E.S.R. of nitroxide radicals. II. Photosensitization of indoles, phenols, and thiols by a diphenylpyrazoline

Abstract

Indoles, phenols, and thiols have been shown to undergo photosensitization by a diphenylpyrazoline in non-polar solvents. The intermediate radicals produced have been trapped using a nitrosoalkane scavenger, and the resulting nitroxide radicals examined in situ by e.s.r. Fluorescence studies of these systems have shown that indoles and phenols strongly quench the singlet excited state of the diphenyl- pyrazoline, whereas thiols have no effect.