It is an object of the present invention to provide a compound that can provide a liquid crystal composition with a high T.sub.ni, a high n, a low V.sub.th, a high .sub.r, a low tan .sub.iso, and high storage stability at low temperatures, a liquid crystal composition, as well as a liquid crystal display element, a sensor, a liquid crystal lens, optical communication equipment, and an antenna each using this. Specifically disclosed are a compound represented by the general formula (i) having an ethynylene group (CC) and an isothiocyanate group (NCS) and a liquid crystal composition containing one or two or more of the compounds.

The present invention provides a liquid crystal dimming device. The liquid crystal dimming device of the present application sequentially comprises, from bottom to top, a lower substrate, a lower conductive layer, a lower alignment layer, a guest-host liquid crystal composition layer, an upper alignment layer, an upper conductive layer, and an upper substrate; alignment directions of the upper alignment layer and the lower alignment layer are parallel alignment; the guest-host liquid crystal composition layer comprises at least one dichroic dye, at least one chiral agent and at least one liquid crystal composition; wherein, the liquid crystal composition comprises at least one compound of general formula N. The liquid crystal dimming device of the present invention has an appropriate transmittance (T.sub.r0, T.sub.r255), an appropriate contrast rate, a higher VHR (initial), a higher VHR (Ra) and a wider operation temperature range. The dimming device of the present invention has a better display effect at the moment of power-off after applying power on it for 2 h, and can effectively avoid the problems of display mura and image sticking.

A compound of formula UI ##STR00001##
and a liquid crystal medium containing the compound of formula UI and high-frequency components containing such media, especially microwave components for high-frequency devices, such as devices for shifting the phase of microwaves, tunable filters, tunable metamaterial structures, and electronic beam steering antennas, for example, phased array antennas.

The present invention provides a self-aligning agent and a liquid crystal composition thereof. The liquid crystal composition comprising the self aligning agent of general formula O in the present invention has a lower residue concentration, a smaller roughness, a better alignment effect as well as a better low-temperature storage stability and a better pre-tilt angle stability while maintaining an appropriate clearing point, an appropriate optical anisotropy, an appropriate absolute value of dielectric anisotropy, a larger K value (K.sub.11 and K.sub.33) and a smaller rotational viscosity.

##STR00001##