Wavelength dependence of the fluorescence quantum yield of some substituted phenols

Abstract

The dependence of the fluorescence quantum yield Q(F) on the excitation wavelength (λ_exc) was studied for phenol, anisole, p-cresol, p-methylanisole, 3,5-dimethylphenol and 2,4,6-trimethylphenol in polar and apolar solvents. All the systems investigated, with the exception of anisole and p-methylanisole exhibit a marked decrease in Q(F) at lower λ_exc values in hydrocarbon solvents. Further it was established that in this case enhanced photochemical cleavage of the OH bond is mainly responsible for this effect. Owing to the formation of H-bonds this dependence diminishes in polar, strongly associating solvents like alcohols and ethers, but not in water.