Cholic acid-derived facial amphiphiles with different ionic characteristics.

A cholate derivative with three epoxide groups was synthesized from cholic acid by allylation followed by epoxidation. Ring opening of the epoxides by various nucleophiles yielded facial amphiphiles with anionic, cationic, or nonionic functional groups. The critical micelle concentrations of these amphiphiles largely depend on the number of charged groups on the molecule. A facial amphiphile with pH-tunable micellization was prepared. Its aggregation behavior changes abruptly at pH = 7.6-6.6 as a result of protonation of its amino groups.