@article{GryszelSchlossarekWuerthneretal.2023, author = {Gryszel, Maciej and Schlossarek, Tim and W{\"u}rthner, Frank and Natali, Mirco and Głowacki, Eric Daniel}, title = {Water-soluble cationic perylene diimide dyes as stable photocatalysts for H\(_2\)O\(_2\) evolution}, series = {ChemPhotoChem}, volume = {7}, journal = {ChemPhotoChem}, number = {9}, issn = {2367-0932}, doi = {10.1002/cptc.202300070}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-370250}, year = {2023}, abstract = {Photocatalytic generation of hydrogen peroxide, H\(_2\)O\(_2\), has gained increasing attention in recent years, with applications ranging from solar energy conversion to biophysical research. While semiconducting solid-state materials are normally regarded as the workhorse for photogeneration of H\(_2\)O\(_2\), an intriguing alternative for on-demand H\(_2\)O\(_2\) is the use of photocatalytic organic dyes. Herein we report the use of water-soluble dyes based on perylene diimide molecules which behave as true molecular catalysts for the light-induced conversion of dissolved oxygen to hydrogen peroxide. In particular, we address how to obtain visible-light photocatalysts which are stable with respect to aggregation and photochemical degradation. We report on the factors affecting efficiency and stability, including variable electron donors, oxygen partial pressure, pH, and molecular catalyst structure. The result is a perylene diimide derivative with unprecedented peroxide evolution performance using a broad range of organic donor molecules and operating in a wide pH range.}, language = {en} } @article{GilSepulcreLindnerSchindleretal.2021, author = {Gil-Sepulcre, Marcos and Lindner, Joachim O. and Schindler, Dorothee and Velasco, Luc{\´i}a and Moonshiram, Dooshaye and R{\"u}diger, Olaf and DeBeer, Serena and Stepanenko, Vladimir and Solano, Eduardo and W{\"u}rthner, Frank and Llobet, Antoni}, title = {Surface-promoted evolution of Ru-bda coordination oligomers boosts the efficiency of water oxidation molecular anodes}, series = {Journal of the American Chemical Society}, volume = {143}, journal = {Journal of the American Chemical Society}, number = {30}, doi = {10.1021/jacs.1c04738}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-351514}, pages = {11651-11661}, year = {2021}, abstract = {A new Ru oligomer of formula {[Ru-\(^{II}\)(bda-\(\kappa\)-N\(^2\)O\(^2\))(4,4'-bpy)]\(_{10}\)(4,4'-bpy)}, 10 (bda is [2,2'-bipyridine]-6,6'-dicarbox-ylate and 4,4'-bpy is 4,4'-bipyridine), was synthesized and thoroughly characterized with spectroscopic, X-ray, and electrochemical techniques. This oligomer exhibits strong affinity for graphitic materials through CH-\(\pi\) interactions and thus easily anchors on multiwalled carbon nanotubes (CNT), generating the molecular hybrid material 10@CNT. The latter acts as a water oxidation catalyst and converts to a new species, 10'(H\(_2\)O)\(_2\)@CNT, during the electrochemical oxygen evolution process involving solvation and ligand reorganization facilitated by the interactions of molecular Ru catalyst and the surface. This heterogeneous system has been shown to be a powerful and robust molecular hybrid anode for electrocatalytic water oxidation into molecular oxygen, achieving current densities in the range of 200 mA/cm\(^2\) at pH 7 under an applied potential of 1.45 V vs NHE. The remarkable long-term stability of this hybrid material during turnover is rationalized based on the supramolecular interaction of the catalyst with the graphitic surface.}, language = {en} } @article{KrausGrimmSeibel2018, author = {Kraus, Michael and Grimm, Clemens and Seibel, J{\"u}rgen}, title = {Reversibility of a Point Mutation Induced Domain Shift: Expanding the Conformational Space of a Sucrose Phosphorylase}, series = {Scientific Reports}, volume = {8}, journal = {Scientific Reports}, doi = {10.1038/s41598-018-28802-2}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-224845}, year = {2018}, abstract = {Despite their popularity as enzyme engineering targets structural information about Sucrose Phosphorylases remains scarce. We recently clarified that the Q345F variant of Bifidobacterium adolescentis Sucrose Phosphorylase is able to accept large polyphenolic substrates like resveratrol via a domain shift. Here we present a crystal structure of this variant in a conformation suitable for the accommodation of the donor substrate sucrose in excellent agreement with the wild type structure. Remarkably, this conformation does not feature the previously observed domain shift which is therefore reversible and part of a dynamic process rather than a static phenomenon. This crystallographic snapshot completes our understanding of the catalytic cycle of this useful variant and will allow for a more rational design of further generations of Sucrose Phosphorylase variants.}, language = {en} } @article{HoernesFaserlJuenetal.2018, author = {Hoernes, Thomas Philipp and Faserl, Klaus and Juen, Michael Andreas and Kremser, Johannes and Gasser, Catherina and Fuchs, Elisabeth and Shi, Xinying and Siewert, Aaron and Lindner, Herbert and Kreutz, Christoph and Micura, Ronald and Joseph, Simpson and H{\"o}bartner, Claudia and Westhof, Eric and H{\"u}ttenhofer, Alexander and Erlacher, Matthias David}, title = {Translation of non-standard codon nucleotides reveals minimal requirements for codon-anticodon interactions}, series = {Nature Communications}, volume = {9}, journal = {Nature Communications}, doi = {10.1038/s41467-018-07321-8}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-321067}, year = {2018}, abstract = {The precise interplay between the mRNA codon and the tRNA anticodon is crucial for ensuring efficient and accurate translation by the ribosome. The insertion of RNA nucleobase derivatives in the mRNA allowed us to modulate the stability of the codon-anticodon interaction in the decoding site of bacterial and eukaryotic ribosomes, allowing an in-depth analysis of codon recognition. We found the hydrogen bond between the N1 of purines and the N3 of pyrimidines to be sufficient for decoding of the first two codon nucleotides, whereas adequate stacking between the RNA bases is critical at the wobble position. Inosine, found in eukaryotic mRNAs, is an important example of destabilization of the codon-anticodon interaction. Whereas single inosines are efficiently translated, multiple inosines, e.g., in the serotonin receptor 5-HT2C mRNA, inhibit translation. Thus, our results indicate that despite the robustness of the decoding process, its tolerance toward the weakening of codon-anticodon interactions is limited.}, language = {en} } @article{HerbstSoberatsLeowanawatetal.2018, author = {Herbst, Stefanie and Soberats, Bartolome and Leowanawat, Pawaret and Stolte, Matthias and Lehmann, Matthias and W{\"u}rthner, Frank}, title = {Self-assembly of multi-stranded perylene dye J-aggregates in columnar liquid-crystalline phases}, series = {Nature Communications}, volume = {9}, journal = {Nature Communications}, doi = {10.1038/s41467-018-05018-6}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-319914}, year = {2018}, abstract = {Many discoid dyes self-assemble into columnar liquid-crystalline (LC) phases with packing arrangements that are undesired for photonic applications due to H-type exciton coupling. Here, we report a series of crystalline and LC perylene bisimides (PBIs) self-assembling into single or multi-stranded (two, three, and four strands) aggregates with predominant J-type exciton coupling. These differences in the supramolecular packing and optical properties are achieved by molecular design variations of tetra-bay phenoxy-dendronized PBIs with two N-H groups at the imide positions. The self-assembly is driven by hydrogen bonding, slipped π-π stacking, nanosegregation, and steric requirements of the peripheral building blocks. We could determine the impact of the packing motifs on the spectroscopic properties and demonstrate different J- and H-type coupling contributions between the chromophores. Our findings on structure-property relationships and strong J-couplings in bulk LC materials open a new avenue in the molecular engineering of PBI J-aggregates with prospective applications in photonics.}, language = {en} } @article{HeWuD'Avinoetal.2018, author = {He, Tao and Wu, Yanfei and D'Avino, Gabriele and Schmidt, Elliot and Stolte, Matthias and Cornil, J{\´e}r{\^o}me and Beljonne, David and Ruden, P. Paul and W{\"u}rthner, Frank and Frisbie, C. Daniel}, title = {Crystal step edges can trap electrons on the surfaces of n-type organic semiconductors}, series = {Nature Communications}, volume = {9}, journal = {Nature Communications}, doi = {10.1038/s41467-018-04479-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-227957}, year = {2018}, abstract = {Understanding relationships between microstructure and electrical transport is an important goal for the materials science of organic semiconductors. Combining high-resolution surface potential mapping by scanning Kelvin probe microscopy (SKPM) with systematic field effect transport measurements, we show that step edges can trap electrons on the surfaces of single crystal organic semiconductors. n-type organic semiconductor crystals exhibiting positive step edge surface potentials display threshold voltages that increase and carrier mobilities that decrease with increasing step density, characteristic of trapping, whereas crystals that do not have positive step edge surface potentials do not have strongly step density dependent transport. A device model and microelectrostatics calculations suggest that trapping can be intrinsic to step edges for crystals of molecules with polar substituents. The results provide a unique example of a specific microstructure-charge trapping relationship and highlight the utility of surface potential imaging in combination with transport measurements as a productive strategy for uncovering microscopic structure-property relationships in organic semiconductors.}, language = {en} } @article{DostalFennelKochetal.2018, author = {Dost{\´a}l, Jakub and Fennel, Franziska and Koch, Federico and Herbst, Stefanie and W{\"u}rthner, Frank and Brixner, Tobias}, title = {Direct observation of exciton-exciton interactions}, series = {Nature Communications}, volume = {9}, journal = {Nature Communications}, doi = {10.1038/s41467-018-04884-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226271}, year = {2018}, abstract = {Natural light harvesting as well as optoelectronic and photovoltaic devices depend on efficient transport of energy following photoexcitation. Using common spectroscopic methods, however, it is challenging to discriminate one-exciton dynamics from multi-exciton interactions that arise when more than one excitation is present in the system. Here we introduce a coherent two-dimensional spectroscopic method that provides a signal only in case that the presence of one exciton influences the behavior of another one. Exemplarily, we monitor exciton diffusion by annihilation in a perylene bisimide-based J-aggregate. We determine quantitatively the exciton diffusion constant from exciton-exciton-interaction 2D spectra and reconstruct the annihilation-free dynamics for large pump powers. The latter enables for ultrafast spectroscopy at much higher intensities than conventionally possible and thus improves signal-to-noise ratios for multichromophore systems; the former recovers spatio-temporal dynamics for a broad range of phenomena in which exciton interactions are present.}, language = {en} } @article{SchneiderSeebauerBeuerleetal.2024, author = {Schneider, Tilman and Seebauer, Florian and Beuerle, Florian and W{\"u}rthner, Frank}, title = {A monodisperse, end-capped Ru(bda) oligomer with outstanding performance in heterogeneous electrochemical water oxidation}, series = {Advanced Materials Technologies}, volume = {9}, journal = {Advanced Materials Technologies}, number = {11}, issn = {2365-709X}, doi = {10.1002/admt.202301721}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-363133}, year = {2024}, abstract = {AbstractWater oxidation catalysis is a key step for sustainable fuel production by water splitting into hydrogen and oxygen. The synthesis of a novel coordination oligomer based on four Ru(bda) (bda = 2,2′-bipyridine-6,6′-dicarboxylate) centers, three 4,4′-bipyridine (4,4′-bpy) linkers, and two 4-picoline (4-pic) end caps is reported. The monodispersity of this tetranuclear compound is characterized by NMR techniques. Heterogeneous electrochemical water oxidation after immobilization on multi-walled carbon nanotubes (MWCNTs) shows catalytic performance unprecedented for this compound class, with a turnover frequency (TOF) of 133 s\(^{-1}\) and a turnover number (TON) of 4.89 × 10\(^6\), at a current density of 43.8 mA cm\(^{-2}\) and a potential of 1.45 V versus normal hydrogen electrode (NHE).}, language = {en} } @article{BruennertSeupelGoyaletal.2023, author = {Br{\"u}nnert, Daniela and Seupel, Raina and Goyal, Pankaj and Bach, Matthias and Schraud, Heike and Kirner, Stefanie and K{\"o}ster, Eva and Feineis, Doris and Bargou, Ralf C. and Schlosser, Andreas and Bringmann, Gerhard and Chatterjee, Manik}, title = {Ancistrocladinium A induces apoptosis in proteasome inhibitor-resistant multiple myeloma cells: a promising therapeutic agent candidate}, series = {Pharmaceuticals}, volume = {16}, journal = {Pharmaceuticals}, number = {8}, issn = {1424-8247}, doi = {10.3390/ph16081181}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-362887}, year = {2023}, abstract = {The N,C-coupled naphthylisoquinoline alkaloid ancistrocladinium A belongs to a novel class of natural products with potent antiprotozoal activity. Its effects on tumor cells, however, have not yet been explored. We demonstrate the antitumor activity of ancistrocladinium A in multiple myeloma (MM), a yet incurable blood cancer that represents a model disease for adaptation to proteotoxic stress. Viability assays showed a potent apoptosis-inducing effect of ancistrocladinium A in MM cell lines, including those with proteasome inhibitor (PI) resistance, and in primary MM cells, but not in non-malignant blood cells. Concomitant treatment with the PI carfilzomib or the histone deacetylase inhibitor panobinostat strongly enhanced the ancistrocladinium A-induced apoptosis. Mass spectrometry with biotinylated ancistrocladinium A revealed significant enrichment of RNA-splicing-associated proteins. Affected RNA-splicing-associated pathways included genes involved in proteotoxic stress response, such as PSMB5-associated genes and the heat shock proteins HSP90 and HSP70. Furthermore, we found strong induction of ATF4 and the ATM/H2AX pathway, both of which are critically involved in the integrated cellular response following proteotoxic and oxidative stress. Taken together, our data indicate that ancistrocladinium A targets cellular stress regulation in MM and improves the therapeutic response to PIs or overcomes PI resistance, and thus may represent a promising potential therapeutic agent.}, language = {en} } @phdthesis{Swain2024, author = {Swain, Asim}, title = {Helically Twisted Graphene Nanoribbons: Bottom-up Stereospecific Synthesis and Characterization}, doi = {10.25972/OPUS-36016}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-360164}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2024}, abstract = {Over the past decade, substantial progress has been made in synthesizing atomically precise carbon nanostructures, with a focus on graphene nanoribbons (NRs) through advanced synthetic techniques. Despite these advancements, precise control over the stereochemistry of twisted NRs remains challenging. This thesis introduces a strategic approach to achieve absolute control over the single-handed helical conformation in a cove-edged NR, utilizing enantiopure [n]helicenes as a molecular wrench to intricately dictate the overall conformation of the NR. Enantiopure [7]helicenes were stitched to the terminal K-regions of a conjugated pyrene NR using a stereospecific and site-selective palladium(II)-catalyzed annulative π-extension (APEX) reaction, resulting in a helically twisted NR with an end-to-end twist of 171°, the second-largest twist reported so far in the literature for twistacenes. The helical end-to-end twist increases with each addition of benzene ring to the central acene core, suggesting that the extra strain induced by the terminal [7]helicenes maintains such a high level of twist. The quantum chemical calculations were conducted to investigate the impact of twisting on the conformational population. At room temperature, the central backbone of the nanoribbon adopts the twisted helicity opposite to that of the attached [7]helicene, constituting around 99\% of the molecular population. For instance, (P)-[7]helicenes produce a left-handed helical nanoribbon, while (M)-[7]helicenes produce a right-handed helical nanoribbon. In the presence of helicenes of opposite chirality, the nanoribbon adopts a waggling conformation. The helically twisted nanoribbons are conformationally robust, as variable temperature chiroptical measurements showed no change in CD and CPL spectra. The proposed strategy, involving the late-stage addition of [n]helicene units through the APEX reaction, appears promising for streamlining the synthesis of diverse cove edge NR variants with desired conformations. In addition to single-handed helically twisted nanoribbons, the symmetry-based functional properties of C2 and C1 symmetric pyrene-fused single and double [n]helicene compounds were studied. Owing to its higher structural rigidity, the C1 symmetric heptagonal ring-containing molecules exhibited exceptional configurational stability along with remarkable chiroptical properties compared to their C2 symmetric as well as pristine helicene congeners.}, subject = {Helicene}, language = {en} } @phdthesis{Roger2024, author = {Roger, Chantal}, title = {Photophysics and Spin Chemistry of Triptycene Bridge Donor-Acceptor-Triads}, doi = {10.25972/OPUS-36303}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-363031}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2024}, abstract = {The goal of this thesis was to investigate the influence of rotational restriction between individual parts and of the varying electron density in the bridging unit of D B A systems on the exchange interaction 2J, and thus the electronic coupling between a donor state and an acceptor state. A better understanding of how to influence the underlaying spin dynamics in such donor acceptor systems can open up the door to new technologies, such as modern molecular electronics or optoelectronic devices. Therefore, three series of molecules consisting of a TAA electron donor, a TTC or ATC bridging unit and a PDI electron acceptor were studied. To investigate the influence of rotational restriction on 2J and the electronic coupling, a series of four rotationally hindered triads (chapter 6) was synthesised. The dihedral angle between the TAA and the TTC as well as between the TTC and the PDI was restricted by ortho methyl groups at the phenylene linkers of the connecting ends to the TTC bridge, producing a twist around the linking single bond which minimises the π overlap. The triads exhibit varying numbers of ortho methyl groups and therefore different degrees of rotational restriction. In order to shine light on the influence of varying electron density on 2J and the electronic coupling, a series of four substituted triptycene triads (chapter 7) was synthesised. The electron density in the TTC bridging unit was varied by electron donating and electron withdrawing groups in 12,13 position of the TTC bridging unit and thus varying its HOMO/LUMO energy. The last series of two anthracene bridge triads (chapter 8) connected both approaches by restricting the rotation with ortho methyl groups and simultaneously by varying the bridge energies. In order to obtain the electronic properties, steady state absorption and emission spectra of all triads were investigated (chapter 4). Here, all triads show spectral features associated with the separate absorption bands of TAA and the PDI moiety. The reduced QYs, compared to the unsubstituted PDI acceptor, indicate a non radiative quenching mechanism in all triads. The CV data (chapter 5) were used to calculate the energies of possible CSSs and those results were used to assign the CR dynamics into the different Marcus regions. fs TA measurements reveal that all triads form a CSS upon excitation of the PDI moiety. The lifetimes of the involved states and the rate constants were determined by global exponential fits and global target analysis. The CR dynamics upon depopulation of the CSSs were investigated using external magnetic field dependent ns TA spectroscopy. The ns TA maps show that all triads recombine via CRT pathway populating the local 3PDI state in toluene and provided the respective lifetimes. The approximate QYs of triplet formation were determined using actinometry. The magnetic field dependent ns TA data reveal the exchange interaction 2J between singlet and triplet CSS for each triad. Those magnetic field dependent ns TA data in toluene were furthermore treated using a quantum mechanical simulation (done by U.E. Steiner) to extract the rate constants kT and kS for CRT and CRS, respectively. However, the error margins of kS were rather wide. Finally, the electronic couplings between the donor and the acceptor states were obtained by combining the aforementioned experimental results of the rate constants and applying the Bixon Jortner theoretical description of diabatic ET and Andersons perturbative theory of the exchange coupling. Therefore, the experimentally determined values of 2J and the calculated values of kCS and kT were used. The rate constant kS was calculated based on the electronic coupling V1CSS 1S0. The rotationally hindered triads (chapter 6) show a strong influence of the degree of rotational restriction on the lifetimes and rate constants of the CS processes. The rate constants of CS are increasing with increasing rotational freedom. The magnetic field dependent decay data show that the exchange interactions increase with increasing rotational freedom. Based on the CR dynamics, the calculated electronic couplings of the ET processes reflect the same trend along the series. Here, only singlet couplings turned out to be strongly influenced while the triplet couplings are not. Therefore, this series shows that the ET dynamics of donor acceptor systems can strongly be influenced by restricting the rotational freedom. In the substituted triptycene triads (chapter 7), decreasing electron density in the bridging unit causes a decrease of the CS rate constants. The magnetic field dependent decay data show that with decreasing electron density in the bridge the exchange interaction decreases. The CR dynamics-based rate constants and the electronic couplings follow the same trend as the exchange interaction. This series shows that varying the HOMO/LUMO levels of the connecting bridge between donor and acceptor strongly influences the ET processes. In the anthracene bridge triads (chapter 8), the CS process is slow in both triads. The CR was fast in the anthracene triad and is slowed down in the methoxy substituted anthracene bridge triad. The increase of the exchange interaction with increasing electron density in the bridge was more pronounced than in the substituted triptycene triads. Thus, the variation of electron density in the bridge strongly influences the ET processes even though the rotation is restricted. In this thesis, it was shown that the influence of the rotational hindrance as well as the electron density in a connecting bridge have strong influence on all ET processes and the electronic coupling in donor acceptor systems. These approaches can therefore be used to modify magnetic properties of new materials.}, subject = {Rotation}, language = {en} } @article{KirchnerSchrammIvanovaetal.2024, author = {Kirchner, Philipp H. and Schramm, Louis and Ivanova, Svetlana and Shoyama, Kazutaka and W{\"u}rthner, Frank and Beuerle, Florian}, title = {A water-stable boronate ester cage}, series = {Journal of the American Chemical Society}, volume = {146}, journal = {Journal of the American Chemical Society}, number = {8}, issn = {0002-7863}, doi = {10.1021/jacs.3c12002}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-361245}, pages = {5305-5315}, year = {2024}, abstract = {The reversible condensation of catechols and boronic acids to boronate esters is a paradigm reaction in dynamic covalent chemistry. However, facile backward hydrolysis is detrimental for stability and has so far prevented applications for boronate-based materials. Here, we introduce cubic boronate ester cages 6 derived from hexahydroxy tribenzotriquinacenes and phenylene diboronic acids with ortho-t-butyl substituents. Due to steric shielding, dynamic exchange at the Lewis acidic boron sites is feasible only under acid or base catalysis but fully prevented at neutral conditions. For the first time, boronate ester cages 6 tolerate substantial amounts of water or alcohols both in solution and solid state. The unprecedented applicability of these materials under ambient and aqueous conditions is showcased by efficient encapsulation and on-demand release of β-carotene dyes and heterogeneous water oxidation catalysis after the encapsulation of ruthenium catalysts.}, language = {en} } @article{NollWuerthner2024, author = {Noll, Niklas and W{\"u}rthner, Frank}, title = {Bioinspired water preorganization in confined space for efficient water oxidation catalysis in metallosupramolecular ruthenium architectures}, series = {Accounts of Chemical Research}, volume = {57}, journal = {Accounts of Chemical Research}, number = {10}, issn = {0001-4842}, doi = {10.1021/acs.accounts.4c00148}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-361232}, pages = {1538-1549}, year = {2024}, abstract = {Conspectus Nature has established a sustainable way to maintain aerobic life on earth by inventing one of the most sophisticated biological processes, namely, natural photosynthesis, which delivers us with organic matter and molecular oxygen derived from the two abundant resources sunlight and water. The thermodynamically demanding photosynthetic water splitting is catalyzed by the oxygen-evolving complex in photosystem II (OEC-PSII), which comprises a distorted tetramanganese-calcium cluster (CaMn\(_4\)O\(_5\)) as catalytic core. As an ubiquitous concept for fine-tuning and regulating the reactivity of the active site of metalloenzymes, the surrounding protein domain creates a sophisticated environment that promotes substrate preorganization through secondary, noncovalent interactions such as hydrogen bonding or electrostatic interactions. Based on the high-resolution X-ray structure of PSII, several water channels were identified near the active site, which are filled with extensive hydrogen-bonding networks of preorganized water molecules, connecting the OEC with the protein surface. As an integral part of the outer coordination sphere of natural metalloenzymes, these channels control the substrate and product delivery, carefully regulate the proton flow by promoting pivotal proton-coupled electron transfer processes, and simultaneously stabilize short-lived oxidized intermediates, thus highlighting the importance of an ordered water network for the remarkable efficiency of the natural OEC. Transferring this concept from nature to the engineering of artificial metal catalysts for fuel production has fostered the fascinating field of metallosupramolecular chemistry by generating defined cavities that conceptually mimic enzymatic pockets. However, the application of supramolecular approaches to generate artificial water oxidation catalysts remained scarce prior to our initial reports, since such molecular design strategies for efficient activation of substrate water molecules in confined nanoenvironments were lacking. In this Account, we describe our research efforts on combining the state-of-the art Ru(bda) catalytic framework with structurally programmed ditopic ligands to guide the water oxidation process in defined metallosupramolecular assemblies in spatial proximity. We will elucidate the governing factors that control the quality of hydrogen-bonding water networks in multinuclear cavities of varying sizes and geometries to obtain high-performance, state-of-the-art water oxidation catalysts. Pushing the boundaries of artificial catalyst design, embedding a single catalytic Ru center into a well-defined molecular pocket enabled sophisticated water preorganization in front of the active site through an encoded basic recognition site, resulting in high catalytic rates comparable to those of the natural counterpart OEC-PSII. To fully explore their potential for solar fuel devices, the suitability of our metallosupramolecular assemblies was demonstrated under (electro)chemical and photocatalytic water oxidation conditions. In addition, testing the limits of structural diversity allowed the fabrication of self-assembled linear coordination oligomers as novel photocatalytic materials and long-range ordered covalent organic framework (COF) materials as recyclable and long-term stable solid-state materials for future applications.}, 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} } @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} } @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} } @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{Neitz2024, author = {Neitz, Hermann}, title = {Hydrophobic recognition motifs in functionalized DNA}, doi = {10.25972/OPUS-34838}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-348382}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2024}, abstract = {In w{\"a}ssriger Umgebung spielen hydrophobe Wechselwirkungen eine wichtige Rolle f{\"u}r die DNA. Die Einf{\"u}hrung von Modifikationen, die auf hydrophoben aromatischen Einheiten basieren, kann die Erkennung und Reaktivit{\"a}t von funktionellen Gruppen in der DNA steuern. Modifikationen k{\"o}nnen durch ein k{\"u}nstliches R{\"u}ckgrat oder in Form einer Erweiterung der Nukleobasen eingebracht werden und so zu zus{\"a}tzlichen Eigenschaften der DNA f{\"u}hren. Diese Dissertation befasst sich mit der Verwendung von hydrophoben Einheiten zur Funktionalisierung von DNA. Im ersten Teil der Arbeit wurde das Tolanmotiv (Diphenylacetylen) in Kombination mit dem acyclischen R{\"u}ckgrat von GNA und BuNA verwendet, um Erkennungseinheiten im DNA-Kontext zu erzeugen. Die gezielte Fluorierung der aromatischen Ringe des Tolan-Bausteins bildete die Grundlage f{\"u}r eine supramolekulare Sprache, die auf Aren-Fluoroaren-Wechselwirkungen basiert. Die spezifische Erkennung wurde mittels thermodynamischer, kinetischer und NMR-spektroskopischer Methoden untersucht. Im zweiten Teil der Arbeit wurden Desoxyuridin-Derivate mit einer hydrophoben aromatischen Modifikation hergestellt und in die DNA-Doppelhelix eingebaut. Die Bestrahlung mit UV-Licht f{\"u}hrte zu einer [2+2]-Cycloaddition zwischen zwei modifizierten Nukleosiden in der DNA. Das Reaktionsprodukt wurde strukturell charakterisiert und die Reaktion in verschiedenen biochemischen und nanotechnologischen DNA-Anwendungen eingesetzt.}, subject = {Supramolekulare Chemie}, language = {en} } @phdthesis{Bauer2023, author = {Bauer, Christian}, title = {Towards ecological and efficient electrochemical energy storage in supercapacitors and sodium ion batteries using onion-like carbon}, doi = {10.25972/OPUS-31795}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-317956}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2023}, abstract = {In this thesis, the usage of onion-like carbon (OLC) for energy storage applications was researched regarding sustainability, performance and processability. This work targets to increase the scientific understanding regarding the role of OLC in electrodes and to facilitate a large-scale production, which is the foundation for commercial application. Research was devoted to increase the knowledge in the particular field, to yield synergistic approaches and a shared value regarding sustainability and performance.}, subject = {Elektrochemie}, language = {en} } @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{BrennerGeigerSchlegeletal.2023, author = {Brenner, Daniela and Geiger, Nina and Schlegel, Jan and Diesendorf, Viktoria and Kersting, Louise and Fink, Julian and Stelz, Linda and Schneider-Schaulies, Sibylle and Sauer, Markus and Bodem, Jochen and Seibel, J{\"u}rgen}, title = {Azido-ceramides, a tool to analyse SARS-CoV-2 replication and inhibition — SARS-CoV-2 is inhibited by ceramides}, series = {International Journal of Molecular Sciences}, volume = {24}, journal = {International Journal of Molecular Sciences}, number = {8}, issn = {1422-0067}, doi = {10.3390/ijms24087281}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-313581}, year = {2023}, abstract = {Recently, we have shown that C6-ceramides efficiently suppress viral replication by trapping the virus in lysosomes. Here, we use antiviral assays to evaluate a synthetic ceramide derivative α-NH2-ω-N3-C6-ceramide (AKS461) and to confirm the biological activity of C6-ceramides inhibiting SARS-CoV-2. Click-labeling with a fluorophore demonstrated that AKS461 accumulates in lysosomes. Previously, it has been shown that suppression of SARS-CoV-2 replication can be cell-type specific. Thus, AKS461 inhibited SARS-CoV-2 replication in Huh-7, Vero, and Calu-3 cells up to 2.5 orders of magnitude. The results were confirmed by CoronaFISH, indicating that AKS461 acts comparable to the unmodified C6-ceramide. Thus, AKS461 serves as a tool to study ceramide-associated cellular and viral pathways, such as SARS-CoV-2 infections, and it helped to identify lysosomes as the central organelle of C6-ceramides to inhibit viral replication.}, language = {en} } @unpublished{SaalSwainSchmiedeletal.2023, author = {Saal, Fridolin and Swain, Asim and Schmiedel, Alexander and Holzapfel, Marco and Lambert, Christoph and Ravat, Prince}, title = {Push-Pull [7]Helicene Diimide: Excited-State Charge Transfer and Solvatochromic Circularly Polarised Luminescence}, edition = {submitted version}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-345207}, year = {2023}, abstract = {In this communication we describe a helically chiral push-pull molecule named 9,10-dimethoxy-[7]helicene diimide, displaying fluorescence (FL) and circularly polarised luminescence (CPL) over nearly the entire visible spectrum dependent on solvent polarity. The synthesised molecule exhibits an unusual solvent polarity dependence of FL quantum yield and nonradiative rate constant, as well as remarkable gabs and glum values along with high configurational stability.}, language = {en} } @phdthesis{Scheitl2023, author = {Scheitl, Carolin P. M.}, title = {In vitro selected ribozymes for RNA methylation and labeling}, doi = {10.25972/OPUS-33004}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-330049}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2023}, abstract = {The focus of this work was the development and application of highly efficient RNA catalysts for the site-specific modification of RNA with special focus on methylation. In the course of this thesis, the first methyltransferase ribozyme (MTR1), which uses m6G as the methyl group donor was developed and further characterized. The RNA product was identified as the natural modification m1A. X-Ray crystallography was used to solve the 3D structure of the ribozyme, which directly suggested a plausible reaction meachnism. The MTR1 ribozyme was also successfully repurposed for a nucleobase transformation reaction of a purine nucleoside. This resulted in a formyl-imidazole moiety directly on the intact RNA, which was directly used for further bioconjugation reactions. Finally, additional selections and reselections led to the identification of highly active alkyltransferase ribozymes that can be used for the labeling of various RNA targets}, subject = {Methylierung}, language = {en} } @article{OkudaLenzSeitzetal.2023, author = {Okuda, Takumi and Lenz, Ann-Kathrin and Seitz, Florian and Vogel, J{\"o}rg and H{\"o}bartner, Claudia}, title = {A SAM analogue-utilizing ribozyme for site-specific RNA alkylation in living cells}, series = {Nature Chemistry}, journal = {Nature Chemistry}, doi = {10.1038/s41557-023-01320-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-328762}, year = {2023}, abstract = {Post-transcriptional RNA modification methods are in high demand for site-specific RNA labelling and analysis of RNA functions. In vitro-selected ribozymes are attractive tools for RNA research and have the potential to overcome some of the limitations of chemoenzymatic approaches with repurposed methyltransferases. Here we report an alkyltransferase ribozyme that uses a synthetic, stabilized S-adenosylmethionine (SAM) analogue and catalyses the transfer of a propargyl group to a specific adenosine in the target RNA. Almost quantitative conversion was achieved within 1 h under a wide range of reaction conditions in vitro, including physiological magnesium ion concentrations. A genetically encoded version of the SAM analogue-utilizing ribozyme (SAMURI) was expressed in HEK293T cells, and intracellular propargylation of the target adenosine was confirmed by specific fluorescent labelling. SAMURI is a general tool for the site-specific installation of the smallest tag for azide-alkyne click chemistry, which can be further functionalized with fluorophores, affinity tags or other functional probes.}, language = {en} } @unpublished{NeitzHoebartner2023, author = {Neitz, Hermann and H{\"o}bartner, Claudia}, title = {A tolane-modified 5-ethynyluridine as a universal and fluorogenic photochemical DNA crosslinker}, series = {Chemical Communications}, journal = {Chemical Communications}, edition = {submitted version}, doi = {10.1039/D3CC03796G}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-328255}, year = {2023}, abstract = {We report the fluorescent nucleoside ToldU and its application as a photoresponsive crosslinker in three different DNA architectures with enhanced fluorescence emission of the crosslinked products. The fluorogenic ToldU crosslinking reaction enables the assembly of DNA polymers in a hybridization chain reaction for the concentration-dependent detectio of a specific DNA sequence.}, language = {en} } @unpublished{DietzschJayachandranMuelleretal.2023, author = {Dietzsch, Julia and Jayachandran, Ajay and Mueller, Stefan and H{\"o}bartner, Claudia and Brixner, Tobias}, title = {Excitonic coupling of RNA-templated merocyanine dimer studied by higher-order transient absorption spectroscopy}, series = {Chemical Communications}, journal = {Chemical Communications}, edition = {submitted version}, doi = {10.1039/D3CC02024J}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-327772}, year = {2023}, abstract = {We report the synthesis and spectroscopic analysis of RNA containing the barbituric acid merocyanine rBAM2 as a nucleobase surrogate. Incorporation into RNA strands by solid-phase synthesis leads to fluorescence enhancement compared to the free chromophore. In addition, linear absorption studies show the formation of an excitonically coupled H-type dimer in the hybridized duplex. Ultrafast third- and fifth-order transient absorption spectroscopy of this non-fluorescent dimer suggests immediate (sub-200 fs) exciton transfer and annihilation due to the proximity of the rBAM2 units.}, 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} } @phdthesis{Menekşe2023, author = {Menek{\c{s}}e, Kaan}, title = {Fabrication of Organic Solar Cells, Screening of Non-Fullerene Acceptors and the Investigation of their Intermolecular Interactions}, doi = {10.25972/OPUS-29112}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-291124}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2023}, abstract = {In this thesis, intermolecular acceptor-acceptor interactions in organic solar cells based on new non-fullerene acceptors are addressed. For this purpose, first the reproducibility of organic electronic devices was tested on a new facility for their fabrication. This was followed by the screening for new acceptor materials. Based on this, three molecular systems were investigated with regard to their acceptor-acceptor interactions and their influence on solar cell efficiency.}, subject = {Organische Solarzelle}, language = {en} } @article{ScheitlOkudaAdelmannetal.2023, author = {Scheitl, Carolin P. M. and Okuda, Takumi and Adelmann, Juliane and H{\"o}bartner, Claudia}, title = {Ribozyme-catalyzed late-stage functionalization and fluorogenic labeling of RNA}, series = {Angewandte Chemie International Edition}, volume = {62}, journal = {Angewandte Chemie International Edition}, doi = {10.1002/anie.202305463}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-327543}, year = {2023}, abstract = {Site-specific introduction of biorthogonal handles into RNAs is in high demand for decorating RNAs with fluorophores, affinity labels or other modifications. Aldehydes represent attractive functional groups for post-synthetic bioconjugation reactions. Here, we report a ribozyme-based method for the synthesis of aldehyde-functionalized RNA by directly converting a purine nucleobase. Using the methyltransferase ribozyme MTR1 as an alkyltransferase, the reaction is initiated by site-specific N1 benzylation of purine, followed by nucleophilic ring opening and spontaneous hydrolysis under mild conditions to yield a 5-amino-4-formylimidazole residue in good yields. The modified nucleotide is accessible to aldehyde-reactive probes, as demonstrated by the conjugation of biotin or fluorescent dyes to short synthetic RNAs and tRNA transcripts. Upon fluorogenic condensation with a 2,3,3-trimethylindole, a novel hemicyanine chromophore was generated directly on the RNA. This work expands the MTR1 ribozyme's area of application from a methyltransferase to a tool for site-specific late-stage functionalization of RNA.}, language = {en} } @phdthesis{Fink2023, author = {Fink, Julian}, title = {Synthese von molekularen Werkzeugen zur Visualisierung und Untersuchung des Sphingolipidmetabolismus und weiterer biologischer Prozesse}, doi = {10.25972/OPUS-28699}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-286992}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2023}, abstract = {Die Zelle stellt die kleinste Einheit des Lebens dar und zeichnet sich durch die hoch koordinierte Anordnung von mehreren Millionen (Bio-)Molek{\"u}len zu einem mikrometergroßen Objekt aus. Als struktureller Bestandteil der Lipiddoppelschicht eukaryotischer Zellen spielt neben Sterolen und Glycerolipiden die Verbindungsklasse der Sphingolipide eine zentrale Rolle bei der Aufrechterhaltung der Membranintegrit{\"a}t.[472] Dar{\"u}ber hinaus sind bioaktive Sphingolipide bei vielen grundlegenden zellul{\"a}ren Prozessen wie Apoptose, Wachstum, Differenzierung, Migration und Adh{\"a}sion entscheidend beteiligt.[87,120] Ein gest{\"o}rtes Gleichgewicht des Sphingolipidmetabolismus und Defekte der entsprechenden Stoffwechselwege stehen im Zusammenhang mit vielen Krankheiten wie Krebs, Diabetes, Adipositas, Arteriosklerose, chronischen Entz{\"u}ndungen und Autoimmunerkrankungen sowie viraler und bakterieller Pathogenese.[22,143,473,474] Die Entwicklung und Anwendung von Sphingolipidanaloga als potenzielle Wirkstoffe r{\"u}ckten in den letzten Jahren immer weiter in den Fokus der interdisziplin{\"a}ren Forschung von Biologen, Chemikern und Medizinern. Als bekanntestes Beispiel ist Fingolimod (FTY720) zu nennen, das als Sphingosin-1-phosphat-Mimetikum heute unter dem Markennamen Gilenya® erfolgreich als Arzneistoff zur Behandlung von Multipler Sklerose eingesetzt wird.[475] Es besteht jedoch die Gefahr, dass Fingolimod zur Sch{\"a}digung anderer Zellfunktionen und zu gravierenden Nebeneffekten wie Bradykardie f{\"u}hren kann.[476] Da Sphingolipide ebenfalls in der Kontrolle von bakteriellen und viralen Infektionen essentiell beteiligt sind, spielen Sphingolipide und deren synthetisch dargestellte Derivate vermehrt eine Rolle in der Wirkstoffentwicklung im Kampf gegen pathogene Krankheitserreger.[175,477-479] Die Wirkweise von antimikrobiellen Sphingolipiden ist bisher nicht vollst{\"a}ndig aufgekl{\"a}rt. F{\"u}r eine Weiterentwicklung von bekannten Medikamenten gegen verschiedene Krankheiten oder f{\"u}r die Entwicklung neuartiger Wirkstoffe gegen Erreger ist eine umfassende Untersuchung der zugrundeliegenden zellul{\"a}ren Mechanismen auf molekularer Ebene entscheidend. Hierf{\"u}r finden aufgrund der relativ einfachen Detektion mittels Fluoreszenzmikroskopie h{\"a}ufig fluoreszenzmarkierte Sphingolipidderivate breite Anwendung.[480] Die kovalent gebundene Farbstoffeinheit bringt jedoch wesentliche Nachteile mit sich, da sich die Biomolek{\"u}le durch die ver{\"a}nderte Struktur und Polarit{\"a}t in ihren biologischen Eigenschaften von den nat{\"u}rlichen Substraten unterscheiden k{\"o}nnen. Die Verwendung von bioorthogonal funktionalisierten Biomolek{\"u}len umgeht dieses Problem, da die strukturellen {\"A}nderungen minimal gehalten werden. Nach dem zellul{\"a}ren Einbau dieser Derivate ist eine schnelle und spezifische Konjugation mit einem komplement{\"a}ren Fluorophor zu einem gew{\"u}nschten Zeitpunkt durch sogenannte Click-Reaktionen wie CuAAC oder SPAAC m{\"o}glich.[12,46] Das Prinzip der Click-Chemie wurde bereits auf eine Vielzahl an Biomolek{\"u}len wie Sphingolipide, Fetts{\"a}uren, Aminos{\"a}uren, Proteine, Kohlenhydrate, Nukleoside oder Nukleins{\"a}uren (DNA und RNA) {\"u}bertragen.[47,280] Jedoch bedarf es weiterer spezifisch modifizierter Verbindungen, die vielf{\"a}ltige bioorthogonale Reaktionen f{\"u}r die Untersuchung von Zellprozessen zulassen ‒ sowohl in vitro als auch in vivo. Um neue Therapieans{\"a}tze gegen verschiedene Krankheiten zu entwickeln und schwerwiegende Nebenwirkungen zu vermeiden, ist die detaillierte Erforschung hochkomplexer Zellvorg{\"a}nge auf molekularer Ebene von entscheidender Bedeutung. Das Ziel dieser Arbeit war daher die Synthese und Charakterisierung von molekularen Werkzeugen, die in Kombination mit verschiedenen aktuellen Mikroskopie- und Massenspektrometriemethoden die Visualisierung und Untersuchung des Sphingolipidmetabolismus und weiterer biologischer Prozesse erm{\"o}glichen. Zusammenfassend wurde in dieser Arbeit eine Vielzahl an Sphingolipiden und deren bioorthogonal funktionalisierte Analoga ausgehend von der Aminos{\"a}ure L-Serin erfolgreich synthetisiert. Die vorgestellten Verbindungen eignen sich in Kombination mit Massenspektrometrie und Fluoreszenz- oder Elektronenmikroskopie als molekulare Werkzeuge zur Untersuchung des komplexen Sphingolipidmetabolismus sowie des Einbaus und der Dynamik von Sphingolipiden in Modell- und Zellmembranen. Sowohl in humanen und tierischen Zellen als auch in Bakterien wurden die azidmodifizierten Sphingolipide durch Click-Reaktionen visualisiert, um ein verbessertes Verst{\"a}ndnis von bakteriellen und viralen Infektionsprozessen zu erhalten. Der modulare Ansatz der Click-Chemie erm{\"o}glicht die Verwendung verschiedener komplement{\"a}r funktionalisierter Farbstoffe, die unterschiedliche Eigenschaften bez{\"u}glich der Membrandurchg{\"a}ngigkeit oder Absorptions- und Emissionswellenl{\"a}ngen besitzen und somit je nach biologischer Fragestellung gezielt eingesetzt werden k{\"o}nnen. Alles in allem tragen die in dieser Arbeit synthetisierten Verbindungen dazu bei, die Rolle von Sphingolipiden bei Infektionsprozessen und Krankheitsverl{\"a}ufen auf subzellul{\"a}rer Ebene aufzukl{\"a}ren. Dadurch wird ein entscheidender Beitrag f{\"u}r die Entwicklung neuartiger Wirkstoffe gegen bakterielle oder virale Erreger sowie innovativer Therapien gegen verschiedene humane Krankheiten geliefert.}, subject = {Chemische Synthese}, 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{EderHollmannMandasarietal.2022, author = {Eder, Sascha and Hollmann, Claudia and Mandasari, Putri and Wittmann, Pia and Schumacher, Fabian and Kleuser, Burkhard and Fink, Julian and Seibel, J{\"u}rgen and Schneider-Schaulies, J{\"u}rgen and Stigloher, Christian and Beyersdorf, Niklas and Dembski, Sofia}, title = {Synthesis and characterization of ceramide-containing liposomes as membrane models for different T cell subpopulations}, series = {Journal of Functional Biomaterials}, volume = {13}, journal = {Journal of Functional Biomaterials}, number = {3}, issn = {2079-4983}, doi = {10.3390/jfb13030111}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-286130}, year = {2022}, abstract = {A fine balance of regulatory (T\(_{reg}\)) and conventional CD4\(^+\) T cells (T\(_{conv}\)) is required to prevent harmful immune responses, while at the same time ensuring the development of protective immunity against pathogens. As for many cellular processes, sphingolipid metabolism also crucially modulates the T\(_{reg}\)/T\(_{conv}\) balance. However, our understanding of how sphingolipid metabolism is involved in T cell biology is still evolving and a better characterization of the tools at hand is required to advance the field. Therefore, we established a reductionist liposomal membrane model system to imitate the plasma membrane of mouse T\(_{reg}\) and T\(_{conv}\) with regards to their ceramide content. We found that the capacity of membranes to incorporate externally added azide-functionalized ceramide positively correlated with the ceramide content of the liposomes. Moreover, we studied the impact of the different liposomal preparations on primary mouse splenocytes in vitro. The addition of liposomes to resting, but not activated, splenocytes maintained viability with liposomes containing high amounts of C\(_{16}\)-ceramide being most efficient. Our data thus suggest that differences in ceramide post-incorporation into T\(_{reg}\) and T\(_{conv}\) reflect differences in the ceramide content of cellular membranes.}, language = {en} } @article{OuyangRueheZhangetal.2022, author = {Ouyang, Guanghui and R{\"u}he, Jessica and Zhang, Yang and Lin, Mei-Jin and Liu, Minghua and W{\"u}rthner, Frank}, title = {Intramolecular Energy and Solvent-Dependent Chirality Transfer within a BINOL-Perylene Hetero-Cyclophane}, series = {Angewandte Chemie International Edition}, volume = {61}, journal = {Angewandte Chemie International Edition}, number = {31}, doi = {10.1002/anie.202206706}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318818}, year = {2022}, abstract = {Multichromophoric macrocycles and cyclophanes are important supramolecular architectures for the elucidation of interchromophoric interactions originating from precise spatial organization. Herein, by combining an axially chiral binaphthol bisimide (BBI) and a bay-substituted conformationally labile twisted perylene bisimide (PBI) within a cyclophane of well-defined geometry, we report a chiral PBI hetero-cyclophane (BBI-PBI) that shows intramolecular energy and solvent-regulated chirality transfer from the BBI to the PBI subunit. Excellent spectral overlap and spatial arrangement of BBI and PBI lead to efficient excitation energy transfer and subsequent PBI emission with high quantum yield (80-98 \%) in various solvents. In contrast, chirality transfer is strongly dependent on the respective solvent as revealed by circular dichroism (CD) spectroscopy. The combination of energy and chirality transfer affords a bright red circularly polarized luminescence (CPL) from the PBI chromophore by excitation of BBI.}, language = {en} } @article{ScheidelOestreicherMarketal.2022, author = {Scheidel, Sebastian and {\"O}streicher, Laurina and Mark, Isabelle and P{\"o}ppler, Ann-Christin}, title = {You cannot fight the pressure: Structural rearrangements of active pharmaceutical ingredients under magic angle spinning}, series = {Magnetic Resonance in Chemistry}, volume = {60}, journal = {Magnetic Resonance in Chemistry}, number = {6}, doi = {10.1002/mrc.5267}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318838}, pages = {572 -- 582}, year = {2022}, abstract = {Although solid-state nuclear magnetic resonance (NMR) is a versatile analytical tool to study polymorphs and phase transitions of pharmaceutical molecules and products, this work summarizes examples of spontaneous and unexpected (and unwanted) structural rearrangements and phase transitions (amorphous-to-crystalline and crystalline-to-crystalline) under magic angle spinning (MAS) conditions, some of them clearly being due to the pressure experienced by the samples. It is widely known that such changes can often be detected by X-ray powder diffraction (XRPD); here, the capability of solid-state NMR experiments with a special focus on \(^{1}\)H-\(^{13}\)C frequency-switched Lee-Goldburg heteronuclear correlation (FSLG HETCOR)/MAS NMR experiments to detect even subtle changes on a molecular level not observable by conventional 1D NMR experiments or XRPD is presented. Furthermore, it is shown that a polymorphic impurity combined with MAS can induce a crystalline-to-crystalline phase transition. This showcases that solid-state NMR is not always noninvasive and such changes upon MAS should be considered in particular when compounds are studied over longer time spans.}, 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} } @article{HongKimKimetal.2022, author = {Hong, Yongseok and Kim, Woojae and Kim, Taeyeon and Kaufmann, Christina and Kim, Hyungjun and W{\"u}rthner, Frank and Kim, Dongho}, title = {Real-time Observation of Structural Dynamics Triggering Excimer Formation in a Perylene Bisimide Folda-dimer by Ultrafast Time-Domain Raman Spectroscopy}, series = {Angewandte Chemie International Edition}, volume = {61}, journal = {Angewandte Chemie International Edition}, number = {13}, doi = {10.1002/anie.202114474}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318788}, year = {2022}, abstract = {In π-conjugated organic photovoltaic materials, an excimer state has been generally regarded as a trap state which hinders efficient excitation energy transport. But despite wide investigations of the excimer for overcoming the undesirable energy loss, the understanding of the relationship between the structure of the excimer in stacked organic compounds and its properties remains elusive. Here, we present the landscape of structural dynamics from the excimer formation to its relaxation in a co-facially stacked archetypical perylene bisimide folda-dimer using ultrafast time-domain Raman spectroscopy. We directly captured vibrational snapshots illustrating the ultrafast structural evolution triggering the excimer formation along the interchromophore coordinate on the complex excited-state potential surfaces and following evolution into a relaxed excimer state. Not only does this work showcase the ultrafast structural dynamics necessary for the excimer formation and control of excimer characteristics but also provides important criteria for designing the π-conjugated organic molecules.}, language = {en} } @article{MuetzelFarrellShoyamaetal.2022, author = {M{\"u}tzel, Carina and Farrell, Jeffrey M. and Shoyama, Kazutaka and W{\"u}rthner, Frank}, title = {12b,24b-Diborahexabenzo[a,c,fg,l,n,qr]pentacene: A Low-LUMO Boron-Doped Polycyclic Aromatic Hydrocarbon}, series = {Angewandte Chemie International Edition}, volume = {61}, journal = {Angewandte Chemie International Edition}, number = {8}, doi = {10.1002/anie.202115746}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318808}, year = {2022}, abstract = {Herein we devise and execute a new synthesis of a pristine boron-doped nanographene. Our target boron-doped nanographene was designed based on DFT calculations to possess a low LUMO energy level and a narrow band gap derived from its precise geometry and B-doping arrangement. Our synthesis of this target, a doubly B-doped hexabenzopentacene (B\(_{2}\)-HBP), employs six net C-H borylations of an alkene, comprising consecutive hydroboration/electrophilic borylation/dehydrogenation and BBr\(_{3}\)/AlCl\(_{3}\)/2,6-dichloropyridine-mediated C-H borylation steps. As predicted by our calculations, B\(_{2}\)-HBP absorbs strongly in the visible region and emits in the NIR up to 1150 nm in o-dichlorobenzene solutions. Furthermore, B\(_{2}\)-HBP possesses a very low LUMO level, showing two reversible reductions at -1.00 V and -1.17 V vs. Fc\(^{+}\)/Fc. Our methodology is surprisingly selective despite its implementation of unfunctionalized precursors and offers a new approach to the synthesis of pristine B-doped polycyclic aromatic hydrocarbons.}, 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{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} } @phdthesis{Mut2023, author = {Mut, J{\"u}rgen}, title = {Synthese komplexer funktionaler Mono- und Oligosaccharid-Bausteine zur Untersuchung und Modifikation von Membranoberfl{\"a}chen humaner mesenchymaler Stromazellen}, doi = {10.25972/OPUS-32065}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-320654}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2023}, abstract = {Bei der Biofabrikation werden Zellen mit einem Biomaterial versetzt (vereint werden diese als Biotinte definiert) und durch additive Fertigungsmethoden wie dem 3D-Druck zu hierarchischen Strukturen aufgebaut. Zur Herstellung von k{\"u}nstlichen Gewebe und zuk{\"u}nftig auch von funktionalen Organen ist ein detailliertes Zellverst{\"a}ndnis essentiell. Im Rahmen dieser Dissertation wurden Systeme generiert, um die Zellmembranen von mesenchymalen Stromazellen gezielt zu ver{\"a}ndern und um die Modifikationen zu charakterisieren. Durch Inkubation mit unnat{\"u}rlichen Zuckern werden diese von Zellen aufgenommen und in den Zellmetabolismus eingeschleust und auf die Glycoproteine {\"u}bertragen. Diese Methode ist als metabolic glycoengineering bekannt. Dazu wurden diverse humane Saccharid-Analoga mit bioorthogonalen Gruppen (Azid oder Alkin) synthetisiert. Alle in dieser Arbeit vorgestellten Molek{\"u}le wurden NMR-spektroskopisch als auch massenspektrometrisch charakterisiert. Die acetylierten Mannosamin-Derivate konnten {\"u}ber zwei Stufen und die Sialins{\"a}ure-Derivate {\"u}ber sechs Stufen synthetisiert werden. Sialins{\"a}uren sind die terminalen Zucker an Glycanketten von Proteinen mit wichtigen biologischen Funktionen. Im Rahmen des SFB TRR225 konnte in Kooperation mit der Gruppe von Prof. Dr. R. Ebert der Einbau der Saccharide in mesenchymalen Stromazellen durch Fluoreszenzmikroskopie evaluiert werden. Aufgrund des effizienteren Einbaus der Sialins{\"a}ure mit Alkingruppe gegen{\"u}ber der mit Azidgruppe, wurde dieser in den folgenden massenspektrometrischen Analysen eingesetzt. Die Messungen der markierten Glycoproteine wurden von Dr. Marc Driessen durchgef{\"u}hrt und der metabolische Einbau von SiaNAl und Ac4ManNAl in den Stromazellen gegen{\"u}bergestellt. 55 Glycoproteine konnten durch SiaNAl und 94 durch Ac4ManNAl charakterisiert werden. Ein Abgleich der Proteindatenbanken eine Anreicherung von Proteine durch F{\"u}tterung von SiaNAl die in Signaltransduktion, Zellkontakte und Differenzierung involviert sind, womit metabolic glycoengineering prinzipiell zur Optimierung von Biofabrikationsprozessen genutzt werden kann.}, subject = {Glykane}, language = {de} } @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{MenekseMahlAlbertetal.2023, author = {Menekse, Kaan and Mahl, Magnus and Albert, Julius and Niyas, M. A. and Shoyama, Kazutaka and Stolte, Matthias and W{\"u}rthner, Frank}, title = {Supramolecularly Engineered Bulk-Heterojunction Solar Cells with Self-Assembled Non-Fullerene Nanographene Tetraimide Acceptors}, series = {Solar RRL}, volume = {7}, journal = {Solar RRL}, number = {2}, doi = {10.1002/solr.202200895}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312099}, year = {2023}, abstract = {A series of novel imide-functionalized C\(_{64}\) nanographenes is investigated as acceptor components in organic solar cells (OSCs) in combination with donor polymer PM6. These electron-poor molecules either prevail as a monomer or self-assemble into dimers in the OSC active layer depending on the chosen imide substituents. This allows for the controlled stacking of electron-poor and electron-rich π-scaffolds to establish a novel class of non-fullerene acceptor materials to tailor the bulk-heterojunction morphology of the OSCs. The best performance is observed for derivatives that are able to self-assemble into dimers, reaching power conversion efficiencies of up to 7.1\%.}, language = {en} } @article{FullWoelflickRadackietal.2022, author = {Full, Felix and W{\"o}lflick, Quentin and Radacki, Krzysztof and Braunschweig, Holger and Nowak-Kr{\´o}l, Agnieszka}, title = {Enhanced Optical Properties of Azaborole Helicenes by Lateral and Helical Extension}, series = {Chemistry - A European Journal}, volume = {28}, journal = {Chemistry - A European Journal}, number = {62}, doi = {10.1002/chem.202202280}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-293671}, year = {2022}, abstract = {The synthesis and characterization of laterally extended azabora[5]-, -[6]- and -[7]helicenes, assembled from N-heteroaromatic and dibenzo[g,p]chrysene building blocks is described. Formally, the π-conjugated systems of the pristine azaborole helicenes were enlarged with a phenanthrene unit leading to compounds with large Stokes shifts, significantly enhanced luminescence quantum yields (Φ) and dissymmetry factors (g\(_{lum}\)). The beneficial effect on optical properties was also observed for helical elongation. The combined contributions of lateral and helical extensions resulted in a compound showing green emission with Φ of 0.31 and |g\(_{lum}\)| of 2.2×10\(^{-3}\), highest within the series of π-extended azaborahelicenes and superior to emission intensity and chiroptical response of its non-extended congener. This study shows that helical and lateral extensions of π-conjugated systems are viable strategies to improve features of azaborole helicenes. In addition, single crystal X-ray analysis of configurationally stable [6]- and -[7]helicenes was used to provide insight into their packing arrangements.}, language = {en} } @article{SchnitzleinZhuShoyamaetal.2022, author = {Schnitzlein, Matthias and Zhu, Chongwei and Shoyama, Kazutaka and W{\"u}rthner, Frank}, title = {π-Extended Pleiadienes by [5+2] Annulation of 1-Boraphenalenes and ortho-Dihaloarenes}, series = {Chemistry - A European Journal}, volume = {28}, journal = {Chemistry - A European Journal}, number = {61}, doi = {10.1002/chem.202202053}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-293919}, year = {2022}, abstract = {Palladium-catalyzed [5+2] annulation of 1-boraphenalenes with ortho-dihaloarenes afforded negatively curved π-extended pleiadienes. Two benzo[1,2-i:4,5-i']dipleiadienes (BDPs) featuring a seven-six-seven-membered ring arrangement were synthesized and investigated. Their crystal structure revealed a unique packing arrangement and theoretical calculations were employed to shed light onto the dynamic behavior of the BDP moiety and its aromaticity. Further, a naphthalene-fused pleiadiene was stitched together by oxidative cyclodehydrogenation to yield an additional five-membered ring. This formal azulene moiety led to distinct changes in optical and redox properties and increased perturbation of the aromatic system.}, language = {en} } @article{KoleKošćakAmaretal.2022, author = {Kole, Goutam Kumar and Košćak, Marta and Amar, Anissa and Majhen, Dragomira and Božinović, Ksenija and Brkljaca, Zlatko and Ferger, Matthias and Michail, Evripidis and Lorenzen, Sabine and Friedrich, Alexandra and Krummenacher, Ivo and Moos, Michael and Braunschweig, Holger and Boucekkine, Abdou and Lambert, Christoph and Halet, Jean-Fran{\c{c}}ois and Piantanida, Ivo and M{\"u}ller-Buschbaum, Klaus and Marder, Todd B.}, title = {Methyl Viologens of Bis-(4'-Pyridylethynyl)Arenes - Structures, Photophysical and Electrochemical Studies, and their Potential Application in Biology}, series = {Chemistry - A European Journal}, volume = {28}, journal = {Chemistry - A European Journal}, number = {40}, doi = {10.1002/chem.202200753}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-287126}, year = {2022}, abstract = {A series of bis-(4'-pyridylethynyl)arenes (arene=benzene, tetrafluorobenzene, and anthracene) were synthesized and their bis-N-methylpyridinium compounds were investigated as a class of π-extended methyl viologens. Their structures were determined by single crystal X-ray diffraction, and their photophysical and electrochemical properties (cyclic voltammetry), as well as their interactions with DNA/RNA were investigated. The dications showed bathochromic shifts in emission compared to the neutral compounds. The neutral compounds showed very small Stokes shifts, which are a little larger for the dications. All of the compounds showed very short fluorescence lifetimes (<4 ns). The neutral compound with an anthracene core has a quantum yield of almost unity. With stronger acceptors, the analogous bis-N-methylpyridinium compound showed a larger two-photon absorption cross-section than its neutral precursor. All of the dicationic compounds interact with DNA/RNA; while the compounds with benzene and tetrafluorobenzene cores bind in the grooves, the one with an anthracene core intercalates as a consequence of its large, condensed aromatic linker moiety, and it aggregates within the polynucleotide when in excess over DNA/RNA. Moreover, all cationic compounds showed highly specific CD spectra upon binding to ds-DNA/RNA, attributed to the rare case of forcing the planar, achiral molecule into a chiral rotamer, and negligible toxicity toward human cell lines at ≤10 μM concentrations. The anthracene-analogue exhibited intracellular accumulation within lysosomes, preventing its interaction with cellular DNA/RNA. However, cytotoxicity was evident at 1 μM concentration upon exposure to light, due to singlet oxygen generation within cells. These multi-faceted features, in combination with its two-photon absorption properties, suggest it to be a promising lead compound for development of novel light-activated theranostic agents.}, language = {en} } @article{NollGrossShoyamaetal.2023, author = {Noll, Niklas and Groß, Tobias and Shoyama, Kazutaka and Beuerle, Florian and W{\"u}rthner, Frank}, title = {Folding-Induced Promotion of Proton-Coupled Electron Transfers via Proximal Base for Light-Driven Water Oxidation}, series = {Angewandte Chemie International Edition}, volume = {62}, journal = {Angewandte Chemie International Edition}, number = {7}, doi = {10.1002/anie.202217745}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312020}, year = {2023}, abstract = {Proton-coupled electron-transfer (PCET) processes play a key role in biocatalytic energy conversion and storage, for example, photosynthesis or nitrogen fixation. Here, we report a series of bipyridine-containing di- to tetranuclear Ru(bda) macrocycles 2 C-4 C (bda: 2,2′-bipyridine-6,6′-dicarboxylate) to promote O-O bond formation. In photocatalytic water oxidation under neutral conditions, all complexes 2 C-4 C prevail in a folded conformation that support the water nucleophilic attack (WNA) pathway with remarkable turnover frequencies of up to 15.5 s\(^{-1}\) per Ru unit respectively. Single-crystal X-ray analysis revealed an increased tendency for intramolecular π-π stacking and preorganization of the proximal bases close to the active centers for the larger macrocycles. H/D kinetic isotope effect studies and electrochemical data demonstrate the key role of the proximal bipyridines as proton acceptors in lowering the activation barrier for the crucial nucleophilic attack of H\(_{2}\)O in the WNA mechanism.}, language = {en} } @article{SchlossarekStepanenkoBeuerleetal.2022, author = {Schlossarek, Tim and Stepanenko, Vladimir and Beuerle, Florian and W{\"u}rthner, Frank}, title = {Self-assembled Ru(bda) Coordination Oligomers as Efficient Catalysts for Visible Light-Driven Water Oxidation in Pure Water}, series = {Angewandte Chemie International Edition}, volume = {61}, journal = {Angewandte Chemie International Edition}, number = {52}, doi = {10.1002/anie.202211445}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312184}, year = {2022}, abstract = {Water-soluble multinuclear complexes based on ruthenium 2,2′-bipyridine-6,6′-dicarboxylate (bda) and ditopic bipyridine linker units are investigated in three-component visible light-driven water oxidation catalysis. Systematic studies revealed a strong enhancement of the catalytic efficiency in the absence of organic co-solvents and with increasing oligomer length. In-depth kinetic and morphological investigations suggest that the enhanced performance is induced by the self-assembly of linear Ru(bda) oligomers into aggregated superstructures. The obtained turnover frequencies (up to 14.9 s\(^{-1}\)) and turnover numbers (more than 1000) per ruthenium center are the highest reported so far for Ru(bda)-based photocatalytic water oxidation systems.}, language = {en} } @article{BrustNaglerShoyamaetal.2023, author = {Brust, Felix and Nagler, Oliver and Shoyama, Kazutaka and Stolte, Matthias and W{\"u}rthner, Frank}, title = {Organic Light-Emitting Diodes Based on Silandiol-Bay-Bridged Perylene Bisimides}, series = {Advanced Optical Materials}, volume = {11}, journal = {Advanced Optical Materials}, number = {5}, doi = {10.1002/adom.202202676}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312599}, year = {2023}, abstract = {Perylene bisimides (PBIs) are among the best fluorophores but have to be enwrapped for optoelectronic applications by large and heavy substituents to prevent their ππ-stacking, which is known to accelerate non-radiative decay processes in the solid state. Here, light-weight di-tert-butylsilyl groups are introduced to bridge 1,12-dihydroxy and 1,6,7,12-tetrahydroxy PBIs to afford sublimable dyes for vacuum-processed optoelectronic devices. For both new compounds, this substitution provides a twisted and shielded perylene π-core whose, via OSiObridges, rigid structure affords well-resolved absorption and emission spectra with strong fluorescence in solution, as well as in the solid state. The usefulness of these dyes for vacuum-processed optoelectronic devices is demonstrated in organic light-emitting diodes (OLEDs) that show monomer-like emission spectra and high maximum external quantum efficiency (EQEmax) values of up to 3.1\% for the doubly silicon-bridged PBI.}, language = {en} } @article{RagerJakowetzGoleetal.2019, author = {Rager, Sabrina and Jakowetz, Andreas C. and Gole, Bappaditya and Beuerle, Florian and Medina, Dana D. and Bein, Thomas}, title = {Scaffold-Induced Diketopyrrolopyrrole Molecular Stacks in a Covalent Organic Framework}, series = {Chemistry of Materials}, volume = {31}, journal = {Chemistry of Materials}, number = {8}, doi = {10.1021/acs.chemmater.8b02882}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-224927}, pages = {2707-2712}, year = {2019}, abstract = {In recent years, covalent organic frameworks (COFs) have attracted considerable attention due to their crystalline and porous nature, which positions them as intriguing candidates for diverse applications such as catalysis, sensing, or optoelectronics. The incorporation of dyes or semiconducting moieties into a rigid two-dimensional COF can offer emergent features such as enhanced light harvesting or charge transport. However, this approach can be challenging when dealing with dye molecules that exhibit a large aromatic backbone, since the steric demand of solubilizing side chains also needs to be integrated into the framework. Here, we report the successful synthesis of DPP2-HHTP-COF consisting of diketopyrrolopyrrole (DPP) diboronic acid and hexahydroxytriphenylene (HHTP) building blocks. The well-known boronate ester coupling motif guides the formation of a planar and rigid backbone and long-range molecular DPP stacks, resulting in a highly crystalline and porous material. DPP2-HHTP-COF exhibits excellent optical properties including strong absorption over the visible spectral range, broad emission into the NIR and a singlet lifetime of over 5 ns attributed to the formation of molecular stacks with J-type interactions between the DPP subcomponents in the COF. Electrical measurements of crystalline DPP2-HHTP-COF pellets revealed conductivity values of up to 10(-6) S cm(-1).}, language = {en} } @article{QuastGescheidtSpichty2020, author = {Quast, Helmut and Gescheidt, Georg and Spichty, Martin}, title = {Topological dynamics of a radical ion pair: Experimental and computational assessment at the relevant nanosecond timescale}, series = {Chemistry}, volume = {2}, journal = {Chemistry}, number = {2}, issn = {2624-8549}, doi = {10.3390/chemistry2020014}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-285195}, pages = {219 -- 230}, year = {2020}, abstract = {Chemical processes mostly happen in fluid environments where reaction partners encounter via diffusion. The bimolecular encounters take place at a nanosecond time scale. The chemical environment (e.g., solvent molecules, (counter)ions) has a decisive influence on the reactivity as it determines the contact time between two molecules and affects the energetics. For understanding reactivity at an atomic level and at the appropriate dynamic time scale, it is crucial to combine matching experimental and theoretical data. Here, we have utilized all-atom molecular-dynamics simulations for accessing the key time scale (nanoseconds) using a QM/MM-Hamiltonian. Ion pairs consisting of a radical ion and its counterion are ideal systems to assess the theoretical predictions because they reflect dynamics at an appropriate time scale when studied by temperature-dependent EPR spectroscopy. We have investigated a diketone radical anion with its tetra-ethylammonium counterion. We have established a funnel-like transition path connecting two (equivalent) complexation sites. The agreement between the molecular-dynamics simulation and the experimental data presents a new paradigm for ion-ion interactions. This study exemplarily demonstrates the impact of the molecular environment on the topological states of reaction intermediates and how these states can be consistently elucidated through the combination of theory and experiment. We anticipate that our findings will contribute to the prediction of bimolecular transformations in the condensed phase with relevance to chemical synthesis, polymers, and biological activity.}, language = {en} }