FLUORESCENCE INVESTIGATION OF MULTIPLE PARTITIONING SITES IN AQUEOUS AND REVERSE MICELLES

Our investigations seek to illustrate the use of fluorescence spectral deconvolution to characterize multiple partitioning sites for aromati c chromophores within aqueous and reverse micelles. The spatial distri bution of solutes within micellar systems is dictated by a variety of noncovalent interactions. To probe far multiple partitioning microenvi ronments, we use the aromatic fluorophore Prodan with its extensive so lubility in a range of media and its appreciable spectral sensitivity to the polarity of its surroundings. We conduct a systematic study of the partitioning of Prodan in aqueous micellar systems with anionic, c ationic, zwitterionic, and nonionic surfactant headgraups and in rever se micellar systems with both anionic and cationic surfactant headgrou ps. By deconvoluting the overall Prodan fluorescence emission spectrum into a sum of overlapping Gaussian functions, the principal microenvi ronments of the Prodan molecules may be ascertained. Fluorescence data are consistent with the location of Prodan in a variety of sites, inc luding partitionings that may be influenced by electrostatic, hydropho bic, dipolar, and cation-pi interactions in both aqueous and reverse m icelles.