The first bent-core mesogens exhibiting a dimorphism B 7–SmCP A

Abstract

New homologous achiral five-ring bent-core mesogens with a lateral fluorine substituent at the central core and chlorine substituents at the terminal rings have been synthesized. Two mesophases could be distinguished by polarizing microscopy, calorimetry, X-ray, and electro-optical investigations. The high-temperature phase was found to be an antiferroelectric SmCP phase whereas the low-temperature phase could be identified as a ferroelectric B 7 phase. This phase sequence was observed for the first time. NMR measurements as well as optical studies indicate that both phases have a helical superstructure.