Mesogenic amido ester with cholesteryl moiety

A new series of mesogenic compounds having a cholesteryl moiety has been synthesized. Thirteen homologues were synthesized by condensing 4-(4'-n-alkoxy benzoyl) amido benzoyl chloride with cholesterol. The methyl to n-hexyl derivatives exhibit only cholesteric mesophases. The n-heptyl to n-dodecyl derivatives exhibit SC and cholesteric phases. The n-tetradecyl to n-octadecyl derivatives exhibit SC, SA and cholesteric phases. The plot of transition temperatures versus number of carbon atoms in the alkoxy chain exibit odd-even effect and falling tendency for cholesteric-isotropic transition temperatures. The mesomorphic and thermal stability is compared with other related homologous series. The results indicate that amide linkage enhances smectic as well as cholesteric thermal stability, but enhancement in smectic phase is much higher.