Synthesis and comparative study on phase transition behavior of triazole-cored liquid crystals armed with cholesterol and double or triple aromatic rings systems

Abstract

Two homologous series of optically active bent-shaped mesogens comprising a cholesterol unit as one of the side arms connected to a 1,2,3-triazole ring while the other arm of the triazole ring is connected to two- and three-ring aromatic systems with varying terminal chain lengths have been synthesized. The molecular structure, thermal and optical activities have been studied extensively in which the compounds from both series exhibit polymorphism ranging from chiral nematic (N*), chiral smectic A (SmA*), chiral smectic C (SmC*) and twist grain boundary (TGBC*) phases. A further comparison between the two series of target compounds has drawn a common remark of which the phase behavior is found to be dependent on the length of the terminal tail and number of aromatic rings in the mesogenic units.