STUDY ON THE PHOTOOXIDATION OF A NEAR-INFRARED-ABSORBING BENZOTHIAZOLONE CYANINE DYE

The direct photooxidation mechanism of a near-infrared-absorbing benzo thiazolone cyanine dye has been studied by UV-Vis absorption spectrosc opy and electron spin resonance. The results shows that the rate of th e photooxidation reaction follows first-order kinetics in acetonitrile . The technique of spin trapping was successfully applied to the detec tion of the photoinduced formation of singlet oxygen (O-1(2))and super oxide (O-2(-)). It was found that both singlet oxygen and superoxide a nion were responsible for the photofading of the cyanine dye. The main photooxidation products of the cyanine dye were identified by NMR (H- 1) and fast atom bombardment(FAB) mass spectometry. (C) 1998 Elsevier Science Ltd.