Interaction of charge transfer fluorescence probe with non-ionic surfactants: Estimation of physico-chemical properties and association constant

Fluorescence behavior of intramolecular charge transfer probe trans-ethyl-p-(dimethylamino) cinnamate (EDAC) is extremely sensitive to the local environment. This study explores the interaction of EDAC with several Igepal, Brij and Tween series of non-ionic surfactants by steady state and picoseconds time-resolved fluorescence spectroscopy. The physico-chemical properties, like critical micelle concentration and micropolarity of the micellar media surrounding the probe were determined. In most of the cases, the observed values were in good agreement with the data reported in the literature. Results obtained from time-resolved fluorescence experiments show a substantial reduction in total non-radiative decay rate of the probe in micellar medium compared to that in aqueous phase. This indicates preferential association of the probe inside the micellar core. The association constant of the probe-micelle interaction was also evaluated in different cases.