A novel family of salicylaldimine-based five-ring symmetric and non-symmetric banana-shaped mesogens derived from laterally substituted resorcinol: synthesis and characterization

TLDR: In this article, the phase behavior of several robust five-ring banana-shaped compounds has been investigated and compared with the corresponding compounds without the lateral substituents, showing a critical dependence on the nature and position of the substituent(s).

Abstract: We present the results of our extensive investigations into the phase behavior of several “robust” five-ring banana-shaped compounds. Six homologous series of either symmetric or non-symmetric bent-core molecules, comprising a laterally substituted 1,3-phenylene ring as the central unit covalently linked to thermally and hydrolytically stable rod-like salicylaldimine segments have been synthesized and evaluated for their mesomorphism. The mesophases have been characterized by optical, calorimetric, X-ray diffraction and electro-optical studies. With a methyl group, polarizable chlorine atom or the more polarizable nitro group as the lateral substituent(s) and terminal alkoxy tails of varying length, the structure–property correlation has been determined. Our study clearly demonstrates that these materials, as predicted, display a different behavior compared to the corresponding compounds without the lateral substituents. The phase behavior shows a critical dependence on the nature and position of the lateral substituent(s). The study includes a comparison with the phase behavior of some of the other types of banana-shaped compounds.