Том 61, № 7 (2016)

The synthesis of hydrolytically active heteroligand coordination compounds [M(C₅H₇O₂)_3‒x(C₅H₁₁Oⁱ)_x] (M = Fe³⁺ and Y³⁺) using iron and yttrium acetylacetonates has been studied. The gel formation kinetics in solutions of these compounds upon hydrolysis and polycondensation has also been studied. Thin films of a solution of these precursors have been applied to polished sapphire substrates by dip coating technology. The crystallization of nanostructured yttrium iron garnet (Y₃Fe₅O₁₂) films during heat treatment of xerogel coatings under various conditions has been studied. How the phase composition, microstructure, and particle size depend on the synthesis parameters has been recognized.

The effect of strontium-containing compounds on the crystallization of strontium-substituted carbonate- hydroxylapatite from a human synovial fluid prototype was studied. Synthesis products were investigated by FT-IR spectroscopy, X-ray diffraction, and differential thermal analysis. The amount of strontium in samples was determined by atomic emission analysis. For the synthesized phases, crystallite sizes were calculated by the Selyakov–Sherer formula, and the unit cell parameters were determined. The kinetically stable brushite phase was shown to transform into the more thermodynamically stable phase of strontium-containing carbonate-hydroxylapatite with increasing exposure time of precipitates under the mother solution. Some schemes were proposed for phase transformations under heat treatment.

Hexafluorosilicate (LH₂)SiF₆ and the cis-[SiF₄(L)] chelate complex characterized by ¹⁹F NMR are products of reaction between hydrofluorosilicic acid and 1,10-phenanthroline (L). XRD findings show that the structure of (LH₂)SiF₆ is stabilized by NH···F hydrogen bonds (N···F 2.618(4), 2.676(4) Å) and CH···F contacts. The relative resistance of the cis-[SiF₄(L)] complex to hydrolysis is associated with the chelate effect.

Specific features of the structures of ten mononuclear octahedral rhenium(V) oxo complexes (I–X) with the oxygen atoms of the ligands DMF, R'OH (R' = Me, Et, Pr), and Lⁿ (Lⁿ = ON₄C₆ ∙ C₆H₁₀ (n = 1), O^–(C₆H₃MeCH₂NH⁺Et₂) (n = 2), O^–(NH⁺C₅H₄) (n = 3)) trans to the multiply bonded oxo ligands have been considered. The Re–O(OR)trans bonds in complexes I–VII (OR = DMF, R'OH, L¹) are elongated owing to the structural manifestation of the trans influence of multiply bonded oxo ligands. The Re–O^–(OR) bonds with a negatively charged oxygen atom in three complexes with zwitterionic ligands L² (in VIII) and L³ (in IX and X) are either comparable with the standard Re–O(ST) bond length (in IX and X) or strongly shortened as compared with Rе–O(ST) (in complex VIII). In the anionic complex [ReO(MeOH)Cl₂(L⁴)]^– (XI), the oxygen atom of the monomeric neutral ligand МеOH is unexpectedly cis to the oxo ligand, while the trans position to =O(oxo) is occupied by the acido oxygen atom of the bidentate chelating monodeprotonated 2-(diphenylphosphonyl) benzoate ligand (L⁴)^–.

The structures of the [M(18C6)]²⁺ cations, where M = Zn, Cu, Hg, Ni, Co, and Pt, and cis- and trans-[M(18C6)(HFA)₂]/[M(18C6)(NO₃)₂] molecules in the gas phase have been calculated by the density functional theory method in the B3LYP/6-31G*//6-311++G** + LanL2Dz approximation. Geometry optimization has been performed, and the strength of binding of the central cation to the crown ether (18C6) and the degree of structural similarity of the [M(18C6)(HFA)₂] compounds for different central atoms M have been evaluated. For all [M(18C6)(NO₃)₂]/[M(18C6)(HFA)₂] molecules (M = Zn, Cu, Hg, Ni, Co, Pt), the vertical ionization potential and the vertical electron affinity have been calculated. These parameters are of interest for analysis of the stability of volatile compounds [M(18C6)(HFA)₂] to donor–acceptor interactions with other components of the gas phase, for example, with water vapor, which is usually a Lewis base with respect to the systems in question and can donate electron density in the course of complexation with the central atom. The propensity of the [M(18C6)(NO₃)₂]/[M(18C6)(HFA)₂] molecules to react with water is considered for a wider range of metals M²⁺ = Ba²⁺, Sr²⁺, Pb²⁺, Mn²⁺, Cd²⁺, Zn²⁺, Cu²⁺, Hg²⁺, Co²⁺, Ni²⁺, and Pt²⁺, with taking into account the degree of matching between the ionic radii of M²⁺ cations and the 18C6 cavity size.

Bi_1–xHo_xFe_1–xMn_xO₃ (x = 0.03, 0.06, and 0.09) solid solutions were prepared by ceramic technology; their crystal structure, thermal expansion, and electrical properties were studied. Bi_1–xHo_xFe_1–xMn_xO₃ compounds were found to crystallize in rhombohedral system (space group R3с). These compounds are p-type semiconductors. Their unit cell parameters, linear thermal expansion coefficient, and thermal emf decrease as x increases, while the electrical conductivity, dielectric permeability, and dielectric loss increase.

Complexation of Cu²⁺ cations with anions of cefotaxime antibiotic (Cxm^–) was studied by pH-metric titration at 37°C in 0.15 mol/L NaCl background electrolyte. The formation of complex of composition CuCxm was revealed, the value of logβ(CuCxm) = 2.3 ± 0.2 was calculated. A computer model of the complex was calculated by DFT using B3LYP hybrid functional and LACV3P**++ basis set. According to calculation results, Cu(II) in the complex has CN = 4, close to square planar structure of coordination sphere, and coordinates Cxm^– through the oxygen atoms of the carboxylate, β-lactame, and amide groups, as well as through the nitrogen atom of the thiazole ring.

Phase equilibria in the stable tetrahedron LiF–KF–KBr–Li₂CrO₄ of the quaternary reciprocal system Li,K||F,Br,CrO₄ were studied by differential thermal analysis. The characteristics of a quaternary eutectic were found.

The phase diagrams of the ternary reciprocal systems Na,K||BO₂,CO₃ and Na,K||BO₂,Cl were studied for the first time by a calculation-experimental method and by differential thermal analysis. Analytical models of phase equilibrium states were derived, and the coordinates of eutectics were found to be (680°C, 32 mol % NaBO₂, 68 mol % KCl) and (648°C, 9 mol % NaBO₂, 45.5 mol % NaCl, 45.5 mol % KCl). Binary solid solutions based on metaborates and carbonates of sodium and potassium were shown to be stable. The possibility of synthesizing tungsten oxide bronzes in a eutectic melt in the ternary system NaBO₂–NaCl–КCl was revealed.

Gold nanoparticles were synthesized in aqueous solutions of AOT using hydrazine as the reducing agent and characterized by spectrophotometry, transmission electron microscopy, and photon-correlation spectroscopy. The effect of gold (C_Au = 10^–4–10^–3 mol/L) and AOT (C_AOT = 5 × 10^–4–2.5 × 10^–2 mol/L) concentrations on the formation of stable gold sols (λ_max = 520 nm) was studied. According to transmission electron microscopy data, the average size of gold nanoparticles in the dispersions was ~10 nm, which was in good agreement with the n-averaged hydrodynamic diameter determined by the photon correlation spectroscopy.

Competitive transport experiments involving Fe⁺³, Cr⁺³, Ni⁺², Co⁺², Ca⁺², Mg⁺² and K⁺ metal cations from an aqueous source phase through some organic membranes into an aqueous receiving phase have been carried out using 4,13-diaza-18-crown-6 (kryptofix 22) as an ionophore present in the organic membrane phase. Fluxes and selectivities for competitive of the metal cations transport across bulk liquid membranes have been determined. A good selectivity was observed for K⁺ cation by kryptofix 22 in 1,2-dichloroethane (1,2-DCE) membrane system. The sequence of selectivity for potassium ion in the organic solvents was found to be: 1,2-DCE > DCM (dichloromethane) >CHCl₃. The transport of K⁺ cation was also studied in the DCM-1,2-DCE, CHCl₃-1,2-DCE and CHCl₃-DCM binary mixed solvents as membrane phase. A non-linear relationship was observed between the transport rate of K⁺ ion and the composition of these binary mixed solvents. The amount of K⁺ transported follows the trend: DCM-DCE > CHCl₃-DCE > CHCl₃-DCM in the bulk liquid membrane studies. Then, the selective transport of K⁺ cation through a DCM-1,2-DCE bulk liquid membrane was studied by kryptofix 22 as an efficient carrier. The highest transport efficiency was obtained by investigating the influence of different parameters such as the concentration of kryptofix 22 in the membrane phase, pH of the source and the receiving phases and the equilibrium time of the transport process. Maximum transport value of 71.62 ± 1.61% was observed for K⁺ ion after 4 hours, when its concentration was 4 × 10^–3 M.