Excimers and exciplex as sensitisers for photo-oxidation reactions

Excimers and exciplexes are shown to sensitise the photo-oxidation of both a sulphide (di-t-butyl sulphide) and an alkene (citronellol). Evidence is presented for the intermediacy of singlet oxygen in these photooxidation reactions. The ability of excimers and exciplexes to decay to yield triplets, oxygen quenching of which may result in the generation of singlet oxygen, has important consequences for interpreting the mechanisms of photo-oxidation in reactions sensitised by electron acceptors, e.g. 9, 10-dicyanoanthracene.