Dye-surfactant interaction: solubilization of styryl pyridinium dyes of varying alkyl chain in alfa-olefinic sulfonate and linear alkyl benzene sulfonate solutions

Cationic dyes, like alkyl styryl pyridinium dyes, are found to interact with anionic surfactant systems differently according to their structural differences. The absorption and emission spectral data of the dyes in various organic solvents and in a wide range of surfactant concentration reveal a variation in the solubilization pattern of the dyes with varying alkyl chain at the pyridinium end. The existence of monomer and H/J-stacked dimers in aqueous medium as well as in surfactant media gets evidence from the spectral data. The difference in binding constant of the dyes with the surfactant aggregates is rationalized through the change in hydrophobicity of the dye due to change in alkyl chain. (C) 2004 Published by Elsevier B.V.