Antiferroelectric liquid crystal from bent-core molecule with vinyl end group

Abstract

Three banana-shaped achiral compounds, 4-chloro-1,3-phenylene bis [4-{4-(undecenyloxy)phenyl iminomethyl}benzoate] derivatives, were synthesized with variation of a substituent (x=H, F, Cl); their antiferroelectric properties are described. The smectic mesophases, including a switchable chiral smectic C(Sm C*) phase, were characterized by differential scanning calorimetry, polarizing optical microscopy, triangular wave method, and X-ray diffractometry. The presence of vinyl groups at the terminals of linear side wings in the banana-shaped achiral molecules induced a decrease in melting temperature and formation of the switchable Sm C* phase in the melt. The smectic phase having a lateral fluorine-substituent at 3-position of the Schiff's base moiety showed antiferroelctric switching, and the value of spontaneous polarization on reversal of an applied electric field was 250 nC/cm2.