FLASH-PHOTOLYSIS OF POLYMETHINE DYES WITH VARIOUS COUNTERIONS IN NONPOLAR MEDIA

Transient species (triplet states, photoisomers, and radicals) of phot oexcitation of the following cationic polymethine dyes: 1,1'-di-n-buty lindocarbocyanine, 1,1'-di-n-decyl-meso-chloroindodicarbocyanine, and 1,1'-di-n-butyl-meso-bromoindodicarbocyanine, which form ion pairs wit h perchlorate and triphenylbutylborate in nonpolar solvents, were stud ied using the technique of flash photolysis. It was found that radical s were formed upon electron transfer as a result of diffusion encounte rs of dye-perchlorate ion pairs in the triplet state or, for dye-triph enylbutylborate ion pairs, in both excited singlet and triplet states of a dye. In the triplet state, electron transfer occurred less than 1 0(-5) s.