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result(s) for
"Abramov, A."
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Not So Similar: Different Ways of Nb(V) and Ta(V) Catecholate Complexation
2023
The reactions between catechol (H2cat) and niobium(V) or tantalum(V) precursors in basic aqueous solutions lead to the formation of catecholate complexes of different natures. The following complexes were isolated and characterized by single-crystal X-ray diffraction (SCXRD): (1) (NH4)3[NbO(cat)3]∙4H2O; (2) K2[Nb(cat)3(Hcat)]·2H2cat·2H2O; (3) Cs3[NbO(cat)3]·H2O; (4) (NH4)4[Ta2O(cat)6]·3H2O; (5) Cs2[Ta(cat)3(Hcat)]·H2cat; (6) Cs4[Ta2O(cat)6]·7H2O. The isolated crystalline products were characterized by elemental analysis, X-ray powder diffraction (XRPD), FTIR, and TGA. The structural features of these complexes, such as Ta2O unit geometry, Cs-π interactions, and crystal packing effects, are discussed.
Journal Article
Novel Route to Cationic Palladium(II)–Cyclopentadienyl Complexes Containing Phosphine Ligands and Their Catalytic Activities
by
Suslov, Dmitry S.
,
Bykov, Mikhail V.
,
Pakhomova, Marina V.
in
1,3-butadiene
,
acetylacetonate
,
Carbon
2023
The Pd(II) complexes [Pd(Cp)(L)n]m[BF4]m were synthesized via the reaction of cationic acetylacetonate complexes with cyclopentadiene in the presence of BF3∙OEt2 (n = 2, m = 1: L = PPh3 (1), P(p-Tol)3, tris(ortho-methoxyphenyl)phosphine (TOMPP), tri-2-furylphosphine, tri-2-thienylphosphine; n = 1, m = 1: L = dppf, dppp (2), dppb (3), 1,5-bis(diphenylphosphino)pentane; n = 1, m = 2 or 3: 1,6-bis(diphenylphosphino)hexane). Complexes 1–3 were characterized using X-ray diffractometry. The inspection of the crystal structures of the complexes enabled the recognition of (Cp–)⋯(Ph-group) and (Cp–)⋯(CH2-group) interactions, which are of C–H…π nature. The presence of these interactions was confirmed theoretically via DFT calculations using QTAIM analysis. The intermolecular interactions in the X-ray structures are non-covalent in origin with an estimated energy of 0.3–1.6 kcal/mol. The cationic palladium catalyst precursors with monophosphines were found to be active catalysts for the telomerization of 1,3-butadiene with methanol (TON up to 2.4∙104 mol 1,3-butadiene per mol Pd with chemoselectivity of 82%). Complex [Pd(Cp)(TOMPP)2]BF4 was found to be an efficient catalyst for the polymerization of phenylacetylene (PA) (catalyst activities up to 8.9 × 103 gPA·(molPd·h)−1 were observed)
Journal Article
Fully integrated ultra-sensitive electronic nose based on organic field-effect transistors
by
Agina, Elena V.
,
Ponomarenko, Sergey A.
,
Abramov, Anton A.
in
639/301/1005/1009
,
639/301/357/341
,
639/638/11/511
2021
Modern solid-state gas sensors approaching ppb-level limit of detection open new perspectives for process control, environmental monitoring and exhaled breath analysis. Organic field-effect transistors (OFETs) are especially promising for gas sensing due to their outstanding sensitivities, low cost and small power consumption. However, they suffer of poor selectivity, requiring development of cross-selective arrays to distinguish analytes, and environmental instability, especially in humid air. Here we present the first fully integrated OFET-based electronic nose with the whole sensor array located on a single substrate. It features down to 30 ppb limit of detection provided by monolayer thick active layers and operates in air with up to 95% relative humidity. By means of principal component analysis, it is able to discriminate toxic air pollutants and monitor meat product freshness. The approach presented paves the way for developing affordable air sensing networks for the Internet of Things.
Journal Article
Seizure activity results in calcium- and mitochondria-independent ROS production via NADPH and xanthine oxidase activation
2014
Seizure activity has been proposed to result in the generation of reactive oxygen species (ROS), which then contribute to seizure-induced neuronal damage and eventually cell death. Although the mechanisms of seizure-induced ROS generation are unclear, mitochondria and cellular calcium overload have been proposed to have a crucial role. We aim to determine the sources of seizure-induced ROS and their contribution to seizure-induced cell death. Using live cell imaging techniques in glioneuronal cultures, we show that prolonged seizure-like activity increases ROS production in an NMDA receptor-dependent manner. Unexpectedly, however, mitochondria did not contribute to ROS production during seizure-like activity. ROS were generated primarily by NADPH oxidase and later by xanthine oxidase (XO) activity in a calcium-independent manner. This calcium-independent neuronal ROS production was accompanied by an increase in intracellular [Na
+
] through NMDA receptor activation. Inhibition of NADPH or XO markedly reduced seizure-like activity-induced neuronal apoptosis. These findings demonstrate a critical role for ROS in seizure-induced neuronal cell death and identify novel therapeutic targets.
Journal Article
Physiological Characteristics of Culturable Prokaryotic Communities of Fumarole Fields in the Permafrost Zone
2025
Abstract—The physiology and taxonomic structure of prokaryotic communities in various volcanogenic deposits have been studied. The samples of fumarole and pyroclastic deposits, as well as primitive soils (Leptic Cryosols), have been collected in such poorly studied areas as fumarole fields on the summits of volcanoes in Kamchatka, the Caucasus, and Japan, as well as on cinder fields on the slopes of a volcanic structure in Antarctica. In this work, a microbiological characterization of culturable aerobic heterotrophic bacteria from the fumarole field of the Hertz crater on the summit of Ushkovsky Volcano (Kamchatka, Russia) is presented for the first time. A collection of isolates has been created, including 105 strains of aerobic heterotrophic bacteria representatives of Bacillus, Cupriavidus, Labedella, Microbacterium, Paenibacillus, Peribacillus, Plantibacter, Pseudomonas, and Staphylococcus genera. Also, for the first time, an analysis of the physiological characteristics of isolated strains, such as temperature conditions of cultivation, pH of the medium, and NaCl concentration has been performed. Our study suggests that tolerance to two or more stress factors is characteristic of 57.1% of isolated strains, and tolerance to all three factors is characteristic of 24.8% of isolated strains.
Journal Article
Au(III) Cyclometallated Compounds with 2-Arylpyridines and Their Derivatives or Analogues: 34 Years (1989–2022) of NMR and Single Crystal X-ray Studies
2023
A review paper on Au(III) cyclometallated compounds with 2-arylpyridines (2-phenylpyridine, 2-benzylpyridine, 2-benzoylpyridine, 2-phenoxypyridine, 2-phenylsulfanylpyridine, 2-anilinopyridine, 2-(naphth-2-yl)pyridine, 2-(9,9-dialkylfluoren-2-yl)pyridines, 2-(dibenzofuran-4-yl)pyridine, and their derivatives) and their analogues (2-arylquinolines, 1- and 3-arylisoquinolines, 7,8-benzoquinoline), with 113 references. A total of 554 species, containing κ2-N(1),C(6′)*-Au(III), or analogous moiety (i.e., chelated by nitrogen of the pyridine-like ring and the deprotonated ortho- carbon of the phenyl-like ring) and, thus, possessing a character intermediate between metal complexes and organometallics, studied in the years 1989–2022 by NMR spectroscopy and/or single crystal X-ray diffraction (207 X-ray structures), are described. The compounds for which biological or catalytic activity and the luminescence properties were studied are also quoted.
Journal Article
Pd(II), Pd(III) and Pd(IV) Cyclometallated Compounds with 2-Arylpyridines and Their Derivatives or Analogues: 44 Years (1980–2023) of NMR and Single Crystal X-ray Studies
2023
In this paper, a review on Pd(II), Pd(III), and Pd(IV) cyclometallated compounds with 2-arylpyridines (2-phenylpyridine, 2-benzylpyridine, 2-benzoylpyridine, 2-phenoxypyridine, 2-phenylsulfanylpyridine, 2-anilinopyridine, 2-(naphth-1-yl)pyridine, 2-(naphth-2-yl)pyridine, and their derivatives) and their analogues (2-phenylquinoline and 7,8-benzoquinoline) with 174 references is presented. A total of 672 species, containing κ2-N(1),C(6′)*-palladium (Pd(II), Pd(III), Pd(IV)) or analogous moiety (i.e., chelated by nitrogen of the pyridine-like ring and the deprotonated ortho-carbon of the phenyl-like ring) and thus possessing a character intermediate between metal complexes and organometallics, studied in the years 1980–2023 by NMR spectroscopy and/or single crystal X-ray diffraction (202 X-ray structures, for 186 species), are described. The biological or catalytic activity and luminescence properties of these species, as well as their possible applications as advanced materials were studied and are also quoted.
Journal Article
Trapping of Ag+ into a Perfect Six-Coordinated Environment: Structural Analysis, Quantum Chemical Calculations and Electrochemistry
by
Komlyagina, Veronika I.
,
Romashev, Nikolay F.
,
Sokolov, Maxim N.
in
Acenaphthenes - chemistry
,
Analysis
,
Carbon Dioxide
2022
Self-assembly of (Bu4N)4[β-Mo8O26], AgNO3, and 2-bis[(2,6-diisopropylphenyl)-imino]acenaphthene (dpp-bian) in DMF solution resulted in the (Bu4N)2[β-Ag(dpp-bian)2Mo8O26] (1) complex. The complex was characterized by single crystal X-ray diffraction (SCXRD), X-ray powder diffraction (XRPD), diffuse reflectance (DR), infrared spectroscopy (IR), and elemental analysis. Comprehensive SCXRD studies of the crystal structure show the presence of Ag+ in an uncommon coordination environment without a clear preference for Ag-N over Ag-O bonding. Quantum chemical calculations were performed to qualify the nature of the Ag-N/Ag-O interactions and to assign the electronic transitions observed in the UV–Vis absorption spectra. The electrochemical behavior of the complex combines POM and redox ligand signatures. Complex 1 demonstrates catalytic activity in the electrochemical reduction of CO2.
Journal Article
A “Lost World” of Mammals in Eastern Indochina: Russian Studies in Vietnam
2023
—
This review is devoted to mammalogical research in Vietnam. A brief history of the study of mammals in eastern Indochina from the 17th century to the present is given. The main attention is paid to Soviet and Russian research carried out within the framework of the activities of the Joint Vietnam–Russia Tropical Research and Technological Center (established in 1987). The main trends of mammalogical research and the scientific publications of Russian scientists are analyzed.
Journal Article
Proton Affinity in the Chemistry of Beta-Octamolybdate: HPLC-ICP-AES, NMR and Structural Studies
by
Sokolov, Maxim N.
,
Volchek, Victoria V.
,
Kompankov, Nikolay B.
in
Catalysis
,
Chemical properties
,
Chemistry
2022
The affinity of [β-Mo8O26]4− toward different proton sources has been studied in various conditions. The proposed sites for proton coordination were highlighted with single crystal X-ray diffraction (SCXRD) analysis of (Bu4N)3[β-Ag(py-NH2)Mo8O26]] (1) and from analysis of reported structures. Structural rearrangement of [β-Mo8O26]4− as a direct response to protonation was studied in solution with 95Mo NMR and HPLC-ICP-AES techniques. A new type of proton transfer reaction between (Bu4N)4[β-Mo8O26] and (Bu4N)4H2[V10O28] in DMSO results in both polyoxometalates transformation into [V2Mo4O19]4−, which was confirmed by the 95Mo, 51V NMR and HPLC-ICP-AES techniques. The same type of reaction with [H4SiW12O40] in DMSO leads to metal redistribution with formation of [W2Mo4O19]2−.
Journal Article