Abstract: The invention discloses optically active liquid crystal compounds represented by the formulas [I], [II] and [III]: ##STR1## wherein R.sub.1 and R.sub.2 each represents an alkyl group of 4-18 carbon atoms, X represents O, COO or a single bond, and (A), (B), (C), (D) and (E) each represents ##STR2## in which l represents a halogen. The invention further discloses optically active liquid crystal compounds which are able to exhibit tristable states, represented by the formulas [IV], [V] and [VI]: ##STR3## wherein R.sub.1 ' and R.sub.2 ' each represents a straight chain alkyl group of 5-16 carbon atoms, X' represents O or COO and (A), (B), (C), (D) and (E), and l each has the same meaning as above.

Abstract: Liquid crystal compound of the formula ##STR1## wherein R.sub.1 and R.sub.2 each is a C.sub.1-18 alkyl group or an aralkyl group, R' is a haloalkyl group, X is --0--, --CO--, --COO-- or direct bond, Y is --COO--, --OCO-- or --CH.sub.2 O--, (A) and (B) each is ##STR2## and p and l each is zero or one.

Abstract: A liquid crystal compound represented by formula (I): ##STR1## wherein R.sub.1 represents an alkyl group having from 3 to 18 carbon atoms or an aralkyl group having from 7 to 18 carbon atoms; R.sub.2 represents an alkenyl group having from 1 to 18 (preferably from 3 to 14) carbon atoms; R.sub.3 represents CF.sub.3 or C.sub.2 F.sub.5 ; X represents a single bond, --O--, --COO--, or --OCO--; Y represents --COO--, --OCO--, --CH.sub.2 O--, or --OCH.sub.2 --; A and B each represents a cyclic group; and * indicates an optically active center.The compound of formula (I) exhibits three stable states of molecular orientation.

Abstract: An optically active compound represent by formula (I): ##STR1## wherein R.sub.1 represents a fluoroalkyl group having from 1 to 18 carbon atoms; R.sub.2 represents an alkyl group having from 1 to 16 carbon atoms and an aralkyl group having from 6 to 16 carbon atoms; R.sub.3 represents C.sub.2 F.sub.5, CF.sub.3, CHF.sub.2, or CH.sub.2 F; X represents a single bond, --O--, --COO--, or --OCO--; Y represents --COO--, --OCO--, --CH.sub.2 O--, or --OCH.sub.2 --; Z represents --COO-- or --O--; (A) and (B) each represent a cyclic group; and * indicates an optically active center, and a liquid crystal composition containing at least one of said optically active compounds are disclosed. The compound is useful not only as a liquid crystal compound but as a chiral dopant to provide a liquid crystal composition exhibiting a chiral smectic phase.

Abstract: There is disclosed herein a ferroelectric liquid crystal electro-optical apparatus of the maxtrix type comprising a liquid crystal cell having first and second electrode substrates which include n striped line electrodes and m striped column electrodes, respectively, facing at right angles each other. A ferroelectric liquid crystal is put in therebetween so as to form n by m indication picture elements. Also included in the apparatus a scanning drive device adapted to supply a scanning signal and a data signal to the n striped line electrodes and the m striped column electrodes, respectively. The ferroelectric liquid crystal shows three stable states in accordance with an application voltage and has a light transmittance with a hysteresis sufficient to a dynamic drive in accordance with increase or decrease in the application voltage in a predetermined voltage range.