SPECTROSCOPIC AND PHOTOPHYSICAL PROPERTIES OF SOME NEW RHODAMINE DERIVATIVES IN CATIONIC, ANIONIC AND NEUTRAL MICELLES

The spectroscopic and photophysical characterization of rhodamine 123 (dye 1), 4,5-dibromorhodamine methyl ester (dye 2) and 4,5-dibromorhod amine n-butyl ester (dye 3) are reported in homogeneous media like wat er and some alcohols and also in microheterogeneous media; anionic sod ium dodecylsulfate (SDS), cationic cetyltrimethylammonium bromide (CTA B) and neutral triton X-100 (TX) micelles. The selective biodistributi on of these ionic drugs in tissues and membranes strongly influence th eir photosensitizing properties which have been part of our earlier st udies, Results suggest that the hydrogen bonding capability of the ami no end group lone pair of these dyes dominates in water. All these dye s interact with anionic SDS micelles, The interaction is mainly electr ostatic in nature. At low SDS concentrations (below c.m.c,), dye-SDS a ggregate formation takes place, But above c.m.c, only the monomeric dy e form is observed. The penetration of dye 3 in SDS is a little less c ompared to dyes 1 and 2, Dyes 2 and 3 show a finite interaction with C TAB micelle unlike dye 1, With neutral TX micelles all the dyes form s trong complexes. The fluorescence quantum yield (Phi(F)) of these thre e dyes in TX is lower. In time-resolved fluorescence experiments, two lifetimes are observed. The effects of the TX concentration on the flu orescence decay are measured. The decay associated spectra of dye 2 in TX are obtained by global compartmental analysis, The dye-surfactant interaction mechanisms are also discussed.