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A. V. Ivanov I. A. Lutsenko M. A. Ivanov A. V. Gerasimenko O. N. Antzutkin 《Russian Journal of Coordination Chemistry》2008,34(8):584-593
Platinum(II) O,O′-dicyclohexyl dithiophosphate [Pt{S2P(O-cyclo-C6H11)2}2] (I) and platinum(II) O,O′-diisopropyl dithiophosphate [Pt{S2P(O-iso-C3H7)2}2] (II) complexes were obtained and studied by solidstate 13C, 31P, and 195Pt CP/MAS NMR spectroscopy. The dithiophosphate (Dtph) ligands in molecular structure I were found to be coordinated by platinum in S,S′-bidentate fashion to form the planar chromophore [PtS4] (single-crystal X-ray diffraction data). For complex II, a new α-form (α-II) was obtained and identified by 31P MAS NMR spectroscopy. The 31P chemical shift anisotropy δaniso and the asymmetry parameter η of the 31P chemical shift tensor were calculated from the whole MAS spectra. 相似文献
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A. V. Ivanov S. A. Zinkin A. V. Gerasimenko O. N. Antzutkin W. Forsling 《Russian Journal of Coordination Chemistry》2007,33(1):20-31
Silver(I) complexes with four symmetrically substituted O,O′-dialkyl derivatives of dithiophosphoric acid of the general formula [Ag{S2P(OR)2}] n (R = C2H5, i-C3H7, C4H9, and s-C4H9) were obtained. Their structures and spectroscopic characteristics were studied by solid-state 13C and 31P CP/MAS NMR spectroscopy and X-ray diffraction analysis. The parameters of the anisotropy of the 31P chemical shift 31P-δ aniso and η (δ aniso is the chemical shift anisotropy and η is the asymmetry parameter) calculated from the diagrams of the x 2-statistic revealed that the (RO)2PS2 groups act as bridging ligands in all the silver(I) complexes obtained. The hexanuclear complex [Ag6{S2P(O-i-C3H7)2}6] was found to form two modifications α and β. According to the X-ray diffraction data, the silver(I) complex with O,O′-di-s-butyl dithiophosphate exists as discrete hexanuclear molecules [Ag6{S2P(O-s-C4H9)2}6]. In the clear molecules β-[Ag6{S2P(O-i-C3H7)2}6], the signals for the phosphorus atoms were assigned to their positions determined from the X-ray diffraction data. 相似文献
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Van Emmerik TJ Sandström DE Antzutkin ON Angove MJ Johnson BB 《Langmuir : the ACS journal of surfaces and colloids》2007,23(6):3205-3213
Sorption of phosphate onto gibbsite (gamma-Al(OH)3) and kaolinite has been studied by both macroscopic and 31P solid-state NMR measurements. Together these measurements indicate that phosphate is sorbed by a combination of surface complexation and surface precipitation with the relative amounts of these phases depending on pH and phosphate concentration. At low pH and high phosphate concentrations sorption is dominated by the presence of both amorphous and crystalline precipitate phases. The similarity between the single-pulse and CP/MAS NMR spectra suggests that the precipitate phases form a thin layer on the surface of the particles in close contact with protons from surface hydroxyl groups or coordinated water molecules. While the crystalline phase is only evident on samples below pH 7, amorphous AlPO4 was found at all pH and phosphate concentrations studied. As pH was increased the fraction of phosphate sorbed as an inner-sphere complex increased, becoming the dominant surface species by pH 8. Comparison of sorption and NMR results suggests that the inner-sphere complexes form by monodentate coordination to singly coordinated Al-OH sites on the edges of the gibbsite and kaolinite crystals. Outer-sphere phosphate complexes, which are readily desorbed, are also present at high pH. 相似文献
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Ivanov A. V. Zinkin S. A. Forzling W. Antzutkin O. N. Kritikos M. 《Russian Journal of Coordination Chemistry》2003,29(2):142-150
High-resolution 13C and 15N solid-state NMR spectra were recorded for seven crystalline tetraalkyl-thiuram disulfides and their cyclic analogs of the general formula [R2NC(S)S]2 (where R = CH3, C2H5, C3H7, and i-C3H7 or R2 = (CH2)5, (CH2)6, and (CH2)4O). The 15N and 13C NMR resonances were assigned to the particular atoms in the compounds studied. Different isotropic 15N chemical shifts for both dialkyldithiocarbamato groups were interpreted while considering the inductive effects of the alkyl substituents combined with the mesomeric effect of the dithiocarbamato group. X-ray diffraction data were used to refine the molecular structure of bis(cyclohexamethylene)thiuram disulfide and to quantitatively characterize the conformations of the seven-membered N(CH2)6 heterocycles. 相似文献
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Victor P. Arkhipov Elisaveta F. Potapova Oleg N. Antzutkin Andrei V. Filippov 《Magnetic resonance in chemistry : MRC》2013,51(7):424-430
The structure and dynamic properties of micellar solutions of nonionic surfactants of a series of isononylphenol ethoxylates, C9H19C6H4O(C2H4O)nH (where n = 6,8,9,10, and 12), were studied by NMR diffusometry, dynamic light scattering, and viscosimetry. The sizes of the micelles were determined for different surfactants and at different surfactant concentrations. The numbers of water molecules bound by a micelle and by one oxyethylene group of the surfactant were estimated. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Rusanova D Pike KJ Persson I Hanna JV Dupree R Forsling W Antzutkin ON 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(20):5282-5292
A number of polycrystalline copper(I) O,O'-dialkyldithiophosphate cluster compounds with Cu4, Cu6, and Cu8 cores were synthesized and characterized by using extended X-ray absorption fine-structure (EXAFS) spectroscopy. The structural relationship of these compounds is discussed. The polycrystalline copper(I) O,O'-diisobutyldithiophosphate cluster compounds, [Cu8{S2P(OiBu)2}6(S)] and [Cu6{S2P(OiBu)2}6], were also characterized by using 31P CP/MAS NMR (CP = cross polarization, MAS = magic-angle spinning) and static 65Cu NMR spectroscopies (at different magnetic fields) and powder X-ray diffraction (XRD) analysis. Comparative analyses of the 31P chemical-shift tensor, and the 65Cu chemical shift and quadrupolar-splitting parameters, estimated from the experimental NMR spectra of the polycrystalline copper(I) cluster compounds, are presented. The adsorption mechanism of the potassium O,O'-diisobutyldithiophosphate collector, K[S2P(OiBu)2], at the surface of synthetic chalcocite (Cu2S) was studied by means of solid-state 31P CP/MAS NMR spectroscopy and scanning electron microscopy (SEM). 31P NMR resonance lines from collector-treated chalcocite surfaces were assigned to a mixture of [Cu8{S2P(OiBu)2}6(S)] and [Cu6{S2P(OiBu)2}6] compounds. 相似文献
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A. V. Ivanov O. A. Bredyuk A. V. Gerasimenko O. N. Antzutkin 《Doklady Physical Chemistry》2008,420(2):130-135
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Dr. Christofer Lendel Dr. Morten Bjerring Dr. Anatoly Dubnovitsky Robert T. Kelly Dr. Andrei Filippov Prof. Dr. Oleg N. Antzutkin Prof. Dr. Niels Chr. Nielsen Prof. Dr. Torleif Härd 《Angewandte Chemie (International ed. in English)》2014,53(47):12756-12760
Oligomeric and protofibrillar aggregates formed by the amyloid‐β peptide (Aβ) are believed to be involved in the pathology of Alzheimer’s disease. Central to Alzheimer pathology is also the fact that the longer Aβ42 peptide is more prone to aggregation than the more prevalent Aβ40. Detailed structural studies of Aβ oligomers and protofibrils have been impeded by aggregate heterogeneity and instability. We previously engineered a variant of Aβ that forms stable protofibrils and here we use solid‐state NMR spectroscopy and molecular modeling to derive a structural model of these. NMR data are consistent with packing of residues 16 to 42 of Aβ protomers into hexameric barrel‐like oligomers within the protofibril. The core of the oligomers consists of all residues of the central and C‐terminal hydrophobic regions of Aβ, and hairpin loops extend from the core. The model accounts for why Aβ42 forms oligomers and protofibrils more easily than Aβ40. 相似文献