Thio-ester compounds and mixtures and devices containing such co

Details Thio-ester compounds and mixtures and devices containing such co Thio-ester compounds and mixtures and devices containing such co

1995-04-12

1996-11-26

Wu, Shean C.

Compositions

Liquid crystal compositions

25229961, 25229962, 25229964, 25229965, 25229966, 359103, C09K 1952, C09K 1934, C09K 1932, G02F 113

Patent

active

055782426

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 3 PCT/GB93/02084, filed Oct. 8, 1993.


BACKGROUND OF THE INVENTION

This invention relates to compounds containing a thio-ester group, and in particular to thio-ester compounds having liquid crystalline properties. The invention also relates to use of thio-ester compounds in liquid crystalline materials, and to use of thio-ester compounds, and materials containing thio-ester compounds, in devices.
Liquid crystal materials and their uses in electro-optical display devices are well known. The most commonly used types of liquid crystal materials are those which can utilise their nematic properties within such devices as the Twisted Nematic (TN) device, Supertwist Nematic (STN) device and Electrically Controlled Birefringence (ECB) device.
Thio-ester compounds are known, and are described in for example S. R. Pandas et al, Synthesis, (1983), pp 605-621: Z-C Chen et al, Synthesis, (1988), pp 723-724; and B. S. Pedersen et al, Bull Soc. Chim. Belg., (1978) Vol 87 pp 293-297. Liquid crystalline thio-ester compounds are described in M. E. Neubert et al Mol. Cryst. Liq. Cryst. (1981) Vol 76, pp 43-77. Thio-ester compounds are also described in German patents DE 2603293, DD 0145914, Japanese patents JP 550023129, JP 560108761, JP 600163858, Isr. J. Chem., 1980, volume data 1979, volume 18 (3-4), pages 197-198; J. Prakt. Chem., 1979, volume 321 (4), pages 619-628.
Liquid crystal materials are generally mixtures of compounds which individually or together show a liquid crystal phase. A number of desirable characteristics are sought in such compounds and materials. Among these are chemical stability, persistence of appropriate liquid crystal phases over a wide temperature range preferably including room temperature, and for some devices a high birefringence (.DELTA.n) is sought.


BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-14 are flow diagrams giving typical synthesis routes to prepare the compounds of Formula I;
FIG. 15 is a schematic representation of a liquid crystal device of the invention; and
FIG. 16 is a representation of a Kerr cell of the invention.


DESCRIPTION OF THE INVENTION

According to this invention, liquid crystal compounds of formula I are provided: --X--(Z.sup.3)--(A.sup.2 --Z.sup.4).sub.n --R.sup.2 Formula I ##STR1## each of Z.sup.1, Z.sup.2, Z.sup.3 and Z.sup.4 are independently selected from phenyl, substituted phenyl, where substitution is lateral substitution selected from F, Cl, Br, NO.sub.2, CN, NCS; naphthalene substituted naphthalene, where substitution is lateral substitution selected from F, Cl, Br, NO.sub.2, CN, NCS, CH.sub.3 ; thiophene, pyridine and pyrimidine;
each of A.sup.1 and A.sup.2 is independently selected from single bond. C.tbd.C, C.dbd.CH;
A.sup.3 is selected from C.tbd.C and single bond;
each of R.sup.1 and R.sup.2 are independently selected from CN, NCS, CH.dbd.C(CN).sub.2, C.tbd.C--CN, C.tbd.C--CF.sub.3, alkyl, alkoxy, thioalkyl, alkenyl, and alkynyl;
m and n are independently selected from 1 and 0, and
except where m and n are O, X is COS and each of R.sup.1 and R.sup.2 are selected from alkyl and alkoxy A.sup.3 is a single bond and each of Z.sup.2 and Z.sup.3 is phenyl provided that when m.dbd.n.dbd.0, Z.sup.2 .dbd.Z.sup.3 .dbd.phenyl, X.dbd.COS, A.sup.3 .dbd.single bond and one of R.sup.1 or R.sup.2 is thioalkyl then the other of R.sup.1 or R.sup.2 does not equal alkyl or alkoxy; and further provided that when X.dbd.COS; Z.sup.2 .dbd.Z.sup.3 .dbd.phenyl; A.sup.1 and A.sup.2, if present, are both single bonds; A.sup.3 is a single bond; Z.sup.1 and Z.sup.4 if present are phenyl; then R.sup.1 and R.sup.2 are the same or different and at least one of R.sup.1 and R.sup.2 is selected from NCS, CH.dbd.C(CN).sub.2, C.tbd.C--CN, C.tbd.C--CF.sub.3, alkenyl or alkynyl.
The structural and other preferences are expressed below on the basis of inter alia desirable liquid crystalline characteristics, in particular high birefringence for use in liquid crystal materials.
Preferably, where R.sup.1 and/or R.sup.2 are alkyl, alkoxy, alkynyl and/or thioalkyl, th

REFERENCES:
patent: 4137250 (1979-01-01), Reynolds
patent: 4372871 (1983-02-01), Toriyama et al.
patent: 5099344 (1992-03-01), Tsuboyama et al.
CA 93:46138. 1980.

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