Doklady Chemistry最新文献

A number of 2-phenylhydrazone derivatives of thiazolo[3,2-a]pyrimidines has been synthesized, and their structure and biological activity have been studied. The structure of the obtained compounds has been confirmed by ¹H and ¹³C NMR spectroscopy and X-ray diffraction analysis. It has been found that hydrazone form with Z configuration of the C=N bond is typical for the obtained derivatives. Low cytotoxicity of the synthesized compounds toward normal and tumor cell lines has been shown.

A new polymeric electrolyte with mobile charges of one type has been synthesized. It is a block copolymer with non-ionic block of poly(2,2,3,3,4,4,5,5-octafluoropentyl methacrylate), which improves mechanical performance, and ionic block as a random copolymer of lithium 1-[3-(methacryloxy)-propylsulfonyl]-1-(trifluoromethanesulfonyl)imide with poly(ethylene glycol) methacrylate. A possibility has been shown for the tuning of ionic conductivity in a wide range (from 1 × 10^–10 to 1 × 10^–7 S cm^–1, 25°C) by varying the ratio of macromolecular weights of neutral and ionic blocks and concentration of lithium monomer units in the ionic block.

The major areas of development and application of supramolecular catalysis over the past five years are presented. Data on the use of macrocyclic receptors and supramolecular and coordination nanocapsules are analyzed. Advantages and specific features of the systems under study are demonstrated. It is concluded that supramolecular catalysis is an extremely rapidly developing area of modern chemistry. The most promising directions of development of this field are shown.

A new medical antibacterial corrosion-resistant steel alloyed with silver and titanium was smelted. The optimal conditions for homogenizing annealing were selected to obtain a uniform structure and give rise to equiaxed grains. The mechanical properties, microstructure, and phase composition were studied. X-ray powder diffraction analysis showed that the steel without alloying elements after rolling has an austenitic structure. The alloying gave rise to a small amount of ferrite in the steel structure. Spectral analysis showed a uniform silver distribution throughout the alloy. It was determined that a steel sample containing silver and titanium has an antibacterial effect on the bacterial strain Pseudomonas marginalis.

Ultra-high-temperature Ta₄HfC₅ ceramics with a submicron structure has been manufactured from a 4Ta + Hf + 5С powder mixture by electro-thermal explosion under pressure. The effect of the duration of mechanical activation of starting 4Ta + Hf powder mixtures on the structure of the resulting precursor has been studied. It has been demonstrated that mechanical activation in hexane for 40–60 min leads to amorphization of metals and nucleation of crystallites of the carbide phase with a cubic structure. This makes it possible to synthesize a single-phase solid solution of tantalum and hafnium carbides with a submicron structure in the course of an electro-thermal explosion.

Carbon nanofibers obtained by catalytic decomposition of methane in a vibrated fluidized bed reactor were chemically treated to increase the specific capacitance of supercapacitors. The material was studied by transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform IR spectroscopy, and cyclic voltammetry. The treatment was conducted in various media (H₂SO₄, HNO₃, H₂Cr₂O₇, and HCl) at 80°C for 6 h. The chemical treatment was accompanied by a significant weight loss (14–67 wt %) and oxidation of the material. Treatment in diluted nitric acid mainly led to the transfer of surface layers of disordered carbon into solution with their removal during washing, while treatment in concentrated acid was more conducive to oxidation of the material surface. The highest specific capacitance (50.6 F g^–1 at 2 mV s^–1 in 3.5 M H₂SO₄ electrolyte) was attained when carbon nanofibers were treated with H₂Cr₂O₇.

A three-dimensional computer model was developed for the integrated chemical engineering process of water shutoff of a high-water-cut oil-bearing rock formation at given geophysical characteristics of the bottomhole formation zone and given rate and volume of a water shutoff solution injected into the formation. The model makes it possible to determine the parameters of filling of pores of the formation with the water shutoff solution, which are necessary for calculating the well’s oil and water production rates. The adequacy of the developed mathematical model was checked against the results of a comparative analysis of the calculated values of the water cut and the oil production rate with the actual well performance data after the water shutoff: the mean absolute errors in oil production rate and water cut were 0.5 t/day and 0.9%, respectively.

Reaction of 1-phthalazinylhydrazone of o-diphenylphosphinobenzaldehyde (HL) with Fe(II) and Co(II) perchlorates has led to complexes of different composition and structure: [Fe(HL)₂](ClO₄)₂ · H₂O (1) and [CoL₂](ClO₄) · H₂O (2) in spite of the use of salts with the same anion. Со²⁺ ion undergoes oxidation to Co³⁺ upon complexation. The structure of the complexes has been established by NMR spectroscopy in solution and by X-ray diffraction in crystal. X-ray diffraction has shown that complexing metal ions have octahedral structure. Compound 2 forms two independent molecules in crystal.

A mathematical model of the change in the solid-phase particle size (mass) distribution was developed, according to which the rate of this change in a complex process can be represented as a superposition of the rates of less complex processes, such as coagulation, breakup, abrasion, etc. The proposed approach allows one to determine the particle size (mass) distribution function of the end product of both continuous-flow, and batch processes. Examples of using the proposed approach for solving specific, practically important problems were given, indicating its efficiency.

A method has been developed for synthesizing composites of titanium oxide nanoparticles (anatase and rutile) on the surface of reduced graphene oxide flakes in supercritical isopropanol. Supercritical isopropanol acts in synthesis not only as a reducing agent but also as a reaction medium, while reducing graphene oxide. After treatment in supercritical isopropanol, anatase and rutile nanoparticles are deposited onto the graphene surface, retaining dispersion and slightly increasing in size. The resulting nanocomposites have been characterized by X-ray diffraction analysis, transmission electron microscopy, and atomic force microscopy. The average size of titanium dioxide nanoparticles on the surface of graphene oxide is 7–9 nm in the case of anatase and 200–220 nm in the case of rutile.