Visible and fluorescence spectral studies on the interaction of Safranine T with reverse micelles of Triton X-100 and Tweens in chloroform

The visible spectra of Safranine T in reverse micelles indicate 1:1 (dye:reverse micelle) charge transfer complex formation with the non-ionic surfactants Triton X-100, Tween 20, Tween 40, Tween 60 and Tween 80. The complexing strength follows the order Tween 80 > Tween 60 > Triton X-100 > Tween 40 > Tween 20. The fluorescence spectrum of the dye is also enhanced by the reverse micellar solution confirming the formation of 1:1 complex having comparable complexing strength as revealed from the ground state spectra. The equilibrium constants of the dye-reverse micelle complex are directly proportional to the carbon number of the non-polar tail of Tweens and their aggregation number. The latter has been determined together with the critical micelle concentrations of the reverse micelles as well as their core polarities.