@phdthesis{Herok2024, author = {Herok, Christoph}, title = {Quantum Chemical Exploration of Potential Energy Surfaces: Reaction Cycles and Luminescence Phenomena}, doi = {10.25972/OPUS-35218}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-352185}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2024}, abstract = {This work aims at elucidating chemical processes involving homogeneous catalysis and photo-physical relaxation of excited molecules in the solid state. Furthermore, compounds with supposedly small singlet-triplet gaps and therefore biradicaloid character are investigated with respect to their electro-chemical behavior. The work on hydroboration catalysis via a reduced 9,10-diboraanthracene (DBA) was preformed in collaboration with the Wagner group in Frankfurt, more specifically Dr. Sven Prey, who performed all laboratory experiments. The investigation of delayed luminescence properties in arylboronic esters in their solid state was conducted in collaboration with the Marder group in W{\"u}rzburg. The author of this work took part in the synthesis of the investigated compounds while being supervised by Dr. Zhu Wu. The final project was a collaboration with the group of Anukul Jana from Hyderabad, India who provided the experimental data.}, subject = {Simulation}, language = {en} } @article{SchmidtFantuzziKlopfetal.2021, author = {Schmidt, Paul and Fantuzzi, Felipe and Klopf, Jonas and Schr{\"o}der, Niklas B. and Dewhurst, Rian D. and Braunschweig, Holger and Engel, Volker and Engels, Bernd}, title = {Twisting versus delocalization in CAAC- and NHC-stabilized boron-based biradicals: the roles of sterics and electronics}, series = {Chemistry - A European Journal}, volume = {27}, journal = {Chemistry - A European Journal}, number = {16}, doi = {10.1002/chem.202004619}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256636}, pages = {5160-5170}, year = {2021}, abstract = {Twisted boron-based biradicals featuring unsaturated C\(_2\)R\(_2\) (R=Et, Me) bridges and stabilization by cyclic (alkyl)(amino)carbenes (CAACs) were recently prepared. These species show remarkable geometrical and electronic differences with respect to their unbridged counterparts. Herein, a thorough computational investigation on the origin of their distinct electrostructural properties is performed. It is shown that steric effects are mostly responsible for the preference for twisted over planar structures. The ground-state multiplicity of the twisted structure is modulated by the σ framework of the bridge, and different R groups lead to distinct multiplicities. In line with the experimental data, a planar structure driven by delocalization effects is observed as global minimum for R=H. The synthetic elusiveness of C\(_2\)R\(_2\)-bridged systems featuring N-heterocyclic carbenes (NHCs) was also investigated. These results could contribute to the engineering of novel main group biradicals.}, language = {en} } @article{WohlfartHolzgrabe2021, author = {Wohlfart, Jonas and Holzgrabe, Ulrike}, title = {Analysis of histamine and sisomicin in gentamicin: search for the causative agents of adverse effects}, series = {Archiv der Pharmazie}, volume = {354}, journal = {Archiv der Pharmazie}, number = {12}, doi = {10.1002/ardp.202100260}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256596}, year = {2021}, abstract = {In 1998, the aminoglycoside antibiotic gentamicin sulfate caused several cases of deaths in the United States, after the switch from twice- to once-daily application. Endotoxins were discussed as the cause for the adverse effects and sisomicin was identified as the lead impurity; batches containing sisomicin were contaminated with more impurities and were responsible for the fatalities. In 2016, anaphylactic reactions in horses, and later in humans with one fatality, were observed after application of gentamicin sulfate contaminated with histamine. To determine whether histamine was responsible for the 1990s death cases as well, histamine was quantified by means of liquid chromatography-tandem mass spectrometry (LC-MS/MS) in 30 samples of gentamicin sulfate analyzed in previous studies. Furthermore, a relative quantification of sisomicin was performed to check for a correlation between histamine and the lead impurity. A maximum amount of 11.52 ppm histamine was detected, which is below the limit for anaphylactic reactions of 16 ppm, and no correlation of the two impurities was observed. However, the European Medicines Agency recommends a stricter limit with regard to the maximum single dose of gentamicin sulfate to reach a greater gap between the maximum histamine exposition of 4.3 µg and the quantity known to cause hypotension of 7 µg. The low amounts of histamine and the fact that there is no connection with the contamination with sisomicin showed that histamine was not the cause for the death cases in the United States in 1998, and endotoxins remain the most probable explanation.}, language = {en} } @article{OttoFriedrichMadunićetal.2020, author = {Otto, Christoph and Friedrich, Alexandra and Madunić, Ivana Vrhovac and Baumeier, Christian and Schwenk, Robert W. and Karaica, Dean and Germer, Christoph-Thomas and Sch{\"u}rmann, Annette and Sabolić, Ivan and Koepsell, Hermann, Hermann}, title = {Antidiabetic Effects of a Tripeptide That Decreases Abundance of Na\(^+\)-D-glucose Cotransporter SGLT1 in the Brush-Border Membrane of the Small Intestine}, series = {ACS Omega}, volume = {5}, journal = {ACS Omega}, number = {45}, doi = {10.1021/acsomega.0c03844}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-230654}, pages = {29127-29139}, year = {2020}, abstract = {In enterocytes, protein RS1 (RSC1A1) mediates an increase of glucose absorption after ingestion of glucose-rich food via upregulation of Na+-D-glucose cotransporter SGLT1 in the brush-border membrane (BBM). Whereas RS1 decelerates the exocytotic pathway of vesicles containing SGLT1 at low glucose levels between meals, RS1-mediated deceleration is relieved after ingestion of glucose-rich food. Regulation of SGLT1 is mediated by RS1 domain RS1-Reg, in which Gln-Ser-Pro (QSP) is effective. In contrast to QSP and RS1-Reg, Gln-Glu-Pro (QEP) and RS1-Reg with a serine to glutamate exchange in the QSP motif downregulate the abundance of SGLT1 in the BBM at high intracellular glucose concentrations by about 50\%. We investigated whether oral application of QEP improves diabetes in db/db mice and affects the induction of diabetes in New Zealand obese (NZO) mice under glucolipotoxic conditions. After 6-day administration of drinking water containing 5 mM QEP to db/db mice, fasting glucose was decreased, increase of blood glucose in the oral glucose tolerance test was blunted, and insulin sensitivity was increased. When QEP was added for several days to a high fat/high carbohydrate diet that induced diabetes in NZO mice, the increase of random plasma glucose was prevented, accompanied by lower plasma insulin levels. QEP is considered a lead compound for development of new antidiabetic drugs with more rapid cellular uptake. In contrast to SGLT1 inhibitors, QEP-based drugs may be applied in combination with insulin for the treatment of type 1 and type 2 diabetes, decreasing the required insulin amount, and thereby may reduce the risk of hypoglycemia.}, language = {en} } @article{HanftLichtenberg2020, author = {Hanft, Anna and Lichtenberg, Crispin}, title = {Dimerization of 2-[(2-((2-aminophenyl)thio)phenyl)amino]-cyclohepta-2,4,6-trien-1-one through hydrogen bonding, C\(_{19}\)H\(_{16}\)N\(_2\)OS}, series = {Zeitschrift f{\"u}r Kristallographie - New Crystal Structures}, volume = {235}, journal = {Zeitschrift f{\"u}r Kristallographie - New Crystal Structures}, number = {4}, doi = {10.1515/ncrs-2020-0124}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-229482}, pages = {963-966}, year = {2020}, abstract = {C\(_{19}\)H\(_{16}\)N\(_2\)OS, triclinic, P (1) over bar (no. 2), a= 8.1510(3) angstrom, b = 8.8021(3) angstrom, c =11.3953(5) angstrom, alpha =72.546(2)degrees, beta=84.568(2)degrees, gamma =80.760(2)degrees, V =768.86(5) angstrom(3), Z =2, R\(_{gt}\)(F) = 0.0491, WR\(_{ref}\)(F-2) = 0.1494, T =100 K.}, language = {en} } @article{WirthensohnFinze2020, author = {Wirthensohn, Raphael and Finze, Maik}, title = {The crystal structure of trimethylsulfonium tris(trifluoromethylsulfonyl)methanide, C\(_7\)H\(_9\)F\(_9\)O\(_6\)S\(_4\)}, series = {Zeitschrift f{\"u}r Kristallographie - New Crystal Structures}, volume = {236}, journal = {Zeitschrift f{\"u}r Kristallographie - New Crystal Structures}, number = {2}, doi = {10.1515/ncrs-2020-0612}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-231358}, pages = {417-419}, year = {2020}, abstract = {C\(_7\)H\(_9\)F\(_9\)O\(_6\)S\(_4\), orthorhombic, P2\(_1\)2\(_1\)2\(_1\) (no. 19), a = 8.80180(10) {\AA}, b= 10.96580(10) {\AA}, c = 16.91360(10) {\AA},V= 1632.48(3) {\AA}\(^3\), Z= 4, R\(_{gt}\)(F) = 0.0222, wR\(_{ref}\)(F\(^2\)) = 0.0604, T = 100 K.}, language = {en} } @article{FayezFeineisAkeAssietal.2019, author = {Fayez, Shaimaa and Feineis, Doris and Ak{\´e} Assi, Laurent and Seo, Ean-Jeong and Efferth, Thomas and Bringmann, Gerhard}, title = {Ancistrobreveines A-D and related dehydrogenated naphthylisoquinoline alkaloids with antiproliferative activities against leukemia cells, from the West African liana Ancistrocladus abbreviatus}, series = {RSC Advances}, volume = {9}, journal = {RSC Advances}, number = {28}, doi = {10.1039/C9RA03105G}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-201686}, pages = {15738-15748}, year = {2019}, abstract = {A unique series of six biaryl natural products displaying four different coupling types (5,10 , 7,10 , 7,80 , and 5,80) were isolated from the roots of the West African liana Ancistrocladus abbreviatus (Ancistrocladaceae). Although at first sight structurally diverse, these secondary metabolites all have in common that they belong to the rare group of naphthylisoquinoline alkaloids with a fully dehydrogenated isoquinoline portion. Among the African Ancistrocladus species, A. abbreviatus is so far only the second one that was found to produce compounds with such a molecular entity. Here, we report on four new representatives, named ancistrobreveines A-D (12-14, and 6). They were identified along with the two known alkaloids 6-O-methylhamateine (4) and entdioncophylleine A (10). The two latter naphthylisoquinolines had so far only been detected in Ancistrocladus species from Southeast Asia. All of these fully dehydrogenated alkaloids have in common being optically active despite the absence of stereogenic centers, due to the presence of the rotationally hindered biaryl axis as the only element of chirality. Except for ent-dioncophylleine A (10), which lacks an oxygen function at C-6, the ancistrobreveines A-D (12-14, and 6) and 6-O-methylhamateine (4) are 6-oxygenated alkaloids, and are, thus, typical 'Ancistrocladaceae-type' compounds. Ancistrobreveine C (14), is the first - and so far only - example of a 7,80-linked fully dehydrogenated naphthylisoquinoline discovered in nature that is configurationally stable at the biaryl axis. The stereostructures of the new alkaloids were established by spectroscopic (in particular HRESIMS, 1D and 2D NMR) and chiroptical (electronic circular dichroism) methods. Ancistrobreveine C (14) and 6-O-methylhamateine (4) exhibited strong antiproliferative activities against drug-sensitive acute lymphoblastic CCRF-CEM leukemia cells and their multidrugresistant subline, CEM/ADR5000.}, language = {en} } @article{MufusamaFeineisMudogoetal.2019, author = {Mufusama, Jean-Pierre and Feineis, Doris and Mudogo, Virima and Kaiser, Marcel and Brun, Reto and Bringmann, Gerhard}, title = {Antiprotozoal dimeric naphthylisoquinolines, mbandakamines B\(_3\) and B\(_4\), and related 5,8′-coupled monomeric alkaloids, ikelacongolines A-D, from a Congolese Ancistrocladus liana}, series = {RSC Advances}, volume = {9}, journal = {RSC Advances}, number = {21}, doi = {10.1039/C9RA01784D}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-201141}, pages = {12034-12046}, year = {2019}, abstract = {From the leaves of a botanically and phytochemically as yet unexplored Ancistrocladus liana discovered in the rainforests of the Central region of the Democratic Republic of the Congo in the vicinity of the town of Ikela, six new naphthylisoquinoline alkaloids were isolated, viz., two constitutionally unsymmetric dimers, the mbandakamines B\(_3\) (3) and B\(_4\) (4), and four related 5,8′-linked monomeric alkaloids, named ikelacongolines A-D (5a, 5b, 6, and 7). The dimers 3 and 4 are structurally unusual quateraryls comprising two 5,8′-coupled monomers linked via a sterically strongly constrained 6′,1′′-connection between their naphthalene units. These compounds contain seven elements of chirality, four stereogenic centers and three consecutive chiral axes. They were identified along with two known related compounds, the mbandakamines A (1) and B\(_2\) (2), which had so far only been detected in two Ancistrocladus species indigenous to the Northwestern Congo Basin. In addition, five known monomeric alkaloids, previously found in related Central African Ancistrocladus species, were isolated from the here investigated Congolese liana, three of them belonging to the subclass of 5,8′-coupled naphthylisoquinoline alkaloids, whereas two compounds exhibited a less frequently occurring 7,8′-biaryl linkage. The stereostructures of the new alkaloids were established by spectroscopic (in particular HRESIMS, 1D and 2D NMR), chemical (oxidative degradation), and chiroptical (electronic circular dichroism) methods. The mbandakamines B\(_3\) (3) and B\(_4\) (4) displayed pronounced activities in vitro against the malaria parasite Plasmodium falciparum and the pathogen of African sleeping sickness, Trypanosoma brucei rhodesiense.}, language = {en} } @article{KraftStanglKrauseetal.2017, author = {Kraft, Andreas and Stangl, Johannes and Krause, Ana-Maria and M{\"u}ller-Buschbaum, Klaus and Beuerle, Florian}, title = {Supramolecular frameworks based on [60]fullerene hexakisadducts}, series = {Beilstein Journal of Organic Chemistry}, volume = {13}, journal = {Beilstein Journal of Organic Chemistry}, doi = {10.3762/bjoc.13.1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-171996}, pages = {1-9}, year = {2017}, abstract = {[60]Fullerene hexakisadducts possessing 12 carboxylic acid side chains form crystalline hydrogen-bonding frameworks in the solid state. Depending on the length of the linker between the reactive sites and the malonate units, the distance of the [60]fullerene nodes and thereby the spacing of the frameworks can be controlled and for the most elongated derivative, continuous channels are obtained within the structure. Stability, structural integrity and porosity of the material were investigated by powder X-ray diffraction, thermogravimetry and sorption measurements.}, language = {en} } @article{FayezFeineisMudogoetal.2017, author = {Fayez, Shaimaa and Feineis, Doris and Mudogo, Virima and Awale, Suresh and Bringmann, Gerhard}, title = {Ancistrolikokines E-H and related 5,8\('\)-coupled naphthylisoquinoline alkaloids from the Congolese liana \(Ancistrocladus\) \(likoko\) with antiausterity activities against PANC-1 human pancreatic cancer cells}, series = {RSC Advances}, volume = {7}, journal = {RSC Advances}, number = {85}, doi = {10.1039/c7ra11200a}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-172008}, pages = {53740-53751}, year = {2017}, abstract = {A striking feature of the metabolite profile of \(Ancistrocladus\) \(likoko\) (Ancistrocladaceae) is the exclusive production of 5,8\('\)-linked naphthylisoquinoline alkaloids varying in their OMe/OH substitution patterns and in the hydrogenation degree in their isoquinoline portions. Here we present nine new compounds of this coupling type isolated from the twigs of this remarkable Central African liana. Three of them, the ancistrolikokines E (9), E\(_2\) (10), and F (11), are the first 5,8\('\)-linked naphthyldihydroisoquinolines found in nature with \(R\)-configuration at C-3. The fourth new metabolite, ancistrolikokine G (12), is so far the only representative of the 5,8\('\)-coupling type that belongs to the very rare group of alkaloids with a fully dehydrogenated isoquinoline portion. Moreover, five new \(N\)-methylated naphthyltetrahydroisoquinolines, named ancistrolikokines A\(_2\) (13), A\(_3\) (14), C\(_2\) (5), H (15), and H\(_2\) (16) are presented, along with six known 5,8\('\)-linked alkaloids, previously identified in related African \(Ancistrocladus\) species, now found for the first time in \(A.\) \(likoko\). The structural elucidation was achieved by spectroscopic analysis (HRESIMS, 1D and 2D NMR) and by chemical (oxidative degradation) and chiroptical (electronic circular dichroism) methods. The new ancistrolikokines showed moderate to good preferential cytotoxic activities towards pancreatic PANC-1 cells in nutrient-deprived medium (NDM), without causing toxicity under normal, nutrient-rich conditions, with ancistrolikokine H\(_2\) (16) being the most potent compound.}, language = {en} } @article{AeschlimannBrixnerCinchettietal.2017, author = {Aeschlimann, Martin and Brixner, Tobias and Cinchetti, Mirko and Frisch, Benjamin and Hecht, Bert and Hensen, Matthias and Huber, Bernhard and Kramer, Christian and Krauss, Enno and Loeber, Thomas H. and Pfeiffer, Walter and Piecuch, Martin and Thielen, Philip}, title = {Cavity-assisted ultrafast long-range periodic energy transfer between plasmonic nanoantennas}, series = {Light: Science \& Applications}, volume = {6}, journal = {Light: Science \& Applications}, doi = {10.1038/lsa.2017.111}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-173265}, year = {2017}, abstract = {Radiationless energy transfer is at the core of diverse phenomena, such as light harvesting in photosynthesis\(^1\), energy-transfer-based microspectroscopies\(^2\), nanoscale quantum entanglement\(^3\) and photonic-mode hybridization\(^4\). Typically, the transfer is efficient only for separations that are much shorter than the diffraction limit. This hampers its application in optical communication and quantum information processing, which require spatially selective addressing. Here, we demonstrate highly efficient radiationless coherent energy transfer over a distance of twice the excitation wavelength by combining localized and delocalized\(^5\) plasmonic modes. Analogous to the Tavis-Cummings model, two whispering-gallery-mode antennas\(^6\) placed in the foci of an elliptical plasmonic cavity\(^7\) fabricated from single-crystal gold plates act as a pair of oscillators coupled to a common cavity mode. Time-resolved two-photon photoemission electron microscopy (TR 2P-PEEM) reveals an ultrafast long-range periodic energy transfer in accordance with the simulations. Our observations open perspectives for the optimization and tailoring of mesoscopic energy transfer and long-range quantum emitter coupling.}, language = {en} } @article{AhmedOjhaHirschetal.2017, author = {Ahmed, Bilal and Ojha, Animesh K. and Hirsch, Florian and Fischer, Ingo and Patrice, Donfack and Materny, Arnulf}, title = {Tailoring of enhanced interfacial polarization in WO\(_3\) nanorods grown over reduced graphene oxide synthesized by a one-step hydrothermal method}, series = {RSC Advances}, volume = {7}, journal = {RSC Advances}, number = {23}, doi = {10.1039/c7ra00730b}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-181829}, pages = {13985-13996}, year = {2017}, abstract = {In the present report, well-defined WO3 nanorods (NRs) and a rGO-WO\(_3\) composite were successfully synthesized using a one-pot hydrothermal method. The crystal phase, structural morphology, shape, and size of the as-synthesized samples were studied using X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. The optical properties of the synthesized samples were investigated by Raman, ultraviolet-visible (UV-Vis) and photoluminescence (PL) spectroscopy. Raman spectroscopy and TEM results validate the formation of WO\(_3\) (NRs) on the rGO sheet. The value of the dielectric constant (ε′) of WO3 NRs and rGO-WO\(_3\) composite is decreased with an increase in frequency. At low frequency (2.5 to 3.5 Hz), the value of ε′ for the rGO-WO3 composite is greater than that of pure WO\(_3\) NRs. This could be due to the fact that the induced charges follow the ac signal. However, at higher frequency (3.4 to 6.0), the value of ε′ for the rGO-WO\(_3\) composite is less compared to that of the pure WO3 NRs. The overall decrease in the value of ε′ could be due to the occurrence of a polarization process at the interface of the rGO sheet and WO3 NRs. Enhanced interfacial polarization in the rGO-WO\(_3\) composite is observed, which may be attributed to the presence of polar functional groups on the rGO sheet. These functional groups trap charge carriers at the interface, resulting in an enhancement of the interfacial polarization. The value of the dielectric modulus is also calculated to further confirm this enhancement. The values of the ac conductivity of the WO\(_3\) NRs and rGO-WO\(_3\) composite were calculated as a function of the frequency. The greater value of the ac conductivity in the rGO-WO\(_3\) composite compared to that of the WO\(_3\) NRs confirms the restoration of the sp:\(^{++}\) network during the in situ synthesis of the rGO-WO\(_3\) composite, which is well supported by the results obtained by Raman spectroscopy.}, language = {en} } @article{HartungSeufertBergesetal.2012, author = {Hartung, Andreas and Seufert, Florian and Berges, Carsten and Gessner, Viktoria H. and Holzgrabe, Ulrike}, title = {One-Pot Ugi/Aza-Michael Synthesis of Highly Substituted 2,5-Diketopiperazines with Anti-Proliferative Properties}, series = {Molecules}, volume = {17}, journal = {Molecules}, number = {12}, doi = {10.3390/molecules171214685}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-130423}, pages = {14685-14699}, year = {2012}, abstract = {The well-known Ugi reaction of aldehydes with amines, carboxylic acids and isocyanides leads to the formation of acyclic alpha-acylaminocarboxamides. Replacement of the carboxylic acid derivatives with beta-acyl substituted acrylic acids gives access to highly substituted 2,5-diketopiperazines in one single reaction-step without additives or complex reaction procedures. The obtained diketopiperazines show anti-proliferative effects on activated T cells and represent therefore potential candidates for targeting unwanted T cell-mediated immune responses.}, language = {en} } @article{KochCappelNockeretal.2011, author = {Koch, Oliver and Cappel, Daniel and Nocker, Monika and Jaeger, Timo and Floh{\´e}, Leopold and Sotriffer, Christoph and Selzer, Paul}, title = {Virtual screening using structure-based consensus pharmacophore models and ensemble docking based on MD-generated conformations : [From 6th German Conference on Chemoinformatics, GCC 2010, Goslar, Germany. 7-9 November 2010]}, series = {Journal of Cheminformatics}, volume = {3}, journal = {Journal of Cheminformatics}, number = {Suppl. 1}, doi = {10.1186/1758-2946-3-S1-O23}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-142830}, pages = {O23}, year = {2011}, abstract = {No abstract available.}, language = {en} }