Photochemistry of 9,10-anthraquinone-2-sulfonate in solution. 1. Intermediates and mechanism

摘要: The photochemistry of aqueous 9,10-anthranquinone-2-sulfonate (AQS) was investigated by using four different approaches: (1) laser photolysis AWS in water as a function concentration and pH; (2) AQS CH/sub 3/CN 3/CN/H/sub 2/O mixtures, combined with emission spectroscopy; (3) steady-state photolytic study the effect pH on yield photohydroxylation water; (4) quenching intermediates inhibition inorganic anions. Our results lead to identification triplet (tau approx. 100 ns water) two other (B C) which are formed parallel reactions H/sub 2/O. nature these is still uncertain, but evidence presented rule out H abstraction or net electron transfer (even case OH/sup -/) leading formation free OH radicals. possibility that B C adducts discussed. role referential solvation 3/CH/H/sub mixures determining its also examined. Species (lambda/sub max/ 600 nm) only transient observed appears react ground-state AQS, this reaction considered tomore » be responsible for photohydroxylation. provide direct validity ''/sup 3/AQS/H/sub 2/O'' mechanism proposed Clark Stonehill (CS), primary step /sup 3/AQS (and not AQS) produce hydoxylation agent. However, modified pHgreater than equal to11 proposing another hydroxylating agent may AQS/sup -/.OH exciplex (or radical pair) produced charge-transfer (CT) -/. Evidence establish various anions including -/.« less