Synthesis of cationic hemicyanine dyes and their interactions with ionic surfactants

Cationic hemicyanine dyes, 1-methyl-4 [4-(di-n-alkylamino) styryl] pyridinium betaines containing dialkyl chains in the range C, to C, were synthesized and characterized. The interactions of dyes with cationic surfactant, cetyltrimethylammonium bromide (CTAB) and an anionic surfactant, sodium dodecyl sulfate (SDS) were studied by measuring their visible absorption spectra as a function of surfactant concentration below and above their critical micelle concentrations. Owing to lower hydrophobicity of the dyes, the electrostatic interactions between the dyes and the surfactants seemed to play an important role in the penetration of the dyes into the surfactant micelles. (C) 1998 Elsevier Science B.V.