Revealing the Molecular Interaction of Surface Active Ionic Liquids [C₈mim][Cl] and [C₁₀mim][Cl] with Anionic Dye Eosin Yellow: A Comparative Study with Analogous Cationic Surfactants

Aggregation behaviour of two cationic surfactants octyltrimethylammonium bromide [OTMAB], decyltrimethylammonium bromide [DTMAB] and two surface active ionic liquids 1-methyl-3-octylimidazolium chloride [C₈mim][Cl], 1-methyl-3-decylimidazolium chloride [C₁₀mim][Cl] with anionic dye eosin yellow were investigated by conductometry, UV–Visible spectroscopy and fluorescence spectroscopy. Decrease in CMC of SAILs/surfactants is observed in presence of eosin yellow. Spectroscopic analysis demonstrates a shift in spectra of dye which implies SAILs/surfactants interaction with dye. Binding constant (K_a) obtained by UV–Visible spectroscopy and fluorescence spectroscopy follows the sequence [C₁₀mim][Cl] > [C₈mim][Cl] and [DTMAB] > [OTMAB]. The binding constant seems to be mostly dependent on the carbon chain length of these SAILs as well as surfactants.