Simulation of glycyrrhizic acid associates with cholesterol in methanol

There are experimental evidences that in the methanol solution of glycyrrhizic acid (GA) and cholesterol, the cholesterol molecules have two different types of the environment. One corresponds to free molecules and another corresponds to the molecules associated with GA. However, the nature of these associates remains unclear. The all-atom molecular dynamics simulation of GA solutions in methanol is performed. It is shown that, contrary to aqueous solutions, GA in methanol does not form small stable clusters, even in the presence of cholesterol. The arising associates do not have distinct structures and exist for no longer than dozens of nanoseconds. The concentrations of these clusters and their stability constants are estimated. It is necessary to assume the existence of larger-scale associates to explain the experimental data.     

X-ray photoelectron and X-ray emission study of the electronic structure of hexanuclear Mn(II,III) pivalate complexes

The electronic structure of hexanuclear Mn(II,III) pivalate complexes with tetrahydrofuran and isonicotinamide are studied by X-ray photoelectron spectroscopy and X-ray emission spectroscopy. It is shown that when isonicotinamide substitutes for tetrahydrofuran the spin state of manganese ions is retained; the electron density increases on the manganese and oxygen atoms of the [Mn₆(O)₂Piv₁₀] core.     

Decomposition of pentaammineaquacobalt(III) perchlorate under laser radiation action

Photolytic decomposition of the complex [Co(NH₃)₅(H₂O)](ClO₄)₃ under the action of a laser with a wavelength of 355 nm, which is resonant in energy to the energy of the (¹ A _1g → ¹ T _2g ) d–d transition, was studied. Decomposition of the complex is accompanied by a release of ammonia with its subsequent oxidation to nitrogen oxides and by partial cobalt reduction with the formation of the mixed cobalt(II, III) oxide Co₃O₄.     

Low-Temperature Plasma-Chemical Deposition of Nanocomposite Antifriction Molybdenum Disulfide (Filler)–Silicon Oxide (Matrix) Coatings

It was demonstrated experimentally that the spatial separation of two processes of chemical vapor deposition, one of which provides synthesis of filler (MoS₂) nanoparticles and the other yields the matrix (SiO₂) of the nanocomposite coating, performed ina common reactor, enables an independent control over two process rates and makes it possible to widely vary the composition of the films deposited in this way. The deposition was performed in a double-zone vertical tubular quartz reactor. Molybdenum disulfide particles were produced by pyrolysis of aerosols of ammonium thiomolybdate solutions in dimethylformamide in the upper zone of the reactor, and the plasma-chemical deposition of a nanocomposite coating occurred in the lower zone into which MoS₂ nanoparticles were transported by the gas flow and tetraethoxysilane was delivered. It was shown that the nanocomposite coatings composed of molybdenum disulfide (filler) and silicon oxide (matrix) possess improve the antifriction properties as compared with the matrix (SiO₂ layers), these properties being determined by the relative amounts of MoS₂ nanoparticles in the layer and by their average size.     

Degradation of physicomechanical properties of epoxy nanocomposites with carbon nanotubes upon heat and humidity aging

The dependence of the physicomechanical properties of epoxy nanocomposites subjected to heat and humidity aging on the type of covalently functionalized carbon nanotubes and on the uniformity of their distribution in the epoxy matrix was studied. Two types of carbon nanotubes were used: those modified with carboxy and amide groups. The elastic modulus, bending deflection, and ultimate bending strength for the initial epoxy nanocomposites with carbon nanotubes and for those subjected to heat and humidity aging were determined. The epoxy binders modified with carboxylated carbon nanotubes are more resistant to the action of aging factors. The presence of aggregates of carboxylated carbon nanotubes in the epoxy matrix positively influences the preservation of physicomechanical properties of the composite subjected to heat and humidity aging. Microscopic examination revealed structural features of the epoxy nanocomposite and their effect on the resistance of the composite to the heat and humidity aging.     

Aggregatively stable suspensions of micrometer powders of doped barium cerate for electrophoretic deposition of thin-film coatings of solid-oxide fuel cells

Potentialities of the method of electrophoretic deposition of thin-film coatings based on micrometer powders of multidoped barium cerate BaCe_0.8Sm_0.19Cu_0.01O_3–δ (BCSCuO) and BaCe_0.89Gd_0.1Cu_0.01O_3–δ (BCGCuO) were considered. Micrometer powders of BCSCuO and BCGCuO were produced by the methods of solid-phase and citrate-nitrate syntheses, respectively. The dispersity, fraction composition, and electrokinetic potential of nonaqueous suspensions of these powders and the electrokinetic parameters of the electrophoretic deposition process were examined. An ultrasonic treatment and ultracentrifugation produced aggregatively stable suspensions of BCGCuO and BCSCuO micrometer particles in a mixed (70/30 vol %) isopropanol–acetyl acetone medium. These suspensions are characterized by high positive values of the zeta potential (+24 and +28 mV, respectively). Thin film coatings of the electrolyte materials BCSCuO and BCGCuO, which are of interest for the technology of medium-temperature solid-oxide fuel cells, were produced by the electrophoretic deposition onto a dense model cathode.     

Synthesis of fused derivatives of 1,8-naphthyridine

Reactions of aromatic aldehyde, 2-aminoprop-1-ene-1,1,3-tricarbonitrile and cyclic enhydrazinoketones led to the formation of N-substituted 5-aryl-2,4-diamino-6-oxo-5,6,7,8,9,10-hexahydrobenzo[b][1,8]- naphthyridine-3-carbonitriles     

New functionalized amino derivatives of 2-hydroxyphenyl-1,3,5-triazines

4-(2-Hydroxyphenyl)-1,3,5-triazin-2-ylcyanamides reacted with sodium azide to give N-(tetrazol-5-yl)-1,3,5-triazin-2-amines, and their reaction with allyl bromide afforded allyl(1,3,5-triazin-2-yl)cyanamides. Acetylation of 4-(2-hydroxyphenyl)-1,3,5-triazin-2-amines involved only the amino group with formation of diacetylamino derivatives, whereas the phenolic hydroxy group remained intact. The reaction of triazinamines with 2,5-dimethoxytetrahydrofuran in the presence of P₂O₅ gave pyrrolyl-substituted triazines.     

Cyclopropanation and epoxidation of 2-ylidene derivatives of lupane series

Russian Journal of Organic Chemistry - Crotone condensation of allobetulone with fluorine-containing benzaldehydes afforded new α,β-unsaturated ketones of lupane series. Their...