Antiferroelectric orthoconic liquid crystalline material with long pitch and the method of its preparation

Abstract

The racemic and chiral compounds expressed by common formula 1 and formula 2: wherein the lateral substituents X, X, X, X, X, X, Xand Xin the benzene rings represent independently hydrogen and fluorine atoms, bridge group Z represent independently the single bond or COO, CHCH, CHO and OCHgroup, substituent Y represents CH, or CHF, CHF, CF, CHgroup, symbols n, m, r and t are independently integers of 1 to 8; symbols p and s signify independently number of 0 to 1 and its orthoconic antiferroelectric long helical pitch mixtures prepared by the methods 1) to the racemic components selected from compounds 1 are added chiral components selected from the compound of formula 1 and/or chiral components selected from the compounds of formula 2 and/or another optically active compounds with high helical twisting power, 2) to chiral compound 1 which helical pitches increases with the temperature increase is added chiral compound 1 which helical pitch decreases with temperature increase. The mixture shows excellent optical contrast and is applied in displays and photonic devices.