Influence of the solvent on the quenching of the fluorescence of anthracene by aromatic amines

The influence of the solvent on the quenching of the fluorescence of anthracene by diethylaniline (DEA) and aniline has been investigated. Fluorescence quenching in these systems obeys the equation of Stern and Volmer. A transition from kinetics-controlled to diffusion-controlled processes takes place with the increase in viscosity () in nonpolar solvents. In polar solvents the quenching rate is limited by diffusion over the whole viscosity range investigated. These peculiar effects of the solvent can be explained by the traditional three-stage quenching scheme of the singlet-excited anthracene by electron donors. It is also possible that the increase in the quenching constant () in polar as compared to nonpolar solvents with the same is related to an increase in the rate constant of non-emitting deactivation in polar media, induced by the quenching agent. In the case of the quenching of fluorescence of anthracene by aniline the process is diffusion-controlled, regardless of the nature of the solvent.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 3, pp. 370–374, May–June, 1985.