Synthesis and mesomorphic properties of chiral nematic liquid crystals based on cholesterol

Abstract

A new series of mesogenic compounds having a cholesteryl moiety has been synthesised by condensing p-amino benzoate of cholesterol and methoxy substituted 4-n-alkoxy cinnamoyl chlorides and their liquid crystalline properties has been studied. All the members of the series are enantiotropic and exhibit chiral nematic (N*) mesophase. The plot of transition temperatures versus number of carbon atoms in the alkoxy chain exhibits odd-even effect and falling tendency for N*-isotropic transition temperatures. The compounds exhibit oily streak textures that on slight disturbance change to the plane textures and show iridescent colours. High anisotropy, linearity and intermolecular hydrogen bonding confer rich mesomorphic properties on the system. Intermolecular hydrogen bonding arising from amide linkage can lead to supramolecular motifs.

Progress in the Chemistry of Macrocyclic Meroterpenoids

“…A group of Chinese scientists led by Lai synthesized calix[4]arenes 85a – b and 86a – b , containing triterpenoid (cholesterol) fragments which had liquid crystal properties [ 53 ]. Cholesterol, 73 , is often used as a good structural unit for the creation of various types of liquid crystal materials with interesting mesomorphic properties [ 57 , 58 , 59 , 60 , 61 ]. The first liquid crystals were obtained from calix[4]arene-cholesterol derivatives 85a – b and 86a – b (Scheme XIV), which were synthesized in 50–80% yields [ 57 ].…”