Quantum chemical study of tautomerism of bullvalene, bullvalenol, and the corresponding ketone

Using the quantum chemical method PBE0/cc-pVTZ, we determined structural parameters and dipole moments of bullvalene (tricyclo[3.3.2.0^4.6]deca-2,7,9-triene), 1-, 2-, 3-, and 4-hydroxytricyclo[3.3.2.0^4.6]-deca-2,7,9-trienes, and isomeric 2- and 3-ketones transforming into each other through the keto-enol tautomerism and Cope rearrangement with the triatomic ring migration. The dominant tautomer is 3-ketone containing a triatomic ring conjugated with the carbonyl group.     

Self-assembling catalytic systems based on new amphiphile containing purine fragment,exhibiting substrate specificity in hydrolysis of phosphorus acids esters

Micellar catalytic systems based on new purine-containing amphiphile for hydrolytic decomposition of organophosphorus toxicants have been prepared. The aggregation threshold of the system has been estimated by means of tensiometry, conductometry, spectrophotometry, and dynamic light scattering. The solubilizing action of the amphiphile towards the hydrophobic dye has been demonstrated. Kinetic studies of hydrolysis of phosphonates differing in the hydrophobicity have disclosed the substrate specificity of the micellar catalysts; inhibition instead of catalysis has been observed in the case of the less hydrophobic substrate.     

Concentration dependence of the hypersonic velocity dispersion in aqueous solutions of 4-methylpyridine

The hypersonic velocity dispersion in aqueous solutions of 4-methylpyridine in the frequency range from 4.7 to 6.1 GHz has been studied by Brillouin scattering spectroscopy. A negative hypersonic velocity dispersion is established for solutions with concentrations of 0.08 and 0.06 molar fractions of 4-methylpyridine.     

Synthesis and identification of bromofullerenes C70Br8 and C70Br10 and their solubility in some aromatic solvents

Bromofullerenes C₇₀Br₈ and C₇₀Br₁₀ were synthesized and identified by electronic absorption and infrared spectroscopy. Their solubility in aromatic solvents (benzene, toluene, o-xylene, and o-dichlorobenzene) was studied in the temperature range from 20 to 60°C.     

Novel organosilicon monomer for preparing transparent matrices doped with lanthanide complexes

Perfluoroadipic bis(trialkoxysilylpropyl)amide was synthesized as a mixture of five compounds with the general formula (EtO) _n (MeO)_3-n Si(CH₂)₃NHC(O)(CF₂)₄C(O)NH(CH₂)₃-Si(OMe) _n (OEt)_3-n (1, n = 1, 2). Hydrolysis of this product by a specified amount of water (1: 4) gave oligomers EtO[(HO)(EtO)Si(CH₂)₃NH(O)C(CF₂)₄C(O)NH(CH₂)₃Si(OEt)₂O]_nH ( _n = 7–9). From oligomer solutions, transparent glassy thermally stable films were obtained. The film material was studied by IR spectroscopy, atomic force microscopy, transmission electron microscopy, and powder X-ray diffraction. Compound 1 and oligomers can efficiently solvate lanthanide diketonate complexes. They displace water from the metal coordination sphere, and this water is then spent for hydrolysis of trialkoxysilyl groups. The luminescence intensity of matrix films based on the oligomers depends on the concentration of lanthanide complexes and is very low at 7n_exc = 330 nm, whereas the luminescence intensity of the Eu³⁺ cation is very high.     

Calculation of the static magnetic field of a system of solenoids

We propose a variant of the algorithm described in [1], which allows one to calculate the magnetic field of a solenoid with rectangular cross section by using one numerical quadrature.     

Frequency spectrum of tantalum at temperatures of 293–2300 K

The temperature dependence of the frequency spectrum of tantalum in the temperature range from room temperature to 2300 K has been studied for the first time using inelastic slow-neutron scattering. The inelastic slow-neutron scattering spectra have been measured at different temperatures on a DIN-2PI time-of-flight spectrometer installed at the IBR-2 nuclear reactor (Joint Institute for Nuclear Research, Dubna, Russia) with the use of a TS3000K high-temperature thermostat. From the measured spectra, the frequency spectra of the tantalum crystal lattice have been determined at temperatures of 293, 1584, and 2300 K by the iteration method. As the temperature increases, the frequency spectrum, on the whole, is softened and the specific features manifested themselves at room temperature are smoothed. The variations observed have been explained by the increase in the role of the effects of vibration anharmonism at high temperatures.     

Tribological coatings with a chromium-based composite structure obtained by reactive deposition in vacuum

The peculiarities inherent to the chemical and phase compositions, microstructure, and tribological behavior of Cr-O, Cr-C-O, Cr-C-H and Cr-C-N-H coatings, obtained by plasma-assisted physical vapor deposition in a chemically active gas atmospheres (activated reactive deposition and magnetron sputtering methods), have been studied. It has been demonstrated that all coatings have a micro- and/or nanocomposite structure comprising nanoscale chromium-based domains, as well as chromium oxide, carbide and nitride phases with different stoichiometries. The tribological properties of the coatings investigated in a broad temperature range under unlubricated friction contact conditions, as well as their correlation with microstructures and reactive-deposition technology parameters, are discussed.     

Synthesis of photochromic 1,2-dihetarylethene using regioselective acylation of thienopyrroles

[formula: see text] The influence of catalysts, acid chlorides, and solvents in the acylation of methyl 2-methyl-4H-thieno[3,2-b]pyrrole-5-carboxylate was studied. Conditions for the regioselective acylation processes were found. Thienopyrrole-based photochrome was synthesized for the first time.     

Hugoniót--Maslov Conditions for Vortex Singular Solutions of the Shallow Water Equations

For the phase of vortex singular solutions of the shallow water equations we justify the Hamilton--Jacobi equation corresponding to the hydrodynamical mode of perturbation propagation. We also obtain the next correction to the Cauchy--Riemann conditions describing how the singular part of the solution affects the smooth background.