The effect of the structure of a number of new laser media based on heteryl-coumarins on their spectral and lasing characteristics is studied under conditions of coherent nanosecond and microsecond lamp pumping. The effect of triazole, oxadiazole, and thiazole heterocycles in the structure of coumarin molecules on the spectral, lasing, and photochemical properties of their ethanol solutions has been studied. The analysis of the influence of heteroatoms, heterocyclic radicals, and an aryl fragment in the conjugation chain on the electron density distribution in the structure of coumarin molecules is carried out. It was shown, that triazole and oxadiazole heterocycles provide better lasing ability and photostability of the compounds under study, which made it possible to create new laser media generating radiation in the spectral range 490-560 nm with a sufficiently high efficiency.

The spectral and generation parameters of coumarins, benzopyrylium derivatives, in ethanol and acetonitrile under coherent excitation were studied. It was found that the absorption spectra of the investigated compounds contain several maxima and the structuredness of the spectra is associated with their bichromophoric structure. It is shown that these organic dyes are bichromophoric compounds. It is noted that the nature of the substituents in positions 6 and 7 of the coumarin base and positions 6′ and 7′ of the benzopyrylium core determines their spectral-luminescent and lasing properties. It is demonstrated that the presence of substituents in certain positions of the coumarin base and the benzopyrylium core changes the conformation of the molecule and, accordingly, the dipole moments and oscillator strengths of the transition. The generation ability of coumarins of this class manifests itself only in the presence of the strongest donor substituents (for example, Et2N and OH) in position 7, and sufficiently strong acceptors in positions 6′ and 7′. Lasing was obtained in the spectral region of 730 –740 nm on dyes – benzopyrylium derivatives.

Background. Metal nanoparticles can have unique properties that differ from those of the solid metal from which they are obtained. This is what determines the increased interest in them on the part of researchers from all over the world. Objective of the study: quantitative assessment of the antibacterial effect of silver and zinc oxide nanoparticles on polyantibiotic-resistant strains of gram-positive and gram-negative microorganisms. Material and methods. The synthesis of silver and zinc oxide nanoparticles was performed by laser ablation in a liquid. The physical properties and sizes of these nanoparticles were studied on the basis of spectral characteristics and atomic force microscopy. The study of the antibacterial resistance of the studied microorganisms was carried out, as well as a quantitative assessment of the antibacterial effect of the obtained nanoparticles based on the determination of the minimum inhibitory and minimum bactericidal concentrations. Results. All microorganisms used in the study were clinical pathogenic strains with polyantibacterial resistance. In this case, the minimum inhibitory concentrations of silver nanoparticles ranged from 7.81 to 31.25 μg/ml, and the minimum bactericidal concentrations - from 31.25 to 62.50 μg/ml, while for zinc oxide nanoparticles the values of the minimum inhibitory concentrations were within the range from 125 to 500 μg/ml, and the values of the minimum bactericidal - from 250 to 1000 μg/ml. Conclusions. The laser ablation method allows the synthesis of chemically pure nanoparticles of silver, zinc oxide, and, if necessary, other metals. Silver and zinc oxide nanoparticles are effective antimicrobial agents against polyantibiotic-resistant pathogenic microbial flora. The obtained values of the minimum bactericidal and minimum inhibitory concentrations must be taken into account in the subsequent clinical implementation of medical devices based on the use of metal nanoparticles.

Spectral-generation properties and the mechanism of formation of "dye-cyclodestrin" inclusion complexes for dyes of different classes (rhodamine 6G, phenalemine 160, cresyl violet) with β-cyclodextrin were studied. The effect of functional groups in the structure of dye molecules on the spectral, generation, and photochemical properties of their inclusion complexes has been studied by electron and IR spectroscopy. It has been shown that the formation mechanism consists in the entry into the β-CD cavity of only individual functional groups and substituents of dye molecules. In this case, micellar complexes consisting of several cyclodextrin molecules and dye molecules and partially intercalated complexes can be formed. The AFM method showed that the characteristic sizes of the formed nanocomplexes are 100-600 nm. Keywords: laser dyes, β-cyclodextrin, inclusion complexes, lasing spectral characteristics, FT-IR spectroscopy, photostability.

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