V. F. Razumov

Photo- and Thermoinitiated Formation of J and H Aggregates in Amorphous Dispersions of a Carbocyanine Dye

We revealed the possibility of formation of J and H aggregates with different structures in amorphous dispersions of 3,3′-di(γ-sulfopropyl)-4,4′,5,5′-dibenzo-9-ethylthiacarbocyanine betaine pyridinium salt prepared in ethanol-water binary solutions upon photoexcitation into the absorption band of the dye dispersion or temperature change.

Effect of the solvent composition in methanol-pentane and methanol-acetonitrile mixtures on the spectral and luminescent properties of 1,2-dihydroquinolines

The dependence of absorption and fluorescence spectra, quantum yields, and lifetimes of fluorescence on the solvent composition in the MeOH-C5H12 and MeOH-MeCN mixtures was studied for 2,2,4,6-tetramethyl-1,2-dihydroquinoline (TMDHQ). The variations in the parameters of deconvolution of the absorption and fluorescence spectra by the Gaussian functions in the MeOH-C5H12 mixtures of various compositions indicate the specificity of methanol clustering in saturated hydrocarbons and hydrogen bonding between TMDHQ and the methanol clusters of different compositions. At low MeOH concentrations (∼0.2 vol %), TMDHQ molecules are practically completely bound with the MeOH molecules by hydrogen bonds. In the MeOH-MeCN mixtures, the changes in the absorption and fluorescence spectra are observed at a substantially higher MeOH concentration (≥10 vol %) and monotonically change at the further increase in the MeOH concentration that is caused by the peculiarities of MeOH clustering in acetonitrile and the distribution of the TMDHQ molecules between the solvent components. At 50–95 vol % of MeOH in the mixture with MeCN, the fluorescence decay kinetics is described by the biexponential curve with the lifetime of the major component (τ1) decreasing from 7.5 to 1.1 ns in pure MeCN and MeOH, respectively, and the lifetime of the minor component τ2 ≈ 4 ns corresponding to the fluorescence lifetime in the solution containing 50 vol % MeOH. This indicates the existence of the free TMDHQ molecules, which are not bound with MeOH molecules or their clusters.

Synthesis of mixed silver halide nanocrystals in reversed micelles

The specifics of the synthesis of silver halide nanocrystals of mixed composition and the core-shell structures in reversed micelles were experimentally studied. It was shown that homogeneous AgBrxI1 − x nanocrystals of ∼5 nm in size with the iodide concentration up to 70%, as well as the core-shell structures AgI/AgBr and AgBr/AgI, can be synthesized by the micellar synthesis. It was found that the relation of the crystalline structures of the core and shell materials plays an important role in the shell formation. The shell of γ-AgI alone is formed on the AgBr nanocrystals with a close lattice type, whereas β-AgI with the hexagonal lattice forms an individual phase of nanoparticles, rather than the shell.

Formation of coordination polymeric structures on the basis of 4,4"-dipyridylethylene and Ag+ in solutions

The formation of coordination polymeric chain structures in which silver ions alternate with dipyridylethylene (DPyEt) ligands was studied. In a homogeneous ethanol solution, complex formation of DPyEt with silver cations takes place. The outcome of this reaction depends on the ligand/cation molar ratio, the initial ligand concentration, and the counter-ion type. Conditions were identified under which the coordination polymer is formed as a microdispersed solid precipitating from the solution. The precipitates formed in the DPyEt—AgNO3 and DPyEt—AgClO4 systems were investigated by various experimental techniques. The counter-ion was found to be incorporated in the polymer and to influence the structure of the precipitate particles.

Photosynthesis of oxygen in the forest ecosystem and its albedo as major factors of prevention of current civilization from the oxygen and freshwater disaster

The interrelation between the resource-forming and environment-forming functions of the phytosphere, on the one hand, and their consumption by the current civilization, on the other hand, is considered. It was shown that the world technogenic consumption of oxygen in excess of its influx to the atmosphere is 1010 t per annum, the globe average vegetation cover has gradually passed from forest to steppe, and the critical movement from steppe to desert is going now. The ecological-economic harmonization of the consumption of the environment-and resource-forming functions of the forest is needed.

One-quantum process of formation oftrans-1,2-di(2-naphthyl)ethylene under photolysis of 4a, 4b-dihydrodibenzphenanthrene

Thetrans-isomer of 1,2-di(2-naphthyl)ethylene is formed along with thecis-isomer in the one-quantum process under irradiation at the wavelength corresponding to the long-wave absorption band of 4a,4b-dihydrodibenzphenanthrene. The quantum yields of the photoinitiated processes were measured. The adiabatic mechanism was suggested for the photoinitiated ring opening in 4a, 4b-dihydrodibenzphenanthrene.