Structure and solvent effect on the photostability of indolenine cyanine dyes

Abstract The structure and solvent effect on the photostability of a series of indolenine cyanine dyes have been investigated. It was found that the photostability did not increase with the increase of the central conjugated chain length and/or substituent groups on the heterocyclic ring. Using UV spectra data, we have found that the photostability of indolenine cyanine dyes in solution increased with increase of the E T (30) values of solvents. The rate of singlet oxygen formation, and β values in different solvents sensitized by the dye alone were measured using fluorescence spectra. Absolute photooxidation rate constants ( k r ) are calculated, based on the determined β values and the decay rate of singlet oxygen ( k d ). All these results well agreed with those obtained from UV spectra.