HYDROPHOBIC INTERACTION OF AMPHIPHILIC HEMICYANINE DYES WITH CATIONICAND ANIONIC SURFACTANT MICELLES

The hydrophobic interaction of amphiphilic hemicyanine dyes, i.e. (dim ethylamino) stilbazolium butyl sulphonate (I) and (dihexylamino)stilba zolium butyl sulphonate (II) with cetyltrimethyl ammonium bromide (CTA B), a cationic surfactant and lithium dodecyl sulphate (LDS), an anion ic surfactant, was studied through absorption spectra as a function of the concentration of surfactants above and below their critical micel le concentrations. The different lengths of dialkyl chains present on these dyes exhibited hydrophobic interaction with micelles of CTAB and LDS; as a result visible spectra of both the dyes exhibited red shift s of different magnitudes when the dye molecules were solubilized into micelles. The approximate number of dye molecules per micelle was als o estimated at a particular concentration of each surfactant. The solu bilization depends on the dilakyl chain length of the dye together wit h the nature of surfactant head groups. (C) 1997 Elsevier Science B.V.