Design and synthesis of an achiral ferroelectric smectic liquid crystal

Abstract

Design and synthesis of a bent-core mesogen possessing the achiral ferroelectric SmAP F phase is reported. The design approach is based upon the discovery of Sadashiva and Reddy, et al. that bent-core mesogens possessing only one tail gave biaxial SmA phases shown to be antiferroelectric (SmAP A ). The SmAP A phase shows antiferroelectric layer stacking with synclinic layer interfaces, as expected based upon typical behavior seen in most bent-core mesogens. In order to obtain the target ferroelectric phase, several tails known to allow the formation of anticlinic layer interfaces were incorporated into the basic Sadashiva/Reddy structure. These tails are thought to suppress out of layer fluctuations, thereby removing the strong entropically driven tendency for synclinic layer interfaces, and allowing formation of anticlinic layer stacking driven by a more subtle, and unknown, factor in the free energy of the system. In the event, the tricarbosilane-terminated alkoxy tail proved effective, providing the first known low molar mass SmAP F material.