TY - JOUR A1 - Dostál, Jakub A1 - Fennel, Franziska A1 - Koch, Federico A1 - Herbst, Stefanie A1 - Würthner, Frank A1 - Brixner, Tobias T1 - Direct observation of exciton–exciton interactions JF - Nature Communications N2 - 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. KW - energy transfer KW - self-assembly KW - optical spectroscopy Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-226271 VL - 9 ER - TY - JOUR A1 - Rager, Sabrina A1 - Jakowetz, Andreas C. A1 - Gole, Bappaditya A1 - Beuerle, Florian A1 - Medina, Dana D. A1 - Bein, Thomas T1 - Scaffold-Induced Diketopyrrolopyrrole Molecular Stacks in a Covalent Organic Framework JF - Chemistry of Materials N2 - 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). KW - Polymers KW - Electron KW - Design Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224927 VL - 31 IS - 8 ER - TY - JOUR A1 - Rushdi, Mohammed I. A1 - Abdel-Rahman, Iman A. M. A1 - Attia, Eman Zekry A1 - Saber, Hani A1 - Saber, Abdullah A. A1 - Bringmann, Gerhard A1 - Abdelmohsen, Usama Ramadan T1 - The biodiversity of the genus Dictyota: phytochemical and pharmacological natural products prospectives JF - Molecules N2 - Although a broad variety of classes of bioactive compounds have already been isolated from seaweeds of the genus Dictyota, most different species are still chemically and biologically unexplored. Dictyota species are well-known brown seaweeds belonging to the Dictyotaceae (Phaeophyta). The phytochemical composition within the genus Dictyota has recently received considerable interest, and a vast array of components, including diterpenes, sesquiterepenes, sterols, amino acids, as well as saturated and polyunsaturated fatty acids, have been characterized. The contribution of these valued metabolites to the biological potential, which includes anti-proliferative, anti-microbial, antiviral, antioxidant, anti-inflammatory, and anti-hyperpigmentation activities, of the genus Dictyota has also been explored. Therefore, this is the most comprehensive review, focusing on the published literature relevant to the chemically and pharmacologically diverse biopharmaceuticals isolated from different species of the genus Dictyota during the period from 1976 to now. KW - Phaeophyceae KW - Dictyotaceae KW - marine macroalgae KW - brown seaweeds KW - natural products KW - bioactivities KW - Dictyota Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-302428 SN - 1420-3049 VL - 27 IS - 3 ER - TY - JOUR A1 - Rieth, Thorsten A1 - Tober, Natalie A1 - Limbach, Daniel A1 - Haspel, Tobias A1 - Sperner, Marcel A1 - Schupp, Niklas A1 - Wicker, Philipp A1 - Glang, Stefan A1 - Lehmann, Matthias A1 - Detert, Heiner T1 - Impact of substitution pattern and chain length on the thermotropic properties of alkoxy-substituted triphenyl-tristriazolotriazines JF - Molecules N2 - Tristriazolotriazines (TTTs) with a threefold alkoxyphenyl substitution were prepared and studied by DSC, polarized optical microscopy (POM) and X-ray scattering. Six pentyloxy chains are sufficient to induce liquid-crystalline behavior in these star-shaped compounds. Thermotropic properties of TTTs with varying substitution patterns and a periphery of linear chains of different lengths, branching in the chain and swallow-tails, are compared. Generally, these disks display broad and stable thermotropic mesophases, with the tangential TTT being superior to the radial isomer. The structure–property relationships of the number of alkyl chains, their position, length and structure were studied. KW - star-shaped compounds KW - discotic liquid crystals KW - X-ray diffraction KW - differential scanning calorimetry KW - polarizing optical microscopy KW - swallow-tail KW - heterocycles KW - structure–property relation Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-220019 SN - 1420-3049 VL - 25 IS - 23 ER - TY - JOUR A1 - Merz, Julia A1 - Dietz, Maximilian A1 - Vonhausen, Yvonne A1 - Wöber, Frederik A1 - Friedrich, Alexandra A1 - Sieh, Daniel A1 - Krummenacher, Ivo A1 - Braunschweig, Holger A1 - Moos, Michael A1 - Holzapfel, Marco A1 - Lambert, Christoph A1 - Marder, Todd B. T1 - Synthesis, Photophysical and Electronic Properties of New Red-to-NIR Emitting Donor-Acceptor Pyrene Derivatives JF - Chemistry - A European Journal N2 - We synthesized new pyrene derivatives with strong bis(para ‐methoxyphenyl)amine donors at the 2,7‐positions and n ‐azaacene acceptors at the K‐region of pyrene. The compounds possess a strong intramolecular charge transfer, leading to unusual properties such as emission in the red to NIR region (700 nm), which has not been reported before for monomeric pyrenes. Detailed photophysical studies reveal very long intrinsic lifetimes of >100 ns for the new compounds, which is typical for 2,7‐substituted pyrenes but not for K‐region substituted pyrenes. The incorporation of strong donors and acceptors leads to very low reduction and oxidation potentials, and spectroelectrochemical studies show that the compounds are on the borderline between localized Robin‐Day class‐II and delocalized Robin‐Day class‐III species. KW - orylation KW - K-region KW - luminescence KW - polycyclic aromatic hydrocarbons KW - redox Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-207486 VL - 26 IS - 2 ER - TY - JOUR A1 - Wiese, Teresa A1 - Dennstädt, Fabio A1 - Hollmann, Claudia A1 - Stonawski, Saskia A1 - Wurst, Catherina A1 - Fink, Julian A1 - Gorte, Erika A1 - Mandasari, Putri A1 - Domschke, Katharina A1 - Hommers, Leif A1 - Vanhove, Bernard A1 - Schumacher, Fabian A1 - Kleuser, Burkard A1 - Seibel, Jürgen A1 - Rohr, Jan A1 - Buttmann, Mathias A1 - Menke, Andreas A1 - Schneider-Schaulies, Jürgen A1 - Beyersdorf, Niklas T1 - Inhibition of acid sphingomyelinase increases regulatory T cells in humans JF - Brain Communications N2 - Genetic deficiency for acid sphingomyelinase or its pharmacological inhibition has been shown to increase Foxp3\(^+\) regulatory T-cell frequencies among CD4\(^+\) T cells in mice. We now investigated whether pharmacological targeting of the acid sphingomyelinase, which catalyzes the cleavage of sphingomyelin to ceramide and phosphorylcholine, also allows to manipulate relative CD4\(^+\) Foxp3\(^+\) regulatory T-cell frequencies in humans. Pharmacological acid sphingomyelinase inhibition with antidepressants like sertraline, but not those without an inhibitory effect on acid sphingomyelinase activity like citalopram, increased the frequency of Foxp3\(^+\) regulatory T cell among human CD4\(^+\) T cells in vitro. In an observational prospective clinical study with patients suffering from major depression, we observed that acid sphingomyelinase-inhibiting antidepressants induced a stronger relative increase in the frequency of CD4\(^+\) Foxp3\(^+\) regulatory T cells in peripheral blood than acid sphingomyelinase-non- or weakly inhibiting antidepressants. This was particularly true for CD45RA\(^-\) CD25\(^{high}\) effector CD4\(^+\) Foxp3\(^+\) regulatory T cells. Mechanistically, our data indicate that the positive effect of acid sphingomyelinase inhibition on CD4\(^+\) Foxp3\(^+\) regulatory T cells required CD28 co-stimulation, suggesting that enhanced CD28 co-stimulation was the driver of the observed increase in the frequency of Foxp3+ regulatory T cells among human CD4\(^+\) T cells. In summary, the widely induced pharmacological inhibition of acid sphingomyelinase activity in patients leads to an increase in Foxp3+ regulatory T-cell frequencies among CD4\(^+\) T cells in humans both in vivo and in vitro. KW - acid sphingomyelinase KW - antidepressants KW - major depression KW - regulatory T cells KW - sphingolipids Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-259868 VL - 3 IS - 2 ER - TY - JOUR A1 - Steinmetzger, Christian A1 - Bäuerlein, Carmen A1 - Höbartner, Claudia T1 - Supramolecular fluorescence resonance energy transfer in nucleobase-modified fluorogenic RNA aptamers JF - Angewandte Chemie, International Edition N2 - RNA aptamers form compact tertiary structures and bind their ligands in specific binding sites. Fluorescence-based strategies reveal information on structure and dynamics of RNA aptamers. Here we report the incorporation of the universal emissive nucleobase analog 4-cyanoindole into the fluorogenic RNA aptamer Chili, and its application as a donor for supramolecular FRET to bound ligands DMHBI+ or DMHBO+. The photophysical properties of the new nucleobase-ligand-FRET pair revealed structural restraints for the overall RNA aptamer organization and identified nucleotide positions suitable for FRET-based readout of ligand binding. This strategy is generally suitable for binding site mapping and may also be applied for responsive aptamer devices. KW - RNA aptamers KW - fluorescence resonance energy transfer KW - large stokes shift KW - isomorphic nucleobase analog KW - structure probing KW - structure probes KW - stokes shift KW - Fluoreszenzresonanz-Energietransfer KW - Isomorphe Nukleobasen-Analoga KW - RNA-Aptamere KW - Stokes-Verschiebung KW - Struktursonden Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-203084 N1 - Parallel erschienen in Angewandte Chemie 2020,132, 6826–6830. DOI: 10.1002/ange.201916707 (Deutsche Ausgabe). VL - 59 ER - TY - JOUR A1 - Dietzsch, Julia A1 - Bialas, David A1 - Bandorf, Johannes A1 - Würthner, Frank A1 - Höbartner, Claudia T1 - Tuning Exciton Coupling of Merocyanine Nucleoside Dimers by RNA, DNA and GNA Double Helix Conformations JF - Angewandte Chemie International Edition N2 - Exciton coupling between two or more chromophores in a specific environment is a key mechanism associated with color tuning and modulation of absorption energies. This concept is well exemplified by natural photosynthetic proteins, and can also be achieved in synthetic nucleic acid nanostructures. Here we report the coupling of barbituric acid merocyanine (BAM) nucleoside analogues and show that exciton coupling can be tuned by the double helix conformation. BAM is a nucleobase mimic that was incorporated in the phosphodiester backbone of RNA, DNA and GNA oligonucleotides. Duplexes with different backbone constitutions and geometries afforded different mutual dye arrangements, leading to distinct optical signatures due to competing modes of chromophore organization via electrostatic, dipolar, - stacking and hydrogen-bonding interactions. The realized supramolecular motifs include hydrogenbonded BAM–adenine base pairs and antiparallel as well as rotationally stacked BAM dimer aggregates with distinct absorption, CD and fluorescence properties. KW - Chromophore Assembly KW - Merocyanine KW - Nucleobase Analogue KW - Supramolecular Element KW - Nucleic Acids Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-254565 ER - TY - JOUR A1 - Ferger, Matthias A1 - Roger, Chantal A1 - Köster, Eva A1 - Rauch, Florian A1 - Lorenzen, Sabine A1 - Krummenacher, Ivo A1 - Friedrich, Alexandra A1 - Košćak, Marta A1 - Nestić, Davor A1 - Braunschweig, Holger A1 - Lambert, Christoph A1 - Piantanida, Ivo A1 - Marder, Todd B. T1 - Electron‐Rich EDOT Linkers in Tetracationic bis‐Triarylborane Chromophores: Influence on Water Stability, Biomacromolecule Sensing, and Photoinduced Cytotoxicity JF - Chemistry – A European Journal N2 - Three novel tetracationic bis‐triarylboranes with 3,4‐ethylenedioxythiophene (EDOT) linkers, and their neutral precursors, showed significant red‐shifted absorption and emission compared to their thiophene‐containing analogues, with one of the EDOT‐derivatives emitting in the NIR region. Only the EDOT‐linked trixylylborane tetracation was stable in aqueous solution, indicating that direct attachment of a thiophene or even 3‐methylthiophene to the boron atom is insufficient to provide hydrolytic stability in aqueous solution. Further comparative analysis of the EDOT‐linked trixylylborane tetracation and its bis‐thiophene analogue revealed efficient photo‐induced singlet oxygen production, with the consequent biological implications. Thus, both analogues bind strongly to ds‐DNA and BSA, very efficiently enter living human cells, accumulate in several different cytoplasmic organelles with no toxic effect but, under intense visible light irradiation, they exhibit almost instantaneous and very strong cytotoxic effects, presumably attributed to singlet oxygen production. Thus, both compounds are intriguing theranostic agents, whose intracellular and probably intra‐tissue location can be monitored by strong fluorescence, allowing switching on of the strong bioactivity by well‐focused visible light. KW - boranes KW - DNA/RNA sensors KW - fluorescent probes KW - singlet oxygen KW - theranostics Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-287241 VL - 28 IS - 48 ER - TY - JOUR A1 - Götz, Ralph A1 - Kunz, Tobias C. A1 - Fink, Julian A1 - Solger, Franziska A1 - Schlegel, Jan A1 - Seibel, Jürgen A1 - Kozjak-Pavlovic, Vera A1 - Rudel, Thomas A1 - Sauer, Markus T1 - Nanoscale imaging of bacterial infections by sphingolipid expansion microscopy JF - Nature Communications N2 - Expansion microscopy (ExM) enables super-resolution imaging of proteins and nucleic acids on conventional microscopes. However, imaging of details of the organization of lipid bilayers by light microscopy remains challenging. We introduce an unnatural short-chain azide- and amino-modified sphingolipid ceramide, which upon incorporation into membranes can be labeled by click chemistry and linked into hydrogels, followed by 4x to 10x expansion. Confocal and structured illumination microscopy (SIM) enable imaging of sphingolipids and their interactions with proteins in the plasma membrane and membrane of intracellular organelles with a spatial resolution of 10-20nm. As our functionalized sphingolipids accumulate efficiently in pathogens, we use sphingolipid ExM to investigate bacterial infections of human HeLa229 cells by Neisseria gonorrhoeae, Chlamydia trachomatis and Simkania negevensis with a resolution so far only provided by electron microscopy. In particular, sphingolipid ExM allows us to visualize the inner and outer membrane of intracellular bacteria and determine their distance to 27.6 +/- 7.7nm. Imaging of lipid bilayers using light microscopy is challenging. Here the authors label cells using a short chain click-compatible ceramide to visualize mammalian and bacterial membranes with expansion microscopy. KW - nanoscale imaging KW - bacterial infection KW - sphingolipid expansion microscopy Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-231248 VL - 11 ER -