Compositions – Liquid crystal compositions – Containing nonsteryl liquid crystalline compound of...
Patent
1989-05-12
1993-07-27
Lovering, Richard D.
Compositions
Liquid crystal compositions
Containing nonsteryl liquid crystalline compound of...
25229963, 25229966, 25229967, 560 65, 560102, 544224, 544298, 546339, C09K 1934, C09K 1920, C07D23902, C07D21170
Patent
active
052308278
DESCRIPTION:
BRIEF SUMMARY
SUMMARY OF THE INVENTION
The invention relates to derivatives of 2,3-difluorobenzoic acid of the formula I ##STR2## in which R.sup.1 and R.sup.2, independently of one another, are each an alkyl group having 1 to 15 C atoms, in which, in addition, one or two non-adjacent CH.sub.2 groups may be replaced by --O--, --CO--, --CH.dbd.CH-- and/or --C.tbd.C--, and which is unsubstituted or substituted by one or two fluorine atoms and in which, in addition, one or two CH groups may be replaced by N, or are trans-1,4-cyclohexylene, or one of the two A.sup.1 and A.sup.2 groups is alternatively a single bond.
For reasons of simplicity below, Cyc is a 1,4-cyclohexylene group, Phe is a 1,4-phenylene group, Pyd is a pyridine-2,5-diyl grop, Pyr is a pyrimidine-2,5-diyl group and Pyn is a pyridazine-2,5-diyl group, where these groups may be unsubstituted or substituted by one or two fluorine atoms. These groups are preferably unsubstituted.
PheF.sub.2 is a group of the formula ##STR3##
The compounds of the formula I can be used as components of liquid-crystalline phases, in particular for displays based on the principle of the twisted cell, on the guesthost effect, on the effect of deformation of aligned phases or on the effect of dynamic scattering.
The compounds of the formula I are distinguished by a clearly negative anisotropy of the dielectric constants and are aligned in an electrical field with their longitudinal molecular axes perpendicular to the field direction. This effect is known and is utilized in various liquid-crystalline displays for controlling the optical transparency, thus, for example, in liquid-crystal cells of the light-scattering type (dynamic scattering), of the so-called DAP type (deformation of aligned phases) or ECB type (electrically controlled birefringence) or of the guest/host type (guest/host interaction).
In addition, compounds of the formula I are suitable as components of chirally tilted smectic phases. Chiral tilted smectic liquid-crystalline phases having ferroelectric properties can be prepared by adding a suitable chiral dope to the base mixtures having one or more tilted smectic phases (L. A. Veresnev et al., Mol. Cryst. Liq. Cryst. 89, 327 (1982); H. R. Brand et al., J. Physique 44 (lett.), L-771 (1983). Phases of this type can be used as dielectrics for rapidly switching displays which are based, for example, on the principle of SSFLC technology, described by Clark and Lagerwall (N. A. Clark and S. T. Lagerwall, Appl. Phys. Lett. 36, 899 (1980); U.S. Pat. No. 4,367,924), on the basis of the ferroelectric properties of the chiral tilted phase.
A number of liquid-crystalline compounds having slightly negative dielectric anisotropy has previously been synthesized. In contrast, relatively few liquid-crystal components having a large negative anisotropy of the dielectric constants are known. In addition, the latter generally have disadvantages, such as, for example, poor solubility in mixtures, high viscosity, high melting point and chemical instability. There is therefore a demand for further compounds having a negative dielectric anisotropy which permit the properties of mixtures to be further improved for a very wide variety of electrooptical applications.
Liquid-crystal compounds which have a negative dielectric anisotropy and contain two or three rings linked via carboxyl groups or covalent bonds and one or more side groups, such as halogen, cyano or nitro groups, are known from DE 2,240,864, DE 2,613,293, DE 2,835,662, DE 2,836,086 and EP 023,728.
The compounds claimed here are covered by a broad formula given in EP 084,194. However, no individual compounds of the formula according to the invention are mentioned therein. For those skilled in the art, it was thus possible neither to easily deduce possible syntheses of the compounds claimed nor to recognize that the compounds according to the invention have mesophase ranges which are predominantly in a favorable position and that the compounds are distinguished by a large negative anisotropy of the dielectric constants with low vi
REFERENCES:
patent: 4368135 (1983-01-01), Osman
patent: 4415470 (1983-11-01), Eidenschink et al.
patent: 4514317 (1985-04-01), Tuong et al.
patent: 4545922 (1985-10-01), Eidenschink et al.
patent: 4551264 (1985-11-01), Eidenschink et al.
patent: 4602851 (1986-07-01), Jenner et al.
patent: 4606845 (1986-08-01), Romer et al.
patent: 4637897 (1987-01-01), Kelly
patent: 4659502 (1987-04-01), Fearon et al.
patent: 4664840 (1987-05-01), Osman
patent: 4709030 (1987-11-01), Petrzilka et al.
patent: 4710315 (1987-12-01), Schad et al.
patent: 4724097 (1988-02-01), Romer et al.
patent: 4776973 (1988-10-01), Bofinger et al.
patent: 4808333 (1989-02-01), Huynh-ba et al.
patent: 4820839 (1989-04-01), Krause et al.
patent: 4834904 (1989-05-01), Krause et al.
patent: 4846998 (1989-07-01), Pohl et al.
patent: 4897216 (1990-01-01), Reiffenrath et al.
patent: 4925278 (1990-05-01), Buchecker et al.
patent: 4925590 (1990-05-01), Reiffenrath et al.
patent: 5087764 (1992-02-01), Reiffenrath et al.
Osman et al., "Stable Liquid Crystals With Large Negative Dielectric Anisotropy--II," Mol. Cryst. Liq. Cryst., vol. 92 (Letters), pp. 57-62, 1983.
Geelhaar Thomas
Krause Joachim
Reiffenrath Volker
Wachtler Andreas
Weber Georg
Harris C.
Lovering Richard D.
Merck Patent Gesellschaft mit beschrankter Haftung
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