Quenching of fluorescence of 3,7-diamino-2,8-dimethyl-5-phenyl phenazinium chloride by halides and pseudohalides in mixed micellar media

The fluorescence quenching of the dye 3,7-diamino-2,8-dimethyl-5-phenyl phenazinium chloride (Safranine T) (ST) by I−, Br−, Cl−, NO2−, N3− in mixed micelles of nonionic surfactants polyoxyethylene sorbitan monolaurate (Tween-20), polyoxyethylene sorbitan monopalmitate (Tween-40), polyoxyethylene sorbitan monostearate (Tween-60) and polyoxyethylene sorbitan monooleate (Tween-80) in different compositions has been investigated at different ionic strength. The ions influence the process to different extents; the medium efficiency depends on the composition of the mixture. The efficiencies of the ions for quenching the fluorescence of Safranine T in mixed micelles are in the order I− > N3− > Br− > NO2− > Cl−. The photophysical process is governed by the electron transfer mechanism. The Stern Volmer quenching constants of the quenching process are presented and rationalization of the results has been attempted.