Showa Shell Sekiyu K.k.

Koichi Numazawa

Yoshiichi Suzuki

Noriko Yamakawa

Ichiro Kawamura

Takashi Hagiwara

A liquid crystal compound represented by formula (I): ##STR1## wherein R.sub.1 represents an alkyl group having from 3 to 18 carbon atoms; R.sub.2 represents an alkyl group having from 3 to 18 carbon atoms; X represents ##STR2## Y represents ##STR3## (A) and (B) each represents a group selected from the group consisting of ##STR4## and ##STR5## and * indicates an optically active center.

Liquid crystal compounds

A liquid crystal compound represented by formula (I): ##STR1## wherein R.sub.1 represents an alkyl group having from 3 to 18 carbon atoms; R.sub.2 represents an alkyl group having from 3 to 18 carbon atoms; X represents ##STR2## (A) and (B) each represents a group selected from the group consisting of ##STR3## and * indicates an optically active center.

Novel ferroelectric and antiferroelectric liquid crystal compounds of the invention, which comprise those showing optically tristable states in phase S*.sub.(3), have a wide range of phase transition temperature so as to be not only preferably used solely as display element material but also mixed with any other liquid crystal to desiredly expand the above range wider and make optical response time faster. Typical compounds are represented by ##STR1## in which Z means CF.sub.3, C.sub.2 F.sub.5, CHF.sub.2, CH.sub.2 F, CClF.sub.2, CCl.sub.2 F, CF.sub.3 CCl.sub.2 or C.sub.3 F.sub.7, m' and n' are same or different with each other and each is an integer of 1-20.

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Tokyo, Japan

Koichi Numazawa