A cyclic hydrocarbon derivative represented by formula (I): STR1 wherein each of Y1 and Y2 is independently F, Cl, CN, OCN, SCN, OCF3, OCF2 H, OCF2 CF3, CF3, R, --OR, --COOR or --OCOR, wherein R is alkyl, alkenyl or alkoxyalkyl, provided that at least one of Y1 and Y2 is R, --OR, --COOR or --OCOR; each of Z, Z1, Z2, Z3 and Z4 is independently a single bond, --CH2 CH2 --, --CH=CH--, --C C--, --COO--, --OCO--, --CH2 O--, OCH2 --, --(CH2)4 --, --(CH2)3 --O-- or --O--(CH2)3 --; ring A is group of formula (II): STR2 wherein each of X1, X2, X3, X4, X5, X6, X7, X8, X9, and X10 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, pyarazine-2,5-diyl or a group of formula (III): STR3 wherein each of X11, X12, X13, X14, X15, X16, X17, X18, X19, and X20 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.
