Provided is 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 dielectric anisotropy, a suitable elastic constant and excellent compatibility with other liquid crystal compounds, a liquid crystal composition containing the compound and a liquid crystal display device including the composition.

A compound, represented by formula (1):

##STR00001##

wherein, in formula (1), R.sup.1 is alkoxy having 1 to 9 carbons or the like; R.sup.2 is alkenyl having 2 to 10 carbons; Z.sup.1 and Z.sup.2 are independently a single bond, —CH.sub.2CH.sub.2—, —CH═CH— or the like; and a and b are independently 0 or 1.

The problem is to provide a polymerizable compound having suitable polymerization reactivity, a high conversion ratio, low polymerization starting temperature, and high solubility in a liquid crystal composition; a liquid crystal composition containing the compound; and a liquid crystal display device including the composition.

A means thereof includes a compound represented by formula (1) and a liquid crystal composition containing the compound.

##STR00001##

In formula (1), R.sup.1, R.sup.2 and R.sup.3 are independently alkyl or the like; n is 0 or the like; ring A.sup.1 is phenyl or the like, and ring A.sup.2 and ring A.sup.3 are independently 1,4-phenylene or the like; Z.sup.1 and Z.sup.2 are independently a single bond or the like; Sp.sup.1 to Sp.sup.4 are a single bond or the like; a is 1 or the like; c, d and e are independently 0 or 1, and a sum of c, d and e is 1 or the like; and P.sup.1 to P.sup.4 are a polymerizable group, and at least one of P.sup.1 to P.sup.4 is a polymerizable group represented by formula (P-1).

##STR00002##

A liquid-crystal composition and a liquid-crystal display device employing the liquid-crystal composition are provided. The liquid-crystal composition includes a first component and a second component. The first component includes one or more compounds represented by Formula (I), and the second component includes one or more compounds represented by Formula (II):

##STR00001## wherein R1, R2, A1, A2, A3, A4, Z1, Z2, Z3, m, m, n, and n are defined as in the specification.

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 and large dielectric anisotropy, 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 compound having small optical anisotropy as a first component, and a specific compound having positive dielectric anisotropy as a second component, and may contain a specific compound having high maximum temperature or small viscosity as a third component, a specific compound having positive dielectric anisotropy as a fourth component, or a specific compound having negative dielectric anisotropy as a fifth component.

Provided is 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 dielectric anisotropy, a suitable elastic constant and excellent compatibility with other liquid crystal compounds, a liquid crystal composition containing the compound and a liquid crystal display device including the composition. A compound, represented by formula (1): ##STR00001##
wherein, in formula (1), R.sup.1 is alkoxy having 1 to 9 carbons or the like; R.sup.2 is alkenyl having 2 to 10 carbons; Z.sup.1 and Z.sup.2 are independently a single bond, CH.sub.2CH.sub.2, CHCH or the like; and a and b are independently 0 or 1.

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 and large dielectric anisotropy, 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 compound having small optical anisotropy as a first component, and a specific compound having positive dielectric anisotropy as a second component, and may contain a specific compound having high maximum temperature or small viscosity as a third component, a specific compound having positive dielectric anisotropy as a fourth component, or a specific compound having negative dielectric anisotropy as a fifth component.

A liquid crystal display device includes: a first substrate including a plurality of pixel areas; a first sub-pixel electrode disposed in a first pixel area on the first substrate; a second sub-pixel electrode disposed in the first pixel area on the first substrate and spaced apart from the first sub-pixel electrode, and a polarity of a voltage applied to the second sub-pixel electrode with reference to a common voltage is different from a polarity of a voltage applied to the first sub-pixel electrode with reference to the common voltage; a second substrate facing the first substrate and spaced apart from the first substrate; and a liquid crystal layer which interposed between the first substrate and the second substrate and including a liquid crystal composition having dielectric anisotropy of about 2.5 to about 1.5.