OXYGEN PHOTOSENSITIZATION IN THE PRESENCE OF SODIUM ANTHRACENE-1-SULFONATE

Sodium anthracene-1-sulphonate (AN1S), UV irradiated in aqueous soluti ons, forms the intermediate anthracene-1-sulphonyl radical (AN-1-SO2.) . In the presence of oxygen, AN1S is converted to quinone and oxygen i s activated to superoxide as indicated by the 5,5-dimethyl-1-pyrroline -N-oxide (DMPO) spin trap adduct, (.)DMPO-O-2-. The products of oxygen activation are OH. radicals identified as (.)DMPO-OH adducts. The tim e dependence of (.)DMPO-OH formation during and after irradiation impl ies the production of an activated complex between oxygen and anthrace ne quinones. Quantum chemical calculations indicate a considerable wea kening of the C-S bond in the photochemically excited state (T-1,S-1) of AN1S. As a consequence, the splitting of (SO3Na)-S-. is probable wh ich, in a subsequent reaction with the sulphonate group in AN1S, may b e responsible for the formation of AN-1-SO2..