Cholesterol-based nonsymmetric liquid crystal dimers: an overview

Nonsymmetric dimers derived from naturally occurring cholesterol represent an exemplary and emerging class of chiral liquid crystals. They are formed by linking the pro-mesogenic cholesterol moiety to one of the termini of aromatic/aromatic-alicyclic/supramolecular mesogenic core through a flexible spacer of varying length and parity. Hitherto, over 300 dimers comprising fourteen different mesogenic cores have been reported. The stabilization of a variety of highly frustrated fluid structures, reentrant phases and unprecedented phase sequences clearly illustrates their unique molecular structural characteristics. Besides, the employed fragments facilitate modulating the properties of technologically important fluid phases. Thus, they are immensely significant in both fundamental science and practical applications. In this Feature Article an overview of these chiral dimers is provided.