The syntheses and characterisation of the 4-[{[4-({n-[4-(4 cyanophenyl)phenyl]-n-yl}oxy)phenyl]-methylidene}amino]phenyl-4-alkoxybenzoates (CBnOIBeOm) are reported with n= 8 and 10 and m= 1-10. The two series display fascinating liquid crystal polymorphism. All twenty reported homologues display enantiotropic nematic (N) phase at high temperature. When the length of the spacer (n) is greater than that of the terminal chain (m), the twist-bend nematic (NTB) phase is observed at temperatures below the N phase. As the length of the terminal chain is increased and extends beyond the length of the spacer up to three smectic phases are observed on cooling the N phase. One of these smectic phases has been assigned as the rare twist-bend smectic C subphase, the SmCTB-α phase. In all the smectic phases, a monolayer packing arrangement is seen, and this is attributed to the anti-parallel associations of the like mesogenic units.
Keywords: Liquid crystal dimers Heliconical twist-bend smectic C phase Twist-bend nematic phase Structure-property relationships.
© 2024 Wiley-VCH GmbH.