Fluorescence quenching of BPBD by aniline in benzene–acetonitrile mixtures

The quenching of fluorescence of 2-(4′-t-butylphenyl)-5-(4′′-biphenylyl)-1,3,4-oxadiazole (BPBD) has been studied by aniline in different solvent mixtures of benzene and acetonitrile at room temperature. The quenching is found to be appreciable and a positive deviation from linearity was observed in the Stern–Volmer plot in all the solvent mixtures. Various rate parameters for the quenching process have been determined by sphere of action static quenching model and finite sink approximation model. The magnitudes of these rate parameters indicate that positive deviation in the Stern–Volmer plot is due to both static and dynamic processes. The dependence of Stern–Volmer constant on dielectric constant of the solvent mixture indicates the possibility of different solvent molecule composition around the fluorescent from that of the bulk.