Vol 513, No 1 (2023)

An effective synthesis of optically pure macrocyclic mono- and dinuclearpolylactones is proposed, based on the condensation of a natural triol – castor oil with sebacic acid dichloride, taken in ratios 1 : 1 or 1 : 2, in boiling carbon tetrachloride in the presence of triethylamine and the catalyst N,N-dimethylaminopyridine.

A method for selective C(2)H alkylation of (benz)oxazoles with tertiary alkyl chlorides and alkyl bromides under photoinduced by visible light (460 nm) catalysis with Pd(PPh₃)₄/[Bu₄N]I system in N,N-dimethylacetamide has been developed. 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.

The approach to the synthesis of bis-phospninesulfides and nickel and platinum chelate complexes of 1,3,6-azadiphosphacycloheptanes is supposed. The approach is based on the ability of 14-membered 1,8-diaza-3,6,10,13-tetraphosphacyclotetradecanes undergo the reversible transformation to the mixture of meso- and rac-isomers of 7-membered bisphosphines during the solution. The reaction of 1,8-diaza-3,6,10,13-tetra-phosphacyclotetradecanes with elementary sulfur results in 14-membered tetra(phosphinesulfides) or 7‑membered bis(phosphinesulfides) that depends on the reaction conditions. The reaction of 1,3,6-azadiphosphacycloheptanes, forming by the reversible dissociation of 14-membered tetraphosphines in chloroform, with Ni(CH₃CN)₆(BF₄)₂ and Pt(COD)Cl₂ give corresponding chelate complexes. The structures of meso-isomer of 1-cyclohexyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptan-3,6-disulfide 8, bis-(κ²-1-isopropyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane)nickel bis(tetrafluoroborate) 9, bis-(κ²-1-icyclohexyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane)chloronickel tetrafluoroborate 10 and cis-dichloro-(κ²-1-cyclohexyl-3,6-diphenyl-1-aza-3,6-diphosphacycloheptane)-platinum(II) 13 were established by single crystal XRD analysis.

One of the most realistic possibilities for reducing anthropogenic carbon dioxide emissions is its involvement as a feedstock in various processes for producing gas chemical products. First of all, it is advisable in the production of the largest-tonnage products, such as syngas, hydrogen and methanol. The paper considers the possibility of involving carbon dioxide in non-catalytic autothermal processes of the production of these products. A combined process for the production of methanol and hydrogen without CO₂ emission based on the matrix conversion of natural gas into syngas is presented.

The first example of intramolecular diastereoselective domino reaction of ferrocene 1,1'-bis-enone to [5]ferrocenophane initiated with sodium ethylate was found. The product is [5]ferrocenophane with two pyridyl and one ethoxy substituents arranged asymmetrically in 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.

Radical copolymerization of coumarin with N-vinylamides (N‑vinylpyrrolidone, N-methyl-N-vinylacetamide, N-vinylformamide) was used to prepare copolymers of various natures and varied molecular masses. After the subsequent reactions in polymer chains, water-soluble copolymers of salts of oxycinnamic acid and its hydrazides were obtained. The synthesized copolymers of salts and hydrazides of oxycinnamic acid with N-vinylamides have low cytotoxicity and demonstrate the pronounced antiviral activity against human respiratory syncytial virus (strain A2).

The investigations in the polycomponent high alkaline systems – TiO₂–H₂SO₄–Na₂SiO₃–NaOH–H₂O and TiO₂–H₂SO₄–(NH₄)₂SO₄–Na₂SiO₃–NaOH–H₂O under hydrothermal synthesis conditions have been carried out to provide new products with the given technical properties. It has been shown that by directed selection of structure-forming components, in particular titanium compounds, together with optimal parameters of hydrothermal treatment of the obtained precursor, it is possible to form compounds with the given phase and chemical composition, morphology and particle size. It was found that the rate of structural transformations during synthesis depends on the phase composition of titanosilicate precursors. During their hydrothermal treatment, alkaline and thermal hydrolysis with subsequent dehydration of hydrolyzed phases of titanium (IV) and silicon take place. The process is accompanied by localization of free bonds providing formation of Ti–O–Si–O-bridges and their subsequent transformation into structured new formations.

The paper presents a new low-temperature method for the synthesis of highly dispersed powders of double phosphates LiCoPO₄ and LiNiPO₄ using low-waste technology. It has been shown that the morphology and particle size of the obtained materials depend on the type of initial precursors. The obtained compounds are characterized by elemental, XRD, SEM, cyclic volammetry, cyclic chronopotentiometry analyses. A new approach to the synthesis of submicron powders of lithium double phosphates and transition metal (nickel, cobalt) is more effective compared to current methods.

The synthesis verification of 3-amino-4-azido-1,2,5-oxadiazole and its structural characterization (IR, NMR, X-Ray, elemental analysis) are reported. Its thermal behavior (TG-DSC), standard enthalpy of formation, sensitivity to mechanical stimuli, detonation parameters were studied. Our study unveils wide application perspectives of 3-amino-4-azidofurazan as a precursor to novel energetic materials for future insights and an eco-friendly primary explosive.

Anodic zirconia nanotubes are a promising functional medium for the formation of non-volatile resistive memory cells. The current-voltage characteristics in the region of low conductivity of the fabricated Zr/ZrO₂/Au memristor structures have been studied in this work. For the first time, the reversible mechanisms of formation/destruction of single quantum conductors based on oxygen vacancies, which participate in processes of multiple resistive switching between low- and high-resistance states in a nanotubular dioxide layer, have been analyzed. An equivalent electrical circuit of a parallel resistor connection have been proposed and discussed to describe the observed memristive behavior of the studied layered structures.

High-entropy carbides are a new class of inorganic compounds promising for a wide range of applications. The paper presents a new concept for the synthesis of powders of high-entropy carbides by the method of self-propagating high-temperature synthesis (SHS) in the gasless thermal explosion mode from previously mechanically synthesized and structured reaction mixtures. For the first time, high-entropy carbides TaTiNbVWC₅ and TaNbVMoWC₅ were obtained by this method, their crystal structure was determined, which was compared with similar compositions obtained by sintering.

Phase equilibria in the Li–Mn–Eu–O system were studied for the first time in the temperature range 700–1000°С, and a concentration diagram was plotted within the Li–Mn–Eu triangle at an oxygen partial pressure of 21 kPa. It is shown that the LiEuO₂–Li₂MnO₃ system is quasi-binary, unlike the sections LiEuO₂–LiMnO₂ and LiEuO₂–LiMn₂O₄. It has been established that, for spinel LiMn₂O₄ (Fd\(\bar {3}\)m), a homogeneous introduction of 2 mol % Eu is possible, while in the case of Li₂MnO₃ (C2/m), the single-phase state decays.