Role of Intersystem Crossing Steps in Singlet Oxygen Chemistry and Photo-Oxidations

摘要

Singlet oxygen chemistry and photo-oxidation reactions, in general, often require one or more critical reaction steps that involve an intersystem crossing from a singlet state to a triplet state or vice versa. This paper considers two important intersystem crossing mechanisms, electron spin-electron (spin orbit) coupling and electron spin-nuclear spin (spin-spin) coupling, and how they may be involved: (1) in the deactivation of singlet oxygen to triplet oxygen; (2) in the thermal catalytic conversion of triplet to singlet oxygen; and (3) in the fragmentation of aromatic endoperoxides to yield O2 and an aromatic substrate.