A compound represented by formula (1). For example, R.sup.1, R.sup.2 and R.sup.3 are alkyl having 1 to 15 carbons; ring A.sup.1 and ring A.sup.3 are cyclohexyl or phenyl, ring A.sup.2 is 1,4-cyclohexylene or 1,4-phenylene; Z.sup.1 and Z.sup.2 are a single bond or alkylene having 1 to 10 carbons; a is 0, 1, 2, 3 or 4; c, d and e are 0, 1, 2, 3 or 4; and P.sup.1 to P.sup.3 are a polymerizable group represented by formula (P-1); wherein M.sup.1 and M.sup.2 are hydrogen or alkyl having 1 to 5 carbons; and R.sup.4 is a polar group represented by formulas (1a) to (1c); wherein Sp.sup.5 and Sp.sup.6 are a single bond or alkylene having 1 to 10 carbons; S.sup.1 is >CH, and S.sup.2 is >C<; and X.sup.1 is OH.

##STR00001##

Provided are a liquid crystal composition satisfying at least one of characteristics such as high maximum temperature, low minimum temperature, small viscosity, suitable optical anisotropy, large dielectric anisotropy and a short helical pitch, or the liquid crystal composition having a suitable balance regarding at least two of the characteristics; and an AM device including the composition. The liquid crystal composition contains a specific optically active compound as an additive, and a specific compound having high maximum temperature or small viscosity as a first component, and may contain a specific compound having positive dielectric anisotropy as a second component, or a specific compound having negative dielectric anisotropy as a third component.

The invention relates to a liquid-crystalline medium which comprises at least one compound of the formula I,

##STR00001## in which R.sup.1 and R.sup.1* each, independently of one another, denote an alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may each be replaced, independently of one another, by

##STR00002##

in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, A.sup.1 denotes

##STR00003## L.sup.1 denotes F, Cl, CF.sub.3, OCF.sub.3 or CHF.sub.2,
and to the use thereof for electro-optical purposes, in particular for shutter glasses, 3D applications, in TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, PS-FFS and PS-VA-IPS displays.

A liquid crystal compound is represented by formula (1):

##STR00001##

In formula (1), R.sup.1 is alkyl or the like; ring A.sup.1 and ring A.sup.2 are independently 1,4-cyclohexylene, 1,4-phenylene or the like; Z.sup.1, Z.sup.2 and Z.sup.3 are independently a single bond, CF.sub.2O or the like; X.sup.1 is fluorine, chlorine, CF.sub.3 or the like; L.sup.1 and L.sup.2 are independently hydrogen, fluorine or the like; a and b are independently 0, 1, 2 or 3; and W is a group represented by formula (1a) or formula (1b);

##STR00002##

In formula (1a) and formula (1b), L.sup.3 to L.sup.8 are independently hydrogen, fluorine or the like.

Provided are a compound having an effect on preventing photolysis of a liquid crystal composition, and high solubility in the liquid crystal composition, a liquid crystal composition containing the compound and a liquid crystal display device including the composition.

A compound is represented by formula (1), a liquid crystal composition contains the compound and a liquid crystal display device uses the composition.

##STR00001##

In formula (1), for example, R1 is alkyl having 1 to 10 carbons; R2 is hydrogen, hydroxy, oxy radical or alkyl; ring A1, ring A2 and ring A3 are independently 1,4-cyclohexylene, 1,4-phenylene or pyridine-2,5-diyl; Z1 and Z2 are independently a single bond or alkylene; and a and b are independently 0 or 1.

Provided are a liquid crystal compound satisfying at least one of physical properties such as high stability to heat or light, a high clearing point (or high maximum temperature), low minimum temperature of a liquid crystal phase, small viscosity, large optical anisotropy, large negative dielectric anisotropy, a suitable elastic constant and good compatibility with other liquid crystal compounds, a liquid crystal composition containing the compound and a liquid crystal display device including the composition.

A compound is represented by formula (1):

##STR00001##

wherein, R.sup.1 and R.sup.2 are alkyl having 1 to 15 carbons; A.sup.1, A.sup.2, A.sup.3 and A.sup.4 are 1,4-cyclohexylene and 1,4-phenylene; Z.sup.1, Z.sup.2, Z.sup.3 and Z.sup.4 are a single bond; Y.sup.1, Y.sup.2 and Y.sup.3 are fluorine; and a, b, c and d are 0 or 1, and a sum of a, b, c and d is an integer from 0 to 3, or the like.

Provided are a liquid crystal compound having larger dielectric anisotropy and superb heating reliability in comparison with a similar compound, a liquid crystal composition containing the compound and a liquid crystal display device including the composition. A compound is represented by formula (1).

##STR00001##

In formula (1), for example, R.sup.1 is alkyl having 1 to 15 carbons, ring A.sup.1 is 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, 1,4-phenylene in which at least one hydrogen is replaced by halogen or tetrahydropyran-2,5-diyl; Z.sup.1 is a single bond or CF.sub.2O; L.sup.1 and L.sup.2 are hydrogen or halogen; Y.sup.1 and Y.sup.2 are hydrogen or halogen; and a is an integer from 1 to 4.

Shown are a liquid crystal compound satisfying at least one of physical properties such as high stability to heat and light, a high clearing point (or high maximum temperature), low minimum temperature of a liquid crystal phase, small viscosity, suitable optical anisotropy, large negative dielectric anisotropy, a suitable elastic constant and satisfactory compatibility with other liquid crystal compounds, a liquid crystal composition containing the compound and a liquid crystal display device including the composition. A compound is represented by formula (1), a liquid crystal composition contains the compound, or the like.

##STR00001##

A liquid crystal compound represented by

##STR00001##

R.sup.1 and R.sup.2 are independently hydrogen, fluorine, chlorine, alkyl or the like; ring A.sup.1 and ring A.sup.3 are independently 1,4-cyclohexylene, 1,4-phenylene or the like; and A.sup.2 is a divalent group represented by formula (A-1) or formula (A-2)

##STR00002##

Z.sup.1, Z.sup.2, Z.sup.3, Z.sup.4 and Z.sup.5 are independently a single bond, COO or the like; and a to d is 0, 1 or the like.

The disclosure shows a liquid crystal composition that contains a compound having an effect of preventing photolysis of the liquid crystal composition and having high solubility in the liquid crystal composition, and that satisfies at least one of characteristics such as high maximum temperature, low minimum temperature, small viscosity, suitable optical anisotropy, large positive or negative dielectric anisotropy, large specific resistance, high stability to ultraviolet light or heat, and a suitable elastic constant, etc. and so on. The disclosure shows a liquid crystal composition that contains a compound having the following azolidine ring (Q-1) or azepane ring (Q-2), a liquid crystal display device and so on. ##STR00001##