Provided is a compound represented by formula (1) described below.

##STR00001##

In formula (1), a and b are independently 0, 1 or 2, and expressions: 0a+b3 hold, ring A.sup.1, ring A.sup.2, ring A.sup.3 and ring A.sup.4 are independently 1,4-cyclohexylene, for example, Z.sup.1, Z.sup.2, Z.sup.3, Z.sup.4 and Z.sup.3 are independently a single bond, alkylene having 1 to 10 carbons, or the like, Sp.sup.1 and Sp.sup.2 are independently a single bond, alkylene having 1 to 10 carbons, or the like, and P.sup.1 and P.sup.2 are independently a specific polymerizable group.

The present invention provides a compound represented by formula (i), a liquid crystal composition using the compound, and a liquid crystal display device using the liquid crystal composition. The compound represented by formula (i) has a partial structure K.sup.i1 represented by any of general formulas (K-1) to (K-17) and further has ring B having at least two P-Sp- groups. Therefore, when used for a liquid crystal composition, the compound adsorbs to substrates sandwiching the liquid crystal composition (liquid crystal layer) and allows liquid crystal molecules to be held such that they are aligned in a vertical direction without a PI layer, and improved alignment stability and low-temperature storage stability can be achieved.

A liquid crystal composition includes at least one compound of general formula I, at least one compound of general formula II and at least one compound of general formula III. The liquid crystal composition has a higher optical anisotropy, the relatively large elastic constants K.sub.11 and K.sub.33 while maintaining a relatively high clearing point, an appropriate dielectric anisotropy and a better low-temperature intersolubility. A liquid crystal display device which includes the liquid crystal composition has advantages of a fast response, a high contrast and a wide temperature range, thereby having a good display effect and a large range of applicability.

##STR00001##

A liquid crystal composition contains: at least one compound of general formula I and at least one polymerizable compound of general formula II. Such a liquid crystal composition has a suitable optical anisotropy, a suitable dielectric anisotropy, and a better pretilt angle consistency while maintaining a relatively high clearing point, and the drop mura is good. When the liquid crystal composition is applied to a PSA liquid crystal display, the liquid crystal composition has an excellent display effect.

##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 negative dielectric anisotropy, large specific resistance, high stability to ultraviolet light and high stability to heat, or has a suitable balance regarding at least two of the characteristics; and an AM device having characteristics such as a short response time, a large voltage holding ratio, low threshold voltage, a large contrast ratio and a long service life. The liquid crystal composition may contain a specific compound having large negative dielectric anisotropy as a first component, a specific compound having high maximum temperature as a second component, a specific compound having negative dielectric anisotropy as a third component, or a specific compound having a polymerizable group as an additive component.

A liquid crystal composition that satisfies at least one of characteristics such as a high maximum temperature, a low minimum temperature, a wide temperature range of a liquid crystal phase, a small viscosity, a large optical anisotropy, a large positive or negative dielectric anisotropy, a large specific resistance, a high stability to light, a high stability to heat and a large elastic constant or that is suitably balanced between at least two of these characteristics. The means is use of a liquid crystal composition that includes a specific compound having a high maximum temperature or a small viscosity as a first component, and that may include a specific compound having a large positive dielectric anisotropy as a second component, or a specific compound having a large negative dielectric anisotropy as a third component or a specific compound having a polymerizable group as a first additive.

A liquid crystal composition that satisfies at least one of characteristics such as a high maximum temperature, a low minimum temperature, a small viscosity, a suitable optical anisotropy and a large negative dielectric anisotropy, or that has a suitable balance between at least two of these characteristics, and an AM device including this composition. The nematic liquid crystal composition includes a specific compound having a large negative dielectric anisotropy as a first component and a specific compound having a small viscosity as a second component, and may include a specific compound having a negative dielectric anisotropy as a third component, and a specific compound having a high maximum temperature or a small viscosity as a fourth component, or a specific compound having a polymerizable group as an additive.

A complex (10) includes a liquid crystal component (13) and a support (11, 12) of the liquid crystal component (13), in which a lubricating interface derivation region (16) is formed between the liquid crystal component (13) and the support (11, 12). An optical element includes a pair of substrates (11, 12) having electrodes (18, 19) on at least one substrate (11), and a liquid crystal component (13) with which a space between the pair of substrates (11, 12) is filled, in which a lubricating interface derivation region (16) is formed between the pair of substrates (11, 12) and the liquid crystal component (13). It is preferable that the lubricating interface deriving agent (14) is present in the lubricating interface derivation region.

Provided are a liquid crystal composition that contains a polar compound having a polymerizable group, in which vertical alignment of liquid crystal molecules can be achieved by action of the compound (or polymer), and a liquid crystal display device including the composition. The composition satisfies at least one of characteristics such as high maximum temperature, low minimum temperature, small viscosity, suitable optical anisotropy, large negative dielectric anisotropy, large specific resistance, high stability to ultraviolet light and heat. The composition is a nematic liquid crystal composition that has negative dielectric anisotropy and contains the polar compound as a first additive, and may contain a specific liquid crystal compound having large negative dielectric anisotropy as a first component, a specific liquid crystal compound having high maximum temperature or small viscosity as a second component and a polymerizable compound as a second additive, and the liquid crystal display device includes the composition.

Provided is a reverse mode light scattering type liquid crystal device that is capable of withstanding practical use, has a low driving voltage, and shows a high haze when voltage is applied and a low haze when no voltage is applied. A reverse mode liquid crystal device includes a light control layer and at least a pair of electrodes, wherein the light control layer includes a polymerization product of a polymerizable material including: (A) a liquid crystal composition, (B) a perpendicular alignment agent, and (C) at least one polymerizable compound selected from polymer forming monomers and polymer forming oligomers.