A polymerizable compound is provided having suitable polymerization reactivity, high conversion and high compatibility in a liquid crystal composition, a polymerizable composition containing the compound, a liquid crystal composite prepared using the composition, and a liquid crystal display device having the composite. The polymerizable compound has at least one monovalent group (A). The polymerizable composition contains the compound. The liquid crystal composition and the liquid crystal composite is prepared using the polymerizable composition. The liquid crystal display device has the liquid crystal composite. ##STR00001##
In the monovalent group (A), R.sup.1 and R.sup.2 are independently alkyl having 1 to 3 carbons, and in the alkyl, at least one of hydrogen may be replaced by fluorine, and R.sup.3 is hydrogen or methyl.

To provide a compound having an effect for preventing photolysis of a liquid crystal composition, and having a high solubility in the liquid crystal composition, a liquid crystal composition containing the compound, and a liquid crystal display device including the composition. The compound is represented by formula (1), a liquid crystal composition contains the compound, and a liquid crystal display device includes the composition:
M(Z-Q).sub.a(R.sup.b).sub.b(1)
wherein, in formula (1), a is 1 to 4, and b is a numerical value: (4a); M is an organic group; Z is a single bond or the like; and Q is a monovalent group represented by formula (Q-1), (Q-2) or (Q-3), in which R.sup.a and R.sup.b are hydrogen, alkyl or the like. ##STR00001##

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

The subject is to provide a liquid crystal compound satisfying at least one of physical properties such as a high stability to heat or light, a high clearing point (or a high maximum temperature), a low minimum temperature of a liquid crystal phase, a small viscosity, a suitable optical anisotropy, a large dielectic anisotropy, a suitable elastic constant and an excellent compatibility with any other liquid crystal compound, a liquid crystal composition including this compound and a liquid crystal display device including this composition. The compound is represented by the following formula (1a): ##STR00001##
wherein R.sup.1 is alkyl having 1 to 15 carbons or the like; ring A.sup.1, ring A.sup.2, ring A.sup.3 and ring A.sup.4 are independently 1,4-phenylene, naphthalene-2,6-diyl or the like; Z.sup.1 and Z.sup.2 are independently a single bond or the like; o and p are independently 0, 1 or 2; and n is an integer from 2 to 10.

A solution is a compound represented by formula (1), a liquid crystal composition containing the compound and a liquid crystal display device including the composition.

##STR00001##

In formula (1), R.sup.a and R.sup.b are independently alkyl having 1 to 30 carbons or the like; and X and Y are independently fluoroalkyl having 1 to 5 carbons, fluoroalkoxy having 1 to 5 carbons or pentafluorosulfanil, and one of X and Y may be fluorine.

Liquid-crystalline media comprising one or more mesogenic compounds of formula I

##STR00001##

and one or more dichroic dyes, and switching elements and window elements containing the LC materials. Also, the use of the liquid-crystalline media in devices for regulating the passage of energy from an outside space into an inside space, for example in switchable windows for solar energy control in smart buildings and vehicles with energy efficiency and improved comfort.