| abstract |
Liquid Crystal compounds represented by the following formula are disclosed. <IMAGE> (1) wherein R and R' are independently selected from alkyl groups containing 1 DIFFERENCE 20 carbon atoms; X is -O-, -O-CO-O- or direct bond; A1 and A2 are independently cyclic groups (such as phenylene and biphenylene), said cyclic groups may be substituted with 1 DIFFERENCE 4 fluorine, chlorine or bromine atoms, or 1 or 2 substituent groups selected from the group consisting of cyano, nitro and trifluoromethyl groups; Y is -CO-O-, -O-CO-, -C 3BOND C-, -CH2O-, -OCH2-, -CH=N-, -N=CH-, -N=N-, -CH2S-, -SCH2- or direct bond; and * represents asymmetric atom providing optical activity. |