Vol 93, No 11 (2023)

The reaction of 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene with carboxylic acid chlorides afforded a series of N -and C -acylsubstituted 2,3,6,7-tetrahydro-1,4-diazepines, which in solutions of deuterated solvents (CD₃OD, DMCO) undergo keto-enol and imino-enamine tautomerism. Structure of the obtained N - and C -acyldiazepines and their tautomeric transformations were characterized by ¹Н and ¹³С NMR spectroscopy using two-dimensional experiments ¹Н-¹³С HMQC, HMBC, ¹Н-¹Н COSY.

A new method for obtaining 4-(2-methyl-1,3-oxazol-5-yl)benzenesulfonamide an antiglaucomatous drug candidate oxazopt was developed using a diazotization reaction. A combined potentiated effect of the antimicrobial action of carbapenems (meropenem) and aminoglycosides (gentamicin) against antibiotic-resistant gram-positive bacteria Enterococcus faecium, Enterococcus faecalis and gram-negative bacteria Escherichia coli and antimonooxidase effect in vitro was revealed for this compound.

Quantum chemical calculations of the transformation of 2,2-di(nitrophenyl)-1,1,1-trichloroethane into 4,4′-dinitrobenzophenone upon reaction with nitrite ion in aprotic polar solvents were performed. It was established that the dehydrochlorination reaction of 2,2-di(nitrophenyl)-1,1,1-trichloroethane proceeds via a synchronous E2H mechanism. A possible scheme for the subsequent formation of 4,4′-dinitrobenzophenone was proposed. For each stage of a multistage process, spatial structures were modeled and the energy parameters of pre-reaction, activated and post-reaction complexes were calculated.

Thermal treatment of linear dipeptides in the solid phase makes it possible to obtain their cyclic analogues in high yield and without additional costs. At the same time, such reactions occurring under the constraints of a crystal lattice with the participation of molecules in the zwitterionic form have not been sufficiently studied. In this work, the cyclization reaction of the dipeptide L-leucyl-L-valine in the crystalline phase upon heating was studied. Using isoconversion kinetics approaches, a kinetic model describing this process is determined, and kinetic parameters are calculated, including activation energy, Arrhenius multiplier, and reaction order. The enantiomeric purity of the resulting cyclic product was assessed. The self-assembly of linear and cyclic dipeptides on a solid support was studied. The results of the study will be useful for establishing the mechanism of the cyclization reaction of dipeptides in the solid phase, and can also be used in the development of effective and cost-effective methods for the production of cyclic dipeptides.

The photolytic decomposition of the Trikhlorbifenil mixture, 2,4,5- and 2,4,6-trichlorobiphenyls under an influence of ultraviolet radiation in presence of tungsten oxide as a catalyst in a methanol medium was studied. A higher rate of photolysis of individual congeners of polychlorbiphenyls was established compared to the congeners of the Trikhlorbifenil mixture. The influence of structural features of polychlorarenes on a depth of photodecomposition and a routes of formation of photodestruction products was considered.

Two methods for preparing mesoporous CeO₂/Au nanocomposites were compared: template synthesis and photochemical modification of fibrous cerium(IV) oxide with gold nanoparticles. The composition, structure, morphology of the obtained nanocomposites, as well as the specific surface area and pore size distribution were studied by a complex of physicochemical methods: X-ray phase analysis, X-ray spectral microanalysis, scanning electron microscopy, low-temperature nitrogen adsorption, and electron spectroscopy. The catalytic properties of the obtained nanocomposites were studied in methyl orange photodegradation reactions. It is shown that the CeO₂/Au catalyst obtained by the photochemical modification method has the highest photocatalytic activity both under the action of UV and visible light.

Organoalumoxane oligomers modified with refractory metals (zirconium, hafnium or chromium) were synthesized. Their physico-chemical and fiber-forming properties were studied. Models of the group and elemental composition of oligomeric molecules of organoalumoxanes containing zirconium, hafnium or chromium were proposed. Based on the results of X-ray elemental microanalysis (SEM) and X-ray diffraction, it was found that pyrolysis of metal-containing organoalumoxanes at 1500°C in air results in the microcrystalline ceramic powders of corundum composition, modified with refractory metal oxides.

Organoleptic evaluations in a ten-point scale of wine experts and experimental physicochemical parameters of red (1599 samples) and white (4898 samples) wines of Portuguese manufacturers were analyzed using STATIS-TICA sofware. Methods of agglomerative and iterative ( k -means algorithm) clustering revealed the grouping of similar wine samples into three, four and six clusters depending on the Euclidean distance of association. The quantitative filling of clusters with samples of bad wines (grades 3 and 4), normal wines (grades 5 and 6) and good wines (grades 7, 8, 9) was established. Neural network (MLP) and discriminant analyzes (DA) were performed; algorithms of classification trees (CT), support vector machines (SVM), naive Bayesian classification (NBC) and nearest neighbors (kNN) were involved. The best performance was demonstrated by neural network models. Multilayer perceptorons classifiers were trained: for red wines - MLP 11-7-3, MLP 11-13-4, MLP 11-14-6; for white wines - MLP 11-9-3, MLP 11-5-4, MLP 11-9-6. The properties of wines, whose contribution to the separating power of classifiers is decisive, are revealed. The ranges of changes in physicochemical parameters in three clusters of red and white wines for bad, normal and good wines were given.