Refine
Has Fulltext
- yes (41)
Is part of the Bibliography
- yes (41) (remove)
Year of publication
- 2022 (41) (remove)
Document Type
- Journal article (29)
- Doctoral Thesis (9)
- Preprint (2)
- Book article / Book chapter (1)
Language
- English (41) (remove)
Keywords
- perylene bisimide (4)
- water oxidation (4)
- RNA (3)
- aromaticity (3)
- catalysis (3)
- fluorescence (3)
- Chemische Synthese (2)
- Merocyanine (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)
- Analysis of RNA Modifications (1)
- Aptamer (1)
- Aromatically annulated triquinacenes (1)
- Aromatisch anellierte Triquinacene (1)
- Asymmetric synthesis (1)
- Asymmetrische Synthese (1)
- CD-Spektroskopie (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)
- Dictyota (1)
- Dictyotaceae (1)
- Drug Delivery System (1)
- Enzymes (1)
- Exziton (1)
- Farbstoff (1)
- Festkörper-NMR (1)
- Fluoreszenzaktivierung (1)
- Grün fluoreszierendes Protein (1)
- Helix-Coil-Transition (1)
- Helix-Knäuel-Umwandlung (1)
- High-Throughput Sequencing Method, DZ-seq (1)
- Hydrogel (1)
- J- and H-Aggregate (1)
- J- and H-Aggregates (1)
- J‐aggregates (1)
- Katalyse (1)
- Kolloidalstabilität (1)
- Lippert–Mataga plot (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)
- Oligomere (1)
- Organelles (1)
- Oxidation (1)
- Perylenbisdicarboximide (1)
- Phaeophyceae (1)
- Polymere (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-State NMR Spectroscopy (1)
- Squaraine (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 (41) (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)
Tribenzotriquinacene (TBTQ) is a polycyclic aromatic framework with a particularly rigid, C3v symmetrical, bowl-shaped core bearing three mutually fused indane wings. It has been discussed as a defect center for a nanographene by Kuck and colleagues. Therefore, extended TBTQ structures are promising models for saturated defect structures in graphene and graphene like molecules and could be used to investigate the role of defects for the electronic properties of graphene. With this motivation, three different pi-extended TBTQ derivatives have been synthesized in this work. Several different Scholl reaction conditions were tried to obtain fully annulated product of hexaphenyl substituted TBTQ. The desired benzannulated TBTQ derivative could not be obtained due to unfavourable electron density in the respective positions of the molecule and increased reactivity of the bay position of the precursor. As an another method for benzannulation is the on-surface synthesis of graphene flakes and can be carried out using electron beams e.g. in a tunneling microscope (STM). According to our previous research, the parent system TBTQ and centro-methyl TBTQ on silver and gold surfaces showed that the gas phase deposition of these molecules gives rise to the formation of highly ordered two-dimensional assemblies with unique structural features. This shows the feasibility for the formation of defective graphene networks starting from the parent structures. Therefore, the same deposition technique was used to deposit Me-TBTQ(OAc)3Ph6, and investigate the molecular self-assembly properties directly on the surface of Cu (111). In summary, the substrate temperature dependent self-assembly of Me-TBTQ(OAc)3Ph6 molecules on Cu(111), shows the following evolution of orientations. At room temperature, molecules form dimers, which construct a higher-coverage honeycomb lattice. Furthermore, one of the acetyl group located in the bay positions of the TBTQ core is cleaved and the remaining two induce the metal-molecule interaction. It was presumed that by increasing the temperature to 393 K, the remaining acetyl and methyl groups would beeliminated from the molecular structure.In addition, the smaller TBTQ-Ph6 molecules preferably lie flat on Cu(111) crystal and allowing the molecules to settle into a C3-symmetry and form a dense hexagonal structure.
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.
Nucleic acids are not only one of the most important classes of macromolecules in biochemistry but also a promising platform for the defined arrangement of chromophores. Thanks to their precise organization by directional polar and hydrophobic interactions, oligonucleotides can be exploited as suitable templates for multichromophore assemblies with predictable properties. To expand the toolbox of emissive, base pairing nucleobase analogs several barbituric acid merocyanine (BAM) chromophores with tunable spectroscopic properties were synthesized and incorporated into RNA, DNA and glycol nucleic acid (GNA) oligonucleotides. A multitude of duplexes containing up to ten BAM chromophores was obtained and analysis by spectroscopic methods revealed the presence of dipolarly coupled merocyanine aggregates with properties
strongly dependent on the chromophore orientation toward each other and the backbone conformation. These characteristics were exploited for various applications such as FRET pair formation and polymerase chain reaction (PCR) experiments. The observed formation of higher-order aggregates implies future applications of these new oligonucleotide-chromophore systems as light-harvesting DNA nanomaterials. Besides oligonucleotide templated covalent assembly of chromophores also non-covalent nucleic acid-chromophore complexes are a broad field of research. Among these, fluorogenic RNA aptamers are of special interest with the most versatile ones based on derivatives of the GFP chromophore hydroxybenzylidene imidazolone (HBI). Therefore, new HBI-derived chromophores with an expanded conjugated system and an additional exocyclic amino group for an enhanced binding affinity were synthesized and analyzed in complex with the Chili aptamer. Among these, structurally new fluorogenes with strong fluorescence activation upon binding to Chili were identified which are promising for further derivatization and application as color-switching sensor devices for example.
A series of donor-acceptor macrocyclic architectures comprising oligothiophene strands that connect the imide positions of a perylene bisimide have been synthesized via a platinum-mediated cross-coupling strategy. The target structures were characterized by steady-state UV/Vis absorption, fluorescence and transient absorption spectroscopy, as well as cyclic and differential pulse voltammetry. Crystal structure analysis of the macrocycles revealed insights into the bridge arrangements. The properties of the macrocyclic bridges were compared to linear oligothiophene reference compounds which itself exhibited an unusual electrochemical effect.
Inspired by the proficiency of natural enzymes, mimicking of nanoenvironments for precise substrate preorganisation is a promising strategy in catalyst design. However, artificial examples of enzyme-like activation of H\(_2\)O molecules for the challenging oxidative water splitting reaction are hardly explored. Here, we introduce a mononuclear Ru(bda) complex (M1, bda: 2,2’-bipyridine-6,6’-dicarboxylate) equipped with a bipyridine-functionalized ligand to preorganize H\(_2\)O molecules in front of the metal center as in enzymatic clefts. The confined pocket of M1 accelerates chemically driven water oxidation at pH 1 by facilitating a water nucleophilic attack pathway with a remarkable turnover frequency of 140 s\(^{−1}\) that is comparable to the oxygen-evolving complex of photosystem II. Single crystal X-ray analysis of M1 under catalytic conditions allowed the observation of a 7th H\(_2\)O ligand directly coordinated to a RuIII center. Via a well-defined hydrogen-bonding network, another H\(_2\)O substrate is preorganized for the crucial O–O bond formation via nucleophilic attack.
The West African liana Ancistrocladus abbreviatus is a rich source of structurally most diverse naphthylisoquinoline alkaloids. From its roots, a series of four novel representatives, named ancistrobrevolines A–D (14–17) have now been isolated, displaying an unprecedented heterocyclic ring system, where the usual isoquinoline entity is replaced by a ring-contracted isoindolinone part. Their constitutions were elucidated by 1D and 2D NMR and HR-ESI-MS. The absolute configurations at the chiral axis and at the stereogenic center were assigned by using experimental and computational electronic circular dichroism (ECD) investigations and a ruthenium-mediated oxidative degradation, respectively. For the biosynthetic origin of the isoindolinones from ‘normal’ naphthyltetrahydroisoquinolines, a hypothetic pathway is presented. It involves oxidative decarboxylation steps leading to a ring contraction by a benzilic acid rearrangement. Ancistrobrevolines A (14) and B (15) were found to display moderate cytotoxic effects (up to 72%) against MCF-7 breast and A549 lung cancer cells and to reduce the formation of spheroids (mammospheres) in the breast cancer cell line.
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.
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.
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.
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.