Absorption and fluorescence spectra of tetrakis(sulphonatophenyl) porphyrin in Triton X-100 micelles: Analysis in terms of four-orbital model parameter

Abstract

Effects of Triton X-100 micelles on the absorption and emission properties of tetrakis(sulphonatophenyl)porphyrin (TPPS) have been studied. An analysis of the absorption spectra in terms of four-orbital model of porphyrin excited state reveals that there is no ground state complex formation. The TPPS molecule is strongly hydrophilic so there is very little possibility of its solubilization within neutral Triton X-100 micelles. Enhancement of fluorescence intensity with increase in surfactant concentration is caused by the surface adsorption of the TPPS molecule at the hydrophilic mantle of the micelle, i.e. the Stern layer, where it is exposed to water, and van der Waals interaction is the main binding force. The inhibition of the radiation less decay by micellar aggregates, rationalized in terms of rigidization of the TPPS by the local environment of the micelle, is further confirmed from fluorescence polarization spectroscopy.