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41.
Flaked capillary columns with an OV-101/CE-Na{in3}PO{in4} hydrophobic-hydrophilic sorbent have been suggested. This sorbent provides for the analysis of polar and nonpolar substances, including amines and aminoalcohols, in aqueous and organic solvents. The efficiency of new columns was demonstrated for the analysis of 25 organic substances of various classes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2169–2173, December, 1994.The work was financially supported by the Russian Foundation for Basic Research, Project No. 93-03-4969. 相似文献
42.
Z. D. Zivkovic 《Journal of Thermal Analysis and Calorimetry》1994,41(1):99-104
The results of comparative thermal analysis (TG-DTG-DTA-DSC) of the thermal decomposition of hexamminecobalt(III) chloride in air atmosphere are reported. The kinetics and mechanism of the thermal decomposition, the process enthalpy and the variation in specific thermal capacity of the solid product reaction with temperature were determined. 相似文献
43.
A series of nitrosyl complexes of empirical formula Kn[M(CN)5NO], where M = V, Cr, Mn and Co and n = 3, or M = Mo and n = 4, have been prepared which are notional analogues of the widely used vasodilator sodium nitroprusside. Their reactivity towards common nucleophiles (OH?, NH2R, NHR2, HS? and RS?), acid and photolysis has been investigated to elucidate the desired properties required of new metal nitrosyls which may have some potential as new non-cyanide-based vasodilators. 相似文献
44.
V. A. Potemkin M. A. Grishina E. V. Bartashevich 《Journal of Structural Chemistry》2007,48(1):155-160
The BiS algorithm is suggested for modeling the drug molecule orientation within a receptor cavity. It is based on the assumption of complementarity of the field created by biologically active compounds and the field of the responsive receptor. The comparison of predicted orientations of various biologically active compounds on the relevant receptors with the data of X-ray structural studies (Protein Data Bank) reveals that the results obtained with this approach surpasses those reported in the literature. The suggested technique made it possible to elucidate the details of the action mechanism of DNA antimetabolites, dihydrofolate reductase inhibitors. The dependence of the activity on the structural parameters of “ligand-receptor” complexes is determined. 相似文献
45.
Piotr Dobrzynski 《Journal of polymer science. Part A, Polymer chemistry》2004,42(8):1886-1900
Lactide polymerization using zirconium(IV) acetylacetonate [Zr(acac)4] as an initiator was investigated. In the reaction between Zr(acac)4 and the monomer molecule, lactide deprotonation and the release of acetylacetone occurred. The structures of the obtained complexes were analyzed with high‐resolution NMR spectroscopy. A computational method was used to calculate the hypothetical structures. The role of the obtained complexes in the initiation of polymerization and the reaction of chain growth was proposed. The influence of the reaction temperature on the structures of the complexes was investigated. Polylactide chain growth proceeded by an insertion‐coordination mechanism. The polymer chain grew on one ligand, which was formed in advance from a deprotonated lactide. The molecular masses of the obtained polymers were the same as the theoretical masses and were directly proportional to the reaction conversion. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1886–1900, 2004 相似文献
46.
E. M. Glebov V. P. Grivin V. F. Plyusnin A. V. Udaltsov 《Journal of Structural Chemistry》2006,47(3):476-483
Interaction between MnCl2 and diethylamine (DEA) in aqueous solutions has been studied by UV, IR, and EPR spectroscopy as part of the design and research program on models of natural photosystems. The composition of the precipitate for comparable concentrations of reagents and solute oxygen has been investigated. Mn(II) was found to be oxidized with oxygen to give MnO2·H2O as a precipitate. In the solution over the precipitate, Mn(III) complexes with DEA are formed; the complex molecule has four and six amine molecules in the coordination sphere. 相似文献
47.
V.V. Glushkov S.V. Demishev M.I. Ignatov Yu.B. Paderno N.Yu. Shitsevalova O.A. Churkin N.E. Sluchanko 《Journal of solid state chemistry》2006,179(9):2871-2874
In order to reveal the nature of the ground state of archetypal intermediate-valence compound SmB6, a comprehensive study of its transport and magnetic properties was carried out on high-quality single crystals at temperatures of 1.8-300 K in magnetic fields up to 7 T. A drastic enhancement of negative magnetoresistance was observed below 14 K, with the maximum absolute value of Δρ/ρB2∼2.2×10−3 T−2 at T≈5.2 K. This effect seems to be attributable to anomalous magnetic scattering of many-body (exciton-polaronic) complexes induced by fast valence fluctuations on Sm sites. The observed anomalies of magnetotransport, thermoelectric and magnetic characteristics are discussed in terms of electron phase transition to the coherent state of interacting many-body complexes occurring at T*∼5 K. 相似文献
48.
New Schiff bases of 2,4‐dihydroxybenzaldehyde with siloxane‐α,ω‐diamines having different numbers of siloxane units in the chain have been synthesized and characterized by spectroscopy, elemental and thermal analyses. These azomethines were found to form complexes readily with copper(II), nickel(II), cobalt(II), cadmium(II) and zinc(II). From IR and UV–Vis studies, the phenolic oxygen and imine nitrogen of the ligand were found to be the coordination sites. Thermogravimetric analysis (TGA) data indicate the chelates to be more stable than the corresponding ligands. The melting points increase with shortening of the siloxane segment from azomethine, as well as the result of complexation. The chelates obtained were covalently inserted in polymeric linear structures by polycondensation through the OH‐difunctionalized ligand with 1,3‐bis(carboxypropyl)tetramethyldisiloxane. Direct polycondensation, assisted either by acetic anhydride or N,N′‐dicyclohexylcarbodiimide as dehydrating agent and the complex 4‐(dimethylamino)pyridinium 4‐toluenesulfonate as catalyst, was used for the synthesis of these compound types. The structures of the polymers obtained were confirmed by IR, UV and 1H NMR. Characterization was undertaken by TGA, solubility tests and viscosity measurements. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
49.
An O-bonded sulphito complex, Rh(OH2)5(OSO2H)2+, is reversibly formed in the stoppedflow time scale when Rh(OH2)
6
3+
and SO2/HSO
3
−
buffer (1 <pH< 3) are allowed to react. For Rh(OH2)5OH2++ SO2 □ Rh(OH2)5(OSO2H)2+ (k1/k-1), k1 = (2.2 ±0.2) × 103 dm3 mol−1 s−1, k−1 = 0.58 ±0.16 s−1 (25°C,I = 0.5 mol dm−3). The protonated O-sulphito complex is a moderate acid (K
d
= 3 × 10−4 mol dm−3, 25°C, I= 0.5 mol dm−3). This complex undergoes (O, O) chelation by the bound bisulphite withk= 1.4 × 10−3 s−1 (31°C) to Rh(OH2)4(O2SO)+ and the chelated sulphito complex takes up another HSO
3
−
in a fast equilibrium step to yield Rh(OH2)3(O2SO)(OSO2H) which further undergoes intramolecular ligand isomerisation to the S-bonded sulphito complex: Rh(OH2)3(O2SO)(OSO2)- → Rh(OH2)3(O2SO)(SO3)− (k
iso
= 3 × 10−4 s−1, 31°C). A dinuclear (μ-O, O) sulphite-bridged complex, Na4[Rh2(μ-OH)2(OH)2(μ-OS(O)O)(O2SO)(SO3) (OH2)]5H2O with (O, O) chelated and S-bonded sulphites has been isolated and characterized. This complex is sparingly soluble in water
and most organic solvents and very stable to acid-catalysed decomposition 相似文献
50.
Dávid Szegvári Romána Zelkó Péter Horváth András Gergely 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):169-172
Enantioselective solubility of rac-norgestrel was found in the presence of γ-cyclodextrin or hydroxypropyl-γ-cyclodextrin.
In both cases the efficacious enantiomer was dissolved in greater extent. Calculating the molar absorptivity and molar ellipticity
spectra of the γ- and hydroxypropyl-γ-cyclodextrin aqueous complexes, a simple and rapid direct circular dichroism (CD) spectrometric
method was obtained for the determination of the enantiomer ratio in aqueous solutions. 相似文献