The supramolecular self-organization of an amphotropic cholesterol derivative Micelles, liposomes and liquid-crystalline phases

Abstract

The cholesterol derivative tetraethoxycholesteryl semisuccinate is both a mesogen and an amphiphile. This combination of both molecular prerequisites permits two types of supramolecular self-organization: the formation of a thermotropic liquid-crystalline phase and of various forms of aggregates in contact with water or other solvents. Depending on the pH of the aqueous medium the compound self organizes in micelles or liposomes. At high concentrations lyotropic liquid-crystalline phases are obtained. The formation of liposomes and lyotropic phases is not restricted to water as a solvent but can also be induced in pure organic media such as water-free diethyleneglycol. Due to the broad range of supramolecular structures that depend both on molecular shape and on amphiphilic properties we propose to call the title compound a model for amphotropic phase behaviour.