Facile solubilization of organochalcogen compounds in mixed micelle formation of binary and ternary cationic-nonionic surfactant mixtures.

This study investigated the water solubility enhancements of organochalcogen compounds, viz. bis(diphenylmethyl)diselenide [(C6H5)2CHSe]2 and 3,3'-dibromo-4,4'-dimethyl-2-dipyridyl diselenide [C12H10N2Se2Br2] in micellar media. Two cationic and one nonionic surfactants possessing the same hydrocarbon tail, namely hexadecyltrimethylammonium bromide (C16Br), hexadecyltrimethylammonium chloride (C16Cl), and polyoxyethylene(20)mono-n-hexadecyl ether (Brij 58), in their single as well as equimolar binary and ternary mixed states have been used. Solubilization capacity has been evaluated in terms of the molar solubilization ratio and the micelle water partition coefficients. The association constants between the solubilizate molecules and that of micelle and the average number of solubilizate molecules per micelle have also been quantified. The results showed that cationic surfactants exhibit less solubilization as compared to nonionic surfactant. The mixing effects of surfactants on micelle formation and solubilization efficiencies have also been discussed. It has been observed that cationic-nonionic binary combinations showed better solubilization capacity as compared to pure cationic, nonionic, or cationic-cationic binary mixtures. An equimolar cationic-cationic-nonionic ternary surfactant system provides higher solubilization than cationic-cationic but lowers than their cationic-nonionic counterpart. In addition, Fourier transform infrared has been employed with fair success to predict the information regarding the aggregates and the mechanism of docking of the surfactant and the chalcogenides in the system. The analysis has provided valuable information for the selection of mixed surfactants for solubilizing water-insoluble compounds. Certainly the solubilization ability of these surfactants is not simply related to molar capacity. The results give sufficient encouragement to warrant more detailed investigation of the features of surfactant properties that affect solubilization.