Russian Journal of General Chemistry

Reaction of tetrafluorosilane with tris(2-hydroxyethyl)-and tris(2-trimethylsiloxyethyl)amine results in formation of 1-fluorosilatrane and fluorosilatrane in 75 and 53% yield, respectively. Reaction of tetrafluorosilane with bis(2-trimethylsiloxyethyl)amine and its N-methyl derivative leads to the hitherto unknown 1,1-difluoroquasisilatranes (N → Si) F2Si(OCH2CH2)2NR (R = H, Me) containing donor-acceptor bond N → Si and pentacoordinate silicon atom. The structure of the synthesized compounds was proved by 1H, 13C, 15N, 19F, 29Si NMR and IR spectroscopy.

By quantum-chemical DFT/GIAO method chemical shifts of all nuclei in the NMR spectra of 3-methylpyrazol-5-one and 1-phenyl-3-methylchalcogenopyrazol-5-ones in chloroform and dimethyl sulfoxide were calculated and analyzed using various solvation models. Low sensitivity to solvent of the chemical shfts of 13C and 1H nuclei (except for “acidic” protons) calculated in the framework of various continuum models is revealed. Discrete and discrete-continuum models reflect well deshielding of the active centers of H-complexation and chemical shifts of “acidic” protons of the studied pyrazolones in solutions. Optimization of geometry of pyrazolones in solutions only slightly improves the agreement between the theoretically calculated and the experimental values. Shielding of nitrogen, oxygen, sulfur, and selenium atoms is more sensitive to the nature of solvent and to the nature of tautomeric forms. The methods of NMR spectroscopy allow to identify reliably the dominating tautomeric form but they are insufficient for the quantitative characterization of tautomeric equilibria.

In order to create heterotopic receptors of polyfunctional substrates we have synthesized the bisporphyrin-calix[4]arene crown ethers [6] with the amino and hydroxy groups in tetrapyrrole fragments and polyethyleneoxide complexing cavity in the calix[4]arene fragment of the macrocycle. Their spectral properties and complexing ability toward the alkali metal cations, organic diamines, and dicarboxylic acid esters were investigated.

Bài báo này mô tả các đặc tính quang điện hóa của oxit titan được hình thành qua quá trình oxy hóa điện ly plasma. Khả năng tương quan giữa hoạt tính quang của các hệ hình thành và các đặc điểm trở kháng của chúng đã được nghiên cứu. Các mạch tương đương cho phép giải thích đặc điểm của phổ trở kháng đã được xây dựng và giải thích. Vai trò của việc xử lý nhiệt và sự biến đổi bề mặt với bạch kim đối với các đặc điểm quang điện hóa và điện hóa của các hệ hình thành đã được chứng minh.

Alkylation of isatin with 1,ω-dihaloalkanes afforded bis(heterocycles) connected by an oligomethylene linker. The reaction of the resulting bis(isatins) with Girard’s T and Girard’s P reagents led to the formation of symmetrical water-soluble acyl hydrazones with high yields. Evaluation of antimicrobial activity of new compounds showed the dependence of the activity level on the hydrocarbon spacer length. The selective activity of nona- and decamethylene derivatives was established with respect to gram-positive bacteria S. aureus 209p and B. cereus 8035. Low hematotoxicity of the obtained heterocycles was revealed.

Reactions of gas-phase synthesis of lead phosphates and tellurates have been studied. Standard enthalpies of formation and atomization of gaseous PbPO2, PbPO3, PbP2O6, PbTeO3, and Pb2TeO4 salts have been determined.

For the V–O–V bonds between closely spaced vanadium hydroxide groups, synthesized by the molecular layering during sequential treatment of the silica surface with VOCl3 and H2O vapors, a scheme of binding based on experimental data was proposed, and patterns of formation were predicted by quantum chemistry methods.