Mesogenic media comprising one or more compounds of formulae I or II ##STR00001##
preferably mesogenic media showing a blue phase, preferably stabilized by a polymer, and their use in electro-optical light modulation elements and their respective use in displays, as well as such devices.

A nematic liquid crystal composition has negative dielectric anisotropy and contains at least one polar compound selected from the group of compounds represented by formula (1) as a first additive, and the liquid crystal display device includes the composition. In formula (1), R.sup.1 is hydrogen, halogen, alkyl having 1 to 12 carbons or the like; R.sup.2 is a group represented by OH, OR.sup.0, NH.sub.2, NHR.sup.0 or N(R.sup.0).sub.2, in which R.sup.0 is alkyl having 1 to 5 carbons; ring A and ring B are independently 1,4-cyclohexylene, 1,4-phenylene or the like; Z.sup.1 is a single bond or the like; Sp.sup.1 and Sp.sup.2 are independently a single bond, alkylene having 1 to 7 carbons or the like; and a is 0 to 4. ##STR00001##

A nematic liquid crystal composition has negative dielectric anisotropy and contains at least one polar compound selected from the group of compounds represented by formula (1) as a first additive, and the liquid crystal display device includes the composition. In formula (1), R.sup.1 is hydrogen, halogen, alkyl having 1 to 12 carbons or the like; R.sup.2 is a group represented by OH, OR.sup.0, NH.sub.2, NHR.sup.0 or N(R.sup.0).sub.2, in which R.sup.0 is alkyl having 1 to 5 carbons; ring A and ring B are independently 1,4-cyclohexylene, 1,4-phenylene or the like; Z.sup.1 is a single bond or the like; Sp.sup.1 and Sp.sup.2 are independently a single bond, alkylene having 1 to 7 carbons or the like; and a is 0 to 4. ##STR00001##

Compound (1) is provided.

R.sup.1-MES-Sp.sup.1-P.sup.1(1)

In compound (1), R.sup.1 is alkyl having 1 to 15 carbons; MES is a mesogen group having an at least one ring; Sp.sup.1 is a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one hydrogen is replaced by group (1a); P.sup.1 is group (1e) or (1f);

##STR00001##

wherein, M.sup.1, M.sup.2, M.sup.3 and M.sup.4 are hydrogen; Sp.sup.2 and Sp.sup.3 are a single bond or alkylene having 1 to 10 carbons; R.sup.2 is alkyl having 1 to 15 carbons; R.sup.3 is group (1g), (1h) or (1i);

##STR00002##

wherein, Sp.sup.4 and Sp.sup.5 are a single bond or alkylene having 1 to 10 carbons; S.sup.1 is >CH, and S.sup.2 is >C<; and X is OH.

Provided is a liquid crystal composite that is suitable for dimming and includes a liquid crystal composition satisfying at least one of characteristics such as a high maximum temperature, a low minimum temperature, a small viscosity, a large optical anisotropy and a large negative dielectric anisotropy or being suitably balanced between at least two of these characteristics, and a liquid crystal dimming device including the liquid crystal composite, where the liquid crystal composite includes a polymer and a liquid crystal composition including a specific compound having a large negative dielectric anisotropy, and the liquid crystal composite may further include a specific compound having a high maximum temperature or a low minimum temperature.

This invention provides an FFS type liquid crystal display containing one type or two or more types of compounds selected from the group of compounds represented by General Formula (i), General Formula (ii), and General Formula (iii) and one type or two or more types of compounds selected from compounds represented by General Formula (II). This display makes it possible to realize excellent display characteristics without deteriorating various liquid crystal display characteristics such as dielectric anisotropy, viscosity, nematic-phase maximum temperature, nematic-phase stability at low temperatures, or .sub.1 and the display burn-in characteristics.

This invention provides an FFS type liquid crystal display containing one type or two or more types of compounds selected from the group of compounds represented by General Formula (i), General Formula (ii), and General Formula (iii) and one type or two or more types of compounds selected from compounds represented by General Formula (II). This display makes it possible to realize excellent display characteristics without deteriorating various liquid crystal display characteristics such as dielectric anisotropy, viscosity, nematic-phase maximum temperature, nematic-phase stability at low temperatures, or .sub.1 and the display burn-in characteristics.

Provided is a polar compound having high chemical stability, high capability of aligning liquid crystal molecules, high solubility in a liquid crystal composition, and a large voltage holding ratio when used in a liquid crystal display device. The compound is represented by formula (1): ##STR00001##
in which, for example, R.sup.1 is alkyl having 1 to 15 carbons; MES is a mesogen group having at least one ring; Sp.sup.1 is a single bond or alkylene having 1 to 10 carbons; M.sup.1 and M.sup.2 are hydrogen; and R.sup.2 is a group represented by formulas (1a) to (1c): ##STR00002##
in which, Sp.sup.2 and Sp.sup.3 are a single bond or alkylene having 1 to 10 carbons; S.sup.1 is >CH; S.sup.2 is >C<; and X.sup.1 is OH.

Provided is a polar compound having high chemical stability, high capability of aligning liquid crystal molecules, high solubility in a liquid crystal composition, and a large voltage holding ratio when used in a liquid crystal display device. The compound is represented by formula (1): ##STR00001##
in which, for example, R.sup.1 is alkyl having 1 to 15 carbons; MES is a mesogen group having at least one ring; Sp.sup.1 is a single bond or alkylene having 1 to 10 carbons; M.sup.1 and M.sup.2 are hydrogen; and R.sup.2 is a group represented by formulas (1a) to (1c): ##STR00002##
in which, Sp.sup.2 and Sp.sup.3 are a single bond or alkylene having 1 to 10 carbons; S.sup.1 is >CH; S.sup.2 is >C<; and X.sup.1 is OH.

The present invention relates to liquid-crystalline media (LC media) having negative or positive dielectric anisotropy comprising self-aligning mesogens (SAMs) which effect homeotropic (vertical) alignment of the LC media at a surface or the cell walls of a liquid-crystal display (LC display). The invention therefore also encompasses LC displays having homeotropic alignment of the liquid-crystalline medium (LC medium) without conventional imide alignment layers. The LC media may be supplemented by a polymerisable or polymerised component, which serves for stabilisation of the alignment, for adjustment of the tilt angle and/or as passivation layer.