The spectral-luminescent and photochemical characteristics of several styrylcyanine dyes in solution

Solvent and concentration effects on the intermolecular interaction processes and its spectroscopic manifestations in solutions of several styrylcyanine dyes with one or two linked chromophores were studied. It was found that, depending on their concentration and structure, dye molecules manifest in their absorption and fluorescence spectra formation of various forms of associated molecules. Bathochromic or hypsochromic shifts in absorption and fluorescence spectral bands, attributable to the changes in the solvation shell of the dye molecules were observed in the transition from water solutions to the water + ethanol, water + DMF, water + dioxane binary solvents. The distribution dipole moments of studied dyes chromophores was determined using semiempirical AM1 method. It is shown, that under the light irradiation of dyes in aqueous solutions and in a water + ethanol mixtures main absorption band decreases, along with increasing exposure time a new shorter wavelength absorption band develops.