The present invention provides a compound represented by formula (i), a liquid crystal composition using the compound, and a liquid crystal display device using the liquid crystal composition. The compound represented by formula (i) has a partial structure K.sup.i1 represented by any of general formulas (K-1) to (K-17) and further has ring B having at least two P-Sp- groups. Therefore, when used for a liquid crystal composition, the compound adsorbs to substrates sandwiching the liquid crystal composition (liquid crystal layer) and allows liquid crystal molecules to be held such that they are aligned in a vertical direction without a PI layer, and improved alignment stability and low-temperature storage stability can be achieved.

A liquid crystal medium containing a) one or more compounds of formula I

##STR00001## b) one or more compounds of the formula IIBa

##STR00002## and c) one or more compounds of the formula IIDa

##STR00003## and the use thereof for optical, electro-optical and/or electronic purposes, in particular in LC displays, especially in IPS, FFS, VA or PS-VA displays.

The present invention belongs to the technical field of liquid crystal materials, and in particular relates to a liquid crystal composition with good frequency dependence and a liquid crystal display element or liquid crystal display containing the liquid crystal composition. The liquid crystal composition of the present invention comprises a compound represented by Formula I, a compound represented by Formula II and a compound represented by Formula III, wherein the mass percentage content of the compound represented by Formula I is not less than 30%. The liquid crystal composition provided by the present invention has an appropriate optical anisotropy, an appropriate dielectric anisotropy, especially a relatively low rotational viscosity, a good low-temperature mutual solubility and a good reliability, especially good frequency dependence.

##STR00001##

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.

The present invention relates to a liquid crystalline medium comprising dichroitic dyes made of benzothiadiazoles and related extended heterocyclic derivatives, the use of said medium for optical, electro-optical and electronic purposes, in particular in devices for regulating the passage of radiation energy from an outside space into an inside space, for example in windows. The invention further relates to devices containing the liquid crystalline medium according to the invention. Some new dichroitic dyes are disclosed.

A liquid-crystalline medium having a nematic phase containing one or more compounds of formula D ##STR00001##
the use thereof in an electro-optical display, particularly in an active-matrix display based on the IPS or FFS effect, displays of this type which contain a liquid-crystalline medium of this type and the use of the compounds of formula D for improvement of the contrast and/or response times of a liquid-crystalline medium which contain one or more additional mesogenic compounds, as well as certain compounds of formula D.

A method for preparing a switching element which is operable in and electrically switchable between an optically clear state and a scattering state, wherein one or more polymerisable mesogenic compounds provided in a layer containing a liquid-crystalline medium which comprises one or more mesogenic compounds, one or more chiral compounds and the one or more polymerisable mesogenic compounds are subjected to polymerisation in the presence of a direct current (DC) electric field in the layer. Also, a switching element obtained or respectively obtainable by carrying out the method and to the use of the switching element in a window.

The present invention relates to a liquid crystal display device. The liquid crystal display device of the present invention comprises a first substrate, a second substrate, and a liquid crystal composition disposed between said first substrate and said second substrate, wherein said first substrate and said second substrate are disposed in parallel and opposite to each other; alignment layers are disposed on the sides of said first and second substrates that are close to said liquid crystal composition; and said alignment layers are provided with vertical alignment films that allow liquid crystal molecules in said liquid crystal composition to be arranged roughly perpendicular to said first and second substrates, with said liquid crystal molecules having a pretilt angle of 88.5° to 89.5°.

A liquid crystal composition, a liquid crystal display element and a liquid crystal display comprising the liquid crystal composition belong to the field of liquid crystal display. The liquid crystal composition of the present disclosure comprises a compound represented by formula I, a compound represented by formula II, one or more compounds represented by formula III, one or more compounds represented by formula IV and more than three compounds represented by formula V. The liquid crystal composition has low rotational viscosity γ1 and high stability to heat and light on the basis of maintaining appropriate optical anisotropy Δn, which can realize fast response of liquid crystal display. ##STR00001##

The present invention relates to a liquid-crystalline medium (LC medium), to the use thereof for electro-optical purposes, and to LC displays containing this medium.