A liquid-crystalline medium which comprises at least one compound selected from the group of compounds of the formulae IA to IH,

##STR00001##

in which Z.sup.1 denotes a single bond, —CH.sub.2CH.sub.2—, —CH═CH—, —CH.sub.2O—, —OCH.sub.2—, —CF.sub.2O—, —OCF.sub.2—, —COO—, —OCO—, —C.sub.2F.sub.4—, —(CH.sub.2).sub.4—, —CHFCHF—, —CF.sub.2CH.sub.2—, —CH.sub.2CF.sub.2—, —C≡C—, —CF═CF—, —CH═CHCHO— or —CH.sub.2CF.sub.2O—,
and the use thereof for an active-matrix display, in particular based on the VA, PSA, PS-VA, PALC, FFS, PS-FFS, SA-VA, PS-IPS or IPS effect.

A liquid crystal composition includes at least one compound of general formula F and at least one compound of general formula N. A liquid crystal display device includes the liquid crystal composition. The liquid crystal composition has a larger K value, a smaller rotational viscosity, a higher VHR value, a longer low temperature storage time and a shorter response time while maintaining an appropriate clearing point, an appropriate optical anisotropy, and an appropriate absolute value of dielectric anisotropy, such that the liquid crystal display device including the liquid crystal composition has a better contrast, a wider temperature range for application, a faster response speed, a better contrast and a higher reliability.

##STR00001##

The invention relates to a liquid-crystalline medium having negative dielectric anisotropy comprising one or more compounds of formula I ##STR00001##
and
one or more compounds selected from the group of the compounds of the formulae IIA, IIB and IIC, ##STR00002##
wherein the groups and parameters have the meanings indicated in claim 1, to a guest-host liquid crystal medium derived therefrom comprising one or more dichroic dyes and the use of said medium in devices such as light shutters, switchable windows, switchable mirrors and guest-host displays. The invention further relates to devices containing the liquid crystalline medium according to the invention.

A positive dielectric anisotropic liquid crystal composition includes one or more compounds of formula I and one or more compounds of formula II: ##STR00001##
wherein R1 represents cyclopropyl, cyclobutyl or cyclopentyl, R2, R3 and R4 are as defined in the specification, and a liquid crystal display device. The liquid crystal composition has positive dielectric properties, a high charge retention ratio, a low rotary viscosity, a fast response time, and especially a high transmittance, and is suitable for manufacturing a TFT-LCD with a high transmittance and a fast response.

The present invention aims to provide a polymerizable compound that has high storage stability without causing crystal precipitation when added to a polymerizable composition and to provide a polymerizable composition containing the polymerizable compound. A polymer film produced by polymerization of the polymerizable composition has a low haze, high thickness uniformity, low occurrence of nonuniform orientation, high surface hardness, high adhesiveness, and good appearances and fewer orientation defects even after ultraviolet irradiation. The present invention also aims to provide a polymer produced by polymerization of the polymerizable composition and an optically anisotropic body produced from the polymer.

Liquid-crystalline medium contains at least one compound of formula I,

##STR00001##

and at least one compound formulae ST-1 to ST-17 and the use thereof for an active-matrix display, in particular based on the VA, PSA, PA-VA, SS-VA, SA-VA, PS-VA, PALC, IPS, PS-IPS, UB-FFS, U-IPS, FFS or PS-FFS effect.

Nonlinear optical chromophore compositions which display lyotropic nematic liquid crystal phases in polar organic solvents and provide a mechanical anisotropic effect allowing for the formation of a non-centrosymmetric chromophore-polymer matrix without the application of an electric field.

A liquid-crystalline medium having a nematic phase, a dielectric anisotropy of 0.5 or more and a ratio of the dielectric constant perpendicular to the director (∈.sub.⊥) to the dielectric anisotropy (Δ∈), i.e. (∈.sub.⊥/Δ∈), of 2.0 or less and comprises one or more compounds of formula I

##STR00001##

wherein the parameters have the meaning given in the text.

An electro-optical display containing such a medium, particularly in an active-matrix display based on the IPS or FFS effect. Methods for using of the compounds of formula I for improvement of the transmission and/or response times of a liquid-crystalline medium which comprises one or more additional mesogenic compounds.

The present invention relates to a compound of the general formula I ##STR00001##
in which the occurring groups and parameters have the meanings indicated in claim 1, to the use thereof in liquid-crystalline or mesogenic media and to liquid-crystalline or mesogenic media comprising these derivatives.

The present invention aims to provide a polymerizable compound that has high storage stability without causing crystal precipitation when added to a polymerizable composition and to provide a polymerizable composition containing the polymerizable compound. A polymer film produced by polymerization of the polymerizable composition has a low haze, high thickness uniformity, low occurrence of nonuniform orientation, high surface hardness, high adhesiveness, and good appearances and fewer orientation defects even after ultraviolet irradiation. The present invention also aims to provide a polymer produced by polymerization of the polymerizable composition and an optically anisotropic body produced from the polymer.