DIRECT AND SENSITIZED PHOTOOXIDATION OF CYANINE DYES

Abstract

Abstract —Direct photooxidation of cyanine dyes was found to be markedly enhanced by formation of hypsochromically shifted (H) aggregates. Singlet oxygen was found to attack many cyanines possessing low oxidation potentials with rate constants in excess of 10 8 t mol ‐1 s ‐1 . Singlet oxygen attack on 3,3′‐diethyl‐8,10‐dimethylthiacarbocyanine yields carbonyl products consistent with 1,2 addition to the 2,8 bond of the methine chain.