Doklady Chemistry最新文献

In order to search for new antibacterial and anticancer agents, the data of amphiphilic quaternary ammonium compounds (QAC) based on natural structures were analyzed and systematized over the past three years in this review. The analysis of publication is considered on the properties of QAS based on heterocyclic and pyridine alkaloids, alkylated phenols, terpenoids and steroids. The relationships between the structure of ammonium salts and their supramolecular self-assembly, biological activity, and cytotoxicity were tried to be revealed. In terms of synthetic ease of chemical modification, availability, biorelevance, and efficacy against strains of bacterial pathogens and antitumor activity, prospects for using natural platforms for extended trials have been identified.

A concept was proposed for integrated catalytic processing of organochlorine waste using self-organizing nickel-based catalysts. The process of carbon erosion of a bulk Ni–Cr alloy to form dispersed particles catalyzing the growth of carbon nanofibers was studied using 1,2-dichloroethane as an example. This approach was found to be universal and applicable to the processing of multicomponent mixtures of organochlorine compounds, including polyvinyl chloride production waste. The potential of using the carbon nanomaterial obtained by the waste processing for the production of polymer composites was discussed.

Ultra-high-molecular-weight polyethylene (UHMWPE) with an elevated melting point T_m of up to 144°C has been successfully fabricated by suspension polymerization initiated by Ziegler–Natta catalysts in a 1H,4H-octafluorobutane medium. This method allows one to efficiently perform the polymerization at a near-ambient temperature and a near-atmospheric ethylene pressure. The obtained polyethylenes have been characterized by IR spectroscopy, elemental analysis, and thermal analysis, and the melting points and degrees of crystallinity of the synthesized polymers have been found.

The review analyzes recent publications dealing with the search for new efficient desulfurization technologies, in particular, oxidative desulfurization using ionic liquids. This technology attracts attention due to its relatively mild conditions compared to hydrodesulfurization and its efficiency in removing heavy sulfur derivatives. Of special interest are solid hybrid compositions consisting of a support coated with an ionic liquid layer containing catalytically active centers. Examples of the use of such polyfunctional systems, simultaneously functioning as an adsorbent, extractant, and catalyst, for the oxidative desulfurization of model fuel and real oil feedstock are considered.

It has been shown that imidazole adds to the triple bond of 3-butoxypropyne under the action of catalytic amounts (5 mol %) of silver salts to give a mixture of α and β isomers: 1-(3-butoxyprop-1-en-2-yl)-imidazole and 1-[(Z)-3-butoxyprop-1-en-1-yl)]-imidazole.

An interaction of 6-aryl-1,2,4-triazine-5-carbonitriles with 2‑amino-4-aryl-substituted thiazoles and oxazoles has been studied. The difference in the reactivity of these aminoheterocycles depending on the presence of an oxygen or a sulfur atom in their composition has been demonstrated. Previously, the 4-aryl-3-hydroxy-2,2′-bipyridines were obtained as products of aza-Diels−Alder reaction between 6-aryl-3-(2-pyridyl)-1,2,4-triazine-5-carbonitriles and 2-amino-4-aryloxazoles. It was shown that the reaction of 6-aryl-1,2,4-triazine-5-carbonitriles with 2-aminothiazoles led to the products of ipso-substitution of cyano group. The aza-Diels−Alder reaction of these compounds with 2,5-norbornadiene gave (2,2′-bi)pyridines with the 2-aminothiazolyl at alpha-position.

The characteristics of lithium iron phosphate cathodes containing various types of commercially available carbon nanotubes—single-walled (SWCNTs), double-walled (DWCNTs), and multi-walled (MWCNTs)—have been compared. Electrochemical characteristics of the cathode materials have been studied by electrochemical impedance spectroscopy and galvanostatic charge/discharge measurements. The cyclic stability at various current densities has been estimated. The best electrochemical characteristics are shown by the cathode materials containing SWCNTs (advantage over the DWCNT-based cathode materials at discharge rates higher than 10C) and DWCNTs (advantage over the SWCNT-based cathode materials during long-term cycling). During the long-term cycling at a current density of 1C, the greatest loss of capacity is observed for the MWCNT-based electrode. At the same time, the SWCNT- and DWCNT-based electrodes demonstrate satisfactory capacity retention after 50 charge/discharge cycles: over 94 and 98%, respectively.

Reaction of 5-hydrazinyl-substituted 1,2,4-triazines and 2,5-norbornadiene at elevated pressure and temperature (in autoclave) has been studied; the reaction yields 2-aminopyridines, 5-amino-1,2,4,-triazines, and 6-unsubstituted pyridines (formation of one of two latter products is dependent on the nature of substituent in the C3 position of triazine).

The study focuses on the development of a method of synthesis of a photosensitive mixture of controlled composition containing cationic water-soluble 5,10,15,20-tetrakis(N-Me-pyridin-3-yl)chlorin and 5,10,15,20-tetrakis(N-Me-pyridin-3-yl)bacteriochlorin. The diimide reduction of 5,10,15,20-tetrakis(pyridin-3-yl)porphine in pyridine and in the absence of a solvent has been studied. It has been shown that the reduction in the melt significantly decreases the reaction duration (from 12 to 1.5 h) and affords compositions in up to 90% yield.

A water-soluble monocationic chlorin photosensitizer for antimicrobial photodynamic therapy of superficial localized infections has been proposed. The antimicrobial activity of this compound against planktonic forms of nosocomial antibiotic-resistant gram-negative pathogens, Pseudomonas aeruginosa, Enterobacter cloacae, and Acinetobacter baumannii, has been studied in comparison with the activity of the photosensitizer Fotoran e₆, widely used in the clinical photodynamic therapy of tumors. It has been shown that both photosensitizers possess low dark toxicity; however, the light toxicity of the monocationic chlorin is higher by several orders of magnitude, and it can be proposed as a new agent for the antimicrobial photodynamic therapy.