Compositions – Liquid crystal compositions – Containing nonsteryl liquid crystalline compound of...
Patent
1991-05-20
1994-05-03
Wu, Shean C.
Compositions
Liquid crystal compositions
Containing nonsteryl liquid crystalline compound of...
25229966, 570127, 359103, C09K 1930, C09K 1912, C07C 2513, G02F 113
Patent
active
053085426
DESCRIPTION:
BRIEF SUMMARY
SUMMARY OF THE INVENTION
The invention relates to novel 4,4'-disubstituted 2',3-difluorobiphenyls of the formula I ##STR2## in which n is 1 to 7, A is trans1,4-cyclohexylene (Cy) or 1,4-phenylene (Ph), r is 0 or 1, Z is F, Cl, --CF.sub.3, --CHF.sub.2, --OCF.sub.3 or --OCHF.sub.2 and Z is H or F.
DE-A 30 42 391 and EP-A 0 256 636 give general formulae which cover some of the compounds according to the invention. However, neither specific derivatives of 2',3-difluorobiphenyl nor the advantageous actions thereof as components of liquid-crystalline media are described therein.
Like similar compounds, for example known from DE-A 30 42 391, the compounds of the formula I can be used as components of liquid-crystalline media, in particular for displays based on the principle of the twisted cell.
The substances employed hitherto for this purpose all have certain disadvantages, for example excessively high melting points, excessively low clearing points, inadequate stability to the action of heat, light or electrical fields, inadequate electrical resistance, or excessive dependence of the threshold voltage on temperature.
In particular in displays of the supertwist type (STN) having twist angles of significantly greater than 220.degree., or in displays having an active matrix, the materials employed hitherto have disadvantages.
The invention had the object of finding novel liquid-crystalline compounds which are suitable as components of liquid-crystalline media, in particular for nematic media having positive dielectric anisotropy, and which do not have the disadvantages of the known compounds, or only do so to a lesser extent. This object has been achieved by the provision of the novel compounds of the formula I.
It has been found that the compounds of the formula I are eminently suitable as components of liquidcrystalline media. In particular, they can be used to obtain liquid-crystalline media having broad nematic ranges, high clearing point and high dielectric anisotropy, excellent nematogeneity down to low temperatures, excellent chemical stability, pronounced .epsilon..perp. at positive dielectric anisotropy, low temperature dependence of the threshold voltage and/or low optical anisotropy. In addition, the novel compounds have good solubility for other components of media of this type and high positive dielectric anisotropy at the same time as favorable viscosity.
The compounds of the formula I make it possible to produce both STN displays having a vary steep electrooptical characteristic line and displays having an active matrix with excellent long-term stability.
In the pure state, the compounds of the formula I are color less and form liquid-crystalline mesophases in a temperature range which is favorable located for electrooptical use.
The invention thus relates to the compounds of the formula I and to the use of the compounds of the formula I as components of liquid-crystalline media, to liquid-crystalline media containing at least one compound of the formula I, and to electrooptical displays which contain media of this type.
Above and below, n, A, r, X and Z are as defined, unless expressly stated otherwise, Cy is 1,4-cyclohexylene and Ph is 1,4-phenylene.
In the compounds of the formula I, the alkyl groups C.sub.n H.sub.2n+1 are preferably straight-chain. Accordingly, C.sub.n H.sub.2n+1 is methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl or n-heptyl. n is preferably 2, 3, 4 or 5.
Compounds of the formula I containing branched alkyl groups may occasionally be of importance due to better solubility in the customary liquid-crystalline base materials, but in particular as chiral dopes if they are optically active. Branched groups of this type generally contain not more than one chain branch. Preferred branched alkyl radicals are isopropyl, 2-butyl (=1-methylpropyl), isobutyl (=2-methylpropyl), 2-methylbutyl, isopentyl (=3-methylbutyl), 2-methylpentyl, 3-methylpentyl or 2-heptyl (=1-methylhexyl).
The radical ##STR3## is preferably ##STR4##
X is preferably F, Cl, --CF.sub.3, OCHF.sub.2 or --OCF.sub.3.
P
REFERENCES:
patent: 4393231 (1983-07-01), Misaki et al.
patent: 4405488 (1983-09-01), Sugimori et al.
patent: 4512636 (1985-04-01), Andrews et al.
patent: 4630897 (1986-12-01), Andrews et al.
patent: 4797228 (1989-01-01), Goto et al.
patent: 4871470 (1989-10-01), Wachtler et al.
patent: 5032313 (1991-07-01), Goto et al.
patent: 5122295 (1992-06-01), Weber et al.
patent: 5174920 (1992-12-01), Iijima
Hittich Reinhard
Poetsch Eike
Reiffenrath Volker
Rieger Bernhard
Merck Patent Gesellschaft mit beschrankter Haftung
Wu Shean C.
LandOfFree
4,4'-disubstituted 2',3-difluorobisphenyls and a liquid-crystall does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with 4,4'-disubstituted 2',3-difluorobisphenyls and a liquid-crystall, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and 4,4'-disubstituted 2',3-difluorobisphenyls and a liquid-crystall will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2112869