Doklady Chemistry最新文献

Doped silicon nanoparticles combine material availability and biocompatibility with a wide variety of functional properties. The review focuses on the methods of fabrication of doped silicon nanoparticles, the prevalent of those being chemical vapor deposition, annealing of substoichiometric silicon compounds, and diffusion doping. Data on the achieved doping levels have been summarized. For the important case of phosphorus, it has been shown that an impurity excessive relative to its solubility in silicon crystals is electrically inactive. The patterns of intraparticle dopant distributions studied in the last decade using powerful techniques of atom probe tomography and solid-state NMR are presented. The promising optical and electrophysical properties of doped silicon nanoparticles are considered, and the significant role of the position of dopants in the design of a material with the desired properties is exemplified by plasmonic behavior.

3,5-Dioxo-1,7-heptanedials, 3,5-dioxo-1,7-heptanediols, and derivatives of 1,3-dioxo-1,7-heptanediboxylic acid have been synthesized for the first time by the low-temperature ozonolysis of 1,3-dioxepins. It has been shown that intermediate ozonolysis products, peroxy compounds, depending on decomposition conditions can produce corresponding individual dialdehydes, diols, and diesters with high selectivity.

In this work, by means of bio-strips and cytotoxic potentials of chemical reactions, the decisive impact of solvent choice on the “overall cytotoxicity” of the process is shown by example of 36 routes of 1,1′-biphenyl synthesis.

Heterocyclic compounds are crucial for medicinal chemistry and the development of therapeutic agents like broad-spectrum antibiotics. This study devised a facile procedure to synthesize novel antimicrobial bicyclic heterocycles from 2-mercapto-3-phenylquinazolin-4(3H)-one. Advanced analytical techniques including ¹H and ¹³C NMR, elemental analysis, and FT-IR spectroscopy characterized the intricate chemical structures of the products. In vitro assays tested the heterocycles against aerobic and anaerobic bacterial strains using fluconazole and ciprofloxacin as antifungal and antibacterial controls. Results demonstrated the formidable broad-spectrum antibacterial and antifungal activities of the synthesized compounds, with growth inhibition approaching that of the positive controls. These findings highlight the immense potential of these novel heterocyclic compounds as antimicrobial agents. Further research can optimize their drug-like properties for eventual clinical use in combating drug-resistant infections.

The surface of an amorphous cobalt-based alloy with a nominal composition of Co75Si15Fe5Cr4.5Al0.5 was modified with nanostructures by anodizing in an ionic liquid—1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. The magnetic (specific saturation magnetization and coercive force) and corrosion (corrosion potential and resistance) characteristics of an amorphous alloy before and after electrochemical modification of the surface with nanostructures have been compared. Modification of the alloy surface partially changes its magnetic properties. After corrosion tests, an increase in the coercive force is observed. Corrosion tests were carried out using the polarization curve method in Ringer’s solution. The corrosion resistance of alloys modified with oxide nanostructures is higher than the corrosion resistance of an abrasive-treated alloy. The increase in corrosion resistance is determined mainly by the presence of nanostructures.

New polymer composite materials (PCMs) were obtained based on a mixture of phenol–formaldehyde and phthalide-containing phenol–formaldehyde resole-type binders reinforced with polyoxadiazole fiber, and their tribological properties were investigated. A study was made of the effect of the content of the phthalide-containing phenol–formaldehyde polymer in the two-component mixture of binders on the hardness of the surface layer and the tribological and thermofrictional properties of the PCM in various systems of dry friction on steel. It was shown that the resulting PCMs are superior in tribological and thermofrictional properties to PCMs based on phenol–formaldehyde or phthalide-containing phenol–formaldehyde resole-type binders.

Heterogeneous and mechanochemical syntheses of new materials based on titanium, calcium, and magnesium phosphates were developed for the first time. The products demonstrated high efficiency as sorbents for the removal of heavy metal cations and radionuclides from solutions. The joint action of the sorption components ensures high sorption capacity towards various cations over a wide pH range. The optimal conditions providing products with a specified phase composition were identified. The use of a solution of a phosphorus-containing agent and solid precursors taken in a stoichiometric ratio, together with mild hydrothermal conditions make it possible to minimize the amount of liquid waste. In the first step of the synthesis, precipitation of titanium phosphate and formation of the precursor needed for the second step (formation of calcium and magnesium phosphates) take place simultaneously. Thus, the synthesis protocol complies with the green chemistry principles.

A method has been developed for the selective C(2)H alkylation of (benz)oxazoles with tertiary alkyl chlorides and alkyl bromides under visible light-induced (460 nm) catalysis with the Pd(PPh₃)₄/[Bu₄N]I system in N,N-dimethylacetamide. The tetraalkylammonium salt has a significant promoting effect on the reaction, which seems to be based on the stabilization of nanosized palladium species in the catalytic system.

A new method has been proposed for the synthesis of bis(phosphine sulfides) and nickel and platinum chelate complexes of 1,3,6-azadiphosphacycloheptanes. The method is based on the ability of 14-membered 3,6,10,13-diazadiphosphacyclotetradecanes to undergo a reversible transformation in solutions into a mixture of meso- and rac-isomers of seven-membered bis-phosphines. The reaction of 3,6,10,13-diazadiphosphacyclotetradecanes with elementary sulfur results in 14-membered tetrakis(phosphine sulfides) or seven-membered bis(phosphine sulfides), depending on the reaction conditions. The reaction of 1,3,6-azadiphosphacycloheptanes, resulting from the reversible dissociation of 14-membered tetraphosphines in chloroform, with Ni(CH₃CN)₆(BF₄)₂ and Pt(COD)Cl₂ gives the corresponding chelate complexes. The structures of the meso-isomer of 1-cyclohexyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane-3,6-disulfide, bis-(κ²-1-isopropyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane)nickel bis(tetrafluoroborate), bis-(κ²-1-cyclohexyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane)chloronickel tetrafluoroborate, and cis-dichloro-(κ²-1-cyclohexyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane)platinum(II), isolated in crystalline form, have been confirmed by single crystal X-ray diffraction.

The first example of intramolecular diastereoselective domino reaction of ferrocene 1,1'-bis-enone to [5]ferrocenophane initiated with sodium ethoxide was found. The product is [5]ferrocenophane with two pyridyl and one ethoxy substituents arranged asymmetrically in a five-carbon bridge. Diffraction studies showed that ferrocene is in almost ideal eclipsed conformation. The fan conformation found in the crystal is also preserved in solution, which was determined by NMR spectroscopy.