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排序方式: 共有1327条查询结果,搜索用时 46 毫秒
1.
Dr. Aleksandra Markovic Luca Gerhards Dr. Pia Sander Dr. Carsten Dosche Prof. Dr. Thorsten Klüner Prof. Dr. Rüdiger Beckhaus Prof. Gunther Wittstock 《Chemphyschem》2020,21(22):2506-2514
Multinuclear transition metal complexes bridged by ligands with extended π-electronic systems show a variety of complex electronic transitions and electron transfer reactions. While a systematic understanding of the photochemistry and electrochemistry has been attained for binuclear complexes, much less is known about trinuclear complexes such as hexaphenyl-5,6,11,12,17,18-hexaazatrinaphthylene-tristitanocene [(Cp2Ti)3HATN(Ph)6]. The voltammogram of [(Cp2Ti)3HATN(Ph)6] shows six oxidation and three reduction waves. Solution spectra of [(Cp2Ti)3HATN(Ph)6] and of the electrochemically formed oxidation products show electronic transitions in the UV, visible and the NIR ranges. Density functional theory (DFT) and linear response time-dependent DFT show that the three formally titanium(II) centers transfer an electron to the HATN ligand in the ground state. The optically excited transitions occur exclusively between ligand-centered orbitals. The charged titanium centers only provide an electrostatic frame to the extended π-electronic system. Complete active self-consistent field (CASSCF) calculation on a structurally simplified model compound, which considers the multi-reference character imposed by the three titanium centers, can provide an interpretation of the experimentally observed temperature-dependent magnetic behavior of the different redox states of the title compound in full consistency with the interpretation of the electronic spectra. 相似文献
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Cover Picture: A new topological insulator built from quasi one‐dimensional atomic ribbons (Phys. Status Solidi RRL 2/2015) 下载免费PDF全文
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Nafissa Dehimeche Bruno Buatois Nadia Bertin Michael Staudt 《Molecules (Basel, Switzerland)》2021,26(1)
The in-vivo monitoring of volatile organic compound (VOC) emissions is a potential non-invasive tool in plant protection, especially in greenhouse cultivation. We studied VOC production from above and belowground organs of the eight parents of the Multi-Parent Advanced Generation Intercross population (MAGIC) tomato population, which exhibits a high genetic variability, in order to obtain more insight into the variability of constitutive VOC emissions from tomato plants under stress-free conditions. Foliage emissions were composed of terpenes, the majority of which were also stored in the leaves. Foliage emissions were very low, partly light-dependent, and differed significantly among genotypes, both in quantity and quality. Soil with roots emitted VOCs at similar, though more variable, rates than foliage. Soil emissions were characterized by terpenes, oxygenated alkanes, and alkenes and phenolic compounds, only a few of which were found in root extracts at low concentrations. Correlation analyses revealed that several VOCs emitted from foliage or soil are jointly regulated and that above and belowground sources are partially interconnected. With respect to VOC monitoring in tomato crops, our results underline that genetic variability, light-dependent de-novo synthesis, and belowground sources are factors to be considered for successful use in crop monitoring. 相似文献
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Dr. Kalaiselvi Natarajan Daniel Müller-Klieser Stefan Rubner Prof. Dr. Thorsten Berg 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(1):148-154
We present a new approach for the identification of inhibitors of phosphorylation-dependent protein–protein interaction domains, in which phenolic fragments are adapted by in silico O-phosphorylation before docking-based screening. From a database of 10 369 180 compounds, we identified 85 021 natural product-derived phenolic fragments, which were virtually O-phosphorylated and screened for in silico binding to the STAT3 SH2 domain. Nine screening hits were then synthesized, eight of which showed a degree of in vitro inhibition of STAT3. After analysis of its selectivity profile, the most potent inhibitor was then developed to Stafia-1, the first small molecule shown to preferentially inhibit the STAT family member STAT5a over the close homologue STAT5b. A phosphonate prodrug based on Stafia-1 inhibited STAT5a with selectivity over STAT5b in human leukemia cells, providing the first demonstration of selective in vitro and intracellular inhibition of STAT5a by a small-molecule inhibitor. 相似文献
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Franziska Pecho Dr. You-Quan Zou Johannes Gramüller Prof. Dr. Tadashi Mori Prof. Dr. Stefan M. Huber Dr. Andreas Bauer Prof. Dr. Ruth M. Gschwind Prof. Dr. Thorsten Bach 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(23):5190-5194
A chiral phosphoric acid with a 2,2’-binaphthol core was prepared that displays two thioxanthone moieties at the 3,3’-position as light-harvesting antennas. Despite its relatively low triplet energy, the phosphoric acid was found to be an efficient catalyst for the enantioselective intermolecular [2+2] photocycloaddition of β-carboxyl-substituted cyclic enones (e.r. up to 93:7). Binding of the carboxylic acid to the sensitizer is suggested by NMR studies and by DFT calculations to occur by means of two hydrogen bonds. The binding event not only enables an enantioface differentiation but also modulates the triplet energy of the substrates. 相似文献
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Oxoanionic Noble Metal Compounds from Fuming Nitric Acid: The Palladium Examples Pd(NO3)2 and Pd(CH3SO3)2 下载免费PDF全文
Jörn Bruns Prof. Dr. Thorsten Klüner Prof. Dr. Mathias S. Wickleder 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(3):1294-1301
The oxidation of elemental palladium at 100 °C in a mixture of fuming nitric acid and a pyridine‐SO3 complex leads to the anhydrous nitrate Pd(NO3)2 (monoclinic, P21/n, Z=2, a=469.12(3) pm, b=593.89(3) pm, c=805.72(4) pm, β=105.989(3)°, V=215.79(2) Å3). The Pd2+ ions are in square‐planar coordination with four monodentate nitrate groups which are connected to further palladium atoms, leading to a layer structure. The reaction of elemental palladium with a mixture of fuming nitric acid and methanesulfonic acid at 120 °C leads to single crystals of Pd(CH3SO3)2 (monoclinic, P21/n, Z=2, a=480.44(1) pm, b=1085.53(3) pm, c=739.78(2) pm, β=102.785(1)°, V=376.254(17) Å3). Also in this structure the Pd2+ ions are in square‐planar coordination with four monodentate anions; however, the connection to adjacent palladium atoms leads to a chain‐type structure. The thermal decomposition of the compounds has been investigated by means of DSC/TG measurements. Furthermore, IR and Raman spectra have been recorded, and an assignment of the observed vibrational frequencies has been carried out based on theoretical investigations. 相似文献