O. N. Antsutkin

Luleå University of Technology, Luleå, Norrbotten, Sweden

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Publications (5)2.98 Total impact

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    ABSTRACT: Single-crystalline cooperite (PtS) with a nearly stoichiometric composition was characterized in detail by X-ray diffraction, electron-probe X-ray microanalysis, and high-resolution scanning electron microscopy. For the first time it was demonstrated that 195Pt static and MAS NMR spectroscopy can be used for studying natural platinum minerals. The 195Pt chemical-shift tensor of cooperite was found to be consistent with the axial symmetry and is characterized by the following principal values: δ xx = −5920 ppm, δ yy = −3734 ppm, δ zz = +4023 ppm, and δiso = −1850 ppm. According to the ESR data, the samples of cooperite contain copper(II), which is adsorbed on the surface during the layer-by-layer crystal growth and is not involved in the crystal lattice.
    Crystallography Reports 04/2008; 53(3):391-397. · 0.52 Impact Factor
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    ABSTRACT: Pulsed-field gradient 1H NMR is employed to investigate the self-diffusion of amyloid Aβ-peptide in an aqueous buffer solution (pH 7.44) with a protein concentration of 50 μmol at 20°C. The self-diffusion coefficient of the peptide in a freshly prepared solution corresponds to its monomeric form. The storage of the solution at 24°C causes part of the peptide molecules to form amyloid aggregates as soon as over 48 h. However, the 1H NMR echo signal typical of aggregated molecules is not observed because of their dense packing in the aggregates and a large mass of the latter. A freezing-fusion of the solution after the aggregation does not cause changes in the self-diffusion coefficients of the peptide. After a peptide solution free of amyloid aggregates is subjected to a freezing-fusion cycle, part of the peptide molecules also remains in the monomeric form in the solution, while another part forms amyloid aggregates, with a portion of the aggregated peptide molecules retaining a high rotational mobility with virtually absolute absence of a translational mobility. The results obtained are interpreted in terms of the formation of “porous aggregates” of amyloid fibrils, with “pores” having sizes comparable with those of peptide molecules, though, being larger than water molecules. Peptide molecules, which do not form fibrils, are captured in the pores. Temperature regime is shown to be of importance for the aggregation of amyloid peptides. In particular, freezing, which is traditionally considered to be a method for the prevention from or temporary interruption of aggregation, may itself lead to the formation of amorphous amyloid aggregates, which remain preserved in solutions after their unfreezing.
    Colloid Journal 01/2008; 70(4):501-506. · 0.63 Impact Factor
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    ABSTRACT: Crystalline tetraphenylantimony and tetratolylantimony complexes with N,N-dialkyldithiocarbamate ligands [Sb(C6H5)4(S2CNR2)] (R = CH3, C2H5, and C3H7 and R2 = (CH2)6) were synthesized by ligand exchange reactions and studied by 13C and 15N CP/MAS NMR spectroscopy. X-ray diffraction analysis revealed that the complex [Sb(n-CH3-C6H4)4{S2CN(C3H7)2}] exists as the single molecular form, while [Sb(C6H5)4{S2CN(CH2)6}] exists as two molecular conformers. The 13C and 15N signals were assigned to the positions of the atoms in the isomeric structures [Sb(C6H5)4{S2CN(CH2)6}] in terms of different degrees of double bonding in the formally single =N-C(S)S-bond.
    Russian Journal of Coordination Chemistry 05/2006; 32(6):387-396. · 0.63 Impact Factor
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    ABSTRACT: We study the interaction of dialkyl substituted and cyclic cadmium dithiocarbamates with [AuCl4]− anions in 2M HCl medium. The state of the chemisorbents upon contact with AuCl3 solutions is controlled by 113Cd MAS NMR spectroscopy. The result of the heterogeneous reactions involving chemisorption binding of gold(III) from the solutions and partial ion exchange is the formation of heteropolynuclear gold(III)-cadmium complexes. The crystal and molecular structure of the acetone-solvated form of polymeric bis-(N,N-diethyldithiocarbamato-S,S′) gold(III) hexachlorodicadmate is identified by single-crystal XRD. The main structural moieties of the compound are complex [Au{S2CN(C2H5)2}2]+ cations and [Cd2Cl6]2− anions. The structural self-organization of the complex at the supramolecular level is attributed to the secondary Au…S bonds between neighboring isomeric complex gold(III) cations; the bonding results in the formation of linear polymer ([Au{S2CN(C2H5)2}2]+)n chains, with [Cd2Cl6]2− anions alternating to the right and left of the chains.
    Journal of Structural Chemistry 54(3). · 0.58 Impact Factor
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    ABSTRACT: Tetraphenylantimony(V) O,O′-di-sec-butyl dithiophosphate (I) and tetraphenylantimony(V) O,O′-dicyclohexyl dithiophosphate (II) [Sb(C6H5)4{S2P(OR)2}] (R = sec-C4H9 or cyclo-C6H11) were obtained. Their structures and spectroscopic properties were studied by X-ray diffraction analysis and 13C and 31P CP/MAS NMR spectroscopy. The dithiophosphate (Dtph) ligands in complexes I and II were found to be coordinated in S-monodentate and S,S′-bidentate fashions, respectively (MAS NMR data). According to X-ray diffraction data, the coordination polyhedron of antimony in molecular structure I is a trigonal bipyramid with unusual monodentate coordination of the Dtph group in the axial position.
    Russian Journal of Coordination Chemistry 34(7). · 0.63 Impact Factor