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排序方式: 共有4021条查询结果,搜索用时 26 毫秒
1.
Dr. Oliver Hegen Jens Braese Prof. Dr. Alexey Y. Timoshkin Prof. Dr. Manfred Scheer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(2):485-489
A new class of neutral bidentate ligands with pnictogenyl-functional sites has been obtained. The reaction of tmeda⋅(BH2I)2 ( 1 , tmeda=tetramethylethylendiamine) with different phosphanides yields the corresponding bidentate phosphanylboranes tmeda⋅(BH2PH2)2 ( 2 a ), tmeda⋅(BH2PPh2)2 ( 2 b ), and tmeda⋅(BH2tBuPH)2 ( 2 c ). This reaction strategy could be further extended to synthesize the first bidentate arsanylborane tmeda⋅(BH2AsPh2)2 ( 3 ). Depending on the substituents on the phosphorus, these compounds form different AuI complexes, to build either polymeric tmeda⋅(BH2PH2AuCl)2 ( 4 a ), or monomeric tmeda⋅(BH2PPh2AuCl)2 ( 4 b ) products. These compounds form also neutral oligomeric group 13/15 chain-like molecules by coordination to a boron moiety such as tmeda⋅(BH2PH2BH3)2 ( 5 a ) and tmeda⋅(BH2AsPh2BH3)2 ( 5 b ). DFT calculations provide insight into the differences between the syntheses of mono- and bidentate pnictogenylboranes. 相似文献
2.
Pingping Hu Dr. Manfred Erwin Schuster Dr. Zhiwei Huang Fei Xu Dr. Shifeng Jin Yaxin Chen Prof. Weiming Hua Prof. Dang Sheng Su Prof. Xingfu Tang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9619-9623
The identification of catalytically active sites (CASs) in heterogeneous catalysis is of vital importance to design and develop improved catalysts, but remains a great challenge. The CASs have been identified in the low‐temperature selective catalytic reduction of nitrogen oxides by ammonia (SCR) over a hollandite manganese oxide (HMO) catalyst with a rod‐shaped morphology and one‐dimensional tunnels. Electron microscopy and synchrotron X‐ray diffraction determine the surface and crystal structures of the one‐dimensional HMO rods closed by {100} side facets and {001} top facets. A combination of X‐ray absorption spectra, molecular probes with potassium and nitric oxide, and catalytic tests reveals that the CASs are located on the {100} side facets of the HMO rods rather than on the top facets or in the tunnels, and hence semi‐tunnel structural motifs on the {100} facets are evidenced to be the CASs of the SCR reaction. This work paves the way to further investigate the intrinsic mechanisms of SCR reactions. 相似文献
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Christoph Riesinger Prof. Dr. Fabian Dielmann Robert Szlosek Dr. Alexander V. Virovets Prof. Dr. Manfred Scheer 《Angewandte Chemie (International ed. in English)》2023,62(16):e202218828
The thermolysis of Cp′′′Ta(CO)4 with white phosphorus (P4) gives access to [{Cp′′′Ta}2(μ,η2 : 2 : 2 : 2 : 1 : 1-P8)] ( A ), representing the first complex containing a cyclooctatetraene-like (COT) cyclo-P8 ligand. While ring sizes of n >6 have remained elusive for cyclo-Pn structural motifs, the choice of the transition metal, co-ligand and reaction conditions allowed the isolation of A . Reactivity investigations reveal its versatile coordination behaviour as well as its redox properties. Oxidation leads to dimerization to afford [{Cp′′′Ta}4(μ4,η2 : 2 : 2 : 2 : 2 : 2 : 2 : 2 : 1 : 1 : 1 : 1-P16)][TEF]2 ( 4 , TEF=[Al(OC{CF3}3)4]−). Reduction, however, leads to the fission of one P−P bond in A followed by rapid dimerization to form [K@[2.2.2]cryptand]2[{Cp′′′Ta}4(μ4,η2 : 2 : 2 : 2 : 2 : 2 : 2 : 2 : 1 : 1 : 1 : 1-P16)] ( 5 ), which features an unprecedented chain-type P16 ligand. Lastly, A serves as a P2 synthon, via ring contraction to the triple-decker complex [{Cp′′′Ta}2(μ,η6 : 6-P6)] ( B ). 相似文献
7.
Dr. Anton Guryev Florian Schuster Lars Herrmann Dr. Friedrich Hahn Christina Wangen Dr. Jan Hodek Dr. Jan Weber Prof. Dr. Manfred Marschall Prof. Dr. Svetlana B. Tsogoeva 《European journal of organic chemistry》2023,26(5):e202200994
We report the development of a metal-free four-step one-pot synthetic strategy to access high-value functionalized phthalazines using o-methyl benzophenones as starting compounds. Combining a light-mediated enolization of o-methyl benzophenones/Diels-Alder reaction domino process with a subsequent deprotection/aromatization domino reaction in one-pot leads to sustainable and efficient organic synthesis. The tangible advantages, i. e., absence of catalysts or additives, utilization of commercially available and/or easily accessible substrates, mild reaction conditions, simplicity, and single work-up procedure, make this combined process highly appealing for the direct construction of various 1-aryl-phthalazines. Importantly, in vitro bioactivity evaluation of these newly prepared heterocyclic compounds demonstrated a strong antiviral efficacy against major human pathogens like HCMV and SARS-CoV-2. 相似文献
8.
Structural and Functional Implications of the Interaction between Macrolide Antibiotics and Bile Acids 下载免费PDF全文
Simon Glanzer Sergio A. Pulido Sarah Tutz Dr. Gabriel E. Wagner Dr. Manfred Kriechbaum Nina Gubensäk Jovana Trifunovic Markus Dorn Prof. Dr. Walter M. F. Fabian Prof. Predrag Novak Prof. Dr. Joachim Reidl Prof. Dr. Klaus Zangger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(11):4350-4358
Macrolide antibiotics, such as azithromycin and erythromycin, are in widespread use for the treatment of bacterial infections. Macrolides are taken up and excreted mainly by bile. Additionally, they have been implicated in biliary system diseases and to modify the excretion of other drugs through bile. Despite mounting evidence for the interplay between macrolide antibiotics and bile acids, the molecular details of this interaction remain unknown. Herein, we show by NMR measurements that macrolides directly bind to bile acid micelles. The topology of this interaction has been determined by solvent paramagnetic relaxation enhancements (solvent PREs). The macrolides were found to be bound close to the surface of the micelle. Increasing hydrophobicity of both the macrolide and the bile acid strengthen this interaction. Both bile acid and macrolide molecules show similar solvent PREs across their whole structures, indicating that there are no preferred orientations of them in the bile micelle aggregates. The binding to bile aggregates does not impede macrolide antibiotics from targeting bacteria. In fact, the toxicity of azithromycin towards enterotoxic E. coli (ETEC) is even slightly increased in the presence of bile, as was shown by effective concentration (EC50) values. 相似文献
9.
Dr. Thomas Lunkenbein Dr. Frank Girgsdies Anna Wernbacher Dr. Johannes Noack Dr. Gudrun Auffermann Akira Yasuhara Achim Klein‐Hoffmann Prof. Wataru Ueda Dr. Maik Eichelbaum Dr. Annette Trunschke Prof. Robert Schlögl Dr. Marc G. Willinger 《Angewandte Chemie (International ed. in English)》2015,54(23):6828-6831
Complex Mo,V‐based mixed oxides that crystallize in the orthorhombic M1‐type structure are promising candidates for the selective oxidation of small alkanes. The oxygen sublattice of such a complex oxide has been studied by annular bright field scanning transmission electron microscopy. The recorded micrographs directly display the local distortion in the metal oxygen octahedra. From the degree of distortion we are able to draw conclusions on the distribution of oxidation states in the cation columns at different sites. The results are supported by X‐ray diffraction and electron paramagnetic resonance measurements that provide integral details about the crystal structure and spin coupling, respectively. 相似文献
10.
Cover Picture: Metal‐Free Addition/Head‐to‐Tail Polymerization of Transient Phosphinoboranes,RPH‐BH2: A Route to Poly(alkylphosphinoboranes) (Angew. Chem. Int. Ed. 46/2015) 下载免费PDF全文