Provided are a liquid crystal composition containing a compound represented by general formula (I-IV):

##STR00001##

and a compound represented by general formula (I):

##STR00002##

and a liquid crystal display device including the liquid crystal composition. The liquid crystal composition according to the present invention has a sufficiently low viscosity (), a sufficiently low rotational viscosity (1), a high elastic constant (K.sub.33), a high voltage holding ratio after UV exposure (VHR(UV)), and a large absolute value of negative dielectric anisotropy () without decreased refractive index anisotropy (n) or nematic-isotropic liquid phase transition temperature (T.sub.ni). The display device including the liquid crystal composition has fast response time and good display quality with reduced or no display defects.

Provided is a liquid crystal composition. The liquid crystal composition includes 1 to 50 wt % of an achiral smectic liquid crystal, and a remaining amount of a nematic liquid crystal. The nematic liquid crystal includes a negative nematic liquid crystal.

The present invention relates to liquid-crystalline media comprising one or more compounds selected from the group of compounds of formulae I, II and III,

##STR00001##

in which the parameters R.sup.1-R.sup.3, Z.sup.21, Z.sup.31, Z.sup.32 and rings A.sup.11, A.sup.12, A.sup.13, A.sup.21, A.sup.22, A.sup.31, and A.sup.32 are as defined herein, and to components comprising these media for high-frequency technology, in particular phase shifters and microwave array antennas.

The present invention relates to a switch element, which is thermoresponsive and which switches between a less transmissive state for radiant energy and a more transmissive state for radiant energy, and which comprises a liquid-crystalline medium. The invention furthermore relates to the use of the switch element for the regulation of radiant energy flow between interior spaces and the environment and for the regulation of the temperature of interior spaces. The invention furthermore relates to a liquid-crystalline medium, characterised in that it comprises 5-95% of a compound of the formula (I), in particular for use in the switch elements according to the invention.

A liquid crystal medium has stability to heat, light and so forth, and significantly high dielectric anisotropy, and develops an optically isotropic liquid crystal phase. Moreover, various kinds of optical devices can be used in a wide temperature range and have a short response time, a large contrast ratio and low driving voltage. A liquid crystal composition contains achiral component T containing at least one compound 1 represented by formula (1) and a chiral agent, and develops the optically isotropic liquid crystal phase. ##STR00001## In formula (1), for examples, R.sup.1 is alkyl, L.sup.1 and L.sup.2 are each independently fluorine or hydrogen, and X.sup.1 is halogen.

The present invention relates to nematic liquid-crystal media of negative dielectric anisotropy which have a peak time (t.sub.max.) of 0.25 ms or less, which is determined as described in the disclosure, and which preferably have a value of the quotient of the peak time and the square of the birefringence (t.sub.max/n.sup.2) of 22 ms or less, and to the use of these liquid-crystal media in liquid-crystal displays, and to these liquid-crystal displays.

The present invention relates to liquid-crystalline media comprising one or more compounds selected from the group of compounds of formulae I, II and III, ##STR00001##
in which the parameters R.sup.1-R.sup.3, Z.sup.21, Z.sup.31, Z.sup.32 and rings A.sup.11, A.sup.12, A.sup.13, A.sup.21, A.sup.22, A.sup.31, and A.sup.32 are as defined herein, and to components comprising these media for high-frequency technology, in particular phase shifters and microwave array antennas.

An organic compound represented by General Formula (G100) is provided. A novel liquid crystal composition containing the organic compound is provided. ##STR00001##

The present invention relates to nematic liquid-crystal media of negative dielectric anisotropy which have a peak time (t.sub.max.) of 0.25 ms or less, which is determined as described in the disclosure, and which preferably have a value of the quotient of the peak time and the square of the birefringence (t.sub.max/n.sup.2) of 22 ms or less, and to the use of these liquid-crystal media in liquid-crystal displays, and to these liquid-crystal displays.

The present invention relates to liquid-crystal (LC) media as defined in claim 1, having negative dielectric anisotropy and to the use thereof for optical, electro-optical and electronic purposes, in particular in LC displays.