Refine
Has Fulltext
- yes (45)
Is part of the Bibliography
- yes (45)
Year of publication
- 2022 (45) (remove)
Document Type
- Journal article (29)
- Doctoral Thesis (13)
- Preprint (2)
- Book article / Book chapter (1)
Keywords
- perylene bisimide (4)
- water oxidation (4)
- Chemische Synthese (3)
- RNA (3)
- aromaticity (3)
- catalysis (3)
- fluorescence (3)
- Flüssigkristalle (2)
- Helix-Coil-Transition (2)
- Helix-Knäuel-Umwandlung (2)
- J- and H-Aggregate (2)
- J- and H-Aggregates (2)
- Merocyanine (2)
- Oligomere (2)
- Polymere (2)
- annulation (2)
- azulene (2)
- luminescence (2)
- macrocycles (2)
- oligothiophenes (2)
- organic chemistry (2)
- phosphorescence (2)
- photocatalysis (2)
- photoinduced electron transfer (2)
- polycyclic aromatic hydrocarbons (2)
- singlet oxygen (2)
- AIE (1)
- API (1)
- Amino Acids (1)
- Aminosäuren (1)
- Analysis of RNA Modifications (1)
- Aptamer (1)
- Aromatically annulated triquinacenes (1)
- Aromatisch anellierte Triquinacene (1)
- Asymmetric synthesis (1)
- Asymmetrische Synthese (1)
- CD-Spektroskopie (1)
- CVD-Diamant (1)
- Chemosensor (1)
- Chiralität <Chemie> (1)
- Chromophore Assembly (1)
- Circular dichroism (1)
- Corannulene (1)
- Crystal structure of MTR1 (1)
- DNA (1)
- DNA/RNA binding (1)
- DNA/RNA sensors (1)
- Deoxyribozymes (1)
- Detonationsdiamant (1)
- Diamant (1)
- Dictyota (1)
- Dictyotaceae (1)
- Donor-Akzeptor-Dyaden (1)
- Drug Delivery System (1)
- Enzymes (1)
- Exziton (1)
- Farbstoff (1)
- Festkörper-NMR (1)
- Festphasenpeptidsynthese (1)
- Fluoreszenzaktivierung (1)
- Flüssigkristall (1)
- Fotovoltaik (1)
- Freiraumfüllung (1)
- Fulleren (1)
- Fullerene (1)
- Grün fluoreszierendes Protein (1)
- High-Throughput Sequencing Method, DZ-seq (1)
- Hydrogel (1)
- J‐aggregates (1)
- Katalyse (1)
- Kohlenstoffnanozwiebel (1)
- Kolloid / Lösung <Chemie> (1)
- Kolloidalstabilität (1)
- Lippert–Mataga plot (1)
- Liquid Crystals (1)
- MAS (1)
- METTL8 (1)
- Makrocyclische Verbindungen (1)
- Metallosupramolekulare Chemie (1)
- Methyltransferase Ribozyme MTR1 (1)
- Mitochondrial Matrix Protein (1)
- Modified Nucleotides in tRNAs (1)
- NMR-Spektroskopie (1)
- Nanodiamant (1)
- Naphthylisoindolinone alkaloids (1)
- Nucleic Acids (1)
- Nucleinsäuren (1)
- Nucleobase Analogue (1)
- Optical Spectroscopy (1)
- Optische Spektroskopie (1)
- Organelles (1)
- Organic Chemistry (1)
- Organische Chemie (1)
- Oxidation (1)
- Perylenbisdicarboximide (1)
- Phaeophyceae (1)
- Phthalocyanin (1)
- Protein Corona (1)
- Quantenchemie (1)
- Quantum Chemical Calculations (1)
- RAFT (1)
- RNA G-quadruplex (1)
- RNA Methyltransferase (1)
- RNA cleavage (1)
- RNA modifications (1)
- RNA structures (1)
- RNA-Cleaving Deoxyribozymes (1)
- RNA-catalyzed RNA methylation (1)
- Ribozymes (1)
- Ringöffnungspolymerisation (1)
- Ruthenium Komplexe (1)
- Ruthenium complexes (1)
- Rutheniumkomplexe (1)
- Röntgendiffraktometrie (1)
- SARS-CoV-2 (1)
- Solid Phase Peptide Synthesis (1)
- Solid-State NMR Spectroscopy (1)
- Squarain (1)
- Squarain-Farbstoff (1)
- Squaraine (1)
- Squaraine-Dye (1)
- Sternmesogene (1)
- Supramolecular Element (1)
- Targeting (1)
- Taxol (1)
- Thiophen (1)
- Triquinacenderivate (1)
- Wasser (1)
- Wasserlösliche Polymere (1)
- Wasseroxidation (1)
- Wirkstoff-Träger-System (1)
- X-Ray Diffraction (1)
- X-ray crystallography (1)
- XNA (1)
- XRPD (1)
- \(^{1}\)H-\(^{13}\)C HETCOR (1)
- acid sphingomyelinase (1)
- aggregation (1)
- arene-fluoroarene (1)
- artificial base pair (1)
- artificial photosynthesis (1)
- azaborole (1)
- bioactivities (1)
- boranes (1)
- boric acid (1)
- boron (1)
- brown seaweeds (1)
- catalyst (1)
- catalyst synthesis (1)
- catalytic DNA (1)
- catalytic mechanisms (1)
- cell imaging (1)
- cell membrane model (1)
- ceramidase (1)
- ceramide (1)
- ceramides (1)
- chirality transfer (1)
- circularly polarized luminescence (1)
- cocrystallization (1)
- conjugated molecule (1)
- coordination oligomer (1)
- covalent organic framework (1)
- crystal engineering (1)
- crystalline (1)
- curved hydrocarbons (1)
- cyclodehydrogenation (1)
- cyclophanes (1)
- deoxyribozymes (1)
- dipole-dipole interaction (1)
- donor-acceptor dyad (1)
- donor-acceptor dyads (1)
- donor–acceptor (1)
- donor–acceptor dyads (1)
- duplex structure (1)
- dye assembly (1)
- dyes/pigments (1)
- electron transfer (1)
- electronic structure (1)
- energy transfer (1)
- enzyme (1)
- epitranscriptomics (1)
- excimer (1)
- exciton coupling (1)
- fluorescent probes (1)
- fluoxetine (1)
- folding (1)
- gekrümmte Kohlenwasserstoffe (1)
- helicene (1)
- homogeneous catalysis (1)
- hydrazone (1)
- in vitro selection (1)
- liposome (1)
- macrocycle (1)
- marine macroalgae (1)
- merocyanine (1)
- merocyanines (1)
- metallosupramolecular chemistry (1)
- methyl viologen (1)
- modified RNA nucleotides (1)
- molecular (1)
- nanoparticles (1)
- naphthalene diimide (1)
- natural products (1)
- near infrared emitter (1)
- oligothiophene (1)
- on surface self-assembly (1)
- optical materials (1)
- organic photodiodes (1)
- organic solar cells (1)
- pentacene (1)
- peptide backbone (1)
- perylenebisimide (1)
- platinum complexes (1)
- polycycles (1)
- polyglycidol (1)
- polymer-peptide-conjugate (1)
- push–pull thienylthiazole (1)
- quantenchemische Berechnungen (1)
- ring opening polymerisation (1)
- room-temperature phosphorescence (RTP) (1)
- ruthenium complexes (1)
- sSupramolecular interaction (1)
- solid-state NMR (1)
- solvatochromism (1)
- solvent effects (1)
- starazine (1)
- starphene analogue (1)
- structural changes (1)
- structural dynamics (1)
- supramolecular chemistry (1)
- sustainable energy source (1)
- tetracoordinated boron (1)
- theranostics (1)
- thiol-ene (1)
- time-resolved impulsive stimulated raman spectroscopy (1)
- triarylborane (1)
- triplet (1)
- triplet sensitization (1)
- triquinacene derivatives (1)
- two-photon absorption (1)
- vibrational coherence (1)
- π-extension (1)
Institute
- Institut für Organische Chemie (45) (remove)
Schriftenreihe
Sonstige beteiligte Institutionen
- Center for Nanosystems Chemistry (CNC), University of Würzburg (1)
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells, Göttingen (1)
- Department of Cellular Biochemistry, University Medical Centre Göttingen (1)
- Department of Molecular Biology, University Medical Centre Göttingen (1)
- Göttingen Center for Molecular Biosciences, University of Göttingen (1)
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.
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.
In terms of the need of environmentally benign renewable and storable energy sources, splitting of water into hydrogen and oxygen by using sunlight is a promising approach. Hereby, water oxidation catalysts (WOCs) are required to perform the water oxidation comprising the transfer of four electrons to provide the reducing equivalents for producing hydrogen. The class of Ru(bda) (bda = 2,2'-bipyridine-6,6'-dicarboxylate) catalysts has proven to be efficient for this reaction.
In this thesis, ligand exchange processes in Ru(bda) complexes have been analyzed and the formation of multinuclear macrocyclic WOCs was studied. Based on the knowledge acquired by these studies, new multinuclear cyclic Ru(bda) complexes have been synthesized and their catalytic efficiencies in homogeneous water oxidation have been investigated. Going one step further for setting up functional devices, molecular WOCs have been immobilized on conducting or semiconducting supporting materials. Direct anchoring on carbon nanotubes generated a promising materials for further applications.
Vom Monomer zum Polymer: Iterative Synthese und optische Spektroskopie von Squarain-Oligomeren
(2022)
Mittels einer Schutzgruppenstrategie wurden Squarain-basierte monodisperse Oligomere synthetisiert. Die lösungsmittelabhängigen Konformationen (Random Coil vs. Helix) wie auch der Faltungsprozess der Homooligomere wurden mittels optischer Spektroskopie, verschiedener NMR-Experimenten, Kleinwinkelneutronenstreuungsexperimenten sowie quantenchemischen Berechnungen näher beleuchtet. Die optisch-spektroskopischen Beobachtungen wurden mithilfe der Exzitonenkopplungstheorie und einer Orientierungs- und Winkelabhängigkeit der Übergangsdipolmomente der Oligomere erklärt. Der hohe Windungsabstand der helikalen Konformation führt zu einer Interkalation von Lösungsmittel, wodurch eine Art Klathrat gebildet wird. Zusätzlich wurden mittels eines Frenkel-Exzitonenmodells die Absorptions- und Fluoreszenzspektren modelliert. Es konnten die Exzitonendelokalisationslängen abgeschätzt und die Auswirkung der energetischen und strukturellen Unordnungen auf die Absorptions- und Fluoreszenzspektren bestimmt werden. Die Absorptionsspektren werden vorwiegend durch strukturelle Unordnungen verbreitert, die Fluoreszenzspektren dagegen von energetischen Übergangsenergieabweichungen.
Weiterhin wurden auch alternierende Squarain-Cooligomere synthetisiert und mittels optischer Spektroskopie untersucht. Es wurde, abhängig von dem gewählten Lösungsmittel, eine Verschiebung der Hauptbande beobachtet, was durch einen Random Coil vs. helikale-/schlaufenartige Konformation erklärt wird. Gestützt wurde dies mittels quantenchemischen Berechnungen der jeweiligen Konformationen.
Abschließend wurden alternierende Squarain-Copolymere synthetisiert, in verschiedenen Größen aufgetrennt und mittels optischer Spektroskopie untersucht. Mittels EEI2D-Experimenten wurde die Exzitonendynamik in Abhängigkeit von der Kettenlänge eingehender untersucht. Hierbei wird eine steigende, aber relativ abnehmende Kohärenzlänge bestimmt, die Auswirkungen auf die Exzitonendynamik hat. Der Exzitonentransport weist erst wellenförmiges und dann subdiffuses Verhalten auf.
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.
Modified nucleotides in tRNAs are important determinants of folding, structure and function. Here we identify METTL8 as a mitochondrial matrix protein and active RNA methyltransferase responsible for installing m\(^3\)C\(_{32}\) in the human mitochondrial (mt-)tRNA\(^{Thr}\) and mt-tRNA\(^{Ser(UCN)}\). METTL8 crosslinks to the anticodon stem loop (ASL) of many mt-tRNAs in cells, raising the question of how methylation target specificity is achieved. Dissection of mttRNA recognition elements revealed U\(_{34}\)G\(_{35}\) and t\(^6\)A\(_{37}\)/(ms\(^2\))i\(^6\)A\(_{37}\), present concomitantly only in the ASLs of the two substrate mt-tRNAs, as key determinants for METTL8-mediated methylation of C\(_{32}\). Several lines of evidence demonstrate the influence of U\(_{34}\), G\(_{35}\), and the m\(^3\)C\(_{32}\) and t\(^6\)A\(_{37}\)/(ms\(^2\))i\(^6\)A\(_{37}\) modifications in mt-tRNA\(^{Thr/Ser(UCN)}\) on the structure of these mt-tRNAs. Although mt-tRNA\(^{Thr/Ser(UCN)}\) lacking METTL8-mediated m\(^3\)C\(_{32}\) are efficiently aminoacylated and associate with mitochondrial ribosomes, mitochondrial translation is mildly impaired by lack of METTL8. Together these results define the cellular targets of METTL8 and shed new light on the role of m\(^3\)C\(_{32}\) within mt-tRNAs.
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.
SARS-CoV-2 variants such as the delta or omicron variants, with higher transmission rates, accelerated the global COVID-19 pandemic. Thus, novel therapeutic strategies need to be deployed. The inhibition of acid sphingomyelinase (ASM), interfering with viral entry by fluoxetine was reported. Here, we described the acid ceramidase as an additional target of fluoxetine. To discover these effects, we synthesized an ASM-independent fluoxetine derivative, AKS466. High-resolution SARS-CoV-2–RNA FISH and RTqPCR analyses demonstrate that AKS466 down-regulates viral gene expression. It is shown that SARS-CoV-2 deacidifies the lysosomal pH using the ORF3 protein. However, treatment with AKS488 or fluoxetine lowers the lysosomal pH. Our biochemical results show that AKS466 localizes to the endo-lysosomal replication compartments of infected cells, and demonstrate the enrichment of the viral genomic, minus-stranded RNA and mRNAs there. Both fluoxetine and AKS466 inhibit the acid ceramidase activity, cause endo-lysosomal ceramide elevation, and interfere with viral replication. Furthermore, Ceranib-2, a specific acid ceramidase inhibitor, reduces SARS-CoV-2 replication and, most importantly, the exogenous supplementation of C6-ceramide interferes with viral replication. These results support the hypotheses that the acid ceramidase is a SARS-CoV-2 host factor.
Arene‐fluoroarene interactions offer outstanding possibilities for engineering of supramolecular systems, including nucleic acids. Here, we implement the tolane‐perfluorotolane interaction as base pair replacement in DNA. Tolane (THH) and perfluorotolane (TFF) moieties were connected to acyclic backbone units, comprising glycol nucleic acid (GNA) or butyl nucleic acid (BuNA) building blocks, that were incorporated via phosphoramidite chemistry at opposite positions in a DNA duplex. Thermodynamic analyses by UV thermal melting revealed a compelling stabilization by THH/TFF heteropairs only when connected to the BuNA backbone, but not with the shorter GNA linker. Detailed NMR studies confirmed the preference of the BuNA backbone for enhanced polar π‐stacking. This work defines how orthogonal supramolecular interactions can be tailored by small constitutional changes in the DNA backbone, and it inspires future studies of arene‐fluoroarene‐programmed assembly of DNA.
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.