@phdthesis{Mahlmeister2023, author = {Mahlmeister, Bernhard}, title = {Twisted Rylene Bisimides for Organic Solar Cells and Strong Chiroptical Response in the Near Infrared}, doi = {10.25972/OPUS-34610}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-346106}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2023}, abstract = {The chirality of the interlocked bay-arylated perylene motif is investigated upon its material prospect and the enhancement of its chiroptical response to the NIR spectral region. A considerable molecular library of inherently chiral perylene bisimides (PBIs) was utilized as acceptors in organic solar cells to provide decent device performances and insights into the structure-property relationship of PBI materials within a polymer blend. For the first time in the family of core-twisted PBIs, the effects of enantiopurity on the device performance was thoroughly investigated. The extraordinary structural sensitivity of CD spectroscopy served as crucial analytical tool to bridge the highly challenging gap between molecular properties and device analytics by proving the excitonic chirality of a helical PBI dimer. The chirality of this perylene motif could be further enhanced on a molecular level by both the expansion and the enhanced twisting of the π-scaffold to achieve a desirable strong chiroptical NIR response introducing a new family of twisted QBI-based nanoribbons. These achievements could be substantially further developed by expanding this molecular concept to a supramolecular level. The geometrically demanding supramolecular arrangement necessary for the efficient excitonic coupling was carefully encoded into the molecular design. Accordingly, the QBIs could form the first J-type aggregate constituting a fourfold-stranded superhelix of a rylene bisimide with strong excitonic chirality. Therefore, this thesis has highlighted the mutual corroboration of experimental and theoretical data from the molecular to the supramolecular level. It has demonstrated that for rylene bisimide dyes, the excitonic contribution to the overall chiroptical response can be designed and rationalized. This can help to pave the way for new organic functional materials to be used for chiral sensing or chiral organic light-emitting devices.}, subject = {Molek{\"u}l}, language = {en} } @article{MahlShoyamaKrauseetal.2020, author = {Mahl, Magnus and Shoyama, Kazutaka and Krause, Ana-Maria and Schmidt, David and W{\"u}rthner, Frank}, title = {Base-Assisted Imidization: A Synthetic Method for the Introduction of Bulky Imide Substituents to Control Packing and Optical Properties of Naphthalene and Perylene Imides}, series = {Angewandte Chemie International Edition}, volume = {59}, journal = {Angewandte Chemie International Edition}, number = {32}, doi = {10.1002/anie.202004965}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218246}, pages = {13401 -- 13405}, year = {2020}, abstract = {We report the direct imidization of naphthalene and perylene dicarboxylic anhydrides/esters with bulky ortho,ortho-diaryl- and ortho,ortho-dialkynylaniline derivatives. This imidization method uses n-butyllithium as a strong base to increase the reactivity of bulky amine derivatives, proceeds under mild reaction conditions, requires only stoichiometric amounts of reactants and gives straightforward access to new sterically crowded rylene dicarboximides. Mechanistic investigations suggest an isoimide as intermediary product, which was converted to the corresponding imide upon addition of an aqueous base. Single-crystal X-ray diffraction analyses reveal dimeric packing motifs for monoimides, while two-side shielded bisimides crystallize in isolated molecules without close π-π-interactions. Spectroscopic investigations disclose the influence of the bulky substituents on the optical properties in the solid state.}, language = {en} } @phdthesis{Mahl2023, author = {Mahl, Magnus}, title = {Polycyclic Aromatic Dicarboximides as NIR Chromophores, Solid-State Emitters and Supramolecular Host Platforms}, doi = {10.25972/OPUS-23462}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-234623}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2023}, abstract = {The present thesis introduce different synthetic strategies towards a variety of polycyclic aromatic dicarboximides (PADIs) with highly interesting and diverse properties. This included tetrachlorinated, tetraaryloxy- and tetraaryl-substituted dicarboximides, fused acceptor‒donor(‒acceptor) structures as well as sterically shielded rylene and nanographene dicarboximides. The properties and thus the disclosure of structure‒property relationships of the resulting dyes were investigated in detail among others with UV‒vis absorption spectroscopy, fluorescence spectroscopy, cyclic voltammetry and single crystal X-ray analysis. For instance, some of the fused and substituted PADIs offer strong absorption of visible and near infrared (NIR) light, NIR emission and low-lying LUMO levels. On the contrary, intriguing optical features in the solid-state characterize the rylene dicarboximides with their bulky N-substituents, while the devised sterically enwrapped nanographene host offered remarkable complexation capabilities in solution.}, subject = {Organische Chemie}, language = {en} } @unpublished{MaghamiScheitlHoebartner2019, author = {Maghami, Mohammad Ghaem and Scheitl, Carolin P. M. and H{\"o}bartner, Claudia}, title = {Direct in vitro selection of trans-acting ribozymes for posttranscriptional, site-specific, and covalent fluorescent labeling of RNA}, series = {Journal of the American Chemical Society}, journal = {Journal of the American Chemical Society}, doi = {10.1021/jacs.9b10531}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-192333}, year = {2019}, abstract = {General and efficient tools for site-specific fluorescent or bioorthogonal labeling of RNA are in high demand. Here, we report direct in vitro selection, characterization, and application of versatile trans-acting 2'-5' adenylyl transferase ribozymes for covalent and site-specific RNA labeling. The design of our partially structured RNA pool allowed for in vitro evolution of ribozymes that modify a predetermined nucleotide in cis (i.e. intramolecular reaction), and were then easily engineered for applications in trans (i.e. in an intermolecular setup). The resulting ribozymes are readily designed for specific target sites in small and large RNAs and accept a wide variety of N6-modified ATP analogues as small molecule substrates. The most efficient new ribozyme (FH14) shows excellent specificity towards its target sequence also in the context of total cellular RNA.}, language = {en} } @article{MaghamiDeyLenzetal.2020, author = {Maghami, Mohammad Ghaem and Dey, Surjendu and Lenz, Ann-Kathrin and H{\"o}bartner, Claudia}, title = {Repurpsing Antiviral Drugs for Orthogonal RNA-Catalyzed Labeling}, series = {Angewandte Chemie, International Edition}, volume = {59}, journal = {Angewandte Chemie, International Edition}, doi = {10.1002/anie.202001300}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-205552}, pages = {9335-9339}, year = {2020}, abstract = {In vitro selected ribozymes are promising tools for site-specific labeling of RNA. Previously known nucleic acid catalysts attached fluorescently labeled adenosine or guanosine derivatives through 2',5'-branched phosphodiester bonds to the RNA of interest. Herein, we report new ribozymes that use orthogonal substrates, derived from the antiviral drug tenofovir, and attach bioorthogonal functional groups, as well as affinity handles and fluorescent reporter units through a hydrolytically more stable phosphonate ester linkage. The tenofovir transferase ribozymes were identified by in vitro selection and are orthogonal to nucleotide transferase ribozymes. As genetically encodable functional RNAs, these ribozymes may be developed for potential cellular applications. The orthogonal ribozymes addressed desired target sites in large RNAs in vitro, as shown by fluorescent labeling of E. coli 16S and 23S RNAs in total cellular RNA.}, language = {en} } @article{LuebtowMarciniakSchmiedeletal.2019, author = {L{\"u}btow, Michael M. and Marciniak, Henning and Schmiedel, Alexander and Roos, Markus and Lambert, Christoph and Luxenhofer, Robert}, title = {Ultra-high to ultra-low drug loaded micelles: Probing host-guest interactions by fluorescence spectroscopy}, series = {Chemistry - A European Journal}, volume = {25}, journal = {Chemistry - A European Journal}, number = {54}, doi = {10.1002/chem.201902619}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-206128}, pages = {12601-12610}, year = {2019}, abstract = {Polymer micelles are an attractive means to solubilize water insoluble compounds such as drugs. Drug loading, formulations stability and control over drug release are crucial factors for drug-loaded polymer micelles. The interactions between the polymeric host and the guest molecules are considered critical to control these factors but typically barely understood. Here, we compare two isomeric polymer micelles, one of which enables ultra-high curcumin loading exceeding 50 wt.\%, while the other allows a drug loading of only 25 wt.\%. In the low capacity micelles, steady-state fluorescence revealed a very unusual feature of curcumin fluorescence, a high energy emission at 510 nm. Time-resolved fluorescence upconversion showed that the fluorescence life time of the corresponding species is too short in the high-capacity micelles, preventing an observable emission in steady-state. Therefore, contrary to common perception, stronger interactions between host and guest can be detrimental to the drug loading in polymer micelles.}, subject = {Polymer-drug interaction}, language = {en} } @phdthesis{Lohr2008, author = {Lohr, Andreas}, title = {Self-Assembly of Merocyanines : Thermodynamic and Kinetic Insights into the Formation of Well-Defined Dye Aggregates}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-28964}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2008}, abstract = {The present thesis demonstrates the potential of dipolar aggregation of merocyanine dyes as novel directional and specific supramolecular binding motif for the creation of more elaborate supramolecular architectures beyond simple dimers. Furthermore, the self-assembly studies into bis(merocyanine) nanorods gave new insights into the kinetics of morphogenesis in supramolecular aggregates.}, subject = {Supramolekulare Chemie}, language = {en} } @article{LiuVonhausenSchulzetal.2022, author = {Liu, Bin and Vonhausen, Yvonne and Schulz, Alexander and H{\"o}bartner, Claudia and W{\"u}rthner, Frank}, title = {Peptide Backbone Directed Self-Assembly of Merocyanine Oligomers into Duplex Structures}, series = {Angewandte Chemie International Edition}, volume = {61}, journal = {Angewandte Chemie International Edition}, number = {21}, doi = {10.1002/anie.202200120}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318797}, year = {2022}, abstract = {The pseudopeptide backbone provided by N-(2-aminoethyl)-glycine oligomers with attached nucleobases has been widely utilized in peptide nucleic acids (PNAs) as DNA mimics. Here we demonstrate the suitability of this backbone for the formation of structurally defined dye stacks. Toward this goal a series of peptide merocyanine (PMC) dye oligomers connected to a N-(2-aminoethyl)-glycine backbone were prepared through peptide synthesis. Our concentration-, temperature- and solvent-dependent UV/Vis absorption studies show that under the control of dipole-dipole interactions, smaller-sized oligomers consisting of one, two or three dyes self-assemble into defined duplex structures containing two up to six chromophores. In contrast, upon further extension of the oligomer, the chosen peptide backbone cannot direct the formation of a defined duplex architecture anymore due to intramolecular aggregation between the dyes. For all aggregate species a moderate aggregation-induced emission enhancement is observed.}, language = {en} } @phdthesis{Liess2017, author = {Liess, Andreas}, title = {Structure-Property Relationships of Merocyanine Dyes in the Solid State: Charge Transport and Exciton Coupling}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-152900}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2017}, abstract = {The present thesis demonstrates the importance of the solid state packing of dipolar merocyanine dyes with regard to charge transport and exciton coupling. Due to the charge transport theory for disordered materials, it is expected that high ground state dipole moments in amorphous thin films lead to low mobility values due to a broadening of the density of states. However, due to their inherent dipolarity, merocyanine dyes usually align in antiparallel dimers in an ordered fashion. The examination of twenty different molecules with ground state dipole moments up to 15.0 D shows that by a high dipolarity and well-defined sterics, the molecules pack in a highly regular two-dimensional brickwork-type structure, which is beneficial for hole transport. Utilization of these molecules for organic thin-film transistors (OTFTs) leads to hole mobility values up to 0.21 cm²/Vs. By fabrication of single crystal field-effect transistors (SCFETs) for the derivative showing the highest mobility values in OTFTs, even hole mobilities up to 2.34 cm²/Vs are achieved. Hence, merocyanine based transistors show hole mobility values comparable to those of conventional p-type organic semiconductors and therefore high ground state dipole moments are not necessarily disadvantageous regarding high mobility applications. By examination of a different series of ten merocyanine dyes with the same chromophore backbone but different donor substituents, it is demonstrated that the size of the donor has a significant influence on the optical properties of thin films. For small and rigid donor substituents, a hypsochromic shift of the absorption compared to the monomer absorption in solution is observed due to the card stack like packing of the molecules in the solid state. By utilization of sterical demanding or flexible donor substituents, a zig-zag type packing is observed, leading to a bathochromical shift of the absorption. These packing motifs and spectral shifts with an offset of 0.93 eV of the H- and J-bands comply with the archetype examples of H- and J-aggregates from Kasha's exciton theory.}, subject = {Exziton}, language = {en} } @phdthesis{LiebschergebBloehbaum2020, author = {Liebscher [geb. Bl{\"o}hbaum], Julia}, title = {Side chain functional poly(2-oxazoline)s for biomedical applications}, doi = {10.25972/OPUS-20396}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-203960}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2020}, abstract = {The aim of the thesis was to develop water soluble poly(2-oxazoline) (POx) copolymers with new side group functionalities, which can be used for the formation of hydrogels in biomedical applications and for the development of peptide-polymer conjugates. First, random copolymers of the monomer MeOx or EtOx with ButEnOx and EtOx with DecEnOx were synthesized and characterized. The vinyl functionality brought into the copolymer by the monomers ButEnOx and DecEnOx would later serve for post-polymerization functionalization. The synthesized copolymers were further functionalized with thiols via post-polymerization functionalization using a newly developed synthesis protocol or with a protected catechol molecule for hydrogel formation. For the formation of peptide-polymer conjugates, a cyclic thioester, namely thiolactone acrylamide and an azlactone precursor, whose synthesis was newly developed, were attached to the side chain of P(EtOx-co-ButEnOx) copolymers. The application of the functionalized thiol copolymers as hydrogels using thiol-ene chemistry for cross-linking was demonstrated. The swelling behavior and mechanical properties were characterized. The hydrophilicity of the network as well as the cross-linking density strongly influenced the swelling behavior and the mechanical strength of the hydrogels. All hydrogels showed good cell viability results. The hydrogel networks based on MeOx and EtOx were loaded with two dyes, fluorescein and methylene blue. It was observed that the uptake of the more hydrophilic dye fluorescein depended more on the ability of the hydrogel to swell. In contrast, the uptake of the more hydrophobic dye methylene blue was less dependent on the swelling degree, but much more on the hydrophilicity of the network. For the potential application as cartilage glue, (biohybrid) hydrogels were synthesized based on the catechol-functionalized copolymers, with and without additional fibrinogen, using sodium periodate as the oxidizing agent. The system allowed for degradation due to the incorporated ester linkages at the cross-linking points. The swelling behavior as well as the mechanical properties were characterized. As expected, hydrogels with higher degrees of cross-linking showed less swelling and higher elastic modulus. The addition of fibrinogen however increased the elasticity of the network, which can be favorable for the intended application as a cartilage glue. Biological evaluation clearly demonstrated the advantage of degradable ester links in the hydrogel network, where chondrocytes were able to bridge the artificial gap in contrast to hydrogels without any ester motifs. Lastly, different ways to form peptide-polymer conjugates were presented. Peptides were attached with the thiol of the terminal cysteine group to the vinyl side chain of P(EtOx-co-ButEnOx) copolymers by radical thiol-ene chemistry. Another approach was to use a cyclic thioester, thiolactone, or an azlactone functionality to bind a model peptide via native chemical ligation. The two latter named strategies to bind peptides to POx side chains are especially interesting as one and in the case of thiolactone two free thiols are still present at the binding site after the reaction, which can, for example, be used for further thiol-ene cross-linking to form POx hydrogels. In summary, side functional poly(oxazoline) copolymers show great potential for numerous biomedical applications. The various side chain functionalities can be introduced by an appropriate monomer or by post-polymerization functionalization, as demonstrated. By their multi-functionality, hydrogel characteristics, such as cross-linking degree and mechanical strength, can be fine-tuned and adjusted depending on the application in the human body. In addition, the presented chemoselective and orthogonal reaction strategies can be used in the future to synthesize polymer conjugates, which can, for example, be used in drug delivery or in tissue regeneration.}, subject = {Polymere}, language = {en} }