Spectral-luminescent and photochemical characteristics of homodimers of the styrylcyanine dye Sbt in solutions

The influence of concentration, solvent nature on the intermolecular interaction and its spectroscopic manifestations in solutions of styrylcyanine dye Sbt ((E)-2-(4-(dimethylamino)styryl)-3-methylbenzo[d]thiazol-3-ium iodide) and its homodimers, i.e. dyes with two interconnected chromophores, was studied.It was found out that, depending on the concentration, the structure of dye molecules, the nature of the solvent various forms of associated molecules are forms; each of these forms is manifested in the spectra of absorption and fluorescence in its own way. It is shown that the intensity of the main absorption band of the studied dyes in aqueous solutions and in a mixture of water + ethanol decreases in the process of light irradiation and a new band is observed in the region of shorter wavelengths; the intensity of the new band increases with increase of radiation exposure of solutions.

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• The spectral-luminescent characteristics of styrylcyanine dye Sbt and homodimers were studied.
• The transition from water to aqueous-dioxane solution formed H-aggregates.
• The irradiation of aqueous solutions and mixtures of water + ethanol observed shortwave band absorption.