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Dr. Andrey Y. Khalimon Prof. Dr. Stanislav K. Ignatov Andrey I. Okhapkin Dipl.‐Ing. Razvan Simionescu Prof. Dr. Lyudmila G. Kuzmina Prof. Dr. Judith A. K. Howard Dr. Georgii I. Nikonov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(26):8573-8590
The reactions of bis(borohydride) complexes [(RN?)Mo(BH4)2(PMe3)2] ( 4 : R=2,6‐Me2C6H3; 5 : R=2,6‐iPr2C6H3) with hydrosilanes afford new silyl hydride derivatives [(RN?)Mo(H)(SiR′3)(PMe3)3] ( 3 : R=Ar, R′3=H2Ph; 8 : R=Ar′, R′3=H2Ph; 9 : R=Ar, R′3=(OEt)3; 10 : R=Ar, R′3=HMePh). These compounds can also be conveniently prepared by reacting [(RN?)Mo(H)(Cl)(PMe3)3] with one equivalent of LiBH4 in the presence of a silane. Complex 3 undergoes intramolecular and intermolecular phosphine exchange, as well as exchange between the silyl ligand and the free silane. Kinetic and DFT studies show that the intermolecular phosphine exchange occurs through the predissociation of a PMe3 group, which, surprisingly, is facilitated by the silane. The intramolecular exchange proceeds through a new non‐Bailar‐twist pathway. The silyl/silane exchange proceeds through an unusual MoVI intermediate, [(ArN?)Mo(H)2(SiH2Ph)2(PMe3)2] ( 19 ). Complex 3 was found to be the catalyst of a variety of hydrosilylation reactions of carbonyl compounds (aldehydes and ketones) and nitriles, as well as of silane alcoholysis. Stoichiometric mechanistic studies of the hydrosilylation of acetone, supported by DFT calculations, suggest the operation of an unexpected mechanism, in that the silyl ligand of compound 3 plays an unusual role as a spectator ligand. The addition of acetone to compound 3 leads to the formation of [trans‐(ArN)Mo(OiPr)(SiH2Ph)(PMe3)2] ( 18 ). This latter species does not undergo the elimination of a Si? O group (which corresponds to the conventional Ojima′s mechanism of hydrosilylation). Rather, complex 18 undergoes unusual reversible β‐CH activation of the isopropoxy ligand. In the hydrosilylation of benzaldehyde, the reaction proceeds through the formation of a new intermediate bis(benzaldehyde) adduct, [(ArN?)Mo(η2‐PhC(O)H)2(PMe3)], which reacts further with hydrosilane through a η1‐silane complex, as studied by DFT calculations. 相似文献
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Stanislav N. Naryzhny Andrey V. Lisitsa Victor G. Zgoda Elena A. Ponomarenko Alexander I. Archakov 《Electrophoresis》2014,35(6):895-900
Insufficient sensitivity of methods for detection of proteins at a single molecule level does not yet allow obtaining the whole image of human proteome. But to go further, we need at least to know the proteome size, or how many different protein species compose this proteome. This is the task that could be at least partially realized by the method described in this article. The approach used in our study is based on detection of protein spots in 2DE after staining by protein dyes with various sensitivities. As the different protein spots contain different protein species, counting the spots opens a way for estimation of number of protein species. The function representing the dependence of the number of protein spots on sensitivity or LOD of protein dyes was generated. And extrapolation of this function curve to theoretical point of the maximum sensitivity (detection of a single smallest polypeptide) allowed to counting the number of different molecules (polypeptide species) at the concentration level of a single polypeptide per proteome. Using this approach, it was estimated that the minimal numbers of protein species for model objects, Escherichia coli and Pirococcus furiosus, are 6200 and 3400, respectively. We expect a single human cell (HepG2) to contain minimum 70 000 protein species. 相似文献
66.
Konstantin P. Arefyev Victor I. Grafutin Evgeny P. Prokopyev Andrey M. Lider Roman S. Laptev Yury S. Bordulev 《Central European Journal of Chemistry》2014,12(12):1280-1284
This article considers the possibility of applying the positron annihilation spectroscopy method for investigating the pore space of rocks from oil-gas and methane-coal deposits. The diagnostics of the structure was performed using the method of spectrometry of angular correlation of annihilation rays (ACAR). Using the samples of porous silicon, the authors have shown the applicability of the ACAR method for determination of the average dimensions of spherical and cylindrical nanosized objects and their concentration 相似文献
67.
Dongliang Gao Andrey Novitsky Tianhang Zhang Fook Chiong Cheong Lei Gao Chwee Teck Lim Boris Luk'yanchuk Cheng‐Wei Qiu 《Laser \u0026amp; Photonics Reviews》2015,9(1):75-82
This paper investigates the singular optics of nonparaxial light beams in the near field when the light behaves as a tractor beam. New insights into the optical pulling force, which is usually represented by integrating the stress tensor at a black box enclosing the object, are interpreted by the optical singularity of the Poynting vector. The negative nonconservative pulling force originates from the transfer of the azimuthal Poynting vector to the longitudinal component partly owing to the presence of a scatterer. The separatrice pattern and singularity shifts of the Poynting vector unanimously exhibit a differentiable near‐field distribution in the presence of optical pulling force. A new method is established to calculate the near‐field optical force using the differential Poynting vector in the far field. The results obtained provide a clear physical interpretation of the light–matter interaction and manifest the significance of singular optics in manipulating objects.
68.
Zaitseva Elvira R. Sokolov Anatolii I. Mikhaylov Andrey A. Baleeva Nadezhda S. Baranov Mikhail S. Smirnov Alexander Yu. 《Chemistry of Heterocyclic Compounds》2022,58(8-9):477-480
Chemistry of Heterocyclic Compounds - A methodology was developed for the synthesis of phenylspiro[imidazole-4,3'-thiochroman]ones by treatment of [2-(benzylsulfanyl)-benzylidene]imidazolones... 相似文献
69.
Jeferson Rodrigo Souza Pina Joo Victor Silva-Silva Josiwander Miranda Carvalho Heriberto Rodrigues Bitencourt Luciano Almeida Watanabe Juan Matheus Pereira Fernandes Guilherme Eduardo de Souza Anna Caroline Campos Aguiar Rafael Victorio Carvalho Guido Fernando Almeida-Souza Ktia da Silva Calabrese Patrícia Santana Barbosa Marinho Andrey Moacir do Rosario Marinho 《Molecules (Basel, Switzerland)》2021,26(11)
The natural compound ravenelin was isolated from the biomass extracts of Exserohilum rostratum fungus, and its antimicrobial, antiplasmodial, and trypanocidal activities were evaluated. Ravenelin was isolated by column chromatography and HPLC and identified by NMR and MS. The susceptibility of Gram-positive and Gram-negative bacteria strains to ravenelin was determined by microbroth dilution assay. Cytotoxicity was evaluated in hepatocarcinoma cells (HepG2) and BALB/c peritoneal macrophages by using MTT. SYBR Green I-based assay was used in the asexual stages of Plasmodium falciparum. Trypanocidal activity was tested against the epimastigote and intracellular amastigote forms of Trypanosoma cruzi. Ravenelin was active against Gram-positive bacteria strains, with emphasis on Bacillus subtilis (MIC value of 7.5 µM). Ravenelin’s antiparasitic activities were assessed against both the epimastigote (IC50 value of 5 ± 1 µM) and the intracellular amastigote forms of T. cruzi (IC50 value of 9 ± 2 µM), as well as against P. falciparum (IC50 value of 3.4 ± 0.4 µM). Ravenelin showed low cytotoxic effects on both HepG2 (CC50 > 50 µM) and peritoneal macrophage (CC50 = 185 ± 1 µM) cells with attractive selectivity for the parasites (SI values > 15). These findings indicate that ravenelin is a natural compound with both antibacterial and antiparasitic activities, and considerable selectivity indexes. Therefore, ravenelin is an attractive candidate for hit-to-lead development. 相似文献
70.
Alexander S. Aldoshin Andrey A. Tabolin Sema L. Ioffe Valentine G. Nenajdenko 《Molecules (Basel, Switzerland)》2021,26(12)
The catalyst-free conjugate addition of pyrroles to β-Fluoro-β-nitrostyrenes was investigated. The reaction was found to proceed under solvent-free conditions to form 2-(2-Fluoro-2-nitro-1-arylethyl)-1H-pyrroles. The effectiveness of this approach was demonstrated through the preparation of a series of the target products in a quantitative yield. The kinetics of a conjugate addition of pyrrole was studied in detail to reveal the substituent effect and activation parameters of the reaction. The subsequent base-induced elimination of nitrous acid afforded a series of novel 2-(2-Fluoro-1-arylvinyl)-1H-pyrroles prepared in up to an 85% isolated yield. The two-step sequence herein proposed is an indispensable alternative to a direct reaction with elusive and unstable 1-Fluoroacetylenes. 相似文献