Quenching of excited-state xanthone and thioxanthone by inorganic anions

Abstract

The quenching rates of both singlet and triplet states of thioxanthone by a group of inorganic anions have been determined, enabling a comparison of their reactivities. The quenching rates of triplet xanthone were also measured. All determinations were made in MeCN–H₂O (3 : 2 v/v). The various rates are correlated with the free-energy change for electron-transfer, ΔG₂₃°, according to the treatments of Rehm and Weller and of Polanyi; an unexpectedly good fit is given by the latter.