind, h{\"a}ufig andere Produkte gebildet und h{\"o}here Selektivit{\"a}ten erreicht werden als in L{\"o}sung.},
  subject      = {Photochemische Reaktion},
  language  = {de}
}
@article{WildervanckHechtNowakKrol2022,
  author    = {Wildervanck, Martijn J. and Hecht, Reinhard and Nowak-Kr{\´o}l, Agnieszka},
  title     = {Synthesis and strong solvatochromism of push-pull thienylthiazole boron complexes},
  series = {Molecules},
  volume    = {27},
  journal   = {Molecules},
  number    = {17},
  issn      = {1420-3049},
  doi       = {10.3390/molecules27175510},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-286186},
  year      = {2022},
  abstract  = {The solvatochromic behavior of two donor-π bridge-acceptor (D-π-A) compounds based on the 2-(3-boryl-2-thienyl)thiazole π-linker and indandione acceptor moiety are investigated. DFT/TD-DFT calculations were performed in combination with steady-state absorption and emission measurements, along with electrochemical studies, to elucidate the effect of two different strongly electron-donating hydrazonyl units on the solvatochromic and fluorescence behavior of these compounds. The Lippert-Mataga equation was used to estimate the change in dipole moments (Δµ) between ground and excited states based on the measured spectroscopic properties in solvents of varying polarity with the data being supported by theoretical studies. The two asymmetrical D-π-A molecules feature strong solvatochromic shifts in fluorescence of up to ~4300 cm\(^{-1}\) and a concomitant change of the emission color from yellow to red. These changes were accompanied by an increase in Stokes shift to reach values as large as ~5700-5800 cm\(^{-1}\). Quantum yields of ca. 0.75 could be observed for the N,N-dimethylhydrazonyl derivative in nonpolar solvents, which gradually decreased along with increasing solvent polarity, as opposed to the consistently reduced values obtained for the N,N-diphenylhydrazonyl derivative of up to ca. 0.20 in nonpolar solvents. These two push-pull molecules are contrasted with a structurally similar acceptor-π bridge-acceptor (A-π-A) compound.},
  language  = {en}
}
@article{WieseDennstaedtHollmannetal.2021,
  author    = {Wiese, Teresa and Dennst{\"a}dt, Fabio and Hollmann, Claudia and Stonawski, Saskia and Wurst, Catherina and Fink, Julian and Gorte, Erika and Mandasari, Putri and Domschke, Katharina and Hommers, Leif and Vanhove, Bernard and Schumacher, Fabian and Kleuser, Burkard and Seibel, J{\"u}rgen and Rohr, Jan and Buttmann, Mathias and Menke, Andreas and Schneider-Schaulies, J{\"u}rgen and Beyersdorf, Niklas},
  title     = {Inhibition of acid sphingomyelinase increases regulatory T cells in humans},
  series = {Brain Communications},
  volume    = {3},
  journal   = {Brain Communications},
  number    = {2},
  doi       = {10.1093/braincomms/fcab020},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-259868},
  year      = {2021},
  abstract  = {Genetic deficiency for acid sphingomyelinase or its pharmacological inhibition has been shown to increase Foxp3\(^+\) regulatory T-cell frequencies among CD4\(^+\) T cells in mice. We now investigated whether pharmacological targeting of the acid sphingomyelinase, which catalyzes the cleavage of sphingomyelin to ceramide and phosphorylcholine, also allows to manipulate relative CD4\(^+\) Foxp3\(^+\) regulatory T-cell frequencies in humans. Pharmacological acid sphingomyelinase inhibition with antidepressants like sertraline, but not those without an inhibitory effect on acid sphingomyelinase activity like citalopram, increased the frequency of Foxp3\(^+\) regulatory T cell among human CD4\(^+\) T cells in vitro. In an observational prospective clinical study with patients suffering from major depression, we observed that acid sphingomyelinase-inhibiting antidepressants induced a stronger relative increase in the frequency of CD4\(^+\) Foxp3\(^+\) regulatory T cells in peripheral blood than acid sphingomyelinase-non- or weakly inhibiting antidepressants. This was particularly true for CD45RA\(^-\) CD25\(^{high}\) effector CD4\(^+\) Foxp3\(^+\) regulatory T cells. Mechanistically, our data indicate that the positive effect of acid sphingomyelinase inhibition on CD4\(^+\) Foxp3\(^+\) regulatory T cells required CD28 co-stimulation, suggesting that enhanced CD28 co-stimulation was the driver of the observed increase in the frequency of Foxp3+ regulatory T cells among human CD4\(^+\) T cells. In summary, the widely induced pharmacological inhibition of acid sphingomyelinase activity in patients leads to an increase in Foxp3+ regulatory T-cell frequencies among CD4\(^+\) T cells in humans both in vivo and in vitro.},
  language  = {en}
}
@phdthesis{Wich2009,
  author    = {Wich, Peter Richard},
  title     = {Multifunctional Oligopeptides as an Artificial Toolkit for Molecular Recognition Events},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38108},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2009},
  abstract  = {The main focus of this thesis was the synthesis and analysis of multifunctional oligopeptides. The study of their non-covalent interactions with various counterparts revealed interesting new results, leading to both methodological and application related progress. The first project of this thesis concentrated on the in-depth analysis of the peptide receptor CBS-Lys-Lys-Phe-NH2 to acquire a better understanding of its binding mode upon complexation with a substrate. In this context it was possible to develop—in cooperation with the group of Prof. Sebastian Schl{\"u}cker—a direct and label free spectroscopic detection of immobilized compounds which are often found in combinatorial libraries. This new screening method utilizes the advantages of the surface enhanced Raman spectroscopy and allowed for the first time a surface mapping of a single polystyrene bead for the identification of peptides in femtomolar concentrations. Hence, this method allows a very fast and sensitive detection of resin bound compounds. The development of this promising new approach set the starting point for future experiments to enable on-bead library screenings and to investigate the complex formation of immobilized compounds. After the comprehensive analysis of the basic structural features of small peptide receptors in the first part of this thesis, the second big block focused on its in vitro evaluation using biological relevant targets. Therefore, several different modifications of the initial peptide structures were synthesized. These modifications provided a molecular toolkit for the tailor made synthesis of structures individually designed for the respective target. The first tests addressed the interaction with Alzheimer's related amyloid fibrils. During these experiments, the successful SPPS syntheses of tri- and tetravalent systems were achieved. The comparison of the multivalent form with the corresponding monovalent version was then under special investigations. These concentrated mainly on the interaction with various bacteria strains, as well as with different parasites. To localize the compounds within the organisms, the synthesis of fluorescence labelled versions was achieved. In addition, several compounds were tested by the Institute for Molecular Infection Biology of the University of W{\"u}rzburg for their antibacterial activity. This thorough evaluation of the biological activity generated precious information about the influence of small structural changes in the peptide receptors. Especially the distinct influence of the multivalency effect and the acquired synthetic skills led to the development of an advanced non-covalent recognition event, as described in the final project of this thesis. The last part of this thesis discussed the development of a novel inhibitor for the serine protease beta-tryptase based on a tailor-made surface recognition event. It was possible to study and analyze the complex interaction with the unique structure of tryptase, that features a tetrameric frame and four catalytic cleavage sites buried deep inside of the hollow structure. However, the point of attack were not the four binding pockets, as mostly described in the literature, but rather the acidic areas around the cleavage sites and at the two circular openings. These should attract peptides with basic residues, which then can block the accessibility to the active sites. A combinatorial library of 216 tetravalent peptide compounds was synthesized to find the best structural composition for the non-covalent inhibition of beta-tryptase. For the screening of the library a new on-bead assay was applied. With this method a simultaneous readout of the total inhibition of all library members was possible, thus allowing a fast and direct investigation of the still resin bound inhibitors. Several additional experiments in solution unveiled the kinetics of the inhibition process. In conclusion, both mono- and multivalent inhibitors interact in a non-destructive and reversible way with the tryptase.},
  subject      = {Peptidsynthese},
  language  = {en}
}
@article{WenNowakKrolNagleretal.2019,
  author    = {Wen, Xinbo and Nowak-Kr{\´o}l, Agnieszka and Nagler, Oliver and Kraus, Felix and Zhu, Na and Zheng, Nan and M{\"u}ller, Matthias and Schmidt, David and Xie, Zengqi and W{\"u}rthner, Frank},
  title     = {Tetrahydroxy-perylene bisimide embedded in zinc oxide thin film as electron transporting layer for high performance non-fullerene organic solar cells},
  series = {Angewandte Chemie International Edition},
  volume    = {58},
  journal   = {Angewandte Chemie International Edition},
  number    = {37},
  doi       = {10.1002/anie.201907467},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204723},
  pages     = {13051-13055},
  year      = {2019},
  abstract  = {By introduction of four hydroxy (HO) groups into the two perylene bisimide (PBI) bay areas, new HO-PBI ligands were obtained which upon deprotonation can complex ZnII ions and photosensitize semiconductive zinc oxide thin films. Such coordination is beneficial for dispersing PBI photosensitizer molecules evenly into metal oxide films to fabricate organic-inorganic hybrid interlayers for organic solar cells. Supported by the photoconductive effect of the ZnO:HO-PBI hybrid interlayers, improved electron collection and transportation is achieved in fullerene and non-fullerene polymer solar cell devices, leading to remarkable power conversion efficiencies of up to 15.95 \% for a non-fullerene based organic solar cell.},
  language  = {en}
}
@phdthesis{Weissenstein2019,
  author    = {Weißenstein, Annike},
  title     = {Optische Chemosensoren aus Naphthalin- und Perylenbisimid-Farbstoffen},
  doi       = {10.25972/OPUS-16199},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-161990},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {Die Liste der interessanten nachzuweisenden Analyte ist lang. Deswegen besteht ein großer Bedarf zur Entwicklung neuer fluoreszierender und kolorimetrischer Chemosensoren. Ziel der vorliegenden Arbeit war daher die Synthese und Charakterisierung neuer optischer bzw. fluoreszierender und kolorimetrischer Chemosensoren mit dem Fokus auf die beiden Substanzklassen der Naphthalinbisimide und Perylenbisimide. Der erste Arbeitsschwerpunkt befasste sich mit wasserl{\"o}slichen Naphthalinbisimiden und ist in drei Unterkapitel aufgeteilt (Kapitel III - 1.1.-1.3., Abbildung 79). Im ersten Unterkapitel (Kapitel III - 1.1.) wurden die Synthesen und optischen Eigenschaften der am Kern Amino-substituierten NBIs 60a-h, mit Dicarbons{\"a}ureresten in Imid-Position und 61a-h, mit 2-Dimethylaminoethyl-Gruppen, in polaren L{\"o}sungsmitteln beschrieben. Die systematische Anbringung verschiedener Amino-Substituenten mit steigendem elektronenziehendem Charakter der Aminoreste diente der mechanistischen Aufkl{\"a}rung der optischen Eigenschaften. Eine vollst{\"a}ndige Untersuchung der optischen Eigenschaften erfolgte in w{\"a}ssriger Pufferl{\"o}sung bei pH 2.1 sowie in Methanol und Acetonitril. Der Einfluss der Imid-Substituenten auf die optischen Eigenschaften war wie zu erwarten gering. Die verschiedenen Kern-Substituenten verursachten hingegen eine hypsochrome Verschiebung der Absorptions- und Fluoreszenzmaxima mit steigendem elektronenziehendem Charakter der an der Aminogruppe angebrachten Reste. Ein unerwarteter Trend konnte im Fall der Fluoreszenzquantenausbeute beobachtet werden. In den protischen L{\"o}sungsmitteln Wasser und Methanol wurde eine lineare Abh{\"a}ngigkeit gegen{\"u}ber der Hammett-σmeta-Konstante ermittelt. Mit steigendem elektronenziehendem Charakter der Kern-Amino-Substituenten erfuhr die Quantenausbeute einen Anstieg auf bis zu 39\% in Wasser f{\"u}r NBI 60h, 61h und 45\% in Methanol f{\"u}r 60h. Die Tatsache, dass in Acetonitril keine solche Abh{\"a}ngigkeit gegen{\"u}ber der Hammett-Konstante beobachtet werden konnte legte eine intermolekulare Wasserstoffbr{\"u}cken-Bindung im angeregten Zustand als konkurrierenden Prozess zur Fluoreszenz nahe. Dieser Prozess tritt zwischen den L{\"o}sungsmittel-Molek{\"u}len und der Akzeptorgruppe (Carbonyl-Sauerstoff) der NBIs, welcher einen strahlungslosen Relaxationsprozess bzw. Fluoreszenzl{\"o}schung zur Folge hat, auf. Der Einfluss dieses Prozesses l{\"a}sst sich durch die St{\"a}rke des elektronenziehenden Amino-Substituentens steuern. Die NBIs 60a-h zeigten zudem in potentiometrischen Titrationen in Wasser eine pH-Unabh{\"a}ngigkeit der optischen Eigenschaften bez{\"u}glich des Imid-Substituentens. Dies macht die NBIs mit Dicarbons{\"a}ureresten f{\"u}r die Anwendung in biologischen Systemen im neutralen pH-Milieu oder als chemische Sensoren besonders geeignet. Aufgrund dieser interessanten Befunde wurde im zweiten Unterkapitel (Kapitel III - 1.2.) das dihalogenierte NBI 58 hinsichtlich der Sensoreigenschaften gegen{\"u}ber prim{\"a}ren, sekund{\"a}ren und terti{\"a}ren Amin- bzw. Diamindampf sowie zur Frischekontrolle von Fleisch untersucht. Die Absorptions- und Fluoreszenz-spektroskopische Untersuchung des D{\"u}nnschichtfilms von NBI 58 zeigte die erfolgreiche, selektive Detektion von prim{\"a}ren Aminen und Diaminen bzw. biogenen Aminen. Zum einen konnte mit bloßen Auge ein Farbumschlag von gelb nach rot und zum anderen {\"A}nderungen in den Absorptionsspektren wie die Entstehung einer neuen bathochrom verschobenen Bande im D{\"u}nnschichtfilm beobachtet werden. Die Erh{\"o}hung der Fluoreszenz wie auch die NMR-spektroskopische Untersuchung konnte hingegen ausschließlich in L{\"o}sung detektiert werden. Hiermit konnte die kovalente Wechselwirkung der Amin-Molek{\"u}le mit dem NBI 58 nachgewiesen werden. Trotz der erfolgreichen Detektion biogener Amind{\"a}mpfe erwies sich NBI 58 aufgrund der zu geringen Reaktivit{\"a}t als ungeeigneter chemischer Sensor zur Frischekontrolle von Fleisch. Das dritte und letzte Unterkapitel (Kapitel III - 1.3.) dieses Abschnittes bestand in der Synthese monochlor-monoamino-substituierter NBIs am Kern (65a,b und 66) und der Wechselwirkungen dieser Farbstoffe mit DNS/RNS. Die NBIs 65a,b und 66 wiesen in der Imidstellung 3-Trimethylammoniumpropyl auf, um die Wasserl{\"o}slichkeit zu gew{\"a}hrleisten und die elektrostatische Wechselwirkung mit dem negativ geladenen Phosphatr{\"u}ckgrad der DNS/RNS zu bewirken. Am Kern wurden die Aminos{\"a}uren (S)-2,3-Diaminopropions{\"a}ure (L-Dap) (65a) und (S)-2,6-Diaminohexans{\"a}ure (L-Lys) (65b) sowie 2-Trimethylammoniumethylamin (66) eingef{\"u}gt. Die Untersuchungen mit Hilfe von thermischen Denaturierungsstudien zeigten mit allen NBIs eine deutliche Schmelzpunkterh{\"o}hung der DNS/RNS (ΔTm-Werte zwischen 17 und 35 °C), was die Bildung von NBI/Polynukleotid-Komplexen nahelegte. Diese Komplex-Bildung konnte erneut aufgrund enormer Fluoreszenzl{\"o}schung in fluorimetrischen Titrationsstudien best{\"a}tigt werden. Hier wurden Bindungskonstanten zwischen logK = 5.9 und 7.2 M-1 ermittelt, wobei NBI 65a und poly(dG-dC)2 der st{\"a}rksten Bindungsaffinit{\"a}t und NBI 65a und poly(dA-dT)2 der schw{\"a}chste zugeordnet werden konnte. F{\"u}r NBI 66 wurde die zweith{\"o}chste Bindungsaffinit{\"a}t zu Polynukleotid ct-DNS (logK = 7.08 M-1) beobachtet, w{\"a}hrend dieser Farbstoff sowie 65a,b nur geringe Bindungskonstanten mit dem Polynukleotid polyA-polyU zeigten. Mit Hilfe der CD-spektroskopischen Messungen wurde der Bindungsmodus und die Unterschiede in den Bindungseigenschaften der Farbstoffe mit DNS/RNS ermittelt. Der Großteil aller NBI-Verbindungen interkalierte in einer parallelen Anordnung zwischen die Basenpaare der Polynukleotide. F{\"u}r NBI 65a und poly(dG-dC)2 ließ sich jedoch eine perpendikulare Anordnung zu den Basenpaaren beobachten. ITC-Titrationsstudien komplettierten letztendlich die Untersuchungen zwischen NBIs und Polynukleotiden. Neben Interkalation als Bindungsmodus konnte zus{\"a}tzlich aufgrund der relativ hohen Entropiewerte eine Wechselwirkung zwischen den Substituenten am Kern und den Phosphatgruppen in der kleinen Furche festgestellt werden. Zusammengefasst sind die sterischen Hinderungen der Amino-Substituenten und die Furcheneigenschaften von ds-DNS/RNS entscheidend. Der zweite Arbeitsschwerpunkt ist ebenfalls in drei Unterkapitel (Kapitel III - 2.1.-2.3.) aufgeteilt und befasste sich mit der Synthese und den Sensoreigenschaften kernfunktionalisierter Perylenbisimide (Abbildung 80). Im ersten Abschnitt (Kapitel III - 2.1) wurde die Synthese und die optischen Eigenschaften in L{\"o}sung der am Kern einfach und zweifach Kronenether-funktionalisierten PBIs 77a,b und 71a,b untersucht. In Imidstellung waren alle PBIs mit 2-Trimethylammoniumethyl-Resten funktionalisiert, um eine L{\"o}slichkeit in polaren L{\"o}sungsmitteln zu gew{\"a}hrleisten. Die Buchtpositionen wurden jeweils ein- bzw. zweifach mit den Kronenether-Einheiten 2-Hydroxymethyl-15-Krone-5 und 2-Hydroxymethyl-18-Krone-6 substituiert. Die anschließende Untersuchung der optischen Eigenschaften der PBIs zeigten bei einer Konzentration von 10-5 M in Acetonitril den monomeren Zustand und in Wasser die Ausbildung von H-Aggregaten. Die Fluoreszenzquantenausbeuten erfuhren in Acetonitril mit steigender Kronenether-Ringgr{\"o}ße eine Zunahme von 73\% auf 81\% f{\"u}r die PBIs 71a,b und eine vernachl{\"a}ssigbare geringe Zunahme von 49\% auf 51\% f{\"u}r die PBIs 77a,b. Die Abnahme der Quantenausbeute vom zweifach funktionalisierten zum einfach funktionalisierten PBI um ca. 30\% ließ sich durch die st{\"a}rker ausgepr{\"a}gten strahlungslosen Relaxationsprozesse dieses flexibleren Molek{\"u}ls im angeregten Zustand erkl{\"a}ren. Im zweiten Unterkapitel (Kapitel III - 2.2.) wurden die Selbstassemblierungseigenschaften der synthetisierten PBIs 71a,b und 77a,b in Gegenwart verschiedener Metallionen (Na+, K+, Rb+, Mg2+, Ca2+ und Ba2+) untersucht. Hier konnte eine Abh{\"a}ngigkeit von der Gr{\"o}ße des Kronenether-Rezeptors sowie von der Art der Metallionen gezeigt werden. Die Absorptions- und Fluoreszenz-spektroskopischen Studien der zweifach funktionalisierten PBIs 71a und 71b bei einer PBI-Konzentration von c = 10-5 M zeigten ausschließlich f{\"u}r das 15-Krone-5-Derivat 71a und Ba2+ eine erfolgreiche Ausbildung von PBI-Stapeln mit H-artiger exzitonischer Kopplung. Aufgrund dessen erfuhr das Absorptionsmaximum eine stetige Abnahme einhergehend mit einer hypsochromen Verschiebung und die Fluoreszenz eine vollst{\"a}ndige L{\"o}schung. Zudem konnte eine 1:1-St{\"o}chiometrie der PBI-Stapeln ermittelt werden. Die Anpassung der spektroskopischen {\"A}nderungen an die Hill-Gleichung best{\"a}tigte letztendlich die Bildung eines [2+2]-Sandwich- bzw. Dimer-Komplexes in einem positiv kooperativen Bindungsprozess, in dem mittels ITC eine enorme Stabilisierung der Ba2+-Komplexierung aufgrund der π-π-Wechselwirkung zwischen zwei PBI-Molek{\"u}len, beobachtet wurde. Die Durchf{\"u}hrung der Titrationsexperimente bei einer h{\"o}heren PBI-Konzentration (c = 10-4 M) zusammen mit DOSY-Experimenten versicherten auch in diesem Fall die Formation diskreter Dimerkomplexe. Das einfach funktionalisierte PBI 77a zeigte in der Anwesenheit von Ba2+ {\"a}hnliche optische {\"A}nderungen. Die nachfolgenden Untersuchungen bzw. Interpretationen best{\"a}tigten die Bildung eines [1+2]-Dimerkomplexes mit H-artiger exzitonischer Kopplung, welches aufgrund der flexibleren Komplexstruktur keine Stabilisierung der Ba2+-Komplexierung erfuhr. Neben der Metallionen-Komplexierung war PBI 71b auch in der Lage, in einer 1:2-St{\"o}chiometrie aromatische Aminos{\"a}uren und Dipeptide zu erkennen (Kapitel III - 2.3.), da hier sowohl die Ammoniumgruppen der Aminos{\"a}uren und Dipeptide mit den Kronenethereinheiten als auch die aromatischen Einheiten mit dem PBI-Kern wechselwirken k{\"o}nnen. Fluoreszenz-Titrationsexperimente zeigten, dass die Aminos{\"a}uren L-Tryptophan und L-Tyrosin, welche elektronenreiche aromatische Gruppen aufweisen, und Dipeptide, die diese Aminos{\"a}uren enthalten, die Fluoreszenz des PBIs stark l{\"o}schen. Die Bindungskonstanten der Wirt-Gast-Komplexierung in Acetonitril konnten aufgrund eines statischen L{\"o}schungsprozesses aus den Fluoreszenztitrationsdaten bestimmt werden. Hier wurde beobachtet, dass die Bindungsst{\"a}rke von der Gr{\"o}ße und der elektronischen Natur der aromatischen Einheiten sowie von dem Abstand zwischen der Ammoniumgruppe und der aromatischen Einheit in Aminos{\"a}uren und Dipeptiden abh{\"a}ngt. Die st{\"a}rkste Bindung konnte zwischen Ala-Trp und PBI 71b mit einem Wert von 3.1 x 105 M-1 beobachtet werden. NMR-Studien best{\"a}tigten ebenfalls die Wirt-Gast-Komplexierung, ließen jedoch offen, ob es zu der Bildung von zwei Diastereomeren aufgrund der eingeschr{\"a}nkten Umwandlung der Atrop-Enantiomere (P und M) des PBI 71b kommt oder zu der Bildung von vier Diastereomeren infolge des Chiralit{\"a}tszentrums im Kronenether. Zusammenfassend wurden in dieser Arbeit Naphthalinbisimde und Perylenbisimide hinsichtlich ihrer Eignung als optische Chemosensoren untersucht. Die NBI-Derivate agierten aufgrund ihrer interessanten optischen Eigenschaften als chemische Sensoren selektiv f{\"u}r prim{\"a}ren Amindampf und f{\"u}r die DNS/RNS-Wechselwirkung. Im Fall der PBI-Verbindungen wurden hervorragende fluorometrische Chemosensoren ermittelt, die Ba2+-Ionen und elektronenreiche aromatische Aminos{\"a}uren und Dipeptide in einer deutlichen Fluoreszenzl{\"o}schung detektieren k{\"o}nnen.},
  subject      = {Chemischer Sensor},
  language  = {de}
}
@article{WehnerRoehrStepanenkoetal.2020,
  author    = {Wehner, Marius and R{\"o}hr, Merle Insa Silja and Stepanenko, Vladimir and W{\"u}rthner, Frank},
  title     = {Control of self-assembly pathways toward conglomerate and racemic supramolecular polymers},
  series = {Nature Communications},
  volume    = {11},
  journal   = {Nature Communications},
  doi       = {10.1038/s41467-020-19189-8},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230580},
  year      = {2020},
  abstract  = {Homo- and heterochiral aggregation during crystallization of organic molecules has significance both for fundamental questions related to the origin of life as well as for the separation of homochiral compounds from their racemates in industrial processes. Herein, we analyse these phenomena at the lowest level of hierarchy - that is the self-assembly of a racemic mixture of (R,R)- and (S,S)-PBI into 1D supramolecular polymers. By a combination of UV/vis and NMR spectroscopy as well as atomic force microscopy, we demonstrate that homochiral aggregation of the racemic mixture leads to the formation of two types of supramolecular conglomerates under kinetic control, while under thermodynamic control heterochiral aggregation is preferred, affording a racemic supramolecular polymer. FT-IR spectroscopy and quantum-chemical calculations reveal unique packing arrangements and hydrogen-bonding patterns within these supramolecular polymers. Time-, concentration- and temperature-dependent UV/vis experiments provide further insights into the kinetic and thermodynamic control of the conglomerate and racemic supramolecular polymer formation. Homo- and heterochiral aggregation is a process of interest to prebiotic and chiral separation chemistry. Here, the authors analyze the self-assembly of a racemic mixture into 1D supramolecular polymers and find homochiral aggregation into conglomerates under kinetic control, while under thermodynamic control a racemic polymer is formed.},
  language  = {en}
}
@phdthesis{Wehner2021,
  author    = {Wehner, Marius},
  title     = {Supramolecular Polymorphism in Homo- and Heterochiral Supramolecular Polymerizations},
  doi       = {10.25972/OPUS-21151},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-211519},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {The aim of the first part of this thesis was to investigate (R,R)-PBI as a model system for polymorphism at its origin by a supramolecular approach. The pathway complexity of (R,R)-PBI was fine-tuned by experimental parameters such as solvent, temperature and concentration to make several supramolecular polymorphs accessible. Mechanistic and quantum chemical studies on the kinetics and thermodynamics of the supramolecular polymerization of (R,R)-PBI were conducted to shed light on the initial stages of polymorphism. The second part of this work deals with mechanistic investigations on the supramolecular polymerization of the racemic mixture of (R,R)- and (S,S)-PBI with regard to homochiral and heterochiral aggregation leading to conglomerates and a racemic supramolecular polymer, respectively.},
  subject      = {Supramolekulare Chemie},
  language  = {en}
}
@article{WehShoyamaWuerthner2023,
  author    = {Weh, Manuel and Shoyama, Kazutaka and W{\"u}rthner, Frank},
  title     = {Preferential molecular recognition of heterochiral guests within a cyclophane receptor},
  series = {Nature Communications},
  volume    = {14},
  journal   = {Nature Communications},
  doi       = {10.1038/s41467-023-35851-3},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-357750},
  year      = {2023},
  abstract  = {The discrimination of enantiomers by natural receptors is a well-established phenomenon. In contrast the number of synthetic receptors with the capability for enantioselective molecular recognition of chiral substrates is scarce and for chiral cyclophanes indicative for a preferential binding of homochiral guests. Here we introduce a cyclophane composed of two homochiral core-twisted perylene bisimide (PBI) units connected by p-xylylene spacers and demonstrate its preference for the complexation of [5]helicene of opposite helicity compared to the PBI units of the host. The pronounced enantio-differentiation of this molecular receptor for heterochiral guests can be utilized for the enrichment of the P-PBI-M-helicene-P-PBI epimeric bimolecular complex. Our experimental results are supported by DFT calculations, which reveal that the sterically demanding bay substituents attached to the PBI chromophores disturb the helical shape match of the perylene core and homochiral substrates and thereby enforce the formation of syndiotactic host-guest complex structures. Hence, the most efficient substrate binding is observed for those aromatic guests, e. g. perylene, [4]helicene, phenanthrene and biphenyl, that can easily adapt in non-planar axially chiral conformations due to their inherent conformational flexibility. In all cases the induced chirality for the guest is opposed to those of the embedding PBI units, leading to heterochiral host-guest structures.},
  language  = {en}
}
@article{WehRueheHerbertetal.2021,
  author    = {Weh, Manuel and R{\"u}he, Jessica and Herbert, Benedikt and Krause, Ana-Maria and W{\"u}rthner, Frank},
  title     = {Deracemization of Carbohelicenes by a Chiral Perylene Bisimide Cyclophane Template Catalyst},
  series = {Angewandte Chemie International Edition},
  volume    = {60},
  journal   = {Angewandte Chemie International Edition},
  number    = {28},
  doi       = {10.1002/anie.202104591},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-244787},
  pages     = {15323 -- 15327},
  year      = {2021},
  abstract  = {Deracemization describes the conversion of a racemic mixture of a chiral molecule into an enantioenriched mixture or an enantiopure compound without structural modifications. Herein, we report an inherently chiral perylene bisimide (PBI) cyclophane whose chiral pocket is capable of transforming a racemic mixture of [5]-helicene into an enantioenriched mixture with an enantiomeric excess of 66 \%. UV/Vis and fluorescence titration studies reveal this cyclophane host composed of two helically twisted PBI dyes has high binding affinities for the respective homochiral carbohelicene guests, with outstanding binding constants of up to 3.9×10\(^{10}\) m\(^{-1}\) for [4]-helicene. 2D NMR studies and single-crystal X-ray analysis demonstrate that the observed strong and enantioselective binding of homochiral carbohelicenes and the successful template-catalyzed deracemization of [5]-helicene can be explained by the enzyme-like perfect shape complementarity of the macrocyclic supramolecular host.},
  language  = {en}
}
@phdthesis{Weh2024,
  author    = {Weh, Manuel},
  title     = {Chiral Perylene Bisimide Cyclophanes},
  doi       = {10.25972/OPUS-31529},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-315296},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2024},
  abstract  = {This work illustrates how the targeted tailoring of supramolecular cavities can not only accomplish high binding due to optimized stereoelectronic shape matches between host and guest but also how molecular engineering of the binding site by a refined substitution periphery of the cavity makes enantiospecific guest recognition and host mediated chirality transfer feasible. Moreover, an enzyme mimic, following the Pauling-Jencks model of enzyme catalysis was realized by the smart design of a PBI host composed of moderately twisted chromophores, which drives the substrate inversion according to the concepts of transition state stabilization and ground state destabilization. The results of this thesis contribute to a better understanding of structure-specific interactions in host-guest complexes as well as the corresponding thermodynamic and kinetic properties and represent an appealing blueprint for the design of new artificial complex structures of high stereoelectronic shape complementarity in order to achieve the goal of sophisticated supramolecular receptors and enzyme mimicry.},
  language  = {en}
}
@article{WawraFeselWidmeretal.2016,
  author    = {Wawra, Stephan and Fesel, Philipp and Widmer, Heidi and Timm, Malte and Seibel, J{\"u}rgen and Leson, Lisa and Kesseler, Leona and Nostadt, Robin and Hilbert, Magdalena and Langen, Gregor and Zuccaro, Alga},
  title     = {The fungal-specific beta-glucan-binding lectin FGB1 alters cell-wall composition and suppresses glucan-triggered immunity in plants},
  series = {Nature Communications},
  volume    = {7},
  journal   = {Nature Communications},
  doi       = {10.1038/ncomms13188},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-165945},
  pages     = {13188},
  year      = {2016},
  abstract  = {β-glucans are well-known modulators of the immune system in mammals but little is known about β-glucan triggered immunity in planta. Here we show by isothermal titration calorimetry, circular dichroism spectroscopy and nuclear magnetic resonance spectroscopy that the FGB1 gene from the root endophyte Piriformospora indica encodes for a secreted fungal-specific β-glucan-binding lectin with dual function. This lectin has the potential to both alter fungal cell wall composition and properties, and to efficiently suppress β-glucan-triggered immunity in different plant hosts, such as Arabidopsis, barley and Nicotiana benthamiana. Our results hint at the existence of fungal effectors that deregulate innate sensing of β-glucan in plants.},
  language  = {en}
}
@article{WangLiKateleetal.2014,
  author    = {Wang, Hui and Li, Min-Yi and Katele, F{\´e}lix Zongwe and Satyanandamurty, Tirumani and Wu, Jun and Bringmann, Gerhard},
  title     = {Decandrinin, an unprecedented \(C_9\)-spiro-fused 7,8-\( seco-ent\)-abietane from the Godavari mangrove \(Ceriops\ decandra\)},
  series = {Beilstein Journal of Organic Chemistry},
  volume    = {10},
  journal   = {Beilstein Journal of Organic Chemistry},
  issn      = {1860-5397},
  doi       = {10.3762/bjoc.10.23},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-119983},
  pages     = {276-81},
  year      = {2014},
  abstract  = {Decandrinin (1), an unprecedented \(C_9\)-spiro-fused 7,8-\(seco-ent\)-abietane, was obtained from the bark of an Indian mangrove, \(Ceriops\ decandra\), collected in the estuary of Godavari, Andhra Pradesh. The constitution and the relative configuration of 1 were determined by HRMS (ESI) and extensive NMR investigations, and the absolute configuration by circular dichroism (CD) and optical-rotatory dispersion (ORD) spectroscopy in combination with quantum-chemical calculations. Decandrinin is the first 7,8-\(seco-ent\)-abietane.},
  language  = {en}
}
@phdthesis{Walter2018,
  author    = {Walter, Tim},
  title     = {Bioorthogonal funktionalisierte Sphingolipide zur Evaluierung von Lipiddynamiken \(in\) \(vivo\)},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-168091},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {In der Kontrolle von viralen oder bakteriellen Infektionen spielen Sphingolipide eine essentielle Rolle[335-336], weshalb sich inzwischen die Forschung vermehrt an Sphingolipiden und -analoga als Wirkstoffen gegen die verschiedensten Erreger besch{\"a}ftigt.[9] Dabei finden in der Synthese und Identifikation potentieller Wirkstoffe auch clickchemiebasierte Ans{\"a}tze Anwendung.[224] Allerdings ist die Wirkweise von sphingolipidbasierten Pharmaka auch in viraler und mikrobieller Pathogenese bisher ungekl{\"a}rt. Mit der Entdeckung der CuAAC[112-113] sowie deren modernen Varianten und Alternativen, die gemeinsam unter dem Begriff Clickchemie zusammengefasst werden, ist es m{\"o}glich, die strukturellen {\"A}nderungen von Biomolek{\"u}len klein zu halten und durch sp{\"a}tere Konjugation mit Farbstoffen Fluoreszenspektroskopie zu erm{\"o}glichen.[339-340] W{\"a}hrend in den letzten Jahren die Clickchemie breite Anwendung zur Modifikation von Proteinen[130], Kohlenhydraten[341] und DNA[340] gefunden hat blieben Lipide lange unbeachtet[342], was vor allem auch f{\"u}r Sphingolipide gilt. In dieser Arbeit werden bioorthogonal funktionalisierte Sphingolipide und -analoga vorgestellt, um die Vielseitigkeit der Clickchemie auf das Feld der Sphingolipide zu {\"u}bertragen. Die clickf{\"a}higen Lipidanaloga erm{\"o}glichen detaillierte Einblicke in die dynamische Organisation von Sphingolipiden bei Infektionsprozessen und ihr Einsatz als therapeutische Wirkstoffe oder zur Generierung von antibakteriellen Oberfl{\"a}chenbeschichtungen wurden untersucht. Die dargestellten azidmodifizierten Sphingolipide und -analoga konnten in Zusammenarbeit mit Kooperationspartnern, bez{\"u}glich ihrer Verwendung in Visualisierungsexperimenten und antibakteriellen Eigenschaften untersucht werden. Die Ceramidderivate konnten genutzt werden, um den Einfluss von Kettenl{\"a}nge und Position des Azides der acylierten S{\"a}ure auf die in vivo-Konjugation mit dem Fluoreszenzfarbstoff DBCO-Sulfo-Cy5 in Jurkatzellen genauer zu untersuchen.[211] Auch konnten azidfunktionalisierte Ceramide auf ihre Eignung zur Visualisierung von Ceramiddynamiken w{\"a}hrend T-Stimulation untersucht werden.[205] In diesem Zusammenhang sind visualisierbare Ceramide von besonderer Bedeutung, da die T-Zellstimulation die ASM-Aktivierung zur Folge hat, die wiederum Ceramide freisetzt. Mit dem azidmodifizierten Phytosphingosinderivat gelang es erstmals ein azidmodifiziertes Sphingolipid nach Inkubation von Arabidopsis thaliana Setzlingen mittels CuAAC mit einem Fluoreszenzfarbstoff zu konjugieren.[258] Des Weiteren konnten die azidfunktionalisierten N-Oleoylserinole in verschiedenen Zelltypten erfolgreich eingebaut und selektiv mit Fluoreszenzfarbstoff visualisiert werden. Kof{\"a}rbungen mit GFP-PKCζ und Antik{\"o}rpermarkierungen von Ceramid sowie PKCζ zeigten, dass es sich bei den Enantiomeren um ceramidimitierende Lipidanaloga handelt. Somit eignen sich diese N-Oleoylserinolanaloga, um die Interaktion von Ceramiden mit der Proteinkinase Cζ zu untersuchen. Da viele nat{\"u}rliche Sphingolipide antibakterielle Eigenschaften aufweisen, konnte in Kooperation mit J{\´e}r{\^o}me Becam der Einsatz azidmodifizierter Ceramide als Wirkstoff gegen Neisseria meningitidis, Neisseria gonorrhoeae sowie Escherichia coli und Staphylococcus aureus untersucht werden. ωN3-C6-Cer zeigt gute bakterizide Eigenschaften gegen Neisseria meningitidis und Neisseria gonorrhoeae, ohne dabei toxisch gegen{\"u}ber den Wirtszellen zu sein. Die Ceramidanaloga αN3-C6-Cer, αN3-C16-Cer und ωN3-C16-Cer weisen keine antibakteriellen Eigenschaften auf, aber sie wurden effizient in die Membran der Neisseriae eingebaut und konnten ebenfalls erfolgreich bioorthogonal markiert werden. Des Weiteren zeigten hochaufl{\"o}sende dSTORM-Aufnahmen der Bakterien, im Gegensatz zu Humanzellen, eine homologe Verteilung der konjugierten Ceramide. Da Ceramide eine wichtige Rolle in der Infektionsbek{\"a}mpfung spielen, sind die in dieser Arbeit synthetisierten azidmodifizierten Ceramide wertvolle Werkzeuge, um die Interaktion von Bakterien mit Humanzellen zu untersuchen. Außerdem konnte im Rahmen dieser Arbeit erfolgreich eine innovative Methode entwickelt werden, um alkinpr{\"a}sentierende Linker auf die Oberfl{\"a}che von Nunc Covalink 96 Microtiterplatten kovalent zu binden und die Alkine konnten anschließend mittels CuAAC mit den in dieser Arbeit synthetisierten azidfunktionalisierten Lipiden zu konjugiert werden. Ziel der Methode war es potentielle Molek{\"u}le f{\"u}r bakterizide Oberfl{\"a}chenmodifikationen zu identifizieren. Mittels solcher Oberfl{\"a}chenmodifikationen soll die Biofilmbildung in Endotrachealtuben verhindert, und damit die Entstehung von beatmungsassozierten Pneumonien unterbunden werden. Die lipidmodifizierten Microtiterplatten sollen zuk{\"u}nftig auch genutzt werden, um sphingolpidaffine Proteine aus Zelllysaten zu identifizieren.},
  subject      = {Click-Chemie},
  language  = {de}
}
@article{WalterCollenburgJaptoketal.2016,
  author    = {Walter, T. and Collenburg, L. and Japtok, L. and Kleuser, B. and Schneider-Schaulies, S. and M{\"u}ller, N. and Becam, J. and Schubert-Unkmeir, A. and Kong, J. N. and Bieberich, E. and Seibel, J.},
  title     = {Incorporation and visualization of azido-functionalized N-oleoyl serinol in Jurkat cells, mouse brain astrocytes, 3T3 fibroblasts and human brain microvascular endothelial cells},
  series = {Chemical Communications},
  volume    = {52},
  journal   = {Chemical Communications},
  number    = {55},
  doi       = {10.1039/c6cc02879a},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-191263},
  pages     = {8612-8614},
  year      = {2016},
  abstract  = {The synthesis and biological evaluation of azido-N-oleoyl serinol is reported. It mimicks biofunctional lipid ceramides and has shown to be capable of click reactions for cell membrane imaging in Jurkat and human brain microvascular endothelial cells.},
  language  = {en}
}
@phdthesis{Walden2009,
  author    = {Walden, Nicholas Sebastian},
  title     = {Neue zwitterionische Halbschalen als Bausteine f{\"u}r supramolekulare Kapseln},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-35256},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2009},
  abstract  = {Ziel der Dissertation „Neue zwitterionische Halbschalen als Bausteine f{\"u}r supramolekulare Kapseln" war die Verkn{\"u}pfung zweier Guanidiniocarbonylpyrrolcarboxylat-Bindungsmotive von Schmuck {\"u}ber starre, sowohl aromatische als auch nichtaromatische Linker. Die so erhaltenen zwitterionische Halbschalen sollten in L{\"o}sung zu supramolekulare Kapseln aggregieren, welche einen Hohlraum ausweisen, in den Gastmolek{\"u}le eingelagert werden k{\"o}nnen. Dieses Bindungsmotiv ist selbstkomplement{\"a}r und daher in der Lage Homodimere auszubilden. Durch die Kombination aus Wasserstoffbr{\"u}cken und Ionenbindungen sind diese selbst in polaren L{\"o}semitteln wie DMSO oder Wasser stabil, im Gegensatz zu Systemen, welche z.B. nur {\"u}ber Wasserstoffbr{\"u}cken verf{\"u}gen und in polaren Medien wieder dissoziieren. Zur Synthese wurden zwei Bindungsmotive mittels Tetrahydroxybenzol verbr{\"u}ckt. Die eindeutige Charakterisierung erfolgte {\"u}ber NMR-Spektroskopie, Massen-Spektrometrie und R{\"o}ntgenstrukturanalyse. Anschließend wurde die Verbindung in die zwitterionische Form {\"u}berf{\"u}hrt und auf Kapselbildung hin untersucht (NMR, DOSY, Masse, Molecular Modelling). Die theoretischen Berechnungen wiesen darauf hin, dass die synthetisierten Halbschalen in der Lage sein sollten, Kapseln zu bilden. Trotz der erfolgreichen Synthese dieses neuartigen zwitterionischen Makrozyklus steht der experimentelle Nachweise auf Grund der schlechten L{\"o}slichkeit der Zwitterionen in allen verwendeten L{\"o}semitteln noch aus. Auch wurde Glucoluril als nichtaromatisches Linkermolek{\"u}l erfolgreich verwendet. Als erstes wurde das 4,4'-Diphenylglucoluril erfolgreich in der Kupplung eingesetzt. Es war m{\"o}glich, die so erhaltenen cis/trans-Makrozyklen s{\"a}ulenchromatographisch zu isolieren und mittels R{\"o}ntgenstrukturanalyse zu charakterisieren. Nach {\"U}berf{\"u}hrung in die Zwitterionen wurden diese wiederum auf die Kapselbildung hin untersucht (NMR, DOSY, Masse, Molecular Modelling). Berechnungen zufolge sollte die Kapselbildung m{\"o}glich sein, jedoch steht auch hier trotz erfolgreicher Synthese der experimentelle Nachweis auf Grund der Unl{\"o}slichkeit noch aus. Zur Verbesserung der L{\"o}slichkeit wurden zwei neue Glucolurilderivate entwickelt, welche am Phenylring mit Octyl- bzw. Triethylenglykolketten substituiert waren. Dadurch sollte die L{\"o}slichkeit der Zwitterionen in organischen bzw. w{\"a}ssrigen L{\"o}sungen erh{\"o}ht werden. Jedoch zeigte die Einf{\"u}hrung dieser Ketten keine wesentliche Verbesserung der L{\"o}slichkeit und somit konnte auch bei diesen neuen zwitterionischen Halbschalen keine Kapselbildung nachgewiesen werden. Im Rahmen dieser Dissertation wurden sieben neue zwitterionische makrozyklische Halbschalen synthetisiert und die daraus gewonnenen Erkenntnisse k{\"o}nnen als Ausgangspunkt verwendet werden, die L{\"o}slichkeit weiter zu verbessern.},
  subject      = {Supramolekulare Chemie},
  language  = {de}
}
@phdthesis{Waidelich2005,
  author    = {Waidelich, Michael},
  title     = {Neue Aspekte zum Design von ionensensitiven und solvatochromen Fluoreszenzsensoren},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-15578},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2005},
  abstract  = {Neuartige Akzeptor-substituierte Fluoresenzsensoren wurden etabliert, die durch signifikante Rotverschiebung der Emissionsmaxima Analyten nachweisen und deren pH-Sensitivit{\"a}t {\"u}ber das Substitutionsmuster variierbar ist. Es wurde gezeigt, dass 2-Methoxyanthracenderivate eine duale Emission aufweisen, die in dieser Form noch nicht detektiert und untersucht worden ist. Desweiteren wurde ein neues Strukturelement f{\"u}r stark solvatochrome Proben etabliert, die als Fluoreszenzsensoren zur Detektion von Fluorid und Analyten mit hoher Akzeptornummer verwendet werden k{\"o}nnen. Außerdem konnte eine Fluoreszenzsonde als Leucht-Sensor zur selektiven, differenzierenden Detektion von Fluorid und Chlorid generiert werden.},
  subject      = {Fluoreszenzsonde},
  language  = {de}
}
@phdthesis{Wagner2019,
  author    = {Wagner, Wolfgang},
  title     = {Supramolecular Block Copolymers by Seeded Living Supramolecular Polymerization of Perylene Bisimides},
  doi       = {10.25972/OPUS-19300},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-193004},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {The research on supramolecular polymerization has undergone a rapid development in the last two decades, particularly since supramolecular polymers exhibit a broad variety of functionalities and applications in organic electronics, biological science or as functional materials (Chapter 2.1). Although former studies have focused on investigation of the thermodynamics of supramolecular polymerization (Chapter 2.2), the academic interest in the recent years shifted towards gaining insight into kinetically controlled self-assembly and pathway complexity to generate novel out-of-equilibrium architectures with interesting nanostructures and features (Chapter 2.3). Along this path, the concepts of seeded and living supramolecular polymerization were recently developed to enable the formation of supramolecular polymers with controlled length and low polydispersity under precise kinetic control (Chapter 2.4). Besides that, novel strategies were developed to achieve supramolecular copolymerization resulting in complex multicomponent nanostructures with different structural motives. The classification of these supramolecular copolymers on the basis of literature examples and an overview of previously reported principles to create such supramolecular architectures are provided in Chapter 2.5. The aim of the thesis was the non-covalent synthesis of highly desirable supramolecular block copolymers by the approach of living seeded supramolecular polymerization and to study the impact of the molecular shape of the monomeric building blocks on the supramolecular copolymerization. Based on the structure of the previously investigated PBI organogelator H-PBI a series of novel PBIs, bearing identical hydrogen-bonding amide side-groups in imide-position and various kind or number of substituents in bay-position, was synthesized and analyzed within this thesis. The new PBIs were successfully obtained in three steps starting from the respective bromo-substituted perylene-3,4:9,10-tetracarboxylic acid tetrabutylesters or from the N,N'-dicyclohexyl-1,7-dibromoperylene-3,4:9,10-tetracarboxylic acid bisimide. All target compounds were obtained in the final step by imidization reactions of the respective perylene tetracarboxylic acid bisanhydride precursors with N-(2-aminoethyl)-3,4,5-tris(dodecyloxy)-benzamide and were fully characterized by 1H and 13C NMR spectroscopy as well as high resolution mass spectrometry. The variation of bay-substituents strongly changes the optical properties of the monomeric PBIs which were investigated by UV/vis and fluorescence spectroscopy. The increase of the number of the methoxy-substituents provokes, for example, a red-shift of the absorption maxima concomitant with a decrease of extinction coefficients and leads to a drastic increase of the fluorescence quantum yields. Furthermore, the molecular geometry of the PBIs is also affected by variations of the bay-substituents. Thus, increasing the steric demand of the bay-substituents leads to an enlargement of the twist angles of the PBI cores as revealed by DFT calculations. Especially the 1,7-dimethoxy bay-substituted MeO-PBI proved to be very well-suited for the studies envisioned within this thesis. The self-assembly of this PBI derivative was analyzed in detail by UV/vis, fluorescence and FT-IR spectroscopy as well as atomic force microscopy (Chapter 3). These studies revealed that MeO-PBI forms in a solvent mixture of methylcyclohexane and toluene (2:1, v/v) kinetically trapped off-pathway H-aggregated nanoparticles upon fast cooling of a monomeric solution from 90 to 20 °C. However, upon slow cooling of the monomer solution fluorescent J-type nanofibers are formed by π π interactions and intermolecular hydrogen-bonding. The kinetically metastable off-pathway H-aggregates can be transformed into the thermodynamically more favored J-type aggregates by addition of seeds, which are produced by ultrasonication of the polymeric nanofibers. Interestingly, the living character of this seed-induced supramolecular polymerization process was proven by a newly designed multicycle polymerization experimental protocol. This living polymerization experiment clearly proves, that the polymerization can only occur at the "active" ends of the polymeric seed and that almost no recombination or chain termination processes are present. Hence, the approach of living supramolecular polymerization enables the formation of supramolecular polymers with controlled length and narrow polydispersity. In Chapter 4 the copolymerization of MeO-PBI with the structurally similar 1,7-dichloro (Cl-PBI) and 1,7-dimethylthio (MeS-PBI) bay-substituted PBIs is studied in detail. Both PBIs form analogous to MeO-PBI kinetically trapped off-pathway aggregates, which can be converted into the thermodynamically stable supramolecular polymers by seed-induced living supramolecular polymerization under precise kinetic control. However, the stability of the kinetically trapped aggregates of Cl-PBI and MeS-PBI is distinctly reduced compared to that of MeO-PBI, because the π-π-interactions of the kinetically metastable aggregates are hampered through the increased twisting of the PBI-cores of the former PBIs. UV/vis studies revealed that the two-component seeded copolymerization of the kinetically trapped state of MeO-PBI with seeds of Cl-PBI leads to the formation of unprecedented supramolecular block copolymers with A-B-A pattern by a living supramolecular polymerization process at the termini of the seeds. Remarkably, the resulting A-B-A block pattern of the obtained copolymers was clearly confirmed by atomic force microscopy studies as the respective blocks formed by the individual monomeric units could be distinguished by the pitches of the helical nanofibers. Moreover, detailed UV/vis and AFM studies have shown that by inverted two-component seed-induced polymerization, e.g., upon addition of seeds of MeO-PBI to the kinetically trapped aggregates of Cl-PBI, triblock supramolecular copolymers with B-A-B pattern can be generated. The switching of the block pattern could only be achieved because of the perfectly matching conditions for the copolymerization process and the tailored molecular geometry of the individual building blocks of both PBIs. These studies have demonstrated for the first time, that the block pattern of a supramolecular copolymer can be modulated by the experimental protocol through the approach of living supramolecular polymerization. Furthermore, by UV/vis analysis of the living copolymerization of MeO-PBI and MeS-PBI similar results were obtained showing also the formation of both A-B-A and B-A-B type supramolecular block copolymers. Although for these two PBIs the individual blocks could not be identified by AFM because the helical nanofibers of both PBIs exhibit identical helical pitches, these studies revealed for the first time that the approach of seeded living polymerization is not limited to a special pair of monomeric building blocks. In the last part of the thesis (Chapter 5) a systematic study on the two-component living copolymerization of PBIs with various sterical demanding bay-substituents is provided. Thus, a series of PBIs containing identical hydrogen-bonding amide groups in imide position but variable number (1-MeO-PBI, MeO-PBI, 1,6,7-MeO-PBI, 1,6,7,12-MeO-PBI) or size (EtO-PBI, iPrO-PBI) of alkoxy bay-substituents was investigated. The molecular geometry of the monomeric building blocks has a strong impact on the thermodynamically and even more pronounced on the kinetically controlled aggregation in solvent mixtures of MCH and Tol. While the mono- and dialkoxy-substituted PBIs form kinetically metastable species, the self-assembly of the tri- and tetramethoxy-substituted PBIs (1,6,7-MeO-PBI and 1,6,7,12-MeO-PBI) is completely thermodynamically controlled. The two 1,7-alkoxy substituted PBIs (EtO-PBI, iPrO-PBI) form very similar to MeO-PBI kinetically off-pathway H-aggregates and thermodynamically more favored J-type aggregates. However, the stability of the kinetically metastable state is drastically lower and the conversion into the thermodynamically favored state much faster than for MeO-PBI. In contrast, the monomethoxy-substituted PBI derivative (1-MeO-PBI) forms a kinetically trapped species by intramolecular hydrogen-bonding of the monomers, which can be transformed into the thermodynamically favored nanofibers by seeded polymerization. Importantly, the two-component seeded copolymerization of the kinetically trapped MeO PBI with seeds of other PBIs of the present series was studied by UV/vis and AFM revealing that the formation of supramolecular block copolymers is only possible for appropriate combinations of PBI building blocks. Thus, the seeded polymerization of the trapped state of the moderately core-twisted MeO-PBI with the, according to DFT-calculations, structurally similar PBIs (EtO-PBI and iPrO-PBI) leads to the formation of A-B-A block copolymers, like in the seeded copolymerization of MeO-PBItrapped with seeds of Cl-PBI and MeS-PBI already described in Chapter 4. However, by addition of seeds of the almost planar PBIs (H-PBI and 1-MeO-PBI) or seeds of the strongly core-twisted PBIs (1,6,7-MeO-PBI and 1,6,7,12-MeO-PBI) to the kinetically trapped state of MeO-PBI no block copolymers can be obtained. The mismatching geometry of these molecular building blocks strongly hampers both the intermolecular hydrogen-bonding and the π-π-interactions between the two different PBIs and consequently prevents the copolymerization process. Furthermore, the studies of the two-component seeded copolymerization of the kinetically trapped species of 1-MeO-PBI with seeds of the other PBIs also corroborated that a precise shape complementarity is crucial to generate supramolecular block copolymers. Thus, by addition of seeds of H-PBI to the kinetically trapped monomers of 1-MeO-PBI supramolecular block copolymers were generated. Both PBIs exhibit an almost planar PBI core according to DFT-calculations leading to strong non-covalent interactions between these PBIs. This perfectly matching geometry of both PBIs also enables the inverted seeded copolymerization of the kinetically trapped monomers of H-PBI with 1-MeO-PBIseed concomitant with a switching of the block pattern of the supramolecular copolymer from A-B-A to B-A-B type. In contrast, the seeding with the moderately twisted (MeO-PBI, EtO-PBI and iPrO-PBI) and the strongly twisted PBIs (1,6,7-MeO-PBI and 1,6,7,12 MeO-PBI) has no effect on the kinetically trapped state of 1-MeO-PBI, because the copolymerization of these PBIs is prevented by the mismatching geometry of the molecular building blocks. In conclusion, the supramolecular polymerization and two-component seeded copolymerization of a series of PBI monomers was investigated within this thesis. The studies revealed that the thermodynamically and kinetically controlled self-assembly can be strongly modified by subtle changes of the monomeric building blocks. Moreover, the results have shown that living supramolecular polymerization is an exceedingly powerful method to generate unprecedented supramolecular polymeric nanostructures with controlled block pattern and length distribution. The formation of supramolecular block copolymers can only be achieved under precise kinetic control of the polymerization process and is strongly governed by the shape complementarity already imparted in the individual components. Thus, these insightful studies might enable a more rational design of monomeric building blocks for the non-covalent synthesis of highly complex supramolecular architectures with interesting properties for possible future applications, e.g., as novel functional materials.},
  subject      = {Supramolekulare Chemie},
  language  = {en}
}
@phdthesis{WagenhaeusergebVonhausen2024,
  author    = {Wagenh{\"a}user [geb. Vonhausen], Yvonne},
  title     = {Thermodynamic Investigations on the Dimerization and Anti-Cooperative Self-Assembly of Dipolar Merocyanines},
  doi       = {10.25972/OPUS-35211},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-352111},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2024},
  abstract  = {Dipolar merocyanines are very attractive supramolecular building blocks, as they combine interesting functional properties with strong, directional intermolecular interactions. The pyridine dioxocyano-pyridine (PYOP) chromophore (Chapter 2.2), used in this thesis, stands out because of its exceptionally high ground state dipole moment (g ~ 17 D), in combination with the option to retain good solubility also in unpolar solvents, by decoration with solubilizing groups. The reliable binding motif of anti-parallel -stacking due to dipole-dipole interactions has allowed the design of molecular building blocks that form assemblies of predictable geometry. The intense unstructured charge transfer UV/Vis absorption band (eg ~ 10.7 D) is a result of the dominant contribution of the zwitterionic resonance structure which brings the PYOP chromophore just beyond the cyanine limit in solvents of low polarity (c2 = 0.60, 1,4 dioxane). The high sensitivity of the S0 - S1 UV/Vis absorption band to the environment manifests itself in a pronounced negative solvatochromism and strong H-type exciton coupling within -stacked PYOP assemblies. In accordance with the classical molecular exciton theory, an increasing hypsochromic shift of the dominant absorption band of these H aggregates can be observed as the stack size increases up to about six chromophores, where it levels out at about max ~ 440 nm (CHCl3). This allows a uniquely simple estimation of the number of interacting chromophores within the self-assembled structure from a single UV/Vis absorption spectrum of an aggregate. The defined and well investigated PYOP dimer formation was employed in this thesis to probe the applicability and limitations of concentration-, temperature-, and solvent-dependent self-assembly studies (Chapter 3). Straightforward theoretical models to evaluate datasets of concentration-, temperature-, and solvent-dependent UV/Vis absorption by nonlinear regression analysis were derived for the case of dimer formation (Chapter 2.1). Although the dimer model is well known and widely applied in literature, this detailed derivation is helpful to understand assumptions and potential problems of the different approaches for the determination of thermodynamic parameters. This helps to decide on the most appropriate method to analyse a system of interest. In this regard it should be noted that covering a large portion of the self-assembly process with the experimental data is a prerequisite for the accuracy of the analysis. Additionally, many of the insights can also be transferred to other self-assembly systems like supramolecular polymerization or host-guest interactions. The concentration-dependent analysis is the most straightforward method to investigate self-assembly equilibria. No additional assumptions, besides mass balance and mass action law, are required. Since it includes the least number of parameters (only K, if M/D are known), it is the most, or even only, reliable method, to elucidate the self-assembly mechanism of an unknown system by model comparison. To cover a large concentration range, however, the compound must be soluble enough and generally sample amounts at least in the low mg scale must be available. The temperature-dependent analysis has the advantage that all thermodynamic parameters G0, H0 and S0 can be obtained from a single sample in one automated measurement. However, the accessible temperature-range is experimentally often quite limited and dependent on the solvent. For systems which do not show the transition from monomer to aggregate in a narrow temperature range, as given for, e.g., cooperative aggregation or processes with a high entropy contribution, often not the entire self-assembly process can be monitored. Furthermore, the assumptions of temperature-independent extinction coefficients of the individual species as well as temperature-independent H0 and S0 must be met. Monte Carlo simulations of data sets demonstrated that even minor changes in experimental data can significantly impact the optimized values for H0 and S0. This is due to the redundancy of these two parameters within the model framework and even small thermochromic effects can significantly influence the results. The G0 value, calculated from H0 and S0, is, however, still rather reliable. Solvent-dependent studies can often cover the entire self-assembly process from monomeric (agg = 0) to the fully aggregated state (agg = 1). However, for dyes with strong solvatochromic effects, such as the dipolar merocyanines investigated in this thesis, the results are affected. Also, the assumption of a linear relation of the binding energy G0 and the fraction of denaturating solvent f, which is based on linear free energy relationships between G0 and the solvent polarity, can lead to errors. Especially when specific solvent effects are involved. For the evaluation of experimental data by nonlinear regression, general data analysis software can be used, where user-defined fit models and known parameters can be implemented as desired. Alternatively, multiple specialized programs for analysing self-assembly data are available online. While the latter programs are usually more user-friendly, they have the disadvantage of being a "black box" where only pre-implemented models can be used without the option for the user to adapt models or parameters for a specific system. In Chapter 3 comprehensive UV/Vis absorption datasets are presented for the dimerization of merocyanine derivative 1 in 1,4-dioxane, which allowed for the first time a direct comparison of the results derived from concentration-, temperature-, and solvent-dependent self-assembly studies. The results for the binding constant K and corresponding G0 from the concentration- and temperature-dependent analysis were in very good agreement, also in comparison to the results from ITC. For the temperature-dependent analysis, though, multiple datasets of samples with different concentration had to be evaluated simultaneously to cover a meaningful part of the self-assembly process. Furthermore, a significant dependence of the optimized parameters H0 and S0 on the wavelength chosen for the analysis was observed. This can be rationalized by the small thermochromic shifts of both the monomer and the dimer UV/Vis absorption band. The results from the solvent-dependent evaluation showed the largest deviation, as expected for the highly solvatochromic merocyanine dye. However, even here by evaluation at 491 and 549 nm the deviation for G0 was only 2.5 kJ mol1 (9\%) with respect to the results from the concentration-dependent analysis (G0 = 29.1 kJ mol1). Thus, despite the strong solvatochromism of the dipolar chromophore, it can still be considered a reliable method for estimating the binding strength. Furthermore, multiple repetitions of the concentration-, temperature-, and solvent-dependent studies provided insight into the reproducibility of the results and possible sources of experimental errors. In all cases, the deviations of the results were small (G0 < 0.4 kJ mol1) and within the same range as the fit error from the nonlinear regression analysis. The insights from these studies were an important basis for the in-depth investigation of a more complex supramolecular system in Chapter 4, as a single method is often not enough to capture the full picture of a more complicated self-assembly process. To elucidate the anti-cooperative self-assembly of the chiral merocyanine 2, a combination of multiple techniques had to be applied. Solvent-dependent UV/Vis absorption studies in CH2Cl2/MCH mixtures showed the step-wise assembly of the merocyanine monomer (max(M) = 549 nm, CH2Cl2) to first a dimer (max(D) = 498 nm, CH2Cl2/MCH 15:85) by dipole-dipole interactions, and then a -stacked higher aggregate (max(H) = 477 nm, MCH), with pronounced H-type coupling. The thermodynamic evaluation of this data, however, suffered from the severe solvatochromism, especially of the monomeric species (max(M, CH2Cl2) = 549 nm, max(M, MCH) = 596 nm). Therefore, concentration-dependent studies were performed at three different temperatures (298, 323, 353 K) to elucidate the self-assembly mechanism and determine reliable thermodynamic parameters. The studies at elevated temperatures were hereby necessary, to obtain experimental data over a larger agg--range. Due to the pronounced difference in the thermodynamic driving force for dimerization and higher aggregate formation (KD/K5 = 6500) a concentration range exists in MCH where almost exclusively the dimer species of 2 is present, before further self-assembly by dispersion interactions occurs. Therefore, the data could be evaluated independently for the two self-assembly steps. The self-assembly of dimers into the higher aggregate could not be described by the isodesmic model but was fitted satisfactorily to a pentamer model. This rather small size of about ten -stacked PYOP chromophores was, furthermore, consistently indicated by AFM, VPO and DOSY NMR measurements. Based on 1D and 2D NMR data as well as the strong bisignate CD signal of the higher aggregate in combination with TD-DFT calculations, a P-helical stack is proposed as its structure. The small size can be rationalized by the anti-cooperative self-assembly mechanism and the sterical demand of the solubilizing trialkoxyphenyl and the chiral tetralin substituents. Additionally, the aliphatic shell formed by the solubilizing chains around the polar chromophore stack, can account for the exceptionally high solubility of 2 in MCH (> 15 mg mL1). These combined studies of the self-assembly process enabled the identification of suitable conditions for the investigation of fluorescence properties of the individual aggregate species. Aggregation-induced emission enhancement was observed for the almost non-emissive monomer (Fl(M) = 0.23\%), which can be rationalized by the increasing rigidification within the dimer (Fl(D) = 2.3\%) and the higher aggregate (Fl(H) = 4.5\%). The helical chirality of the PYOP decamer stack, furthermore, gave rise to a strong CPL signal with a large glum value of 0.011. The important conclusion of this thesis is that the temperature- and solvent-dependent analyses are valid alternatives to the classical concentration-dependent analysis to determine thermodynamic parameters of self-assembly equilibria. Although, for a specific supramolecular system, one approach might be favourable over the others for a variety of reasons. The experimental limitations often demand a combination of techniques to fully elucidate a self-assembly process and to gain insights in the aggregate structure. The anti-cooperative merocyanine self-assembly, which was described here for the first time for the PYOP merocyanine 2, is no exception. Besides the interest in the merocyanine assemblies from a structural and functional point of view, the insights gained from the presented studies can also be transferred to other self-assembly systems and be a guide to find the most appropriate analysis technique.},
  subject      = {Merocyanine},
  language  = {en}
}
@phdthesis{Wachtler2020,
  author    = {Wachtler, Stefan},
  title     = {Synthese und Charakterisierung von funktionalisierten Nanodiamantmaterialien f{\"u}r biomedizinische Anwendungen},
  doi       = {10.25972/OPUS-21075},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-210757},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2020},
  abstract  = {In dieser Arbeit ist die Synthese von funktionalisiertem Nanodiamant mit bioaktiven Substanzen, welche vor allem als Wirkstofftransporter eingesetzt werden sollen, beschrieben. Dazu werden zum einen bereits bekannte Anbindungsm{\"o}glichkeiten an Nanodiamant, wie zum Beispiel die Klick-Reaktion, sowie die Ausbildung von Amidbr{\"u}cken verwendet. Zum anderen werden neuartige Funktionalisierungsm{\"o}glichkeiten wie Protein Ligation und Thioharnstoffbr{\"u}cken verwendet und somit das Repertoire an bekannten Anbindungsreaktion erweitert. Des weiteren wurde ein multifunktionales Nanodiamantsystem synthetisiert. Dieses ist in der Lage, zwei verschiedene Molek{\"u}le auf einem Partikel zu immobilisieren. Die verwendeten Methoden erm{\"o}glichen die Anbindung verschiedener Substanzen aus unterschiedlichen Molek{\"u}lgruppen an Nanodiamanten und sind somit universell einsetzbar.},
  subject      = {Synthesediamant},
  language  = {de}
}
@article{VolzShinPrinzbachetal.1978,
  author    = {Volz, H. and Shin, J.-H. and Prinzbach, H. and Babsch, H. and Christl, Manfred},
  title     = {Stability of Tricyclo[4.1.0.0\(^{2,7}\)]heptenyl-Cations},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-58001},
  year      = {1978},
  abstract  = {No abstract available},
  subject      = {Organische Chemie},
  language  = {en}
}
@phdthesis{Urban2009,
  author    = {Urban, Christian},
  title     = {Design, Synthese und Untersuchung eines Membrantransporters f{\"u}r acetylierte Aminos{\"a}uren},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-38094},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2009},
  abstract  = {Im Rahmen dieser Arbeit wurde ein synthetischer Membrantransporter f{\"u}r acetylierte Aminos{\"a}urecarboxylate entworfen und hergestellt. Als Bindungsstelle f{\"u}r die Carboxylate wurde das Guanidiniocarbonylpyrrol-Motiv von Schmuck verwendet. In den Seitenarm des Pyrrols wurde ein L-Valinamid-Rest eingebracht, um die M{\"o}glichkeit zu zus{\"a}tzlichen Wasserstoffbr{\"u}ckenbindungen zu bieten und gegebenenfalls Substrat- und Enantioselektivit{\"a}t zu erreichen. Zur Herstellung der L{\"o}slichkeit in unpolaren Medien wie dem Inneren der Zellmembran musste eine lipophile Gruppe eingebracht werden. Als l{\"o}slichkeitsvermittelnder Rest wurde Tris-(Dodecyloxy)phenylmethylen ausgew{\"a}hlt, das drei lange unpolare Alkylreste tr{\"a}gt. Zusammengenommen ergab sich so ein Rezeptor f{\"u}r Oxo-Anionen und speziell f{\"u}r Aminos{\"a}urecarboxylate mit erh{\"o}hter L{\"o}slichkeit in organischen Medien. Somit war die F{\"a}higkeit zu Membrantransport gegeben. In Kraftfeldrechnungen erhielt man die vermutliche Struktur des Rezeptor-Substrat-Komplexes, der eine Kombination aus einer Salzbr{\"u}cke, Wasserstoffbr{\"u}ckenbindungen und einer Stapelwechselwirkung von Guanidinum-Kation, Benzylgruppe und ggf. aromatischem Rest des Aminos{\"a}uresubstrates aufweist. Nach erfolgreicher Synthese wurde in Extraktionsexperimenten die F{\"a}higkeit des Rezeptors erprobt, Aminos{\"a}urecarboxylate aus einer w{\"a}ssrigen in eine organische Phase aus zu {\"u}berf{\"u}hren. Man erhielt das beste Extraktionsverm{\"o}gen f{\"u}r Ac-Trp-OH, gefolgt von Ac Phe OH und Ac Tyr OH. Es wurde eine neue Formel aufgestellt, mit der aus den pKS-Werten der Substrate und den Extraktionsdaten mit und ohne Rezeptor die Bindungskonstanten der Rezeptor-Substrat-Komplexe berechnet werden konnten. Die Gr{\"o}ße der Bindungkonstanten entsprach der Reihenfolge Trp > Tyr > Phe ~ Val mit den h{\"o}chsten Bindungskonstanten f{\"u}r das Tryptophanderivat mit 1.5*10E4 1/M. Zur Best{\"a}tigung der Bindungskonstanten wurden ITC-Messungen durchgef{\"u}hrt. Es wurden Messungen des Rezeptors in Chloroform mit den tert-Butylammoniumsalzen der acetylierten Aminos{\"a}uren Phenylalanin, Tyrosin und Valin durchgef{\"u}hrt. F{\"u}r die Werte von Enthalpie und Entropie konnten bei dieser Auswertung konsistente Werte ermittelt werden. Die h{\"o}chsten Werte der Enthalpie erhielt man f{\"u}r das Tyrosinderivat mit 3.7*10E3 cal/mol, gefolgt vom Phenylalaninderivat mit 2.8*10E3 cal/mol und Valinderivat mit 1.3*10E3 cal/mol. Diese Abstufung entspricht dem Einfluss des aromatischen Restes, der durch die Stapelwechselwirkung mit dem Guanidinium-Kation die Bindungsw{\"a}rme erh{\"o}ht und durch den damit verbundenen engeren Komplex den Wert f{\"u}r die Entropie senkt. F{\"u}r die Evaluierung des Transportverm{\"o}gens wurden U-Rohr-Versuche verschiedener Art durchgef{\"u}hrt. Es wurde ein Gradient von pH 6 in der Ausgangsphase auf pH 8 in der Zielphase eingesetzt, wodurch der Rezeptor an der Grenzfl{\"a}che zur Zielphase deprotoniert wurde, was zu gerichtetetem Transport f{\"u}hrte. Es ergaben sich recht starke Unterschiede f{\"u}r die Fluxwerte der einzelnen Substraten, die der Reihenfolge Val > Phe > Ala > Trp > Tyr folgten. Dabei wurde das Valinderivat um den Faktor 17 schneller als das Tyrosinderivat bef{\"o}rdert, mit dem recht hohen Flux von 1.11*10E-6 mol/m2*s, was nahe an den h{\"o}chsten literaturbekannten Wert f{\"u}r acetylierte Aminos{\"a}uren heranreicht. Durch Verwendung gleicher Substratkonzentrationen in Start- und Zielphase konnte aktiver Transport nachgewiesen werden, d.h. Transport gegen das Konzentrationsgef{\"a}lle. Die Triebkraft des Transportes war der Gradient von pH 6 auf pH 8 zwischen Ausgangs- und Zielphase, der durch den Symport von Substrat und einem Proton ausgeglichen wurde. Bei einem kompetitiven Versuch mit einer Mischung der verschiedenen Substrate in der Ausgangsphase wurden ver{\"a}nderte Fluxwerte und Selektivit{\"a}ten festgestellt. Die neue Reihenfolge der Transportgeschwindigkeit war nun Trp > Phe > Val > Tyr > Ala, wobei die Fluxwerte fast durchgehend niedriger waren als im Einzelversuch. Die Ver{\"a}nderung der Werte erschließt sich bei Vergleich mit den thermodynamischen Daten aus den Extraktionsexperimenten. Bei direkter Konkurrenz um den Rezeptor wurden diejenigen Substrate mit den h{\"o}chsten Bindungskonstanten bevorzugt, unabh{\"a}ngig von ihrer Transportgeschwindigkeit. Die schw{\"a}cher bindenden Substrate wurden aus dem Komplex verdr{\"a}ngt und wiesen deswegen niedrigere Transportwerte auf. Der kompetitive Versuch ist somit eine st{\"a}rkere Abbildung der Bindungsst{\"a}rke und entspricht eher der Situation in einer realen Zelle.},
  subject      = {Molekulare Erkennung},
  language  = {de}
}
@article{TurkinHolzapfelAgarwaletal.2021,
  author    = {Turkin, Arthur and Holzapfel, Marco and Agarwal, Mohit and Fischermeier, David and Mitric, Roland and Schweins, Ralf and Gr{\"o}hns, Franziska and Lambert, Christoph},
  title     = {Solvent Induced Helix Folding of Defined Indolenine Squaraine Oligomers},
  series = {Chemistry—A European Journal},
  volume    = {27},
  journal   = {Chemistry—A European Journal},
  number    = {32},
  doi       = {10.1002/chem.202101063},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256869},
  pages     = {8380-8389},
  year      = {2021},
  abstract  = {A protecting group strategy was employed to synthesise a series of indolenine squaraine dye oligomers up to the nonamer. The longer oligomers show a distinct solvent dependence of the absorption spectra, that is, either a strong blue shift or a strong red shift of the lowest energy bands in the near infrared spectral region. This behaviour is explained by exciton coupling theory as being due to H- or J-type coupling of transition moments. The H-type coupling is a consequence of a helix folding in solvents with a small Hansen dispersity index. DOSY NMR, small angle neutron scattering (SANS), quantum chemical and force field calculations agree upon a helix structure with an unusually large pitch and open voids that are filled with solvent molecules, thereby forming a kind of clathrate. The thermodynamic parameters of the folding process were determined by temperature dependent optical absorption spectra.},
  language  = {en}
}
@phdthesis{Turkin2022,
  author    = {Turkin, Arthur},
  title     = {Vom Monomer zum Polymer: Iterative Synthese und optische Spektroskopie von Squarain-Oligomeren},
  doi       = {10.25972/OPUS-25795},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257950},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {Mittels einer Schutzgruppenstrategie wurden Squarain-basierte monodisperse Oligomere synthetisiert. Die l{\"o}sungsmittelabh{\"a}ngigen Konformationen (Random Coil vs. Helix) wie auch der Faltungsprozess der Homooligomere wurden mittels optischer Spektroskopie, verschiedener NMR-Experimenten, Kleinwinkelneutronenstreuungsexperimenten sowie quantenchemischen Berechnungen n{\"a}her beleuchtet. Die optisch-spektroskopischen Beobachtungen wurden mithilfe der Exzitonenkopplungstheorie und einer Orientierungs- und Winkelabh{\"a}ngigkeit der {\"U}bergangsdipolmomente der Oligomere erkl{\"a}rt. Der hohe Windungsabstand der helikalen Konformation f{\"u}hrt zu einer Interkalation von L{\"o}sungsmittel, wodurch eine Art Klathrat gebildet wird. Zus{\"a}tzlich wurden mittels eines Frenkel-Exzitonenmodells die Absorptions- und Fluoreszenzspektren modelliert. Es konnten die Exzitonendelokalisationsl{\"a}ngen abgesch{\"a}tzt und die Auswirkung der energetischen und strukturellen Unordnungen auf die Absorptions- und Fluoreszenzspektren bestimmt werden. Die Absorptionsspektren werden vorwiegend durch strukturelle Unordnungen verbreitert, die Fluoreszenzspektren dagegen von energetischen {\"U}bergangsenergieabweichungen. Weiterhin wurden auch alternierende Squarain-Cooligomere synthetisiert und mittels optischer Spektroskopie untersucht. Es wurde, abh{\"a}ngig von dem gew{\"a}hlten L{\"o}sungsmittel, eine Verschiebung der Hauptbande beobachtet, was durch einen Random Coil vs. helikale-/schlaufenartige Konformation erkl{\"a}rt wird. Gest{\"u}tzt wurde dies mittels quantenchemischen Berechnungen der jeweiligen Konformationen. Abschließend wurden alternierende Squarain-Copolymere synthetisiert, in verschiedenen Gr{\"o}ßen aufgetrennt und mittels optischer Spektroskopie untersucht. Mittels EEI2D-Experimenten wurde die Exzitonendynamik in Abh{\"a}ngigkeit von der Kettenl{\"a}nge eingehender untersucht. Hierbei wird eine steigende, aber relativ abnehmende Koh{\"a}renzl{\"a}nge bestimmt, die Auswirkungen auf die Exzitonendynamik hat. Der Exzitonentransport weist erst wellenf{\"o}rmiges und dann subdiffuses Verhalten auf.},
  subject      = {Squarain},
  language  = {de}
}
@article{TshitengeTshitengeBruhnFeineisetal.2019,
  author    = {Tshitenge Tshitenge, Dieudonn{\´e} and Bruhn, Torsten and Feineis, Doris and Mudogo, Virima and Kaiser, Marcel and Brun, Reto and Bringmann, Gerhard},
  title     = {An unusually broad series of seven cyclombandakamines, bridged dimeric naphthylisoquinoline alkaloids from the Congolese liana Ancistrocladus ealaensis},
  series = {Scientific Reports},
  volume    = {9},
  journal   = {Scientific Reports},
  doi       = {10.1038/s41598-019-46336-z.},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-200759},
  pages     = {9812},
  year      = {2019},
  abstract  = {A series of seven unusual dimeric naphthylisoquinoline alkaloids was isolated from the leaves of the tropical liana Ancistrocladus ealaensis J. L{\´e}onard, named cyclombandakamine A (1), 1-epi-cyclombandakamine A (2), and cyclombandakamines A3-7 (3-7). These alkaloids have a chemically thrilling structural array consisting of a twisted dihydrofuran-cyclohexenone-isochromene system. The 1′″-epimer of 4, cyclombandakamine A1 (8), had previously been discovered in an unidentified Ancistrocladus species related to A. ealaensis. Both lianas produce the potential parent precursor, mbandakamine A (9), but only A. ealaensis synthesizes the corresponding cyclized form, along with a broad series of slightly modified analogs. The challenging isolation required, besides multi-dimensional chromatography, the use of a pentafluorophenyl stationary phase. Featuring up to six stereocenters and two types of chiral axes, their structures were elucidated by means of 1D and 2D NMR, HRESIMS, in combination with oxidative chemical degradation experiments as well as chiroptical (electronic circular dichroism spectroscopy) and quantum chemical calculations. Compared to the 'open-chain' parent compound 9, these dimers displayed rather moderate antiplasmodial activities.},
  language  = {en}
}
@article{TshitengeFeineisMudogoetal.2017,
  author    = {Tshitenge, Dieudonn{\´e} Tshitenge and Feineis, Doris and Mudogo, Virima and Kaiser, Marcel and Brun, Reto and Bringmann, Gerhard},
  title     = {Antiplasmodial Ealapasamines A-C,'Mixed' Naphthylisoquinoline Dimers from the Central African Liana Ancistrocladus ealaensis},
  series = {Scientific Reports},
  volume    = {7},
  journal   = {Scientific Reports},
  number    = {5767},
  doi       = {10.1038/s41598-017-05719-w},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170645},
  year      = {2017},
  abstract  = {Three unusual heterodimeric naphthylisoquinoline alkaloids, named ealapasamines A-C (1-3), were isolated from the leaves of the tropical plant Ancistrocladus ealaensis J. L{\´e}onard. These 'mixed', constitutionally unsymmetric dimers are the first stereochemically fully assigned cross-coupling products of a 5,8′- and a 7,8′-coupled naphthylisoquinoline linked via C-6′ in both naphthalene portions. So far, only two other West and Central Ancistrocladus species were known to produce dimers with a central 6,6″-axis, yet, in contrast to the ealapasamines, usually consisting of two 5,8′-coupled monomers, like e.g., in michellamine B. The new dimers 1-3 contain six elements of chirality, four stereogenic centers and the two outer axes, while the central biaryl axis is configurationally unstable. The elucidation of the complete stereostructures of the ealapasamines was achieved by the interplay of spectroscopic methods including HRESIMS, 1D and 2D NMR (in particular ROESY measurements), in combination with chemical (oxidative degradation) and chiroptical (electronic circular dichroism) investigations. The ealapasamines A-C display high antiplasmodial activities with excellent half-maximum inhibition concentration values in the low nanomolar range.},
  language  = {en}
}
@phdthesis{Tribl2005,
  author    = {Tribl, Florian},
  title     = {Isolierung und Charakterisierung Neuromelanin-assoziierter Proteine aus Neuromelanin-Granula des menschlichen Gehirns mittels subzellul{\"a}rer Proteomanalyse},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-16117},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2005},
  abstract  = {Im Mittelpunkt dieser Arbeit stehen Untersuchungen zur Bildung des Pigments Neuromelanin, das die Ursache f{\"u}r die dunkle Farbgebung der humanen Substantia nigra pars compacta ist. Eine Beteiligung von Neuromelanin an den pathobiochemischen Ereignissen bei Parkinson-Krankheit erkl{\"a}rt das klinische Interesse an Neuromelanin. Die Untersuchungsm{\"o}glichkeiten von Neuromelanin sind limitiert: einerseits ist eine chemische Strukturaufkl{\"a}rung aufgrund der Unl{\"o}slichkeit dieses amorphen Polymers kaum zu bewerkstelligen, andererseits wird mangels geeigneter biologischer Testsysteme ein Einblick in die Biogenese von Neuromelanin verwehrt. Zurzeit wird die Bildung von Neuromelanin anhand der beiden konkurrierenden Hypothesen als Autoxidation von Dopamin oder durch Beteiligung eines Enzyms („Tyrosinase-Konzept") erkl{\"a}rt. In dieser Arbeit wurden beide hypothetischen Ans{\"a}tze bearbeitet, wobei einer enzymatischen Biogenese von Neuromelanin die Pr{\"a}ferenz gegeben wird. Zur globalen Untersuchung von Neuromelanin-Granula wurde nun erstmals eine Isolierung der Pigment-haltigen Organelle vorgestellt, die die Basis f{\"u}r eine umfassende Proteomanalyse mittels 1-D-SDS-PAGE und ESI-Tandem-Massenspektrometrie bildete. Mit diesem methodischen Ansatz wurden ingesamt 73 Proteinen identifiziert. Diese waren vor allem lysosomalen Proteinen zuordenbar, z.B. charakteristischen Membranproteinen (LAMP-1), s{\"a}mtlichen Proteasen, Proteinen des Metabolismus von (Glyco-)Lipiden und Glycoproteinen, aber auch Proteinen des Cytosols und des vesikul{\"a}ren Verkehrs. Entscheidend war die Anwesenheit von Proteinen des Endoplasmatischen Reticulums (ER); Calnexin gilt als ein melanogenes Chaperon, das nicht in Lysosomen vorkommt, dagegen aber in Lysosomen-verwandten Organellen. Im Vergleich mit bereits existierenden Proteinprofilen von Lysosomen und Lysosomen-verwandten Organellen zeigten die in Neuromelanin-Granula identifizierten lysosomalen Proteine und Proteine des ER, dass diese Organellen der humanen Substantia nigra keine konventionellen Lysosomen sind, sondern mit hoher Wahrscheinlichkeit der Gruppe der Lysosomen-verwandten Organellen zuzuordnen sind.},
  subject      = {Melanin},
  language  = {de}
}
@phdthesis{Toksabay2022,
  author    = {Toksabay, Sinem},
  title     = {Synthesis and on surface self assembly properties of pi extended tribenzotriquinacenes},
  doi       = {10.25972/OPUS-24573},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-245734},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {Tribenzotriquinacene (TBTQ) is a polycyclic aromatic framework with a particularly rigid, C3v symmetrical, bowl-shaped core bearing three mutually fused indane wings. It has been discussed as a defect center for a nanographene by Kuck and colleagues. Therefore, extended TBTQ structures are promising models for saturated defect structures in graphene and graphene like molecules and could be used to investigate the role of defects for the electronic properties of graphene. With this motivation, three different pi-extended TBTQ derivatives have been synthesized in this work. Several different Scholl reaction conditions were tried to obtain fully annulated product of hexaphenyl substituted TBTQ. The desired benzannulated TBTQ derivative could not be obtained due to unfavourable electron density in the respective positions of the molecule and increased reactivity of the bay position of the precursor. As an another method for benzannulation is the on-surface synthesis of graphene flakes and can be carried out using electron beams e.g. in a tunneling microscope (STM). According to our previous research, the parent system TBTQ and centro-methyl TBTQ on silver and gold surfaces showed that the gas phase deposition of these molecules gives rise to the formation of highly ordered two-dimensional assemblies with unique structural features. This shows the feasibility for the formation of defective graphene networks starting from the parent structures. Therefore, the same deposition technique was used to deposit Me-TBTQ(OAc)3Ph6, and investigate the molecular self-assembly properties directly on the surface of Cu (111). In summary, the substrate temperature dependent self-assembly of Me-TBTQ(OAc)3Ph6 molecules on Cu(111), shows the following evolution of orientations. At room temperature, molecules form dimers, which construct a higher-coverage honeycomb lattice. Furthermore, one of the acetyl group located in the bay positions of the TBTQ core is cleaved and the remaining two induce the metal-molecule interaction. It was presumed that by increasing the temperature to 393 K, the remaining acetyl and methyl groups would beeliminated from the molecular structure.In addition, the smaller TBTQ-Ph6 molecules preferably lie flat on Cu(111) crystal and allowing the molecules to settle into a C3-symmetry and form a dense hexagonal structure.},
  subject      = {Triquinacenderivate},
  language  = {en}
}
@phdthesis{SanchezNaya2023,
  author    = {S{\´a}nchez Naya, Roberto},
  title     = {Synthesis and Characterization of Dye-Containing Covalent Organic Frameworks},
  doi       = {10.25972/OPUS-28899},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-288996},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2023},
  abstract  = {The present thesis adress the synthesis and characterization of novel COFs that contain dye molecules as integral components of the organic backbone. These chromophore-containing frameworks open new research lines in the field and call for the exploration of applications such as catalysis, sensing, or in optoelectronic devices. Initially, the fabrication of organic-inorganic composites by the growth of DPP TAPP COF around functionalized iron oxide nanoparticles is reported. By varying the ratio between inorganic nanoparticles and organic COFs, optoelectronic properties of the materials are adjusted. The document also reports the synthesis of a novel boron dipyrromethene-containing (BODIPY) COF. Synthesis, full characterization and the scope of potential applications with a focus on environmental remediation are discussed in detail. Last, a novel diketopyrrolopyrrole-containing (DPP) DPP-Py-COF based on the combination of DDP and pyrene building blocks is presented. The very low bandgap of these materials and initial investigations on the photosensitizing properties are discussed.},
  subject      = {Organische Chemie},
  language  = {en}
}
@article{SyamalaWuerthner2020,
  author    = {Syamala, Pradeep P. N. and W{\"u}rthner, Frank},
  title     = {Modulation of the Self-Assembly of π-Amphiphiles in Water from Enthalpy- to Entropy-Driven by Enwrapping Substituents},
  series = {Chemistry - A European Journal},
  volume    = {26},
  journal   = {Chemistry - A European Journal},
  number    = {38},
  doi       = {10.1002/chem.202000995},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218107},
  pages     = {8426 -- 8434},
  year      = {2020},
  abstract  = {Depending on the connectivity of solubilizing oligoethylene glycol (OEG) side chains to the π-cores of amphiphilic naphthalene and perylene bisimide dyes, self-assembly in water occurs either upon heating or cooling. Herein, we show that this effect originates from differences in the enwrapping capability of the π-cores by the OEG chains. Rylene bisimides bearing phenyl substituents with three OEG chains attached directly to the hydrophobic π-cores are strongly sequestered by the OEG chains. These molecules self-assemble at elevated temperatures in an entropy-driven process according to temperature- and concentration-dependent UV/Vis spectroscopy and calorimetric dilution studies. In contrast, for rylene bisimides in which phenyl substituents with three OEG chains are attached via a methylene spacer, leading to much weaker sequestration, self-assembly originates upon cooling in an enthalpy-driven process. Our explanation for this controversial behavior is that the aggregation in the latter case is dictated by the release of "high energy water" from the hydrophobic π-surfaces as well as dispersion interactions between the π-scaffolds which drive the self-assembly in an enthalpically driven process. In contrast, for the former case we suggest that in addition to the conventional explanation of a dehydration of hydrogen-bonded water molecules from OEG units it is in particular the increase in conformational entropy of back-folded OEG side chains upon aggregation that provides the pronounced gain in entropy that drives the aggregation process. Thus, our studies revealed that a subtle change in the attachment of solubilizing substituents can switch the thermodynamic signature for the self-assembly of amphiphilic dyes in water from enthalpy- to entropy-driven.},
  language  = {en}
}
@article{SuterPlessErnzerhofetal.1994,
  author    = {Suter, H. U. and Pleß, V. and Ernzerhof, M. and Engels, Bernd},
  title     = {Difficulties in the Calculation of Electron Spin Resonance Parameters using Density Functional Methods},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59113},
  year      = {1994},
  abstract  = {Density functional theory is applied to the calculation ofthe isotropic byperfine coupJing constants in some small molecules. Various functionals are tested. The agreement of the calculated values to experimental data and values obtained from sophisticated ab initio methods depends on the functionals used and the system under consideration. With respect to spin density calculations the functional of Lee, Yang and Parr with Becke's excbange functional (BLYP) is found to give good results for tbe heavier center of the CH and the NH molecule, while the spin densities of other molecules such as OH, H\(_2\)CN, H\(_2\)CO\(^+\), NO and O\(_2\) deviate considerably from experimental and/or other theoretical results (30\%-60\%). In cases where the singly occupied orbital can contribute to the isotropic hyperfine coupling constants, accurate results are obtained. The reason fortbis is analyzed.},
  subject      = {Organische Chemie},
  language  = {en}
}
@article{SuterHuangEngels1994,
  author    = {Suter, H. U. and Huang, M.-B. and Engels, Bernd},
  title     = {A Multireference Configuration Interaction Study of the Hyperfine Structure of the Molecules CCO, CNN and NCN in their triplet ground states},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59108},
  year      = {1994},
  abstract  = {The hyperfine structures of the isoelectronic molecules CCO. CNN, and NCN in their triplet ground states (X\(^3 \sum ^-\)) are investigated by means of ab initio methods. The infrared frequencies and geometries are detennined and compared with experiment. Configuration selected multireference configuration interaction calculations in combination with perturbation theory to correct the wave function (MRD-CI/B\(_K\)) employing extended atomic orbital (AO) basis sets yielded very accurate hyperfine properties. The theoretical values for CCO are in excellent agreement with the experimental values determined by Smith and Weltner [J. Chem. Phys. 62,4592 (1975)]. For CNN, the first assignment of Smith and Weltner for the two nitrogen atoms has to be changed. A qualitative discussion of the electronic structure discloses no simple relation between the structure of the singly occupied orbitals and the measured hyperfine coupling constants. Vibrational effects were found to be of little importance.},
  subject      = {Organische Chemie},
  language  = {en}
}
@article{SuterEngels1994,
  author    = {Suter, H. U. and Engels, Bernd},
  title     = {Theoretical investigation of ESR parameters: H\(_2\)CN and H\(_2\)CO\(^+\)},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59029},
  year      = {1994},
  abstract  = {The hyperfine structure of the two isoelectronic molecules H\(_2\)CN and H\(_2\)CO\(^+\) in their electronic ground state (X\(^2\)B\(_2\)) is studied. The influence of the atomic orbital (AO), basis sets, of the correlation treatment, and of the. equilibrium geometry on the obtained hyperfine propertles 1s - investigated. It is found that the multireference double excitation-configuration interaction (MRD-CI)/ BK treatment in which an MRD-CI wave function is corrected by a modified B\(_K\) method yields equivalent results to quadratic CI [QCISD(T)], coupled cluster single doubles [CCSD(T)), or Brueckner doubled [BD(T)]. Uncertainties in the equilibrium geometries are found to be the major source for discrepancies between theoretically and experimentally determined isotropic hyperfine coupling constants (hfccs). For the heavier centers, the calculated values of the isotropic hfccs agrees nearly perfectly with experimental values (\(\approx\) 1\%-2\%). The calculated values for the hydrogens are too low, but using the equilibrium structure suggested by Yamamoto and Sato [J. Chem. Phys. 96, 4157 ( 1992)], the best estimate deviates by less than 3\%.},
  subject      = {Organische Chemie},
  language  = {en}
}
@phdthesis{Suraru2013,
  author    = {Suraru, Sabin-Lucian},
  title     = {Elektronenarme und kernerweiterte Naphthalindiimide und Diketopyrrolopyrrole f{\"u}r organische D{\"u}nnschichttransistoren},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-87880},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2013},
  abstract  = {Im Rahmen dieser Arbeit wurde gezeigt, dass die elektronischen Eigenschaften und das Packungsverhalten von Naphthalindiimid (NDI)- und Diketopyrrolopyrrol (DPP)- Derivaten durch Einf{\"u}hren geeigneter Substituenten sowie durch Erweiterung des konjugierten Pi-Systems zur Optimierung der Eigenschaften als organische Halbleitermaterialien eingestellt werden k{\"o}nnen. W{\"a}hrend DPP-Halbleiter zwar in Polymeren, nicht jedoch als niedermolekulare Halbleiter, f{\"u}r die organische Elektronik von Bedeutung sind, stellen vor allem die hier vorgestellten cyanierten DPP-Derivate eine synthetisch leicht zug{\"a}ngliche Klasse an niedermolekularen p-Halbleitern mit exzellenten Lochtransporteigenschaften dar. Die Expansion des NDI- und DPP-Kerns er{\"o}ffnet zudem den synthetischen Zugang zu neuen Verbindungsklassen mit ver{\"a}nderten elektronischen Eigenschaften. Gerade das f{\"u}r die Carbazolocarbazoldiimide postulierte Konzept einer elektronenreichen p-Transportachse konnte durch Wahl geeigneter Imidsubstituenten zur Entwicklung zweidimensionaler p-Halbleiter mit sehr guten Mobilit{\"a}ten f{\"u}hren. Schließlich stellen 2,6-kernhalogenierte NDI-Derivate mit fluorierten Imidgruppen aufgrund der herausragenden Elektronenmobilit{\"a}ten und der sehr hohen Luftstabilit{\"a}t außergew{\"o}hnliche Kandidaten f{\"u}r den Einsatz als n-Halbleiter in organischen D{\"u}nnschichttransistoren dar.},
  subject      = {D{\"u}nnschichttransistor},
  language  = {de}
}
@article{SungKimFimmeletal.2015,
  author    = {Sung, Jooyoung and Kim, Pyosang and Fimmel, Benjamin and W{\"u}rthner, Frank and Kim, Dongho},
  title     = {Direct observation of ultrafast coherent exciton dynamics in helical π-stacks of self-assembled perylene bisimides},
  series = {Nature Communications},
  volume    = {6},
  journal   = {Nature Communications},
  number    = {8646},
  doi       = {10.1038/ncomms9646},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148157},
  year      = {2015},
  abstract  = {Ever since the discovery of dye self-assemblies in nature, there have been tremendous efforts to exploit biomimetic supramolecular assemblies for tailored artificial photon processing materials. This feature necessarily has resulted in an increasing demand for understanding exciton dynamics in the dye self-assemblies. In a sharp contrast with pi-type aggregates, however, the detailed observation of exciton dynamics in H-type aggregates has remained challenging. In this study, as we succeed in measuring transient fluorescence from Frenkel state of π-stacked perylene tetracarboxylic acid bisimide dimer and oligomer aggregates, we present an experimental demonstration on Frenkel exciton dynamics of archetypal columnar π-π stacks of dyes. The analysis of the vibronic peak ratio of the transient fluorescence spectra reveals that unlike the simple π-stacked dimer, the photoexcitation energy in the columnar π-stacked oligomer aggregates is initially delocalized over at least three molecular units and moves coherently along the chain in tens of femtoseconds, preceding excimer formation process.},
  language  = {en}
}
@article{SunAnhaltSarosietal.2022,
  author    = {Sun, Meng-Jia and Anhalt, Olga and S{\´a}rosi, Menyh{\´a}rt B. and Stolte, Matthias and W{\"u}rthner, Frank},
  title     = {Activating Organic Phosphorescence via Heavy Metal-π Interaction Induced Intersystem Crossing},
  series = {Advanced Materials},
  volume    = {34},
  journal   = {Advanced Materials},
  number    = {51},
  doi       = {10.1002/adma.202207331},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312248},
  year      = {2022},
  abstract  = {Heavy-atom-containing clusters, nanocrystals, and other semiconductors can sensitize the triplet states of their surface-bonded chromophores, but the energy loss, such as nonradiative deactivation, often prevents the synergistic light emission in their solid-state coassemblies. Cocrystallization allows new combinations of molecules with complementary properties for achieving functionalities not available in single components. Here, the cocrystal formation that employs platinum(II) acetylacetonate (Pt(acac)\(_{2}\)) as a triplet sensitizer and electron-deficient 1,4,5,8-naphthalene diimides (NDIs) as organic phosphors is reported. The hybrid cocrystals exhibit room-temperature phosphorescence confined in the low-lying, long-lived triplet state of NDIs with photoluminescence (PL) quantum yield (Φ\(_{PL}\)) exceeding 25\% and a phosphorescence lifetime (τ\(_{Ph}\)) of 156 µs. This remarkable PL property benefits from the noncovalent electronic and spin-orbital coupling between the constituents.},
  language  = {en}
}
@article{SulimanSunPedersenetal.2016,
  author    = {Suliman, Salwa and Sun, Yang and Pedersen, Torbjorn O. and Xue, Ying and Nickel, Joachim and Waag, Thilo and Finne-Wistrand, Anna and Steinm{\"u}ller-Nethl, Doris and Krueger, Anke and Costea, Daniela E. and Mustafa, Kamal},
  title     = {In vivo host response and degradation of copolymer scaffolds functionalized with nanodiamonds and bone morphogenetic protein 2},
  series = {Advanced Healthcare Materials},
  volume    = {5},
  journal   = {Advanced Healthcare Materials},
  number    = {6},
  doi       = {10.1002/adhm.201500723},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-189764},
  pages     = {730-742},
  year      = {2016},
  abstract  = {The aim is to evaluate the effect of modifying poly[(L-lactide)-co-(epsilon-caprolactone)] scaffolds (PLCL) with nanodiamonds (nDP) or with nDP+physisorbed BMP-2 (nDP+BMP-2) on in vivo host tissue response and degradation. The scaffolds are implanted subcutaneously in Balb/c mice and retrieved after 1, 8, and 27 weeks. Molecular weight analysis shows that modified scaffolds degrade faster than the unmodified. Gene analysis at week 1 shows highest expression of proinflammatory markers around nDP scaffolds; although the presence of inflammatory cells and foreign body giant cells is more prominent around the PLCL. Tissue regeneration markers are highly expressed in the nDP+BMP-2 scaffolds at week 8. A fibrous capsule is detectable by week 8, thinnest around nDP scaffolds and at week 27 thickest around PLCL scaffolds. mRNA levels of ALP, COL1 alpha 2, and ANGPT1 are signifi cantly upregulating in the nDP+BMP-2 scaffolds at week 1 with ectopic bone seen at week 8. Even when almost 90\% of the scaffold is degraded at week 27, nDP are observable at implantation areas without adverse effects. In conclusion, modifying PLCL scaffolds with nDP does not aggravate the host response and physisorbed BMP-2 delivery attenuates infl ammation while lowering the dose of BMP-2 to a relatively safe and economical level.},
  language  = {en}
}
@article{SulimanMustafaKruegeretal.2016,
  author    = {Suliman, Salwa and Mustafa, Kamal and Krueger, Anke and Steinm{\"u}ller-Nethl, Doris and Finne-Wistrand, Anna and Osdal, Tereza and Hamza, Amani O. and Sun, Yang and Parajuli, Himalaya and Waag, Thilo and Nickel, Joachim and Johannessen, Anne Christine and McCormack, Emmet and Costea, Daniela Elena},
  title     = {Nanodiamond modified copolymer scaffolds affects tumour progression of early neoplastic oral keratinocytes},
  series = {Biomaterials},
  volume    = {95},
  journal   = {Biomaterials},
  doi       = {10.1016/j.biomaterials.2016.04.002},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-188287},
  pages     = {11-21},
  year      = {2016},
  abstract  = {This study aimed to evaluate the tumorigenic potential of functionalising poly(LLA-co-CL) scaffolds. The copolymer scaffolds were functionalised with nanodiamonds (nDP) or with nDP and physisorbed BMP-2 (nDP-PHY) to enhance osteoinductivity. Culturing early neoplastic dysplastic keratinocytes (DOK\(^{Luc}\)) on nDP modified scaffolds reduced significantly their subsequent sphere formation ability and decreased significantly the cells' proliferation in the supra-basal layers of in vitro 3D oral neoplastic mucosa (3D-OT) when compared to DOK\(^{Luc}\) previously cultured on nDP-PHY scaffolds. Using an in vivo non-invasive environmentally-induced oral carcinogenesis model, nDP scaffolds were observed to reduce bioluminescence intensity of tumours formed by DOK\(^{Luc}\) + carcinoma associated fibroblasts (CAF). nDP modification was also found to promote differentiation of DOK\(^{Luc}\) both in vitro in 3D-OT and in vivo in xenografts formed by DOKLuc alone. The nDP-PHY scaffold had the highest number of invasive tumours formed by DOK\(^{Luc}\) + CAF outside the scaffold area compared to the nDP and control scaffolds. In conclusion, in vitro and in vivo results presented here demonstrate that nDP modified copolymer scaffolds are able to decrease the tumorigenic potential of DOK\(^{Luc}\), while confirming concerns for the therapeutic use of BMP-2 for reconstruction of bone defects in oral cancer patients due to its tumour promoting capabilities.},
  language  = {en}
}
@phdthesis{Sturm2006,
  author    = {Sturm, Christian},
  title     = {Theoretical Investigation of the Geometrical Arrangements of alpha-alanyl-peptide Nucleic Acid Hexamer Dimers and the Underlying Interstrand Binding Motifs},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-20363},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2006},
  abstract  = {Die Funktionalit{\"a}ten der DNA oder RNA werden haupts{\"a}chlich durch die verschiedenen Wechselwirkungen der paarenden Nucleinbasen bestimmt. Um die komplexen Zusammenh{\"a}nge dieser verschiedenen Wechselwirkungen zu verstehen, werden Modellsysteme ben{\"o}tigt, die weniger Restriktionen durch das R{\"u}ckgrat besitzen. Ein Beispiel f{\"u}r solche Systeme sind Peptidnucleins{\"a}uren (PNA), in denen das Zuckerphosphatr{\"u}ckgrat der DNA oder RNA durch ein Peptidr{\"u}ckgrat ersetzt wird. Diederichsen et al. gelang es, eine große Anzahl solcher Systeme mit einen alpha-Alanyl-R{\"u}ckgrat zu synthetisieren, an das kanonische und nicht-kanonische Nucleins{\"a}uren gebunden sind. Diese Systeme aggregieren in verschiedenen Bindungsmotiven, die nicht in der DNA oder RNA auftauchen. Diese ungew{\"o}hnlichen Paarungsmotive k{\"o}nnten einen tiefen Einblick in das Zusammenspiel der Wechselwirkungen der Nucleinbasen geben, aber die geringen L{\"o}slichkeit der alpha-Alanyl-PNA Oligomere verhinderte eine experimentelle Charakterisierung der geometrischen Anordnung durch R{\"o}ntgenstruktur- oder NMR-Experimente. Lediglich die absolute Stabilit{\"a}t der verschiedenen Aggregate konnte durch Messungen der Schmelztemperatur mit Hilfe der UV-Spektroskopie bestimmt werden. Da die Kenntnis der geometrischen Strukturen sowie der ausgebildeten Bindungsmotive wichtig ist, um einen Einblick in das Zusammenspiel der einzelnen Wechselwirkungen zu erlangen, besteht das Ziel der vorliegenden Arbeit darin, solche Informationen mit der Hilfe von theoretischen Methoden zu erlangen. Zus{\"a}tzlich sind Effekte von Interesse, aus denen sich Trends bez{\"u}glich der Stabilit{\"a}t bestimmen lassen. Solche Untersuchungen sind einfacher zu realisieren als die Berechnung der absoluten Stabilit{\"a}ten, da viele Beitr{\"a}ge zur absoluten Energie f{\"u}r {\"a}hnliche Systeme (entropische und dynamische Effekte) in etwa gleich groß sind. Somit sind diese entropischen und dynamischen Effekte f{\"u}r das Ziel dieser Arbeit weniger wichtig. Zur Untersuchung der Bindungseigenschaften und der Stabilit{\"a}ten von alpha-Alanyl-PNA Oligomeren war es notwendig, bis dato nicht parametrisierte Nucleinbasen in den Parametersatz des Amber4.1 Kraftfelds zu integrieren. Die fehlenden Ladungen wurden durch Berechungen mit dem R.E.D-Programm-Paket ermittelt. Das Programm bestimmt aus dem elektrostatischen Potential einer optimierten Struktur die atomzentrierten Ladungen. Die fehlenden Bindungsparameter wurden der Literatur entnommen. Die Untersuchungen der einzelnen Dimere begannen jeweils mit der Konstruktion der alpha-Alanyl-PNAs f{\"u}r alle m{\"o}glichen Paarungsmodi. Es konnte gezeigt werden, dass bestimmte Paarungsmodi aufgrund der geometrischen Gegebenheiten der Dimere und des R{\"u}ckgrats nicht realisierbar waren. F{\"u}r andere Dimere war ein Aufbau der alpha-Alanyl-PNA-Dimere zwar m{\"o}glich, jedoch zerfielen die Dimere wieder w{\"a}hrend einer ersten Geometrieoptimierung aufgrund der hohen Spannung im R{\"u}ckgrat. Die stabilen Systeme wurden zun{\"a}chst in verschiedenen Molekulardynamik-(MD)-L{\"a}ufen simuliert. Informationen {\"u}ber die Geometrie bei T=0 K wurden durch Geometrieoptimierungen erhalten, die an verschieden Punkten der MD L{\"a}ufe gestartet wurden. Die resultierenden Geometrien aus den verschiedenen Anfangspunkten waren identisch. F{\"u}r die geometrieoptimierten Strukturen wurden f{\"u}r das T=0 K Modell die Wechselwirkungsenergien zwischen den Nucleinbasen und der Einfluss der R{\"u}ckgrats auf die Stabilit{\"a}t der Dimer in zwei separaten Schritten bestimmt. Im ersten Schritt wurde das R{\"u}ckgrat entfernt und die Schnittstellen mit Methylgruppen abges{\"a}ttigt. Die Wechselwirkungsenergie zwischen den Nucleinbasen wurde durch die Differenz der Energien des gesamten Systems und der Summe der Energien der einzelnen Nucleinbasen in der Geometrie des Dimers bestimmt. Aufgrund der durchgef{\"u}hrten Untersuchungen und die sich daraus ergebenen Korrelation der berechneten Stabilisierungsenergien mit der Schmelztemperatur konnte gezeigt werden, dass mit der vorgeschlagenen Methode eine verl{\"a}ssliche Beschreibung der PNA Systeme m{\"o}glich ist. F{\"u}r eine weitere Verbesserung des vorgestellten Modells bedarf es zus{\"a}tzliche R{\"o}ntgenstruktur- oder NMR-Experimente, die zur Strukturaufkl{\"a}rung der alpha-Alanyl-PNA Dimere entscheidend beitragen. Weitere detaillierte Daten {\"u}ber die Enthalpiebeitr{\"a}ge zur absoluten Energie der verschiedenen Komplexe w{\"a}ren sehr hilfreich, um die vorgestellte Methode zu best{\"a}tigen und zu verbessern. Diese Informationen k{\"o}nnten zum einen durch die Auswertung der Form der Schmelzkurve sowie durch Mikrokalorimetrie erhalten werden. F{\"u}r den Fall, dass die Vorhersagen durch die experimentellen Befunde best{\"a}tigt w{\"u}rden, k{\"o}nnte der Ansatz auf verwandte Systeme wie zum Beispiel beta-Alanyl-PNA, DNA oder RNA angewandt werden. Durch diese weiteren Informationen k{\"o}nnte unser Ansatz zus{\"a}tzlich durch die Ber{\"u}cksichtigung von dynamischen und/oder entropischen Effekte erweitert werden.},
  subject      = {Peptid-Nucleins{\"a}uren},
  language  = {en}
}
@article{StolteHechtXieetal.2020,
  author    = {Stolte, Matthias and Hecht, Reinhard and Xie, Zengqi and Liu, Linlin and Kaufmann, Christina and Kudzus, Astrid and Schmidt, David and W{\"u}rthner, Frank},
  title     = {Crystal Engineering of 1D Exciton Systems Composed of Single- and Double-Stranded Perylene Bisimide J-Aggregates},
  series = {Advanced Optical Materials},
  volume    = {8},
  journal   = {Advanced Optical Materials},
  number    = {18},
  doi       = {10.1002/adom.202000926},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218221},
  year      = {2020},
  abstract  = {Single crystals of three at bay area tetraphenoxy-substituted perylene bisimide dyes are grown by vacuum sublimation. X-ray analysis reveals the self-assembly of these highly twisted perylene bisimides (PBIs) in the solid state via imide-imide hydrogen bonding into hydrogen-bonded PBI chains. The crystallographic insights disclose that the conformation and sterical congestion imparted by the phenoxy substituents can be controlled by ortho-substituents. Accordingly, whilst sterically less demanding methyl and isopropyl substituents afford double-stranded PBI chains of complementary P and M atropo-enantiomers, single hydrogen-bonded chains of homochiral PBIs are observed for the sterically more demanding ortho-phenyl substituents. Investigation of the absorption and fluorescence properties of microcrystals and thin films of these PBIs allow for an unambiguous interpretation of these exciton systems. Thus, the J-aggregates of the double-stranded crystals exhibit a much larger (negative) exciton coupling than the single-stranded one, which in contrast has the higher solid-state fluorescence quantum yield.},
  language  = {en}
}
@phdthesis{Stiller2023,
  author    = {Stiller, Carina},
  title     = {Synthesis and applications of modified nucleosides and RNA nucleotides},
  doi       = {10.25972/OPUS-31135},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-311350},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2023},
  abstract  = {As central components of life, DNA and RNA encode the genetic information. However, RNA performs several functions that exceed the competences stated in the 'central dogma of life'. RNAs undergo extensive post-transcriptional processing like chemical modifications. Among all classes of RNA, tRNAs are the most extensively modified. Their modifications are chemically diverse and vary from simple methylations (e.g. m3C, m6A) to more complex residues, like isopentenyl group (e.g. i6A, hypermodifications: e.g. ms2i6A) or even amino acids (e.g. t6A). Depending on their location within the overall structure, modifications can have an impact on tRNA stability and structure, as well as affinity for the ribosome and translation efficiency and fidelity. Given the importance of tRNA modifications new tools are needed for their detection and to study their recognition by proteins and enzymatic transformations. The chemical synthesis of these naturally occurring tRNA modifications as phosphoramidite building blocks is a prerequisite to incorporate the desired modification via solid-phase synthesis into oligonucleotides. With the help of the m3C, (ms2)i6A, and t6A oligonucleotides, the importance and impact of tRNA modifications was investigated in this thesis. To this end, the role of METTL8 as the methyltransferase responsible for the installation of the methyl group at C32 for mt-tRNAThr and mt-tRNASer(UCN) was resolved. Thereby, the respective adenosine modification on position 37 is essential for the effectiveness of the enzyme. Besides, by means of NMR analysis, CD spectroscopy, thermal denaturation experiments, and native page separation, the impact of m3C32 on the structure of the tRNA ASLs was shown. The modification appeared to fine-tune the tRNA structure to optimize mitochondrial translation. To investigate the regulation of the dynamic modification pathway of m3C, demethylation assays were performed with the modified tRNA-ASLs and the (α-KG)- and Fe(II)-dependent dioxygenase ALKBH1 and ALKHB3. A demethylation activity of ALKBH3 on the mt-tRNAs was observed, even though it has so far only been described as a cytoplasmic enzyme. Whether this is physiologically relevant and ALKBH3 present a mitochondrial localization needs further validation. In addition, ALKBH1 was confirmed to not be able to demethylate m3C on mt-tRNAs, but indications for a deprenylation and exonuclease activity were found. Furthermore, the aforementioned naturally occurring modifications were utilized to find analytical tools that can determine the modification levels by DNAzymes, which cleave RNA in the presence of a specific modification. Selective DNA enzymes for i6A, as well as the three cytidine isomers m3C, m4C, and m5C have been identified and characterized. Besides the naturally occurring tRNA modifications, the investigation on artificially modified nucleosides is also part of this thesis. Nucleosides with specific properties for desired applications can be created by modifying the scaffold of native nucleosides. During the pandemic, the potential of antiviral nucleoside analogues was highlighted for the treatment of the SARS-CoV-2 infection. For examinations of the potential drug-candidate Molnupiravir, the N4-hydroxycytidine phosphoramidite building block was synthesized and incorporated into several RNA oligonucleotides. A two-step model for the NHC-induced mutagenesis of SARS-CoV-2 was proposed based on RNA elongation, thermal denaturation, and cryo-EM experiments using the modified RNA strands with the recombinant SARS-CoV-2 RNA-dependent RNA polymerase. Two tautomeric forms of NHC enable base pairing with guanosine in the amino and with adenosine in the imino form, leading to error catastrophe after the incorporation into viral RNA. These findings were further corroborated by thermal melting curve analysis and NMR spectroscopy of the NHC-containing Dickerson Drew sequence. In conclusion, the anti-amino form in the NHC-G base pair was assigned by NMR analysis using a 15N-labeld NHC building block incorporated into the Dickerson Drew sequence. This thesis also addressed the synthesis of a 7-deazaguanosine crosslinker with a masked aldehyde as a diol linker for investigations of DNA-protein interactions. The diol functional group can be unmasked to release the reactive aldehyde, which can specifically form a covalent bond with amino acids Lys or Arg within the protein complex condensin. The incorporation of the synthesized phosphoramidite and triphosphate building blocks were shown and the functionality of the PCR product containing the crosslinker was demonstrated by oxidation and the formation of a covalent bond with a fluorescein label. The development of assays that detect changes in this methylation pattern of m6A could provide new insights into important biological processes. In the last project of this thesis, the influence of RNA methylation states on the structural properties of RNA was analyzed and a fluorescent nucleoside analog (8-vinyladenosine) as molecular tools for such assays was developed. Initial experiments with the fluorescent nucleoside analog N6-methyl-8-vinyladenosine (m6v8A) were performed and revealed a strong fluorescence enhancement of the free m6v8A nucleoside by the installation of the vinyl moiety at position 8. Overall, this thesis contributes to various research topics regarding the application of naturally occurring and artificial nucleoside analogues. Starting with the chemical synthesis of RNA and DNA modifications, this thesis has unveiled several open questions regarding the dynamic (de-)methylation pathway of m3C and the mechanism of action of molnupiravir through in-depth analysis and provided the basis for further investigations of the protein complex condensin, and a new fluorescent nucleoside analog m6v8A.},
  subject      = {Nucleins{\"a}uren},
  language  = {en}
}
@phdthesis{Stepanenko2008,
  author    = {Stepanenko, Vladimir},
  title     = {Self-Assembly of Bay-Substituted Perylene Bisimide by Ligand-Metal Ion Coordination},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-32063},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2008},
  abstract  = {The subject of this thesis is the synthesis and characterization of PBI-based fluorescent metallosupramolecular polymers and cyclic arrays. Terpyridine receptor functionalized PBIs of predesigned geometry have been used as building blocks to construct desired macromolecular structures through metal-ion-directed self-assembly. These metallosupramolecular architectures have been investigated by NMR, UV/Vis and fluorescence spectroscopy, mass spectrometry, and atomic force microscopy.},
  subject      = {Supramolekulare Chemie},
  language  = {en}
}
@phdthesis{Stepanenko2008,
  author    = {Stepanenko, Svetlana},
  title     = {Global Optimization Methods based on Tabu Search},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-30605},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2008},
  abstract  = {This work encompasses three parts. The first part provides a concise review of the most prominent metaheuristic concepts currently available and gives essential preliminaries together with definition of the combinatorial optimization problems. It substantiates the choice of the investigation direction and basis idea of the developed methods. In the second part the new nonlinear global optimization routines based on the TS strategy are described. The new approaches are the Gradient Tabu Search (GTS), the Gradient Only Tabu Search (GOTS), and the Tabu Search with Powell's Algorithm (TSPA). In the last part of the work the GOTS is applied for such chemical optimization problems. The chapter provides a systematic approach how the variables are chosen and the adjustable parameters are set. As test cases the global minimum energy conformation of some amino acids, of two angiotensin converting enzyme (ACE) inhibitors, of 2-acetoxy-N,N,N-trimethylethanaminium, and of a HIV-1 protease inhibitor is determined.},
  subject      = {Tabusuche},
  language  = {en}
}
@unpublished{StennettBissingerGriesbecketal.2019,
  author    = {Stennett, Tom E. and Bissinger, Philipp and Griesbeck, Stefanie and Ullrich, Stefan and Krummenacher, Ivo and Auth, Michael and Sperlich, Andreas and Stolte, Matthias and Radacki, Krzysztof and Yao, Chang-Jiang and W{\"u}rthner, Frank and Steffen, Andreas and Marder, Todd B. and Braunschweig, Holger},
  title     = {Near-Infrared Quadrupolar Chromophores Combining Three-Coordinate Boron-Based Superdonor and Superacceptor Units},
  series = {Angewandte Chemie, International Edition},
  journal   = {Angewandte Chemie, International Edition},
  doi       = {10.1002/anie.201900889},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-180391},
  year      = {2019},
  abstract  = {In this work, two new quadrupolar A-π-D-π-A chromophores have been prepared featuring a strongly electron- donating diborene core and strongly electron-accepting dimesitylboryl F(BMes2) and bis(2,4,6-tris(trifluoromethyl)phenyl)boryl (BMes2) end groups. Analysis of the compounds by NMR spectroscopy, X-ray crystallography, cyclic voltammetry and UV-vis-NIR absorption and emission spectroscopy indicated that the compounds possess extended conjugated π-systems spanning their B4C8 cores. The combination of exceptionally potent π-donor (diborene) and π- acceptor (diarylboryl) groups, both based on trigonal boron, leads to very small HOMO-LUMO gaps, resulting in strong absorption in the near-IR region with maxima in THF at 840 and 1092 nm, respectively, and very high extinction coefficients of ca. 120,000 M-1cm-1. Both molecules also display weak near-IR fluorescence with small Stokes shifts.},
  language  = {en}
}
@article{SteinmetzgerBaeuerleinHoebartner2020,
  author    = {Steinmetzger, Christian and B{\"a}uerlein, Carmen and H{\"o}bartner, Claudia},
  title     = {Supramolecular fluorescence resonance energy transfer in nucleobase-modified fluorogenic RNA aptamers},
  series = {Angewandte Chemie, International Edition},
  volume    = {59},
  journal   = {Angewandte Chemie, International Edition},
  doi       = {10.1002/anie.201916707},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-203084},
  pages     = {6760-6764},
  year      = {2020},
  abstract  = {RNA aptamers form compact tertiary structures and bind their ligands in specific binding sites. Fluorescence-based strategies reveal information on structure and dynamics of RNA aptamers. Here we report the incorporation of the universal emissive nucleobase analog 4-cyanoindole into the fluorogenic RNA aptamer Chili, and its application as a donor for supramolecular FRET to bound ligands DMHBI+ or DMHBO+. The photophysical properties of the new nucleobase-ligand-FRET pair revealed structural restraints for the overall RNA aptamer organization and identified nucleotide positions suitable for FRET-based readout of ligand binding. This strategy is generally suitable for binding site mapping and may also be applied for responsive aptamer devices.},
  language  = {en}
}
@article{SteinmetzgerBessiLenzetal.2019,
  author    = {Steinmetzger, Christian and Bessi, Irene and Lenz, Ann-Kathrin and H{\"o}bartner, Claudia},
  title     = {Structure-fluorescence activation relationships of a large Stokes shift fluorogenic RNA aptamer},
  series = {Nucleic Acids Research},
  journal   = {Nucleic Acids Research},
  doi       = {10.1093/nar/gkz1084/5628921},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-192340},
  pages     = {gkz1084},
  year      = {2019},
  abstract  = {The Chili RNA aptamer is a 52 nt long fluorogen-activating RNA aptamer (FLAP) that confers fluorescence to structurally diverse derivatives of fluorescent protein chromophores. A key feature of Chili is the formation of highly stable complexes with different ligands, which exhibit bright, highly Stokes-shifted fluorescence emission. In this work, we have analyzed the interactions between the Chili RNA and a family of conditionally fluorescent ligands using a variety of spectroscopic, calorimetric and biochemical techniques to reveal key structure - fluorescence activation relationships (SFARs). The ligands under investigation form two categories with emission maxima of ~540 nm or ~590 nm, respectively, and bind with affinities in the nanomolar to low-micromolar range. Isothermal titration calorimetry was used to elucidate the enthalpic and entropic contributions to binding affinity for a cationic ligand that is unique to the Chili aptamer. In addition to fluorescence activation, ligand binding was also observed by NMR spectroscopy, revealing characteristic signals for the formation of a G-quadruplex only upon ligand binding. These data shed light on the molecular features required and responsible for the large Stokes shift and the strong fluorescence enhancement of red and green emitting RNA-chromophore complexes.},
  language  = {en}
}
@phdthesis{Steinmetzger2020,
  author    = {Steinmetzger, Christian},
  title     = {Fluorogenic Aptamers and Fluorescent Nucleoside Analogs as Probes for RNA Structure and Function},
  doi       = {10.25972/OPUS-20760},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-207604},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2020},
  abstract  = {RNA plays a key role in numerous cellular processes beyond the central dogma of molecular biology. Observing and understanding this wealth of functions, discovering new ones and engineering them into purpose-built tools requires a sensitive means of observation. Over the past decade, fluorogenic aptamers have emerged to fill this niche. These short oligonucleotides are generated by in vitro selection to specifically interact with small organic fluorophores and can be utilized as genetically encoded tags for RNAs of interest. The most versatile class of fluorogenic aptamers is based on derivatives of hydroxybenzylidene imidazolone (HBI), a conditional fluorophore mimicking the chromophore structure found in green and red fluorescent proteins. The respective aptamers are well-known by the "vegetable" nomenclature, including Spinach, Broccoli and Corn, and have found numerous applications for studying RNA function in vitro and in cells. Their success, however, is somewhat overshadowed by individual shortcomings such as a propensity for misfolding, dependence on unphysiologically high concentrations of magnesium ions or, in the case of Corn, dimerization that might affect the function of the tagged RNA. Moreover, most fluorogenic aptamers exhibit limited ligand promiscuity by design, thereby restricting their potential for spectral tuning to a narrow window of wavelengths. This thesis details the characterization of a new fluorogenic aptamer system nicknamed Chili. Chili is derived from an aptamer that was originally selected to bind 4-hydroxy-3,5-dimethoxy¬hydroxy-benzylidene imidazolone (DMHBI), resulting in a green fluorescent complex. Unlike other aptamers of its kind, Chili engages in a proton transfer cycle with the bound ligand, resulting in a remarkably large Stokes shift of more than 130 nm. By means of an empirical ligand optimization approach, several new DMHBI derivatives were found that bind to Chili with high affinity, furnishing complexes up to 7.5 times brighter compared to the parent ligand. In addition, Chili binds to π-extended DMHBI derivatives that confer fluorescence in the yellow-red region of the visible spectrum. The highest affinity and degree of fluorescence turn-on for both green and red fluorogenic ligands were achieved by the incorporation of a unique, positively charged substituent into the HBI scaffold. Supplemented by NMR spectroscopy, kinetic and thermodynamic studies showed that the binding site of Chili is loosely preorganized in the absence of ligand and likely forms a G-quadruplex upon ligand binding. To showcase future applications, Chili was incorporated into a FRET sensor for monitoring the cleavage of an RNA substrate by a 10-23 DNAzyme. Besides aptamers as macromolecular fluorescent complexes, fluorescent nucleobase analogs are powerful small isomorphic components of RNA suitable for studying structure and folding. Here, the highly emissive nucleobase analog 4-cyanoindole (4CI) was developed into a ribonucleoside (r4CI) for this purpose. A new phosphoramidite building block was synthesized to enable site-specific incorporation of 4CI into RNA. Thermal denaturation experiments confirmed that 4CI behaves as a universal nucleobase, i.e. without bias towards any particular hybridization partner. Photophysical characterization established r4CI as a generally useful fluorescent ribonucleoside analog. In this work, it was employed to gain further insight into the structure of the Chili aptamer. Using several 4CI-modified Chili-HBI complexes, a novel base-ligand FRET assay was established to obtain a set of combined distance and orientation restraints for the tertiary structure of the aptamer. In addition to their utility for interrogating structure and binding, supramolecular FRET pairs comprising a fluorescent nucleobase analog donor and an innately fluorogenic acceptor hold great promise for the construction of color-switchable RNA aptamer sensor devices.},
  subject      = {Aptamer},
  language  = {en}
}
@phdthesis{Steinert2015,
  author    = {Steinert, Claudia},
  title     = {Detektion, Isolierung und Strukturaufkl{\"a}rung von Sekund{\"a}rmetaboliten aus Ancistrocladus congolensis und Arabidopsis thaliana},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-117656},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2015},
  abstract  = {Die Produktion von Abwehr-, Signal- und Botenstoffen sichert vielen Pflanzen und Mikroorganismen das {\"U}berleben in einer sich st{\"a}ndig wandelnden Umwelt mit zahlreichen Konkurrenten und Feinden. Diese Sekund{\"a}rmetabolite k{\"o}nnen oft medikament{\"o}s gegen Pathogene eingesetzt werden, die den Menschen befallen und Krankheiten verursachen. Die Herausforderung besteht dabei in der selektiven und sensitiven Detektion, der schonenden Isolierung und der richtigen und kompletten Strukturaufkl{\"a}rung dieser Molek{\"u}le, sowie der eventuellen synthetischen Modifikation, um eine bessere Vertr{\"a}glichkeit oder Wirkung f{\"u}r den menschlichen K{\"o}rper zu erreichen. Leistungsf{\"a}hige chromatographische Instrumente zur Trennung wie HPLC und CZE, emfindliche Detektoren wie UV- und Massenspektrometer, sowie aussagekr{\"a}ftige Messverfahren zur Charakterisierung struktureller Merkmale wie NMR- und CD-Spektroskopie und quantenchemische Rechnungen sind dabei von essentieller Bedeutung. Mit diesen - und weiteren - Methoden gelang in der vorliegenden Arbeit die Detektion, Isolierung und Strukturaufkl{\"a}rung neuer Naphthylisochinolin-Alkaloide aus zwei tropischen Ancistrocladus-Lianen, die Charakterisierung von bekannten und neuen Polyketiden aus einem Pilz der Gattung Streptomyces, sowie die Analyse von Glucosinolaten im Phloemsaft der Modellpflanze Arabidopsis thaliana.},
  subject      = {Ancistrocladaceae},
  language  = {de}
}
@phdthesis{Steiner2010,
  author    = {Steiner, Melanie},
  title     = {Chirale 9-Oxabispidine - Design, enantioselektive Darstellung und Anwendung in der asymmetrischen Synthese},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-51909},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2010},
  abstract  = {Der bekannteste Vertreter der Bispidine ist das Lupinenalkaloid (-)-Spartein, das vor allem in enantioselektiven Deprotonierungen aber auch {\"U}bergangsmetall-katalysierten asymmetrischen Reaktionen als Ligand der Wahl eingesetzt wird. Daneben gibt es nur wenige weitere synthetische Vertreter, da keine flexiblen Darstellungsmethoden zu enantiomerenreinen Bispidinen mit variablen Substituenten in 2-endo-Position existieren. Ein zielgerichtetes Design solcher Verbindungen war daher bisher nur eingeschr{\"a}nkt m{\"o}glich. So sollte in dieser Arbeit eine neue Substanzklasse als chirale Liganden in der asymmetrischen Synthese etabliert werden: 2-endo-substituierte 9-Oxabispidine. Das Br{\"u}cken-Sauerstoffatom sollte die Synthese stark vereinfachen. Insgesamt wurden drei strategisch unterschiedliche Methoden zur enantioselektiven Synthese von 2-endo-substituierten 9-Oxabispidinen entwickelt. Zun{\"a}chst ist die sehr kurze Route zu 2-endo-Phenyl-substituierten Derivaten mit diversen Resten R' an den Stickstoff-Funktionen zu nennen. Ausgehend von k{\"a}uflichem (R,R)-Phenylglycidol wurde (S,S)-3-Benzylamino-3-phenyl-1,2-propandiol dargestellt, das in einer Dreistufen-Eintopf-Reaktion mit (S)-Epichlorhydrin kondensiert und zum all-cis-konfigurierten 2,6-Dimesyloxymethyl-3-phenylmorpholin mesyliert wurde. Die finale Cylisierung erfolgte mit prim{\"a}ren Aminen zu verschiedenen 2-endo-Phenyl-9-oxabispidinen in insgesamt drei bis f{\"u}nf Stufen. Die Darstellung des tricyclischen 9-Oxa-Derivats eines bekannten (+)-Spartein-Ersatzstoffs gelang nach einem verwandten Syntheseprotokoll. F{\"u}r eine effiziente Variation des 2-endo-Substituenten auf einer sp{\"a}ten Synthesestufe wurde zun{\"a}chst enantiomerenreines 3N-Boc-7N-Methyl-9-oxabispidin-2-on als Schl{\"u}sselintermediat ausgew{\"a}hlt, das aus (R)-Epichlorhydrin und racemischem Glycids{\"a}uremethylester dargestellt wurde. Die weitere {\"U}berf{\"u}hrung in die 9-Oxabispidine wurde durch Grignard-Addition, Abspaltung der N-Boc-Gruppe vom resultierenden, ringoffenen N-Boc-Aminoketon, Cyclisierung zum Imin und abschließende, exo-selektive Reduktion oder Hydrierung erreicht. So wurden bi- und tricyclische 9-Oxabispidine in nur drei Stufen und 51\% Ausbeute synthetisiert. Ein gr{\"o}ßeres Potenzial besitzt jedoch der prim{\"a}r von David Hein parallel zu den eigenen Arbeiten entwickelte Zugang {\"u}ber ein cis-konfiguriertes 6-(N-Boc-Aminomethyl)morpholin-2-carbonitril als zentrale Zwischenstufe, das auch im 10-g-Maßstab problemlos erh{\"a}ltlich war. Die allgemeine Anwendbarkeit und Flexibilit{\"a}t dieser Methode wurde anhand der Darstellung einer Reihe an 9-Oxabispidinen demonstriert. Die dargestellten chiralen 9-Oxabispidine wurden erstmalig in den folgenden f{\"u}nf unterschiedlichen Gebieten der asymmetrischen Synthese getestet: Organolithium- und Organomagnesium-vermittelte Umsetzungen sowie Pd(II)-, Cu(II) und Zink(II)-katalysierte Reaktionen. F{\"u}r enantioselektive Deprotonierungen schwach C-H-acider Verbindungen mit sBuLi erwiesen sich die 9-Oxabispidine als ungeeignet, da sie selbst in Br{\"u}ckenkopfposition lithiiert wurden. Die Stabilit{\"a}t der resultierenden -Lithioether war unerwartet hoch; sie ließen sich beispielsweise bei -78 °C in guten Ausbeuten mit Elektrophilen abfangen. Umlagerungen traten erst beim Aufw{\"a}rmen ein, wenn kein Elektrophil als Reaktionspartner zur Verf{\"u}gung stand. Als definierte Produkte wurden dabei Ring-kontrahierte N,O-Acetale erhalten. Zusammen mit den weniger basischen Grignard-Reagenzien wurden die 9-Oxabispidine erfolgreich zur Desymmetrisierung von meso-Anhydriden verwendet. Bei Pd(II)-katalysierten oxidativen kinetischen Racematspaltungen sekund{\"a}rer Alkohole konnten mit einem 9-Oxabispidin-Pd(II)-Katalysator Selektivit{\"a}tsfaktoren s vergleichbar zu denen mit (-)-Spartein erzielt werden. Die Ursache f{\"u}r die geringere Reaktivit{\"a}t der 9-Oxabispidin-Komplexe liegt gem{\"a}ß quantenchemischen Berechnungen in der Elektronegativit{\"a}t des Br{\"u}cken-Sauerstoffatoms, was die Elektronendichte am Palladiumatom verringert. In Kooperation mit David Hein wurde ein von einem tricyclischen 9-Oxabispidin abgeleiteter Cu-Katalysator entwickelt, der bei der Addition von Nitromethan an zahreiche aromatische, heteroaromatische und aliphatische Aldehyde exzellente Enantioselektivit{\"a}ten im Bereich von 91-97\% lieferte. Mit bicyclischen, 2-endo-substituierten 9-Oxabispidinen als chiralen Liganden wurden hingegen lediglich 33-57\% ee erreicht  bemerkenswerterweise entstanden hierbei bevorzugt die enantiokomplement{\"a}ren β-Nitroalkohole. In Zusammenarbeit mit Janna B{\"o}rner aus der Arbeitsgruppe von S. Herres-Pawlis wurde der erste chirale, neutrale Diamin-Zink(II)-Katalysator f{\"u}r die Ring{\"o}ffnungs-Polymerisation von D,L-Lactid entwickelt. Die Reaktion ben{\"o}tigte kein weiteres anionisches Additiv und konnte ohne L{\"o}sungsmittel mit nicht-aufgereinigtem, k{\"a}uflichem Lactid durchgef{\"u}hrt werden.},
  subject      = {Bispidinderivate},
  language  = {de}
}
@phdthesis{Steeger2015,
  author    = {Steeger, Markus},
  title     = {Energy and Charge Transfer in Donor-Acceptor Substituted Hexaarylbenzenes},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-112520},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2015},
  abstract  = {The focus of this work was the investigation of energy transfer between charge transfer states. For this purpose the multidimensional chromophores HAB-S, HAB-A, B1 and B2 were synthesised, each consisting of three electron donor and three electron acceptor redox centres linked symmetrically or asymmetrically by the hexaarylbenzene framework. Triarylamines represent in all these compounds the electron donors, whereas the electron poor centres were triarylboranes in B1 and B2 and PCTM centres in HAB-S and HAB-A, respectively. The hexaarylbenzenes were obtained by cobalt catalysed cyclotrimerisation of the respective tolan precursors. In addition, Star was synthesised, which consists of a central PCTM linked to three triarylamin centres by tolan bridging units in a star-like configuration. The hexaarylbenzene S1a/b substituted with six squaraine chromophores could not be realised. It is assumed that the cyclotrimerisation catalyst Co2(CO)8 does not tolerate the essential hydroxyl groups in the tolan precursor S2a. The alternative reaction pathway to execute the cyclotrimerisation reaction first and introduce the hydroxyl groups thereafter failed as well, because the required hexaarylbenzene substituted by six semisquaric acid moieties could not be synthesised. However, energy transfer interactions could be investigated in the tolan precursor S2a with two squaraine units to obtain information about the electronic coupling provided by the tolan bridge. For all multidimensional compounds model molecules were synthesised with only a single donor-acceptor pair (B3, Star-Model and HAB-Model). This allows a separate consideration of energy and charge transfer processes. It has to be stressed that in all before mentioned multidimensional compounds the "through bond" energy transfer interaction between neighbouring IV-CT states is identical to a transfer of a single electron between two redox centres of the same kind (e.g. TAA -> TAA+). The latter can be analysed by electron transfer theory. This situation is observed when the two IV-CT states transferring energy share one redox centre. All compounds containing PCTM centres were characterised by paramagnetic resonance spectroscopy. Thereby, a weak interaction between the three PCTM units in HAB-S and HAB-A was observed. In addition, when oxidising Star-Model, a strongly interacting singlet or triplet state was obtained. In contrast, signals corresponding to a weakly interacting biradical were obtained for HAB-Model+. This indicates a strong electronic coupling between the redox centres provided by the tolan bridge and a weak coupling when linked by the hexaarylbenzene. This trend is supported by UV/Vis/NIR absorption measurements. The analysis of the observed IV-CT absorption bands by electron transfer theory reveals a weak electronic coupling of V = 340 cm-1 in HAB-Model and a distinctly stronger coupling of V = 1190-2900 cm-1 in Star-Model. In the oxidised HAB-S+, Star+ and Star-Model+ a charge transfer reversed from that of the neutral species, that is, from the PCTM radical to the electron poorer cationic TAA centre, was observed by spectroelectrochemistry. The temporal evolution of the excited states was monitored by ultrafast transient absorption measurements. Within the first picosecond stabilisation of the charge transfer state was observed, induced by solvent rotation. Anisotropic transient absorption measurements revealed that within the lifetime of the excited state (tau = 1-4 ps) energy transfer does not occur in the HABs whereas in the star-like system ultrafast and possibly coherent energy redistribution is observed. Taken this information together the identity between energy transfer and electron transfer in the specific systems were made apparent. It has to be remarked that neither energy transfer nor charge transfer theory can account for the very fast energy transfer in Star. The electrochemical and photophysical properties of B1 and B2 were investigated by cyclic voltammetry, absorption and fluorescence measurements and were compared to B3 with only one neighbouring donor-acceptor pair. For the asymmetric B2 CV measurements show three oxidations as well as three reduction peaks whose peak separation is greatly influenced by the conducting salt due to ion-pairing and shielding effects. Consequently, peak separations cannot be interpreted in terms of electronic couplings in the generated mixed valence species. Transient absorption, fluorescence solvatochromism and absorption spectra show that charge transfer states from the amine to the boron centres are generated after optical excitation. The electronic donor-acceptor interaction is weak though as the charge transfer has to occur predominantly through space. The electronic coupling could not be quantified as the CT absorption band is superimposed by pi-pi* transitions localised at the amine and borane centres. However, this trend is in good agreement to the weak coupling measured for HAB-Model. Both transient absorption and fluorescence upconversion measurements indicate an ultrafast stabilisation of the charge transfer state in B1- B3 similar to the corresponding observations in HAB-S and Star. Moreover, the excitation energy of the localised excited charge transfer states can be redistributed between the aryl substituents of these multidimensional chromophores within fluorescence lifetime (ca. 60 ns). This was proved by steady state fluorescence anisotropy measurements, which further indicate a symmetry breaking in the superficially symmetric HAB. Anisotropic fluorescence upconversion measurements confirm this finding and reveal a time constant of tau = 2-3 ps for the energy transfer in B1 and B2. It has to be stressed that, although the geometric structures of B1 and HAB-S are both based on the same framework and furthermore the neighbouring CT states show in both cases similar Coulomb couplings and negligible "through bond" couplings, very fast energy transfer is observed in B1 whereas in HAB-S the energy is not redistributed within the excited state lifetime. To explain this, it has to be kept in mind that the energy transfer and the relaxation of the CT state are competing processes. The latter is influenced moreover by the solvent viscosity. Hence, it is assumed that this discrepancy in energy transfer behaviour is caused by monitoring the excited state in solvents of varying viscosity. Adding fluoride ions causes the boron centres to lose their acceptor ability due to complexation. Consequently, the charge transfer character in the donor-acceptor chromophores vanishes which could be observed in both the absorption and fluorescence spectra. However, the fluoride sensor ability of the boron centre is influenced strongly by the moisture content of the solvent possibly due to hydrogen bonding of water to the fluoride anions. UV/Vis/NIR absorption measurements of S2a show a red-shift by 1800 cm-1 of the characteristic squarain band compared to the model compound S20. From exciton theory a Coulomb coupling of V = 410 cm-1 is calculated which cannot account for this strong spectral shift. Consequently, "through-bond" interactions have to contribute to the strong communication between the two squaraine chromophores in S2a. This is in accordance with the strong charge transfer coupling calculated for the tolan spacer in Star-Model.},
  subject      = {Energietransfer <Mikrophysik>},
  language  = {en}
}
@article{StanglJelinekFinkChristl1992,
  author    = {Stangl, R. and Jelinek-Fink, H. and Christl, Manfred},
  title     = {Darstellung phenylsubstituierter Derivate des Tricyclo[4.1.0.0\(^{2,7}\)]heptans und des 1,2,3,4-Tetrahydro-1,2,3-methenonaphthalins},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-58610},
  year      = {1992},
  abstract  = {No abstract available},
  subject      = {Organische Chemie},
  language  = {de}
}
@article{StaikovaPericEngelsetal.1994,
  author    = {Staikova, M. and Peric, M. and Engels, Bernd and Peyerimhoff, S. D.},
  title     = {Ab initio Investigation of the Structure of the X\(^2\)A', A\(^2\)A'' (1\(^2\)Π) Spectral System of HCO: Investigation of the Magnetic Hyperfine Effects},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59089},
  year      = {1994},
  abstract  = {Results ofan ab initio study ofthe hyperfine structure of the X\(^2\)A', A\(^2\) A" ( 1\(^2 \Pi\)) system ofthe formyl radical are presented. Special attention is paid to the analysis of the interplay between the vibronic and magnetic hyperfine etfects. The results of computations are in very good agreement with the available experimental findings. The values for the hyperfine coupling constants in lower bending Ievels of both electronic species are predicted.},
  subject      = {Organische Chemie},
  language  = {en}
}
@article{StaikovaEngelsPericetal.1993,
  author    = {Staikova, M. and Engels, Bernd and Peric, M. and Peyerimhoff, S. D.},
  title     = {Ab initio calculation of the vibronically averaged hyperfine coupling constants in the two lowest electronic states of H\(_2\)O\(^+\)},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-58998},
  year      = {1993},
  abstract  = {No abstract available},
  subject      = {Organische Chemie},
  language  = {en}
}
@article{StaikovaEngelsPeric1994,
  author    = {Staikova, M. and Engels, Bernd and Peric, M.},
  title     = {Ab initio investigation of the hyperfine structure in the 1\(^2\)Π\(_u\)(X\(^2\)A\(_1\), A\(^2\)B\(_1\) system of BH\(_2\))},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59000},
  year      = {1994},
  abstract  = {No abstract available},
  subject      = {Organische Chemie},
  language  = {en}
}
@phdthesis{Stahl2005,
  author    = {Stahl, Rainer},
  title     = {Electroactive Conjugated Polymers as Charge-Transport Materials for Optoelectronic Thin-Film Devices},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-16980},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2005},
  abstract  = {In this work the electrochemical and spectroelectrochemical properties of a series of pi-conjugated organic polymers were studied. The polymers were deposited on platinum electrodes or ITO-coated glass substrates by potentiodynamic electro-polymerisation of the corresponding monomeric precursor molecules. The electro-chemical and photophysical properties of the triarylborane monomers were studied in detail in order to estimate possible influences on the behaviour of the corresponding polymer. The first part of this work aimed at the synthesis and investigation of conjugated donor-acceptor polymers which combine the prerequisites of an OLED within one material: the transport of positive and negative charges and the formation of emissive excited states. With the carbazole-substituted oxadiazoles 1-3 it was shown that on the one hand the carbazole functionality is suitable for enabling the electrochemical polymerisation of the monomers and on the other hand it facilitates reversible p-doping of the resultant polymers. Although n-doping of poly-1-poly-3 is possible due to the electron-deficient oxadiazole rings, it causes the continuous degradation of these electron-acceptor units. Interestingly, this process does not influence the capability of p-doping of the polymers. With respect to its electrochemical and spectroelectrochemical properties the behaviour of the borane polymer poly-4 is absolutely identical with that of the oxadiazole polymers. Moreover, the optical excitation of poly-4 in the solid state leads to the emission of blue-green light which suggests that this polymer might also possess electroluminescent properties. AFM-measurements of poly-4 films on ITO-coated glass substrates revealed, that the film thickness can be controlled to a certain extent by the number of polymerisation redox cycles. It was shown from the electrochemical and photophysical properties of the triarylboranes 4-6 that the pi-pi-interaction between boron and nitrogen atoms is comparably weak in these molecules. This leads to an unexpected ground-state polarisation with a partially positive boron atom and a partially negative nitrogen atom. Moreover, it was found that TAB 4 possesses a lower symmetry than D3 in solution and that excitation energy can be transferred amongst the three subchromophores of 4. By titration experiments it was also demonstrated that TAB 4 can reversibly bind fluoride ions and that the binding event significantly influences the optical absorption characteristics of the chromophore. It can be assumed, that the above mentioned properties, which have a profound influence on the photophysical behaviour of these triarylborane chromophores, also determine the behaviour of the corresponding polymer in a solid state environment. The aim of the second part of this work was the investigation of purely n-conducting materials based on electron-deficient borane and viologen polymers. The corresponding precursor molecules should be polymerised on platinum electrodes by reductive electropolymerisation. However, a reductive polymerisation was not possible for the borane monomer 19 which is thought to be due to a strong localisation of the unpaired electron on the central boron atom of the radical anion. An electropolymerisation of the cyano-substituted bispyridinio-compound 17 failed because of the poor quality of CN- as a leaving group. Thus, a synthesis of the analogous isomer 18 was developed, in which the cyano-substituents were exchanged by the better leaving group Cl-. The viologen polymer poly-18, which can be regarded as an electron-deficient iso-electronic analogue of poly(para-phenylene), was successfully deposited on a platinum electrode by reductive electropolymerisation of 18. Poly-18 can be reversibly n-doped at comparably low potentials; however, at higher potentials the polymer is overcharged and destroyed irreversibly. As the synthetic strategy for 18 allows the variation of both spacer unit and leaving group in the last two steps of the reaction sequence, a series of analogous compounds can be easily synthesised using this route.},
  subject      = {Polymerhalbleiter},
  language  = {en}
}
@article{SpenstYoungWasielewskietal.2016,
  author    = {Spenst, Peter and Young, Ryan M. and Wasielewski, Michael R. and W{\"u}rthner, Frank},
  title     = {Guest and solvent modulated photo-driven charge separation and triplet generation in a perylene bisimide cyclophane},
  series = {Chemical Science},
  volume    = {7},
  journal   = {Chemical Science},
  number    = {8},
  doi       = {10.1039/c6sc01574c},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-191252},
  pages     = {5428-5434},
  year      = {2016},
  abstract  = {Cofacial positioning of two perylene bisimide (PBI) chromophores at a distance of 6.5 angstrom in a cyclophane structure prohibits the otherwise common excimer formation and directs photoexcited singlet state relaxation towards intramolecular symmetry-breaking charge separation (τ\(_{CS}\) = 161 +/- 4 ps) in polar CH\(_2\)Cl\(_2\), which is thermodynamically favored with a Gibbs free energy of ΔG\(_{CS}\) = -0.32 eV. The charges then recombine slowly in τ\(_{CR}\) = 8.90 +/- 0.06 ns to form the PBI triplet excited state, which can be used subsequently to generate singlet oxygen in 27\% quantum yield. This sequence of events is eliminated by dissolving the PBI cyclophane in non-polar toluene, where only excited singlet state decay occurs. In contrast, complexation of electron-rich aromatic hydrocarbons by the host PBI cyclophane followed by photoexcitation of PBI results in ultrafast electron transfer (<10 ps) from the guest to the PBI in CH\(_2\)Cl\(_2\). The rate constants for charge separation and recombination increase as the guest molecules become easier to oxidize, demonstrating that charge separation occurs close to the peak of the Marcus curve and the recombination lies far into the Marcus inverted region.},
  language  = {en}
}
@phdthesis{Spenst2017,
  author    = {Spenst, Peter},
  title     = {Xylylene Bridged Perylene Bisimide Cyclophanes and Macrocycles},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-139015},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2017},
  abstract  = {This work is concerned with the syntheses and photophysical properties of para-xylylene bridged macrocycles nPBI with ring sizes from two to nine PBI units, as well as the complexation of polycyclic aromatic guest compounds. With a reduced but substantial fluorescence quantum yield of 21\% (in CHCl3) the free host 2PBI(4-tBu)4 can be used as a dual fluorescence probe. Upon encapsulation of rather electron-poor guests the fluorescence quenching interactions between the chromophores are prevented, leading to a significant fluorescence enhancement to > 90\% ("turn-on"). On the other hand, the addition of electron-rich guest molecules induces an electron transfer from the guest to the electron-poor PBI chromophores and thus quenches the fluorescence entirely ("turn-off"). The photophysical properties of the host-guest complexes were studied by transient absorption spectroscopy. These measurements revealed that the charge transfer between guest and 2PBI(4-tBu)4 occurs in the "normal region" of the Marcus-parabola with the fastest charge separation rate for perylene. In contrast, the charge recombination back to the PBI ground state lies far in the "inverted region" of the Marcus-parabola. Beside complexation of planar aromatic hydrocarbons into the cavity of the cyclophanes an encapsulation of fullerene into the cyclic trimer 3PBI(4-tBu)4 was observed. 3PBI(4-tBu)4 provides a tube-like structure in which the PBI subunits represent the walls of those tubes. The cavity has the optimal size for hosting fullerenes, with C70 fitting better than C60 and a binding constant that is higher by a factor of 10. TA spectroscopy in toluene that was performed on the C60@3PBI(4-tBu)4 complex revealed two energy transfer processes. The first one comes from the excited PBI to the fullerene, which subsequently populates the triplet state. From the fullerene triplet state a second energy transfer occurs back to the PBI to generate the PBI triplet state. In all cycles that were studied by TA spectroscopy, symmetry-breaking charge separation (SB-CS) was observed in dichloromethane. This process is fastest within the PBI cyclophane 2PBI(4-tBu)4 and slows down for larger cycles, suggesting that the charge separation takes place through space and not through bonds. The charges then recombine to the PBI triplet state via a radical pair intersystem crossing (RP-ISC) mechanism, which could be used to generate singlet oxygen in yields of ~20\%. By changing the solvent to toluene an intramolecular folding of the even-numbered larger cycles was observed that quenches the fluorescence and increases the 0-1 transition band in the absorption spectra. Force field calculations of 4PBI(4-tBu)4 suggested a folding into pairs of dimers, which explains the remarkable odd-even effect with respect to the number of connected PBI chromophores and the resulting alternation in the absorption and fluorescence properties. Thus, the even-numbered macrocycles can fold in a way that all chromophores are in a paired arrangement, while the odd-numbered cycles have open conformations (3PBI(4-tBu)4, 5PBI(4-tBu)4, 7PBI(4-tBu)4) or at least additional unpaired PBI unit (9PBI(4-tBu)4). With these experiments we could for the first time give insights in the interactions between cyclic PBI hosts and aromatic guest molecules. Associated with the encapsulation of guest molecules a variety of possible applications can be envisioned, like fluorescence sensing, chiral recognition and photodynamic therapy by singlet oxygen generation. Particularly, these macrocycles provide photophysical relaxation pathways of PBIs, like charge separation and recombination and triplet state formation that are hardly feasible in monomeric PBI dyes. Furthermore, diverse compound specific features were found, like the odd-even effect in the folding process or the transition of superficial nanostructures of the tetrameric cycle influenced by the AFM tip. The comprehensive properties of these macrocycles provide the basis for further oncoming studies and can serve as an inspiration for the synthesis of new macrocyclic compounds.},
  subject      = {Supramolekulare Chemie},
  language  = {en}
}
@article{SolgerKunzFinketal.2020,
  author    = {Solger, Franziska and Kunz, Tobias C. and Fink, Julian and Paprotka, Kerstin and Pfister, Pauline and Hagen, Franziska and Schumacher, Fabian and Kleuser, Burkhard and Seibel, J{\"u}rgen and Rudel, Thomas},
  title     = {A Role of Sphingosine in the Intracellular Survival of Neisseria gonorrhoeae},
  series = {Frontiers in Cellular and Infection Microbiology},
  volume    = {10},
  journal   = {Frontiers in Cellular and Infection Microbiology},
  issn      = {2235-2988},
  doi       = {10.3389/fcimb.2020.00215},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204111},
  year      = {2020},
  abstract  = {Obligate human pathogenic Neisseria gonorrhoeae are the second most frequent bacterial cause of sexually transmitted diseases. These bacteria invade different mucosal tissues and occasionally disseminate into the bloodstream. Invasion into epithelial cells requires the activation of host cell receptors by the formation of ceramide-rich platforms. Here, we investigated the role of sphingosine in the invasion and intracellular survival of gonococci. Sphingosine exhibited an anti-gonococcal activity in vitro. We used specific sphingosine analogs and click chemistry to visualize sphingosine in infected cells. Sphingosine localized to the membrane of intracellular gonococci. Inhibitor studies and the application of a sphingosine derivative indicated that increased sphingosine levels reduced the intracellular survival of gonococci. We demonstrate here, that sphingosine can target intracellular bacteria and may therefore exert a direct bactericidal effect inside cells.},
  language  = {en}
}
@phdthesis{Smolan2022,
  author    = {Smolan, Willi},
  title     = {Linear Multifunctional PEG-Alternatives for Bioconjugation and Hydrogel Formation},
  doi       = {10.25972/OPUS-27873},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-278734},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {The objective of this thesis was the synthesis and characterisation of two linear multifunctional PEG-alternatives for bioconjugation and hydrogel formation: i) Hydrophilic acrylate based copolymers containing peptide binding units and ii) hydrophilic polyether based copolymers containing different functional groups for a physical crosslinking. In section 3.1 the successful synthesis of water soluble and linear acrylate based polymers containing oligo(ethylene glycol) methyl ether acrylate with either linear thioester functional 2-hydroxyethyl acrylate, thiolactone acrylamide, or vinyl azlactone via the living radical polymerisation technique Reversible Addition Fragmentation Chain Transfer (RAFT) and via free-radical polymerisation is described. The obtained polymers were characterized via GPC, 1H NMR, IR and RAMAN spectroscopy. The RAFT end group was found to be difficult to remove from these short polymer chains and accordingly underwent the undesired side reaction aminolysis with the peptide during the conjugation studies. Besides that, polymers without RAFT end groups did not show any binding of the peptide at the thioester groups, which can be improved in future by using higher reactant concentrations and higher amount of binding units at the polymer. Polymers containing the highly reactive azlactone group showed a peptide binding of 19 \%, but unfortunately this function also underwent spontaneous hydrolysis before the peptide could even be bound. In all cases, oligo(ethylene glycol) methyl ether acrylate was used with a relatively high molecular weight (Mn = 480 Da) was used, which eventually was efficiently shielding the introduced binding units from the added peptide. In future, a shorter monomer with Mn = 300 Da or less or hydrophilic N,N'-dialkyl acrylamide based polymers with less steric hindrance could be used to improve this bioconjugation system. Additionally, the amount of monomers containing peptide binding units in the polymer can be increased and have an additional spacer to achieve higher loading efficiency. The water soluble, linear and short polyether based polymers, so called polyglycidols, were successfully synthesized and modified as described in section 3.2. The obtained polymers were characterized using GPC, 1H NMR, 31P{1H} NMR, IR, and RAMAN spectroscopy. The allyl groups which were present up to 20 \% were used for radical induced thiol-ene chemistry for the introduction of functional groups intended for the formation of the physically crosslinking hydrogels. For the positively charged polymers, first a chloride group had to be introduced for the subsequent nucleophilic substitution with the imidazolium compound. There, degrees of modifications were found in the range 40-97 \% due to the repulsion forces of the charges, decreased concentration of active chloride groups, and limiting solution concentrations of the polymer for this reaction. For the negatively charged polymers, first a protected phosphonamide moiety was introduced with a deprotection step afterwards showing 100 \% conversion for all reactions. Preliminary hydrogel tests did not show a formation of a three-dimensional network of the polymer chains which was attributed to the short backbone length of the used polymers, but the gained knowledge about the synthetic routes for the modification of the polymer was successfully transferred to longer linear polyglycidols. The same applies to the introduction of electron rich and electron poor compounds showing π-π stacking interactions by UV-vis spectroscopy. Finally, long linear polyglycidyl ethers were synthesised successfully up to molecular weights of Mn ~ 30 kDa in section 3.3, which was also proven by GPC, 1H NMR, IR and RAMAN spectroscopy. This applies to the homopolymerisation of ethoxyethyl glycidyl ether, allyl glycidyl ether and their copolymerisation with an amount of the allyl compound ~ 10 \%. Attempts for higher molecular weights up to 100 kDa showed an uncontrolled polymerisation behaviour and eventually can be improved in future by choosing a lower initiation temperature. Also, the allyl side groups were modified via radical induced thiol-ene chemistry to obtain positively charged functionalities via imidazolium moieties (85 \%) and negatively charged functionalities via phosphonamide moieties (100 \%) with quantitative degree of modifications. Hydrogel tests have still shown a remaining solution by using long linear polyglycidols carrying negative charges with long/short linear polyglycidols carrying positive charges. The addition of calcium chloride led to a precipitate of the polymer instead of a three-dimensional network formation representing a too high concentration of ions and therefore shielding water molecules with prevention from dissolving the polymer. These systems can be improved by tuning the polymers structure like longer polymer chains, longer spacer between polymer backbone and charge, and higher amount of functional groups. The objective of the thesis was partly reached containing detailed investigated synthetic routes for the design and characterisation of functional polymers which could be used in future with improvements for bioconjugation and hydrogel formation tests.},
  subject      = {Wasserl{\"o}sliche Polymere},
  language  = {en}
}
@phdthesis{Siewert2021,
  author    = {Siewert, Aaron},
  title     = {Nucleotide analogs as rigid spin labels for DNA and RNA},
  doi       = {10.25972/OPUS-24765},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-247657},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Nucleic acids are one of the important classes of biomolecules together with carbohydrates, proteins and lipids. Both deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are most well known for their respective roles in the storage and expression of genetic information. Over the course of the last decades, nucleic acids with a variety of other functions have been discovered in biological organisms or created artificially. Examples of these functional nucleic acids are riboswitches, aptamers and ribozymes. In order to gain information regarding their function, several analytical methods can be used. Electron paramagnetic resonance (EPR) spectroscopy is one of several techniques which can be used to study nucleic acid structure and dynamics. However, EPR spectroscopy requires unpaired electrons and because nucleic acids themselves are not paramagnetic, the incorporation of spin labels which carry a radical is necessary. Here, three new spin labels for the analysis of nucleic acids by EPR spectroscopy are presented. All of them share two important design features. First, the paramagnetic center is located at a nitroxide, flanked by ethyl groups to prevent nitroxide degradation, for example during solid phase synthesis. Furthermore, they were designed with rigidity as an important quality, in order to be useful for applications like pulsed electron double resonance (PELDOR) spectroscopy, where independent motion of the spin labels relative to the macromolecule has a noticeable negative effect on the precision of the measurements. Benzi-spin is a spin label which differs from most previous examples of rigid spin labels in that rather than being based on a canonical nucleoside, with a specific base pairing partner, it is supposed to be a universal nucleoside which is sufficiently rigid for EPR measurements when placed opposite to a number of different nucleosides. Benzi-spin was successfully incorporated into a 20 nt oligonucleotide and its base pairing behavior with seven different nucleosides was examined by UV/VIS thermal denaturation and continuous wave (CW) EPR experiments. The results show only minor differences between the different nucleosides, thus confirming the ability of benzi-spin to act as a universally applicable spin label. Lumi-spin is derived from lumichrome. It features a rigid scaffold, as well as a free 2'-hydroxy group, which should make it well suited for PELDOR experiments once it is incorporated into RNA oligonucleotides. E{\c{C}}r is based on the {\c{C}} family of spin labels, which contains the most well known rigid spin labels for nucleic acids to this day. It is essentially a version of E{\c{C}}m with a free 2'-hydroxy group. It was converted to triphosphate E{\c{C}}rTP and used for primer extension experiments to test the viability of enzymatic incorporation of rigid spin labels into oligonucleotides as an alternative to solid-phase synthesis. Incorporation into DNA by Therminator III DNA polymerase in both single-nucleotide and full-length primer extensions was achieved. All three of these spin labels represent further additions to the expanding toolbox of EPR spectroscopy on nucleic acids and might prove valuable for future research.},
  subject      = {Nucleins{\"a}uren},
  language  = {en}
}
@article{ShenBialasHechtetal.2021,
  author    = {Shen, Chia-An and Bialas, David and Hecht, Markus and Stepanenko, Vladimir and Sugiyasu, Kazunori and W{\"u}rthner, Frank},
  title     = {Polymorphism in squaraine dye aggregates by self-assembly pathway differentiation: panchromatic tubular dye nanorods versus J-aggregate nanosheets},
  series = {Angewandte Chemie International Edition},
  journal   = {Angewandte Chemie International Edition},
  number    = {21},
  edition   = {60},
  doi       = {10.1002/anie.202102183},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256443},
  pages     = {11949-11958},
  year      = {2021},
  abstract  = {A bis(squaraine) dye equipped with alkyl and oligoethyleneglycol chains was synthesized by connecting two dicyanomethylene substituted squaraine dyes with a phenylene spacer unit. The aggregation behavior of this bis(squaraine) was investigated in non-polar toluene/tetrachloroethane (98:2) solvent mixture, which revealed competing cooperative self-assembly pathways into two supramolecular polymorphs with entirely different packing structures and UV/Vis/NIR absorption properties. The self-assembly pathway can be controlled by the cooling rate from a heated solution of the monomers. For both polymorphs, quasi-equilibrium conditions between monomers and the respective aggregates can be established to derive thermodynamic parameters and insights into the self-assembly mechanisms. AFM measurements revealed a nanosheet structure with a height of 2 nm for the thermodynamically more stable polymorph and a tubular nanorod structure with a helical pitch of 13 nm and a diameter of 5 nm for the kinetically favored polymorph. Together with wide angle X-ray scattering measurements, packing models were derived: the thermodynamic polymorph consists of brick-work type nanosheets that exhibit red-shifted absorption bands as typical for J-aggregates, while the nanorod polymorph consists of eight supramolecular polymer strands of the bis(squaraine) intertwined to form a chimney-type tubular structure. The absorption of this aggregate covers a large spectral range from 550 to 875 nm, which cannot be rationalized by the conventional exciton theory. By applying the Essential States Model and considering intermolecular charge transfer, the aggregate spectrum was adequately reproduced, revealing that the broad absorption spectrum is due to pronounced donor-acceptor overlap within the bis(squaraine) nanorods. The latter is also responsible for the pronounced bathochromic shift observed for the nanosheet structure as a result of the slip-stacked arranged squaraine chromophores.},
  language  = {en}
}
@phdthesis{Shen2021,
  author    = {Shen, Chia-An},
  title     = {Dicyanomethylene Squaraines: Aggregation and G-Quadruplex Complexation},
  doi       = {10.25972/OPUS-24359},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-243599},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Squaraine dyes have attracted more attention in the past decade due to their strong and narrow absorption and fluorescence along with the easily functionalized molecular structure. One successful approach of core functionalization is to replace one oxygen of the squaric carbonyl group with a dicyanomethylene group, which shifts the absorption and emission into the near infrared (NIR) region and at the same time leads to a rigid, planar structure with C2v symmetry. However, such squaraines tend to aggregate cofacially in solution due to dispersion forces and dipole-dipole interactions, usually leading to H-type exciton coupling with undesired blue-shifted spectrum and quenched fluorescence. Therefore, the goal of my research was the design of dicyanomethylene-substituted squaraine dyes that self-assemble into extended aggregates in solution with J-type coupling, in order to retain or even enhance their outstanding optical properties. Toward this goal, bis(squaraine) dyes were envisioned with two squaraine units covalently linked to trigger a slip-stacked packing motif within the aggregates to enable J-type coupling. In my first project, bis(squaraine) dye BisSQ1 was synthesized, in which two dicyanomethylene squaraine chromophores are covalently linked. Concentration and temperature-dependent UV/Vis/NIR spectroscopy experiments reveal that BisSQ1 undergoes cooperative self-assembly resulting in J-type aggregates in a solvent mixture of toluene/1,1,2,2-tetrachloroethane (TCE) (98:2, v/v). The J type exciton coupling is evident from the significantly red shifted absorption maximum at 886 nm and the fluorescence peak at 904 nm. In conclusion, this was a first example to direct squaraine dye aggregation in solution to the more desired slip-stacked packing leading to J-type exciton coupling by simply connecting two dyes in a head-to-tail bis chromophore structure. Connecting two squaraine dyes with an additional phenylene spacer (BisSQ2) leads to two different polymorphs with very distinct absorption spectra upon cooling down a solution of BisSQ2 in a solvent mixture of toluene/TCE (98:2, v/v) with different rates. Accordingly, rapid cooling resulted in rigid helical nanorods with an absorption spectrum showing a panchromatic feature, while slow cooling led to a sheet-like structure with a significant bathochromic shift in the absorption spectrum. It was discovered that the conventional molecular exciton model failed to explain the panchromatic absorption features of the nanorods for the given packing arrangement, therefore more profound theoretical investigations based on the Essential States Model (ESM) were applied to unveil the importance of intermolecular charge transfer (ICT) to adequately describe the panchromatic absorption spectrum. Moreover, the red-shift observed in the spectrum for the sheet-like structure can be assigned to the interplay of Coulomb coupling and ICT-mediated coupling. Furthermore, the same bis-chromophore strategy was adopted for constructing an NIR-II emitter with a bathochromically-shifted spectrum. In chloroform, BisSQ3 exhibits an absorption maximum at 961 nm with a significant bathochromic shift (1020 cm-1) compared to the reference mono-squaraine SQ, indicating intramolecular J-type coupling via head-to-tail arrangement of two squaraine dyes. Moreover, BisSQ3 shows a fluorescence peak at 971 nm with a decent quantum yield of 0.33\%. In less polar toluene, BisSQ3 self-assembles into nanofibers with additional intermolecular J-type coupling, causing a pronounced bathochromic shift with absorption maximum at 1095 nm and a fluorescence peak at 1116 nm. Thus, connecting two quinoline-based squaraines in a head-to-tail fashion leads to not only intra-, but also intermolecular J-type exciton coupling, which serves as a promising strategy to shift the absorption and emission of organic fluorophores into the NIR-II window while retaining decent quantum yields. In conclusion, my research illustrates based on squaraine dyes how a simple modification of the molecular structure can significantly affect the aggregation behavior and further alter the optical properties of dye aggregates. Elongated supramolecular structures based on dicyanomethylene substituted squaraine dyes were successfully established by covalently linking two squaraine units to form a bis-chromophore structure. Then, a simple but efficient general approach was established to direct squaraine dye aggregation in solution to the more desired slip-stacked packing leading to J-type exciton coupling by directly connecting two squaraine dyes in a head-to-tail fashion without spacer units. Moreover, the additional spacer between the squaraine dyes in BisSQ2 allowed different molecular conformations, which leads to two different morphologies depending on the cooling rates for a hot solution. Hence, this is a promising strategy to realize supramolecular polymorphism. In general, it is expected that the concept of constructing J-aggregates by the bis-chromophore approach can be extended to entirely different classes of dyes since J-aggregates possess a variety of features such as spectral shifts into the NIR window, fluorescence enhancement, and light harvesting, which are commonly observed and utilized for numerous fundamental studies and applications. Moreover, the insights on short-range charge transfer coupling for squaraine dyes is considered of relevance for all materials based on alternating donor-acceptor π-systems. The panchromatic spectral feature is in particular crucial for acceptor-donor-acceptor (ADA) dyes, which are currently considered as very promising materials for the development of bulk heterojunction solar cells.},
  subject      = {Squaraine},
  language  = {en}
}
@phdthesis{Shao2012,
  author    = {Shao, Changzhun},
  title     = {Programming Self-assembly: Formation of Discrete Perylene Bisimide Aggregates},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69298},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2012},
  abstract  = {The objective of this thesis focuses on the development of strategies for precise control of perylene bisimide (PBI) self-assembly and the in-depth elucidation of structural and optical features of discrete PBI aggregates by means of NMR and UV/Vis spectroscopy. The strategy for discrete dimer formation of PBIs is based on delicate steric control that distinguishes the two facets of the central perylene surface. The strategy applied in this thesis for accessing discrete PBI quadruple and further oligomeric stacks relies on backbone-directed PBI self-assembly. For this purpose, two tweezer-like PBI dyads bearing the respective rigid backbones, diphenylacetylene (DPA) and diphenylbutydiyne (DPB), were synthesized. The distinct aggregation behavior of these structurally similar PBI dyads can be ascribed to the intramolecular distance between the two PBI chromophores imparted by the DPA and DPB spacers.},
  subject      = {Farbstoff},
  language  = {en}
}
@phdthesis{Shamburger2021,
  author    = {Shamburger, William},
  title     = {Total Synthesis of Mono- and Dimeric Naphthylisoquinoline Alkaloids and Related Analogs},
  doi       = {10.25972/OPUS-25061},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-250612},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Our research group focusses on the isolation, structural elucidation, and synthesis of bioactive natural products, among others, the naphthylisoquinoline alkaloids from tropical lianas. This intriguing class of compounds comprises representatives with activities against, e.g. P. falciparum, the cause of Malaria tropica, against the neglected disease leishmaniasis, and, as discovered more recently, against different types of cancer cells. Based on the high potency of theses extraordinary secondary metabolites, this thesis was devoted to the total synthesis of bioactive natural products and closely related analogs.},
  subject      = {Naphthylisochinolinalkaloide},
  language  = {en}
}
@phdthesis{Seupel2018,
  author    = {Seupel, Raina},
  title     = {Antiinfektive und Antitumorale Naphthylisochinolin-Alkaloide: Isolierung und Strukturaufkl{\"a}rung, Totalsynthese und Untersuchungen zum Wirkmechanismus},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-167950},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {Bedingt durch ihre strukturelle Diversit{\"a}t und biologischen Eigenschaften sind Naturstoffe seit jeher Quelle und Inspiration f{\"u}r Arzneimittel vor allem im therapeutischen Bereich der Onkologie und der Infektionskrankheiten. Ihr einzigartiges pharmakologisches Potenzial wird durch die selektive Interaktion mit einer Vielzahl von Zielmolek{\"u}len hervorgerufen. Aufgrund der zentralen Bedeutung von Naturstoffen in der Entdeckung und Entwicklung von neuen Arzneimitteln sind nach wie vor die Isolierung und Strukturaufkl{\"a}rung, die totalsynthetische Darstellung und Derivatisierung sowie die Identifizierung der Zielmolek{\"u}le und die Aufkl{\"a}rung des Wirkmechanismus dieser nat{\"u}rlichen Wirkstoffe unabdingbar. Die kleine, aber spannende Klasse der Naphthylisochinolin-Alkaloide, die ausschließlich aus den beiden Pflanzenfamilien der Dioncophyllaceae und der Ancistrocladaceae gewonnen werden, zeichnet sich mit ihren mehr als 200 Vertretern nicht nur durch ihre strukturelle Vielfalt aus, sondern zeigt vor allem pharmakologisch interessante Wirksamkeiten. Neben ausgepr{\"a}gten In-vitro-Aktivit{\"a}ten gegen protozoische Erreger wie Leishmanien, Plasmodien und Trypanosomen besitzen die Vertreter dieser einzigartigen Naturstoffklasse nach neuesten Untersuchungen auch vielversprechende antitumorale Aktivit{\"a}ten. F{\"u}r deren Weiterentwicklung zu m{\"o}glichen Arzneistoffen ist es daher unabdingbar, ihr pharmakologisches Potenzial tiefergehend zu untersuchen. Ziel der vorliegenden Dissertation war die Entwicklung totalsynthetischer Zug{\"a}nge zu biologisch interessanten Naphthylisochinolin-Alkaloiden mit Hilfe unterschiedlicher Synthesestrategien. Ebenfalls sollten durch die Darstellung strukturell vereinfachter Derivate sowie markierter Naturstoffe in Zusammenarbeit mit Kooperationspartnern m{\"o}gliche Zielmolek{\"u}le identifiziert und Beitr{\"a}ge zum Wirkmechanismus untersucht werden.},
  subject      = {Naphthylisochinolinalkaloide},
  language  = {de}
}
@phdthesis{Sengupta2011,
  author    = {Sengupta, Sanchita},
  title     = {Bio-inspired Zinc Chlorin Dye Assemblies for Supramolecular Electronics},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-66935},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2011},
  abstract  = {Chlorophylls are the most important pigments owing to their involvement in photosynthesis. They perform multiple functions that arise due to their optical and redox as well as packing properties. Semisynthetic zinc chlorins investigated in this thesis are the counterparts for the natural protein-free bacteriochlorophyll (BChl) c assemblies in light-harvesting (LH) systems in bacterial chlorosomes. The major advantage of the zinc chlorin model compounds over the native BChls lies in their facile semisynthetic accessibility from chlorophyll a (Chl a), their higher chemical stability and the possibility to influence their packing by suitable chemical modifications of peripheral side chains. Whilst the favorable excitonic properties and the suitability of ZnChl and natural BChl c dye aggregates for long distance exciton transport are well documented, charge transport properties of aggregates of semisynthetic ZnChls are hitherto unexplored. The present study involves structural elucidations of aggregates of a variety of semisynthetic zinc chlorin derivatives in solution, in solid state and on surfaces by combination of spectroscopic, crystallographic and microscopic techniques, followed by investigation of charge transport properties and conductivities of these aggregates. Chart 1 shows the different ZnChls synthesized in this work that are functionalized with hydroxy or methoxy substituents at 31 position and contain different substituents at the 172-position benzyl ester functional group. The self-assembly of these dyes is strongly dependent upon their chemical structures. While ZnChls 1a, 2a, 3, which are functionalized with 31-hydroxy group bearing dodecyl and oligoethylene glycol side chains form well-soluble rod aggregates, the corresponding 31-methoxy functionalized counterparts 1b, 2b form stacks in solution and on surfaces. These supramolecular polymers have been studied in detail in Chapter 3 by UV/Vis and circular dichroism (CD) spectroscopy and dynamic light scattering (DLS). These studies provided useful insights into the aggregation process of these two types of aggregates. Whereas 31-hydroxy functionalized ZnChl 1a self-assemble into rod aggregates via an isodesmic mechanism, corresponding stack aggregates of ZnChl 1b are formed by a cooperative nucleation-elongation pathway. Detailed electron microscopic studies such as transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) provided unequivocal evidence for hollow tubular nanostructures of water-soluble 31-hydroxy zinc chlorin 3 aggregates for the first time. The measured tube diameter of ~ 5-6 nm of these aggregates is in excellent agreement with electron microscopy data of BChl c rod aggregates in chlorosomes (Chloroflexus aurantiacus, diameter ~ 5-6 nm) and thus complied with the tubular model postulated by Holzwarth and Schaffner... In concord with their highly organized structures, micrometer-scale one dimensionality, robust nature and efficient charge transport capabilities, these self-assembled ZnChl nanotubular, stack and liquid crystalline assemblies are highly promising for supramolecular electronic applications. Research efforts in utilizing these assemblies for (opto)electronic device fabrication, for instance, in organic field effect transistors, should thus be rewarding in the future...},
  subject      = {Supramolekulare Chemie},
  language  = {en}
}
@phdthesis{Selby2022,
  author    = {Selby, Joshua},
  title     = {Design and Chiroptical Properties of Chirally Substituted Indolenine Squaraine Mono-, Oligo-, and Polymers},
  doi       = {10.25972/OPUS-28206},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-282067},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {A series of monomeric chirally substituted indolenine squaraine monomers were successfully synthesized and utilized for the construction of various oligo- and polymers, in order to study their chiroptical properties in terms of exciton chirality. The quaternary carbon atom at the 3-position of the indolenine subunit, as well as the alkyl side chain attached to the indolenine nitrogen were selected as the most suitable site for chiral functionalization. For the C(3)-chiral derivatives, two synthetic routes depending on the desired substitution at the stereogenic center were established. The chiral side chains were prepared via Evans asymmetric alkylation where the resulting branching point at the 2 position constituted the chiral center. While the chiral substitution only had minor effects on the linear optical properties and geometric structure of the chromophore, all compounds exhibited a distinct and measurable CD signal that correlated with the distance of the chiral center to the central chromophore. Polymers bearing chiral side chains exhibited a solvent- and temperature-dependent helix-coil equilibrium, which was influenced by the type of side chain used. CD spectroscopy revealed the helical conformation to possess a preferred twist sense, and temperature-dependent measurements showed the degree of homohelicity to be nearly complete in certain cases. Furthermore, a CPL signal was able to be obtained for the helical conformer of one polymer. Various (co)oligo- and polymers comprising the C(3)-chiral monomers only displayed a solvent-independent J-type absorption behavior and thus did not form helical conformations in solution. CD spectroscopy revealed a solvent-dependent adoption of quasi-enantiomeric conformers, which was elucidated by quantum chemical TDDFT calculations.},
  subject      = {Squaraine},
  language  = {en}
}
@unpublished{SeitzJungnickelKleiberetal.2024,
  author    = {Seitz, Florian and Jungnickel, Tina and Kleiber, Nicole and Kretschmer, Jens and Dietzsch, Julia and Adelmann, Juliane and Bohnsack, Katherine E. and Bohnsack, Markus T. and H{\"o}bartner, Claudia},
  title     = {Atomic mutagenesis of N\(^6\)-methyladenosine reveals distinct recognition modes by human m\(^6\)A reader and eraser proteins},
  series = {Journal of the American Chemical Society},
  journal   = {Journal of the American Chemical Society},
  doi       = {10.1021/jacs.4c00626},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-352376},
  year      = {2024},
  abstract  = {N\(^6\)-methyladenosine (m\(^6\)A) is an important modified nucleoside in cellular RNA associated with multiple cellular processes and is implicated in diseases. The enzymes associated with the dynamic installation and removal of m\(^6\)A are heavily investigated targets for drug research, which requires detailed knowledge of the recognition modes of m\(^6\)A by proteins. Here, we use atomic mutagenesis of m\(^6\)A to systematically investigate the mechanisms of the two human m\(^6\)A demethylase enzymes FTO and ALKBH5 and the binding modes of YTH reader proteins YTHDF2/DC1/DC2. Atomic mutagenesis refers to atom-specific changes that are introduced by chemical synthesis, such as the replacement of nitrogen by carbon atoms. Synthetic RNA oligonucleotides containing site-specifically incorporated 1-deaza-, 3-deaza-, and 7-deaza-m\(^6\)A nucleosides were prepared by solid-phase synthesis and their RNA binding and demethylation by recombinant proteins were evaluated. We found distinct differences in substrate recognition and transformation and revealed structural preferences for the enzymatic activity. The deaza m\(^6\)A analogues introduced in this work will be useful probes for other proteins in m\(^6\)A research.},
  language  = {en}
}
@phdthesis{Seitz2023,
  author    = {Seitz, Florian},
  title     = {Synthesis, enzymatic recognition and antiviral properties of modified purine nucleosides},
  doi       = {10.25972/OPUS-31323},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-313238},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2023},
  abstract  = {Beyond the four canonical nucleosides as primary building blocks of RNA, posttranscriptional modifications give rise to the epitranscriptome as a second layer of genetic information. In eukaryotic mRNA, the most abundant posttranscriptional modification is N6-methyladenosine (m6A), which is involved in the regulation of cellular processes. Throughout this thesis, the concept of atomic mutagenesis was employed to gain novel mechanistic insights into the substrate recognition by human m6A reader proteins as well as in the oxidative m6A demethylation by human demethylase enzymes. Non-natural m6A atomic mutants featuring distinct steric and electronic properties were synthesized and incorporated into RNA oligonucleotides. Fluorescence anisotropy measurements using these modified oligonucleotides revealed the impact of the atomic mutagenesis on the molecular recognition by the human m6A readers YTHDF2, YTHDC1 and YTHDC2 and allowed to draw conclusions about structural prerequisites for substrate recognition. Furthermore, substrate recognition and demethylation mechanism of the human m6A demethylase enzymes FTO and ALKBH5 were analyzed by HPLC-MS and PAGE-based assays using the modified oligonucleotides synthesized in this work. Modified nucleosides not only expand the genetic alphabet, but are also extensively researched as drug candidates. In this thesis, the antiviral mechanism of the anti-SARS-CoV-2 drug remdesivir was investigated, which causes delayed stalling of the viral RNA-dependent RNA polymerase (RdRp). Novel remdesivir phosphoramidite building blocks were synthesized and used to construct defined RNA-RdRp complexes for subsequent studies by cryogenic electron microscopy (cryo-EM). It was found that the 1'-cyano substituent causes Rem to act as a steric barrier of RdRp translocation. Since this translocation barrier can eventually be overcome by the polymerase, novel derivatives of Rem with potentially improved antiviral properties were designed.},
  subject      = {Nucleins{\"a}uren},
  language  = {en}
}
@article{SeifertShoyamaSchmidtetal.2016,
  author    = {Seifert, Sabine and Shoyama, Kazutaka and Schmidt, David and W{\"u}rthner, Frank},
  title     = {An electron-poor C\(_{64}\) nanographene by palladium-catalyzed cascade C-C bond formation: one-pot synthesis and single-crystal structure analysis},
  series = {Angewandte Chemie-International Edition},
  volume    = {55},
  journal   = {Angewandte Chemie-International Edition},
  number    = {22},
  doi       = {10.1002/anie.201601433},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-188889},
  pages     = {6390-6395},
  year      = {2016},
  abstract  = {Herein, we report the one-pot synthesis of an electron-poor nanographene containing dicarboximide groups at the corners. We efficiently combined palladium-catalyzed Suzuki-Miyaura cross-coupling and dehydrohalogenation to synthesize an extended two-dimensional pi-scaffold of defined size in a single chemical operation starting from N-(2,6-diisopropylphenyl)-4,5-dibromo-1,8-naphthalimide and a tetrasubstituted pyrene boronic acid ester as readily accessible starting materials. The reaction of these precursors under the conditions commonly used for Suzuki-Miyaura cross-coupling afforded a C\(_{64}\) nanographene through the formation of ten C-C bonds in a one-pot process. Single-crystal X-ray analysis unequivocally confirmed the structure of this unique extended aromatic molecule with a planar geometry. The optical and electrochemical properties of this largest ever synthesized planar electron-poor nanographene skeleton were also analyzed.},
  language  = {en}
}
@phdthesis{Seifert2018,
  author    = {Seifert, Sabine},
  title     = {New Electron-Deficient Polycyclic Aromatic Dicarboximides by Palladium-Catalyzed C-C Coupling and Core Halogenation-Cyanation},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-156200},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {The thesis describes the development of new synthetic strategies towards planar nanometer-sized and electron-deficient polycyclic aromatic dicarboximides, which are rather unexplored compared with the large variety of electron-rich polycyclic aromatic hydrocarbons and nanographenes. Thus, new polycyclic aromatic systems containing a different number of dicarboximide groups were designed since this class of compounds has revealed its significance in the past due to a range of desirable molecular properties and its high thermal and photochemical stability. The synthetic concept towards these systems includes different C-C coupling techniques that were combined within coupling cascade reactions. Therefore, this thesis provides new insights into the reactivity of aromatic substrates and elucidates mechanistic aspects of C-C coupling cascade reactions to facilitate the precise design of new and desirable materials based on polycyclic aromatic dicarboximides. Furthermore, structure-property relationships as well as the optical and electrochemical properties were investigated by UV/Vis absorption and fluorescence spectroscopy and cyclic or square wave voltammetry. Insights into the molecular structures in the solid state were obtained by single-crystal X-ray analysis. In subsequent studies, highly electron-deficient perylene bisimides and their reduced species have been investigated in detail. Thus, core-functionalized perylene bisimides were synthesized and UV/Vis absorption spectroscopy, spectroelectrochemistry and cyclic or square wave voltammetry were used to determine their optical properties and the stability of the individual reduced species.},
  subject      = {Kupplungsreaktion},
  language  = {en}
}
@unpublished{SednevMykhailiukChoudhuryetal.2018,
  author    = {Sednev, Maksim V. and Mykhailiuk, Volodymyr and Choudhury, Priyanka and Halang, Julia and Sloan, Katherine E. and Bohnsack, Markus T. and H{\"o}bartner, Claudia},
  title     = {N\(^6\)-methyladenosine-sensitive RNA-cleaving deoxyribozymes},
  series = {Angewandte Chemie, International Edition},
  journal   = {Angewandte Chemie, International Edition},
  doi       = {https://doi.org/10.1002/anie.201808745},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-171753},
  year      = {2018},
  abstract  = {Deoxyribozymes are synthetic enzymes made of DNA that can catalyze the cleavage or formation of phosphodiester bonds and are useful tools for RNA biochemistry. Here we report new RNA-cleaving deoxyribozymes to interrogate the methylation status of target RNAs, thereby providing an alternative method for the biochemical validation of RNA methylation sites containing N\(^6\)-methyladenosine, which is the most wide-spread and extensively investigated natural RNA modification. Using in vitro selection from random DNA, we developed deoxyribozymes that are sensitive to the presence of N\(^6\)-methyladenosine in RNA near the cleavage site. One class of these DNA enzymes shows faster cleavage of methylated RNA, while others are strongly inhibited by the modified nucleotide. The general applicability of the new deoxyribozymes is demonstrated for several examples of natural RNA sequences, including a lncRNA and a set of C/D box snoRNAs, which have been suggested to contain m\(^6\)A as a regulatory element that influences RNA folding and protein binding.},
  language  = {en}
}
@unpublished{SednevLiaqatHoebartner2022,
  author    = {Sednev, Maksim V. and Liaqat, Anam and H{\"o}bartner, Claudia},
  title     = {High-Throughput Activity Profiling of RNA-Cleaving DNA Catalysts by Deoxyribozyme Sequencing (DZ-seq)},
  series = {Journal of the American Chemical Society},
  journal   = {Journal of the American Chemical Society},
  doi       = {10.1021/jacs.1c12489},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-258520},
  year      = {2022},
  abstract  = {RNA-cleaving deoxyribozymes have found broad application as useful tools for RNA biochemistry. However, tedious in vitro selection procedures combined with laborious characterization of individual candidate catalysts hinder the discovery of novel catalytic motifs. Here, we present a new high-throughput sequencing method, DZ-seq, which directly measures activity and localizes cleavage sites of thousands of deoxyribozymes. DZ-seq exploits A-tailing followed by reverse transcription with an oligo-dT primer to capture the cleavage status and sequences of both deoxyribozyme and RNA substrate. We validated DZ-seq by conventional analytical methods and demonstrated its utility by discovery of novel deoxyribozymes that allow for cleaving challenging RNA targets or the analysis of RNA modification states.},
  language  = {en}
}
@phdthesis{Seaf2019,
  author    = {Seaf, Shaimaa Fayez Ali Mohammed},
  title     = {Isolation, structural elucidation, and biological evaluation of Naphthylisoquinoline alkaloids from two African Ancistrocladus species},
  doi       = {10.25972/OPUS-19158},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-191588},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {The indepth metabolic profiling of the crude extracts of two African Ancistrocladus species viz. A. likoko from Central Africa and A. abbreviatus from West Africa, resulted in a total of 87 alkaloids among them 54 new ones. All of the compounds were intensely elucidated by 1D and 2D NMR, HRESIMS, as well as chemical and chiroptical techniques. Among the newly discovered compounds are quinoid naphthylisoquinolines with an ortho-diketone in the naphthalene portion, nor-naphthylisoquinoline alkaloid lacking the always present methyl group at C-1, seco-(ring cleaved) naphthylisoquinolines, and a newly discovered class of natural products called the naphthylisoindolinones. Some of the compounds displayed strong antitumoral activities against human pancreatic cancer cells and leukemia cells in-vitro.},
  subject      = {Naphthylisochinolinalkaloide},
  language  = {en}
}
@article{SchaeferBuehlerHeyeretal.2021,
  author    = {Sch{\"a}fer, Natalie and B{\"u}hler, Michael and Heyer, Lisa and R{\"o}hr, Merle I. S. and Beuerle, Florian},
  title     = {Endohedral Hydrogen Bonding Templates the Formation of a Highly Strained Covalent Organic Cage Compound},
  series = {Chemistry—A European Journal},
  volume    = {27},
  journal   = {Chemistry—A European Journal},
  number    = {19},
  doi       = {10.1002/chem.202005276},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256762},
  pages     = {6077-6085},
  year      = {2021},
  abstract  = {A highly strained covalent organic cage compound was synthesized from hexahydroxy tribenzotriquinacene (TBTQ) and a meta-terphenyl-based diboronic acid with an additional benzoic acid substituent in 2'-position. Usually, a 120° bite angle in the unsubstituted ditopic linker favors the formation of a [4+6] cage assembly. Here, the introduction of the benzoic acid group is shown to lead to a perfectly preorganized circular hydrogen-bonding array in the cavity of a trigonal-bipyramidal [2+3] cage, which energetically overcompensates the additional strain energy caused by the larger mismatch in bite angles for the smaller assembly. The strained cage compound was analyzed by mass spectrometry and \(^{1}\)H, \(^{13}\)C and DOSY NMR spectroscopy. DFT calculations revealed the energetic contribution of the hydrogen-bonding template to the cage stability. Furthermore, molecular dynamics simulations on early intermediates indicate an additional kinetic effect, as hydrogen bonding also preorganizes and rigidifies small oligomers to facilitate the exclusive formation of smaller and more strained macrocycles and cages.},
  language  = {en}
}
@phdthesis{Schaefer2018,
  author    = {Sch{\"a}fer, Julian},
  title     = {Synthesis and Photophysical Investigation of Donor-Acceptor-Substituted meta- and para-Benzene Derivatives},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-155007},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {Im ersten Teil dieser Arbeit wurde die erfolgreiche Synthese einer Serie von bisTriarylamin (bisTAA) Verbindungen vorgestellt. Zum einen wurde das Substitutionmuster an der Benzol Br{\"u}ckeneinheit in Form einer meta- bzw. para-St{\"a}ndigkeit der Redoxzentren (pX bzw. mX), und zum anderen die energetische Lage der Br{\"u}ckeneinheit durch zwei elektronen-schiebende oder ziehende Substituenten X (mit X = OMe, Me, Cl, CN, NO2) in 2,5-Position variiert. Im Falle der meta-Serie wurden auch einige in 4,6-Position substituierte Verbinungen hergestellt (mX46). Die neutral Verbindungen wurden bez{\"u}glich ihrer elektrochemischen und photophysikalischen Eigenschaften untersucht. Durch Oxidation konnten die gemischt valenten (MV), kationischen bisTAA-Verbindungen erzeugt werden. Der thermisch induzierte Lochtransfer (HT) wurde durch temperatur-abh{\"a}ngige ESR-Spektroskopie untersucht. W{\"a}hrend die HT-Rate k und HT-Barriere ΔG in mX unbeeinflusst von den Substituenten X sind, steigen gleichzeitig k und ΔG in der pX-Serie mit zunehmenden Elektonenschub von X an. Diese zun{\"a}chst widerspr{\"u}chliche Beobachtung konnte durch einen ansteigenden Einfluss von L{\"o}sungsmitteleffekten und dadurch resultierend, einer zus{\"a}tzlichen effektiven Barriere erkl{\"a}rt werden. Der optisch induzierte Lochtransfer wurde mittels UV/Vis/NIR-Spektroskopie untersucht. Die pX-Serie zeigte eine Zuhname der elektronischen Kopplung V und dementsprechende eine Abnahme von ΔG, mit Anstieg des elektonenschiebenden Charakters von X. F{\"u}r mX war eine spektroskopische Bestimmung dieser Parameter nicht m{\"o}glich. Die mX46-Serie zeigte ein intermedi{\"a}res Verhalten, wobei MV-Verbindungen mit stark elektronenschiebenden X eine {\"a}hnliche hohe Kopplungen wie pX aufwiesen, was mit Hilfe von DFT-Rechnungen bez{\"u}glich der Molek{\"u}lorbitale erkl{\"a}rt werden konnte. Im zweiten Teil dieser Arbeit wurde die Synthese einer Serie von Verbindungen mit Triarylamin (TAA) als Donor und Naphthalindiimid (NDI) als Akzeptor vorgestellt. Auch hier wurde zum einen das Substitutionmuster an der Benzol-Br{\"u}ckeneinheit in Form einer meta- bzw. para-St{\"a}ndigkeit der Redoxzentren (pXNDI bzw. mXNDI) variieiet und die energetische Lage der durch X (mit X = OMe, Me, Cl, CN, NO2) in 2,5-Position variiert. Außerdem wurde die in 4,6-Position substituierte Verbinungen mOMe46NDI hergestellt. Alle Verbindungen wurden bez{\"u}glich ihrer elektochemischen und photophysikalischen Eigenschaften untersucht. Die Elektronentransferprozesse der Ladungsseparierung (CS) und Ladungsrekombination (CR) dieser Verbindungen sollten mittels transienter Absorptionsspektroskopie (TA) in Toluol untersucht werden. F{\"u}r die Nitroverbindungen p-/mNO2NDI war dies nicht m{\"o}glich, da sich diese unter Bestrahung zersetzten. Die CR von pXNDI waren nicht im ns-Bereich detektierbar, weshalb sich auf die mXNDI-Serie (mit X = OMe-CN) konzentriert wurde. Die CS wurde mittels fs-TA untersucht. Nach optischer Anregung konnte die Bildung eines CS-Zustandes detektiert werden, dessen Bildungsgeschwindigkeit hin zu elektronen-ziehenden Substituenten X steigt. Die CR wurde mit ns-TA untersucht. Sie findet in der Marcus invertierten Region statt und zeichnet sich wird durch ein biexponentialles Abklingverhaten, was durch ein Singulet-Triplett Gleichgewicht im CS-Zustand zustande kommt, aus. Durch Anlegen eines externen Magnetfeldes ließ sich das Abklingverhalten entscheidend ver{\"a}ndern und es konnte eine Singulett-Triplett Aufspaltung nachgewiesen werden. Dieser Befund konnte weiterhin durch Simulation der Abklingkurven best{\"a}tigt werden. In beiden Teilen dieser Arbeit konnte ein entscheidender Einfluss der Benzolbr{\"u}cke auf die auftretenden Ladungstransferprozesse gezeigt werden. F{\"u}r den HT in Grundzustand der MV bisTAA Verbindungen, sowie der ET im angeregten Zustand der Donor-Akzeptor-Verbindungen, wurden die h{\"o}chsten ET-Raten f{\"u}r die para-Serien pX und pXNDI gefunden, w{\"a}hrend die meta-Serien mX und mXNDI deutlch kleine Transferraten aufwiesen. In beiden Studien zeigten die meta46-Verbindungen mX46 und mOMeNDI46 ein intermedi{\"a}res Verhalten, zwischen denen der para- und meta-Verbindungen.},
  subject      = {Synthese},
  language  = {en}
}
@phdthesis{Schwegmann2006,
  author    = {Schwegmann, Michael},
  title     = {Eine molekulare Fliegenfalle zur Erkennung von biologisch relevanten (poly)-anionischen Substraten},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-17829},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2006},
  abstract  = {Im Rahmen dieser Arbeit konnte ein multivalenter Rezeptor auf Basis von Guanidiniocarbonylpyrrolen zur Komplexierung von biologisch relevanten (poly)- anionischen Substraten wie Citrat, Malat und Tatrat dargestellt werden. Der Rezeptor bindet Citrat selbst in Gegenwart eines 1000fachen {\"U}berschusses an NaCl und einem 10fachen {\"U}berschuss an Bis-tris Puffer mit einer hohen Bindungskonstante von KAss = 86000 M-1 in Wasser. Wenn man Rezeptoren auf Metall- und Borons{\"a}urebasis nicht ber{\"u}cksichtigt, handelt es sich nach meinem Wissen um den besten Citrat-Rezeptor, der in der Literatur bisher publiziert ist. Außerdem zeigt der Rezeptor mit einem Faktor von mindestens 8 eine hohe Selektivit{\"a}t f{\"u}r Citrat gegen{\"u}ber anderen biologisch relevanten Dicarboxylaten wie Malat und Tatrat. Mithilfe von Bindungsstudien und Molecular Modeling Rechnungen konnte hergeleitet werden, welchen Einfluss die verschiedenen nicht-kovalenten Wechselwirkungen auf die Bindungskonstante haben. Dabei konnte gezeigt werden, dass Flexibilit{\"a}t, Hydroxy-Funktionen, pi-Stacking und Symmetrie bei den Substraten Einfluss auf die Bindungskonstanten zeigen, wobei vor allem die unpolaren Wechselwirkungen und die zus{\"a}tzliche Hydroxy-Funktionen einen hohen Anteil an der Bindung zu haben scheinen. Neben der selektiven Erkennung von Citrat durch den Rezeptor konnte zus{\"a}tzlich ein Sensorsystem mit Carboxyfluorescein auf Basis eines indicator displacement assays entwickelt werden, mit dem die Anwesenheit von Citrat im Gegensatz zu anderen Carboxylaten mit dem bloßen Auge (naked eye) erkannt werden kann. Neben den Polycarboxylaten zeigt der Rezeptor außerdem noch hohe Bindungskonstanten f{\"u}r polyanionische Zucker. So konnten z.B. f{\"u}r Glucophosphate mit UV-Spektroskopie Bindungskonstanten von KAss = ca. 20000 M-1 in dem sehr polaren L{\"o}semittelgemisch 10 \% DMSO/Wasser (pH = 4, Acetat-Puffer) gefunden werden.},
  subject      = {Supramolekulare Chemie},
  language  = {de}
}
@phdthesis{Schweeberg2019,
  author    = {Schweeberg, Sarah},
  title     = {Biomedizinische Anwendung von Nanodiamant: Untersuchungen zu den Wechselwirkungen mit der biologischen Umgebung und zur gezielten Wirkstofffreisetzung},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-174619},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {Nanodiamant bietet in der Medizin und in der Biologie zahlreiche Anwendungsm{\"o}glichkeiten aufgrund der guten Biokompatibilit{\"a}t und geringen Toxizit{\"a}t. Durch die umfangreichen Funktionalisierungsm{\"o}glichkeiten der Oberfl{\"a}che der nanometergroßen Partikel k{\"o}nnen viele unterschiedliche Wirkstoffe, Rezeptormolek{\"u}le oder Peptidsequenzen angebunden werden ,die zusammen mit Nanodiamant ein anderes, durchaus besseres Wirkprofil aufweisen als der Wirkstoff allein. Ziel dieser Arbeit war die Synthese eines pH-labilen Linkersystems, dass hydroxylhaltige Wirkstoffe kovalent bindet und zusammen mit Nanodiamant in die Zelle, in der ein saurer pH-Wert herrscht, eingeschleust werden. {\"U}ber die {\"A}nderung des pH-Wertes in der Zelle soll der Wirkstoff freigesetzt werden und seine Wirkung entfalten k{\"o}nnen. Weiterhin wurde ein pH-labiles Linkersystem auf der Basis eines Hydrazons hergestellt. {\"U}ber das synthetisierte Hydrazinderivat k{\"o}nnen Wirkstoffe, die {\"u}ber eine Aldehyd- oder Ketonfunktion verf{\"u}gen angebunden werden und pH-labil in der Zelle freigesetzt werden. Zus{\"a}tzlich tr{\"a}gt der Nanodiamant ein kovalent angebundenes Targeting-Molek{\"u}l, welches eine verbesserte Adressierung der Wirkorte gew{\"a}hr¬leisten soll. Die Freisetzung wurde mittels UV-Vis-Spektroskopie detektiert und ausgewertet. Neben der spezifischen Funktionalisierung von Nanodiamant besitzt auch die Interaktion der Nanodiamantpartikel mit biologischen Medien eine besondere Bedeutung f{\"u}r zuk{\"u}nftige biomedizinische Anwendungen. Wenn die Partikeloberfl{\"a}che durch Proteinadsorption gegen{\"u}ber dem Wirkort abgeschirmt wird, so kann der angebundene Wirkstoff gegebenenfalls nicht freigesetzt werden und somit nicht seine Wirkung entfalten und bleibt letztlich ungenutzt. So war es von besonderem Interesse die Wechselwirkungen von Nanodiamant in Humanserum und auch weiteren physiologischen Medien zu untersuchen. Dabei wurden sowohl freie Nanodiamantpartikel als auch solche, die auf klinisch bereits eingesetzten Ger{\"u}stmaterialien im Bereich der Therapie großer Knochendefekte adsorbiert waren, untersucht. Auch wurden die Wechselwirkungen von Nanodiamant mit der physiologischen Umgebung untersucht, die zur Agglomeration der Nanopartikel f{\"u}hren k{\"o}nnen. Es wurde ein unter¬schiedliches Agglomerationsverhalten der Nanodiamanten in w{\"a}ssriger Umgebung verglichen mit Nanodiamanten in physiologischen Medien sowie deren Stabilit{\"a}t im Serum beobachtet. Durch die in dieser Arbeit vorgestellten Untersuchungen konnten wichtige Erkenntnisse zur Wechselwirkung verschieden pr{\"a}parierter und funktionalisierter Nanodiamanten mit physiologisch relevanten Umgebungen sowie zu stimuli-responsiven Wirkstofffreisetzung aus Nanodiamant-Konjugaten gewonnen werden. Zudem wurde mit der Untersuchung der angelagerten Proteine um Nanodiamant ein erster Schritt in Richtung eines umfassenden Verst{\"a}ndnisses der Wechselwirkung dieses Materials mit biologischen Umgebungen unternommen. Auch wenn diese Wechselwirkungen sehr komplex sind, so sind erste Aussagen bez{\"u}glich der Art der angelagerten Proteine m{\"o}glich. Erste Versuche der Stabilisierung von Nanodiamant in physiologischen Medien wurden ebenfalls erfolgreich durchgef{\"u}hrt und zeigen eine effiziente und einfache M{\"o}glichkeit, Nanodiamant in biologischen Medien vor der Agglomeration zu bewahren. Die im Rahmen dieser Arbeit gewonnen Erkenntnisse bez{\"u}glich mehrfacher Funktionalisierungsm{\"o}glichkeiten von Nanodiamant sowie dessen Stabilisierung in physiologischen Medien zeigen die breite Anwendungsm{\"o}glichkeit und das enorme Potential von Nanodiamant im Bereich medizinischer und biologischer Anwendungen auf.},
  subject      = {Nanopartikel},
  language  = {de}
}
@phdthesis{Schulze2016,
  author    = {Schulze, Marcus},
  title     = {Ruthenium Complexes as Water Oxidation Catalysts and Photosensitizers},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-142454},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2016},
  abstract  = {In der vorliegenden Arbeit werden Aspekte der photokatalytischen Wasseroxidationsreaktion behandelt. Der erste Themenschwerpunkt der Dissertation besch{\"a}ftigt sich mit einem supramolekularen Makrozyklus, der drei Rutheniummetallzentren enth{\"a}lt. Dieser neuartige Katalysator zeigt eine sehr hohe katalytische Aktivit{\"a}t und gew{\"a}hrt neue Einblicke in den Mechanismus der Wasseroxidationsreaktion. Des Weiteren wird auf die mit Licht interagierenden Komponenten der photokatalytischen Wasseroxidation eingegangen. Hierbei haben sich azabenz-anellierte Perylenderivate als vielseitige Farbstoffklasse herausgestellt. Die Kombination dieser Farbstoffe mit Metallkomplexen liefert metallorganische Verbindungen, die als Photosensibilisatoren eingesetzt werden k{\"o}nnen.},
  subject      = {Farbstoff},
  language  = {en}
}
@article{SchulzWuerthner2022,
  author    = {Schulz, Alexander and W{\"u}rthner, Frank},
  title     = {Folding-induced fluorescence enhancement in a series of merocyanine hetero-folda-trimers},
  series = {Angewandte Chemie International Edition},
  volume    = {61},
  journal   = {Angewandte Chemie International Edition},
  number    = {2},
  doi       = {10.1002/anie.202114667},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256582},
  year      = {2022},
  abstract  = {Many dyes suffer from fast non-radiative decay pathways, thereby showing only short-lived excited states and weak photoluminescence. Here we show a pronounced fluorescence enhancement for a weakly fluorescent merocyanine (MC) dye by being co-facially stacked to other dyes in hetero-folda-trimer architectures. By means of fluorescence spectroscopy (lifetime, quantum yield) the fluorescence enhancement was explained by the rigidification of the emitting chromophore in the defined foldamer architecture and the presence of a non-forbidden lowest exciton state in H-coupled hetero-aggregates. This folding-induced fluorescence enhancement (FIFE) for specific sequences of π-stacked dyes points at a viable strategy toward improved fluorophores that relates to the approach used by nature in the green fluorescent protein (GFP).},
  language  = {en}
}
@article{SchroerToussaintBachmannetal.2021,
  author    = {Schroer, Guido and Toussaint, Val{\´e}rie and Bachmann, Stephanie and P{\"o}ppler, Ann-Christin and Gierlich, Christian Henning and Delidovich, Irina},
  title     = {Functional Phenylboronate Polymers for the Recovery of Diols, Sugar Alcohols, and Saccharides from Aqueous Solution},
  series = {ChemSusChem},
  volume    = {14},
  journal   = {ChemSusChem},
  number    = {23},
  doi       = {10.1002/cssc.202002887},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-239889},
  pages     = {5207 -- 5215},
  year      = {2021},
  abstract  = {The ongoing transition from fossil to renewable feedstocks demands new efficient processes for an economically viable production of biomass-derived commodities and fine chemicals. Novel energy- and material-efficient product purification and separation will play a crucial role due to altered product and feed composition. The present study comprises the synthesis and tests of cross-linked p-vinylphenylboronate polymers for the separation of 18 diols, sugar alcohols, and saccharides, which can be obtained during biomass processing. The separation was based on molecular recognition, that is, esterification of the phenylboronate with vicinal diols. A correlation of the molecular complexation constant, the polymer swelling, and the maximum adsorption capacity was found. The adsorption curves over time were recorded. Preliminary results on competitive adsorption of binary mixtures showed a high potential for the separation of substrates with significantly different complexation constants. Desorption tests implied easier desorption of substrates that only adsorb on the outer polymer shell.},
  language  = {en}
}
@article{SchreckChristl1987,
  author    = {Schreck, Michael and Christl, Manfred},
  title     = {Generation and Interception of 1-Oxa-3,4-cyclohexadiene},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-31601},
  year      = {1987},
  abstract  = {No abstract available},
  subject      = {Chemie},
  language  = {en}
}
@article{SchreckChristl1987,
  author    = {Schreck, Michael and Christl, Manfred},
  title     = {Freisetzung und Abfangreaktionen von 1-Oxa-3,4-cyclohexadien},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-31597},
  year      = {1987},
  abstract  = {No abstract available},
  subject      = {Chemie},
  language  = {de}
}