The synthesis and study of multilayer polymer structures based on 1,2-bis(2-methylbenzo[b]thiophen-3-yl)cyclopent-1-ene

Acylation of 1,2-bis(2-methylbenzo[b]thiophen-3-yl)cyclopent-1-ene gave symmetric and asymmetric 1,2-dihetarylethenes, which are of interest as photosensitive components of photochromic recording media for optical read/write storage. The formation of the photoinduced diffraction grating in a dihetarylethene-containing photochromic photorefractive layer of a waveguide multilayer system was studied.     

Effect of the graphite oxide composition on the structure of products obtained by sulfuric acid treatment at elevated temperatures

The electronic structure and functional composition of products of the graphite oxide (GO) interaction with concentrated sulfuric acid (H₂SO₄) are studied, depending on the oxygen content in the precursor and the treatment temperature. X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure (NEXAFS) measured at the CK edge, and infrared spectroscopy are used to show the recovery of the π electron system of graphene planes at a temperature of 200 °C. Aggregation of functional groups in GO containing more than 40% of oxygen causes the formation of vacancy defects in the planes with treatment. When the GO treatment temperature rises to 280 °C, the oxidation of the basal plane π-regions occurs. The results can underlie the control of the functional composition, vacancy number, and size in graphite materials.     

Temperature dependence of the critical current in YBa2Cu3O7−δ and Bi2Sr2Ca1Cu2O8 Josephson junctions

We have studied the stationary Josephson effect on YBa₂Cu₃O_7−δ (T_c=90 K) and Bi₂Sr₂Ca₁Cu₂ O₈ (T_c=80 Kand 87 Kfortwosamplesofdifferentorigin) ceramic based junctions. The temperature dependence of the critical current near T_c has been found as I_c≈(T_c-T) for the Y-Ba-Cu-O samples indicating that they should be classified as S-N-I-N-S type junctions. The I-V curves of the Bi-Sr-Ca-Cu samples show the typical behaviour of S-I-S structures. Using Ambegaokar-Baratoff's theory for Bi₂Sr₂Ca₁Cu₂O₈, the temperature dependence of the superconducting state gap Δ(T) was calculated and it was evaluated that 1.452Δ(0)/k_BT_c3.5.     

Boundary conditions for the formation of a ferromagnetic phase during the deposition of Ti<Subscript>1-<Emphasis Type="Italic">x</Emphasis></Subscript>Co<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>2-δ</Subscript> thin films

The conditions and the mechanism of the formation of a ferromagnetic phase in a Ti_1-xCo _x O_2-δ oxide semiconductor are studied. It is found that the ferromagnetism manifests itself at room temperature in the films of Co-doped TiO_2-δ oxide deposited on SrTiO₃ (100) substrates only within a limited range of charge carrier densities: 2 × 10¹⁸?3 × 10²² cm^?3. The minimum concentration of charge carriers corresponding to the formation of the ferromagnetic phase increases with a decrease in the cobalt content in the material under study. The ferromagnetism in Ti_1-xCo _x O_2-δ thin films can be attributed to Co-enriched clusters with above critical sizes.     

Surface and Bulk Reactions of Solid Nickel Dimethylglyoximate with Electron-Active Gases

The action of ammonia on the surface of solid nickel dimethylglyoximate Ni(HDm)_d2 is reversible and is accompanied by a change in the electrophysical properties of the surface layer of the complex in proportion to the ammonia content in the air. The action of chlorine on the complex gives rise to bulk chemical reactions yielding the Ni(III) complex {[Ni^III(HDm)₂(H₂O)]₂Cl⁰₂}Cl^I₂ with a bridging μ-dichloride group, which is further oxidized to a substance presumably containing such ligands as one dimethylglyoxime group and products of its oxidation by chlorine.     

Two-path reduction of molecular nitrogen by transition metal hydroxides

The kinetics of the reduction of N₂ to N₂H₄ and NH₃ by Ti^III-Mo^III hydroxide was studied at pH I I and 303-333 K, and the activation energies for these reactions and also for the reaction N₂H₄ 2 NH₃ were determined (29, 70, and 25 kJ mol^– respectively). It was concluded that -90 % of ammonia was formed by the direct reduction of N₂ without intermediate formation of hydrazine. A mechanism of this reaction is suggested, which includes the proton insertion into the N-N bond favored by an enhanced electron density at the nitrogen atoms, according to the data of the quantum-mechanical calculation.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1402–1405, June, 1996.     

Technology for production of calcium carbonate with prescribed properties

Physicochemical conditions for production of calcium carbonate with prescribed size and shape of particles and crystal structure by reaction of CaCl₂ and Na₂CO₃ solutions were studied. A technology for manufacture of calcium carbonate with prescribed properties was developed.     

Spectral Manifestations of the Interaction of Silicon Dioxide Nanoparticles with Molecules of Photochromic Compounds

The spectral and kinetic properties of water–ethanol photochromic systems of photochromic compounds from the classes of spiropyrans, spirooxazines, chromenes, and diarylethenes with and without silica nanoparticles have been comparatively studied. It has been found that, depending on the structure of a compound, its molecules can interact either chemically or physically with the surface of nanoparticles.     

Synthesis, photochromic properties, and complex formation with metal ions of hydrazones based on a spiropyran of oxaindane series

A series of hydrazones based on a new spiropyran oxaindane series was synthesized. The compounds were found to possess photochromism and are characterized by a high rate of spontaneous decoloration of their photoinduced merocyanine form. Dark and photoinduced formation of complex compounds in the reaction of metal ions with molecules of the hydrazones in solution was observed.     

Extracoordination sensitivity of tetraphenylporphyrin complexes to gaseous ammonia

The sensitivity of metal tetraphenylporphyrin complexes MTPP (M = Pt^II, Pt^IVCl₂, Re^IVO; TPP is tetraphenylporphyrin) to gaseous ammonia was studied. The gas sensitivity of MTPP is due to the heterogeneous catalytic oxidation of ammonia with the dioxygen ligands in the composition of MTPP. The influence of water vapor on the electrophysical properties of the surface layer of the complexes during adsorption of water and its participation in reactions of the coordinated ammonia and dioxygen were found. Empirical equations relating the conductivity of the MTPP surface layer to the content of water vapor and the concentration of gaseous ammonia were found.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2069–2074, October, 2004.