Supramolecular systems based on gemini surfactants for enhancing solubility of spectral probes and drugs in aqueous solution

Herein, novel dicationic surfactants bearing morpholinium moieties in polar group, 14-s-14 Mor (s = 4, 6, 8, 10) are synthesized, and their aggregation behavior is studied and compared with reference surfactants, single-head morpholinium surfactant Mor-14, typical gemini with ammonium head group and dicationic surfactants with heterocyclic polar fragment. Geminis studied are found to exhibit superior solubilization capacity toward a pH indicator thymolphthalein and an inflammatory drug indomethacin, exceeding that of reference amphiphiles. The solubility of the probes is contributed by multifactor mechanism involving the solubilization in nonpolar core of micelles and periphery electrostatic interaction between micellar surface charge and ionic moieties of the drug. Mutual influence of the components occurs on their properties, including pK(a) shift of ionogenic groups of a guest molecule and decrease in critical micelle concentration of geminis. (C) 2016 Elsevier B.V. All rights reserved.