GROUND AND EXCITED-STATE PROTON-TRANSFER OF 4-METHYL-2,6-DIFORMYLPHENOL IN DIFFERENT SOLVENT MIXTURES

Proton transfer in the ground and excited states of 4-methyl-2,6-difor mylphenol (MFOH) in ethanol/water, ethanol/methanol and ethanol/dioxan e solvent mixtures has been studied using steady state and nanosecond transient emission spectroscopy. The lifetime is not affected much in water/alcohol mixtures, although in ethanol/dioxane mixture the lifeti me varies considerably with solvent composition. The emission intensit y and fluorescence quantum yield varies with the mixed solvent composi tion. It is proposed that both dissociation and recombination reaction s contribute to the decay rates in ethanol/water and ethanol/methanol solvent mixtures. The presence of methanol or water in the mixture que nches the fluorescence in ethanol. To study the photochemical quenchin g intensity the data are analyzed by the Stern-Volmer equation.