A liquid crystal display comprising a compound of the formula ##STR1## wherein each of Y.sup.1 and Y.sup.2 is independently F, Cl, CN, OCN, SCN, OCF.sub.3, OCF.sub.2 H, OCF.sub.2 CF.sub.3, CF.sub.3, R, --OR, --COOR or --OCOR, wherein R is alkyl, alkenyl or alkoxyalkyl, provided that at least one of Y.sup.1 and Y.sup.2 is R, --OR, --COOR or --OCOR; each of Z, Z.sup.1, Z.sup.2, Z.sup.3 and Z.sup.4 is independently a single bond. CH.sub.2 CH.sub.2 --, --CH.dbd.CH--, --C.dbd.C--, --COO--, --OCO--, --CH.sub.2 O--, OCH.sub.2 --, --(CH.sub.2).sub.4 --, --(CH.sub.2).sub.3 --O-- or --O--(CH.sub.2).sub.3 --: ring A is a group of formula (II): ##STR2## wherein each of X.sup.1, X.sup.2, X.sup.3, X.sup.4, X.sup.5, X.sup.6, X.sup.7, X.sup.8, X.sup.9, and X.sup.10 is independently H or D, provided that at least one of them is D; each of rings K, L, J, M and N is independently trans-1,4-cyclohexylene, 1,4-cyclohexenylene, substituted trans-1,4-cyclohexylene, 1,4-phenylene, substituted 1,4-phenylene, 1,3-dioxane-2,6-diyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl, pyrazine-2,5-diyl or a group of formula (III): ##STR3## wherein each of X.sup.11, X.sup.12, X.sup.13, X.sup.14, X.sup.15, X.sup.16, X.sup.17, X.sup.18, X.sup.19, and X.sup.20 is independently H or D, provided that at least one of them is D; in which the ring of formula (III) may be the same as or different from ring A; and k, l, m, and n each independently is 0 or 1, provided that the sum of k, l, m, and n is 0, 1 or 2. The compound is useful as an electro-optic liquid crystal display material.