Synthesis and mesomorphic properties of new heterocyclic liquid crystals with Central Ester–Chalcone linkages

Abstract A series of new calamitic liquid crystals, 4-[3-(pyridin-4-yl)prop-2-enoyl]phenyl 4-alkyloxybenzoates, comprising a pyridyl core, ester–chalcone central linkage and terminal alkyloxy chain were synthesized and characterized. This series consists of four members that differ by the length of the alkyloxy chain (C n H 2 n +1 O , where n  = 10, 12, 14, 16). The structures of the title compounds were elucidated using spectroscopic and spectrometric techniques, such as FT-IR, NMR ( 1 H and 13 C) and EI-MS. The mesomorphic properties were studied using differential scanning calorimetry and optical polarizing microscopy. The decyloxy-containing compound was found to be non-mesogenic, whilst the compounds containing n -dodecyloxy to n -hexadecyloxy chains exhibited an enantiotropic smectic A phase with a fan-shaped texture. From the structure–property relationship study, it was proposed that the number of carbons in the alkyloxy chain must be at least 12 ( n  ≥ 12) to generate the smectic phase in the corresponding substituted ArCOOArCOCH CHC 5 H 4 N compounds.