Liquid crystal mixtures

Abstract

A nematic liquid crystal mixture comprises at least one nematic liquid crystal compound and an amount, sufficient to impart a positive DC anisotropy of at least about 15 to said mixture, of at least one liquid crystalline or potentially liquid crystalline compound having a positive DC anisotropy of above about 25, of the formula (1) ##STR1## wherein X is a monovalent radical of the formula --NR.sup.3 R.sup.4 or --N(R.sup.5)(CHO); Y is a bivalent radical of the formula --CH.dbd.N--, --N.dbd.CH--, --N.dbd.N--, --CH.dbd.CH--, --C(O)O--, --O(O)C--, --C(O)S--, --S(O)C--, --C.tbd.C-- or ##STR2## Z is a monovalent radical of the formula --CN, --NO.sub.2, --SO.sub.2 CH.sub.3, --SO.sub.2 CF.sub.3 or --NHCOR.sup.5 ; R.sup.1 and R.sup.2 are the same or different and each is fluorine, chlorine, bromine, methyl or hydroxy; R.sup.3 and R.sup.4 are the same or different and each is hydrogen or an alkyl group containing from 1 to 8 carbon atoms; R.sup.5 is an alkyl group containing from 1 to 8 carbon atoms; p is zero or 1; and m and n are the same or different integers from zero to 4.

Dependencies are inferred from the claim text.