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Abstract The results of experimental studies of the interaction of the S-protein with a monohetaryl-substituted porphyrin containing a benzimidazole residue are presented. It has been revealed that the S-protein forms high-affinity complexes with the specified porphyrin. The porphyrin binding by the SARS-CoV-2 S-protein has proceeded stepwise; at the first stage, the driving force of the complexation is electrostatic interaction between the surface negatively charged regions of the protein and cationic substituents of the porphyrin. At the second stage, the target complex of the S-protein with the porphyrin is formed. It has been established that the introduction of 5-[4′-(N-methyl-1,3-benzimidazol-2-yl)phenyl]-10,15,20-tri-(N-methyl-3′-pyridyl)porphyrin triiodide into a solution of the S-protein complex with the angiotensin-converting enzyme leads to the replacement of the latter with the porphyrin. Displacement of the angiotensin-converting enzyme from the complex with the S-protein under the action of 5-[4′-(N-methyl-1,3-benzimidazol-2-yl)phenyl]-10,15,20-tri-(N-methyl-3′-pyridyl)porphyrin triiodide is the experimental evidence for the porphyrin binding at the receptor-binding domain of the S-protein.

Novel porphyrin compounds containing benzothiazole, benzoxazole, and benzimidazole moieties have been prepared and their structures have been confirmed. Molecular docking of non-symmetric hetaryl-substituted porphyrins and chlorin e6 with SARS-CoV-2 helicase has been carried out. The affinity of hetaryl-substituted porphyrins to this protein has been found significantly higher than that of the drugs approved by the FDA and chlorin e6. The structure of the complexes of SARS-CoV-2 helicase with the considered macroheterocyclic compounds has been analyzed. Possible ways to inhibit and photoinactivate SARS-CoV helicase have been suggested basing on the localization of porphyrins and chlorin e6 in the helicase domains.

Composites of polycaprolactone with cellulose nanocrystals were produced, and their morphological, thermal, and strength characteristics were examined. It was found that nanocrystalline cellulose as a filler increased the porosity of the resultant composite materials. A conclusion was made that nanocrystalline cellulose can act as an initiator of polycaprolactone crystallization and affect the growth of the polymer crystallites. Incorporation of cellulose nanocrystals into the polycaprolactone matrix increased the hydrophilicity of the material and promoted an increase in water sorption while making the composite more brittle as indicated by decrease in the elongation at break and icreases in the tensile strength and Young’s modulus.

The possibility of obtaining graphite-like structures from chitosan by microwave processing was studied. A comparative analysis of the products of pyrolysis and microwave treatment of chitosan was carried out.

The physical and phase transitions of a series of chitosans differing in molecular weight and deacetylation degree have been revealed by means of differential scanning calorimetry, thermogravimetry, and mass spectrometry. The temperature ranges corresponding to the dehydration and thermolysis of the considered polymers have been determined. The devitrification temperature of the polymers has been recorded, and its two-parametric regression on the chitosans molecular weight and deacetylation degree has been found. The molecular weight of the polymer revealed stronger effect on the devitrification temperature in comparison with the deacetylation degree.

The interaction of styryl derivatives of pyridine N-oxides with proton donors in various solvents was studied. UV-Vis spectroscopy and thermogravimetric analysis were applied to determine the spectral and thermo-chemical characteristics of the resulting molecular complexes. The dependences of the thermodynamic parameters of the complexes on the N-oxide structure and on the solvating medium were established. The DSC method was used to determine the temperature and enthalpy characteristics of the desolvation and melting processes for both N-oxides and their complexes with proton donors.

Types of dimers of aluminum and cobalt complexes of tetraanthraquinoneporphyrazines were identified. Thermodynamic characteristics of dissociation of the dimers in aqueous media were obtained. The kinetics of the deactivation of the triplet state of the aluminum complexes of sulfonated phthalocyanine and tetraanthraquinoneporphyrazine was studied.

The behavior of bovine serum albumin as a function of the pH of the medium and the presence in the test systems of symmetrical and asymmetrical hydrophobic porphyrins was investigated. It was established that 4-[(tert-butoxycarbonylamino)acetamido]phenyl group favors stronger protein binding to porphyrin, and this effect enhances in an alkaline medium. Solubilization of protein by porphyrins leads to the fact that the particles are spherical in solution, the hydrodynamic radius of the protein globule reduced in an alkaline medium but in neutral medium, in contrast, increases. By IR spectroscopy it was shown that beta-structuring and the proportion of disordered coils of the polypeptide chain in an alkaline medium increases, because the complexability of the protein towards porphyrin is changes.