Žurnal obŝej himii

The review presents achievements in the field of synthesis and study of biological activity of various bis-1,3,4-oxadiazoles from 1999 to 2024. The methods for obtaining bis-1,3,4-oxadiazoles repeat the methods used to obtain 1,3,4-oxadiazoles and are mainly implemented due to intramolecular cyclization under the action of phosphorus oxychloride or bases. Oxidative cyclization reactions play a major role. Single examples of the application of the Huisgen reaction and an electrochemical version of cyclization are presented. The main direction of the study of biological activity is antibacterial, and studies of antifungal and anticancer activity are also presented.

6-Aryl-2-(2,6-dimethylphenyl)-3-imino-3,5-dihydro-1H-pyrrol[3,4-c]pyridine-1,4(2H)-diones were obtained by the reaction of N-2,6-dimethylphenylamides of 4-aryl-2-hydroxy-4-oxo-2-butenoic acids with cyanoacetamide in ethanol or propan-2-ol. Structure of the obtained compounds was confirmed by IR, ¹H and ¹³C NMR spectroscopy, and single crystal X-ray diffraction analysis.

The acylation reactions of 4-(2,4-di-tert-butyl-10-methoxy-12H-quinoxalino[2,3-b]phenoxazin-12-yl)aniline with acid chlorides of various structures, including substituents with the properties of anchor groups (hydroxyphenyl, carboxyl, acrylamide, methacrylamide), as well as isobenzofuran-1,3-dione and dihydrofuran-2,5-dione led to the formation of the corresponding 4-(2,4-di-tert-butyl-10-methoxy-12H-quinoxalino[2,3-b]phenoxazin-12-yl)anilides in high yield (79–92%). The resulting amides were characterized by strong (ε = 2.94–4.26∙10⁴ M^–1·cm^–1) absorption bands in the range of 470–630 nm with maxima at 548–551 nm. They also exhibit a photovoltaic effect and high open-circuit parameters (up to 0.57 V) in DSSC solar cells and the ability to exhibit photodiode properties.

N-[Dimethyl(chloromethyl)silyl]amides of chloroacetic acids were synthesized by the reaction of amides of mono-, di-, and trichloroacetic acids with bifunctional silane ClCH₂SiMe₂Cl in hexane or benzene in the presence of a base. Their structure was confirmed by multinuclear NMR spectroscopy using ¹H, ¹³C, ²⁹Si, and ¹⁵N nuclei.

Mg(II)-5,15-diphenylporphyrin, Mg(II)-5,10,15,20-tetraphenylporphyrin, Mg(II)-2,3,7,8,12,12,13,17,18-octaethylporphyrin and Mg(II)-5,10,15,20-tetra-(pentafluorophenyl)porphyrin were obtained using the coordination reaction of the corresponding porphyrins with magnesium acetate in a boiling dimethylformamide–ethylene glycol mixture. The complexation of β-octachloro-5,10,15,20-tetra(pentafluorophenyl)porphyrin with magnesium acetate in dimethylformamide already at room temperature led to the formation of the corresponding Mg(II)-porphyrinate. A facile method for the preparation of magnesium complexes with magnesium chloride in dimethylformamide has been proposed as an example of the metal exchange reaction of Cd(II)-5,10,15,20-tetraphenylporphyrin and Cd(II)-2,3,7,8,12,13,17,18-octaethylporphyrin. The synthesized compounds were identified by UV-Vis, NMR spectroscopy,mass spectrometry and elemental analysis methods. The fluorescence properties of Mg-porphyrins in acetone have been studied. The values of fluorescence quantum yields and Stokes shifts of the studied compounds were calculated. The influence of the nature of substituents on the fluorescence characteristics of Mg-porphyrins was evaluated. The coordination reaction of β-octachloro-5,10,15,20-tetra(pentafluorophenyl)porphyrin with magnesium acetate in dimethylformamide was studied by spectrophotometric method. The kinetic parameters were calculated and the stoichiometric mechanism of the studied reaction has been proposed.

Cubic pyrochlore Bi₂Cu_1/3Ni_1/3Co_1/3Ta₂O_9±δ [space group Fd-3m, a = 10.5323(8) Å] was synthesized from oxides for the first time using the solid-phase reaction method. The ceramics are characterized by a low-porosity grain-free microstructure. The chemical state of transition element cations in multi-element pyrochlore was characterized using photoelectron spectroscopy (XPS) and NEXAFS. For pyrochlore, a characteristic shift of the Ta4f spectrum to lower energies by 0.65 eV is observed, which causes the effective charge of tantalum cations +(5–δ). It is shown that the NEXAFS Cu2p spectra of oxide ceramics, according to the main characteristics of the spectrum, represent a superposition of the spectra of Cu(I) and Cu(II) cations. Based on the analysis of the relative intensity of the peaks in the XPS spectrum of Cu2p, the quantitative ratio of Cu(I)/Cu(II) cations in pyrochlore is 1.06. The NEXAFS Ni2p spectrum of ceramics coincides with the spectrum of NiO according to the main characteristics of the spectrum. XPS studies indicate the state of Ni(III). According to the nature of the Co2p spectrum, cobalt ions are in the state of Co(II,III).

Iron-graphene composites were synthesized by heat treatment of a mixture of iron (III) nitrate and graphite oxide in an argon flow, followed by reduction in a hydrogen flow. The composites were characterized by elemental analysis, thermogravimetry, scanning electron microscopy with energy-dispersive X-ray spectra and construction of maps of the spatial distribution of components, X-ray phase analysis, and Mössbauer spectroscopy. It was shown that the synthesized composites are sheets of a graphene-like material with iron-containing nanoparticles deposited on them, the size of which depends on the concentration of the iron compound in the original mixture. Iron nanoparticles in the obtained composites are rapidly oxidized upon short-term contact with air and can be restored by cyclic treatment at 400°C, including vacuuming the composite followed by exposure to hydrogen under pressure.