# Patent

## Title
Alkenyl compound having a negative Δε value, liquid crystal composition, and liquid crystal display device

## Abstract

Liquid crystalline compounds having a large negative Δε low viscosity, a large K33/K11 value, a small Δε/Δ⊥ and mutually excellent solubility even at low temperature, compositions containing at least one of the compounds and liquid crystal display devices containing such a liquid crystal compositions are disclosed.

## Background
This application is a continuation of application Ser. No. 09/323,820, filed Jun. 2, 1999, now U.S. Pat. No. 6,692,657.


TECHNICAL FIELD
The present invention relates to a liquid crystalline compound and a liquid crystal composition, and more particularly, to a novel liquid crystalline compound simultaneously having an alkenyl group and 2,3-difluorophenyl group, a liquid crystal composition containing such a compound, and a liquid crystal display device constituted from such a liquid crystal composition.
BACKGROUND ART
When a voltage is impressed to a conventional TN mode TFT display or a conventional STN display, liquid crystal molecules rotate to extend in the direction perpendicular to the substrate. When such liquid crystal molecules rise diagonally (i.e., such that they extend perpendicular to the substrate), there arise problems in that the optical properties of the liquid crystal molecules differ depending on the angle from which the liquid crystal panel is viewed, and in that the view angle is narrow.
As systems for realizing a wide view angle, the In-Plane-Switching (IPS) system characterized in the formation of comb style electrodes on one substrate (G. Baur, Freiburger Arbeistagung Flussigkristalle, Abstract No. 22 (1993), M. Oh-e, et al., ASIA DISPLAY '95, 577 (1995)), and the Vertically Aligned (VA) system (K. Ohmuro, et al., SID 97 DIGEST, 845 (1997)) have attracted attention, and have been put into practical use.
In the IPS system, since liquid crystal molecules rotate within the surface plane of the glass substrate, the view angle is greatly widened. In the VA system, liquid crystal molecules rotate from the vertical direction to the horizontal direction to the substrate, and a wide view angle is realized by controlling orientation in a kind of multi-domain system.
However, as compared to CRTs, these display systems still have problems, and there are the demands for improvement of response time, improvement of contrast, and decrease of driving voltage.
The liquid crystalline compound employed in IPS and VA systems must have the large negative value of dielectric anisotropy (Δε) for its display properties, and a low viscosity for improving response time. Since active matrix driving is utilized as the driving method, the compound must have a high voltage holding ratio (V.H.R.) in order to improve contrast.
Various compounds have been known to have negative values of dielectric anisotropy, and the following compounds (a) and (b) are disclosed in Japanese Patent Application Laid Open No. 2-4725 and Japanese-translated PCT Patent Application Laid-open No. 2-503441:




Where, R′ represents an alkyl group or an alkoxy group.

Although each of the above liquid crystalline compounds, (a) and (b), has 2,3-difluoro-1,4-phenylene group as part of its structure, and has a negative Δε, |Δε| is not sufficiently large and viscosity is high. Furthermore, mutually good solubility its with other liquid crystalline compounds, especially mutually good solubility at very low temperature, is not sufficiently high, and a liquid crystal composition containing such compounds is so unstable that low-temperature storage results in precipitation of crystals or appearance of a smectic phase.
In order to solve the problems involved in the prior art techniques, an object of the present invention is to provide a liquid crystalline compound having a wide temperature range within which a liquid crystal phase exists (hereinafter called a “liquid crystal phase temperature range”), a large negative Δε, low viscosity, and mutually good solubility at low temperature, which can contribute to improving response time and contrast and lowering driving voltage in IPS and VA systems and can contribute to improving steepness of the V-T (voltage-transmissivity) curve and contrast by increasing the K33/K11 value in the STN system; a liquid crystal composition containing such liquid crystalline compounds, and a liquid crystal display device constituted from such a liquid crystal composition.
DISCLOSURE OF INVENTION
The present inventors conducted repeated examinations for achieving the above and other objects, and found that each of a group of compounds containing an alkenyl group and 2,3-difluoro-1,4-phenylene group, represented by formula (1), exhibits a large negative Δε, wide liquid crystal phase temperature range, low viscosity, and mutually excellent solubility at low temperature, and that Δε/ε⊥, can be decreased and the K33/K11 value can be increased by appropriate selection of the positions of double bonds in the alkenyl group to attain the present invention.
The present invention is described as follows.
According to a first aspect of the present invention, there is provided a liquid crystalline compound represented by the following general formula (1):




where, R1 represents hydrogen, fluorine, an alkyl group having 1 to 15 carbon atoms, or an alkenyl group having 2 to 15 carbon atoms; each of rings A1, A2 and A3 independently represents trans-i 4-cyclohexylene group, 1 ,4-cyclohexenylene group, trans-1,4-silacyclohexylene group, 1,4-phenylene group, 2,3-difluoro- 1,4-phenylene group, 2-fluoro-1,4-phenylene group, 3-fluoro-1,4-phenylene group, pyrimidine-2,5-diyl group, pyridine-2,5-diyl group, 1,3-dioxane-2,5-diyl group, tetrahydro-pyrane-2,5-diyl group, 1,3-dithiane-2,5-diyl group, or tetrahydrothiopyrane-2,5-diyl group; X1 represents hydrogen or fluorine; Y1 represents hydrogen or an alkyl group having 1 to 15 carbon atoms, in which each of optional nonadjacent methylene groups (—CH2—) may be substituted by oxygen; l represents an integer from 0 to 10; in which each of optional nonadjacent methylene groups in (—CH2—)e may be substituted by oxygen; and each of m and n independently represents 0 or 1.

According to a second aspect of the present invention, there is provided a liquid crystalline compound according to the first aspect, wherein the ring A1 in the general formula (1) is trans-1,4-cyclohexylene group and m and n are both 0.
According to a third aspect of the present invention, there is provided a liquid crystalline compound according to the first aspect, wherein each of the rings A1 and A2 in general formula (1) is independently trans-1,4-cyclohexylene group, 2,3-difluoro-1,4-phenylene group or 1,3-dioxane-2,5-diyl group; m is 1; and n is 0.
According to a fourth aspect of the present invention, there is provided a liquid crystalline compound according to the first aspect, wherein each of the rings A1, A2 and A in general formula (1) is independently trans-1,4-cyclohexylene group, 2,3-difluoro-1,4-phenylene group or 1,3-dioxane-2,5-diyl group; and m and n are both 1.
According to a fifth aspect of the present invention, there is provided a liquid crystal composition comprising at least two components, characterized by containing at least one liquid crystalline compound represented by general formula (1).
According to a sixth aspect of the present invention, there is provided a liquid crystal composition comprising at least one liquid crystalline compound according to any of the first through fourth aspects as a first component and at least one compound selected from a group consisting of compounds represented by general formulas (2), (3) and (4) as a second component,




where R2 represents an alkyl group having 1 to 10 carbon atoms, in which each of optional nonadjacent methylene groups may be substituted by oxygen or —CH═CH— group, and in which each of optional hydrogen in these methylene groups may be substituted by fluorine; Y2 represents fluorine, chlorine, —OCF3, —OCF2H, —CF3, —CF2H, —CFH2, —OCF2CF2H or —OCF2CFHCF3; each of L1 and L2 independently represents hydrogen or fluorine; each of Z1 and Z2 independently represents 1,2-ethylene group, vinylene group, 1,4-butylene group, —COO—, —CF2O—, —OCF2— or a single bond; ring B represents trans-1,4-cyclohexylene group, 1,3-dioxane-2,5-diyl group or 1,4-phenylene group, in which each of hydrogen may be substituted by fluorine; and ring C represents trans-1,4-cyclohexylene group or 1,4-phenylene group, in which each of hydrogen may be substituted by fluorine.

According to a seventh aspect of the present invention, there is provided a liquid crystal composition comprising at least one liquid crystalline compound according to any of the first through fourth aspects as a first component, and at least one compound selected from a group consisting of compounds represented by general formulas (5) and (6) as a second component,




where each of R3 and R4 independently represents an alkyl group having 1 to 10 carbon atoms, in which each of optional nonadjacent methylene groups may be substituted by oxygen or vinylene group, and in which each of optional hydrogen in these methylene groups may be substituted by fluorine; Y3 represents —CN or —C≡C—CN; ring D represents trans-1,4-cyclohexylene group, 1,4-phenylene group, pyrimidine-2,5-diyl group or 1,3-dioxane-2,5-diyl group; ring E represents trans-1,4-cyclohexylene group or 1,4-phenylene group, in which each of optional hydrogen may be substituted by fluorine; or pyrimidine-2,5-diyl group; ring F represents trans-1,4-cyclohexylene group or 1,4-phenylene group; Z3 represents 1,2-ethylene group, —COO— or a single bond; each of L3, L4 and L5 independently represents hydrogen or fluorine; and each of a, b and c independently represents 0 or 1.

According to an eighth aspect of the present invention, there is provided a liquid crystal composition comprising at least one liquid crystalline compound according to any of the first through fourth aspects as a first component and at least one compound selected from a group consisting of compounds represented by general formulas (7), (8) and (9) as a second component,




where each of R5 and R6 independently represents an alkyl group having 1 to 10 carbon atoms, in which each of optional nonadjacent methylene groups may be substituted by oxygen or vinylene group and in which each of optional hydrogen in these methylene groups may be substituted by fluorine; each of rings G, I and J independently represents trans-1,4-cyclohexylene group, pyrimidine-2,5-diyl group or 1,4-phenylene group in which hydrogen may be substituted by fluorine; and each of Z4 and Z5 independently represents 1,2-ethylene group, vinylene group, —COO—, —C≡C— or a single bond.

According to a ninth aspect of the present invention, there is provided a liquid crystal composition comprising at least one liquid crystalline compound according to any of the first through fourth aspects as a first component and at least one compound selected from a group consisting of compounds represented by general formulas (10), (11) and (12) as a second component,




where each of R7 and R8 independently represents an alkyl group having 1 to 10 carbon atoms, in which each of optional nonadjacent methylene groups may be substituted by oxygen or vinylene group, and in which each of optional hydrogen in these methylene groups may be substituted by fluorine; each of rings K and M independently represents trans-1,4-cyclohexylene group or 1,4-phenylene group; each of L6 and L7 independently represents hydrogen or fluorine, but L6 and L7 are not both hydrogen simultaneously; and each of Z6 and Z7 independently represents —CH2CH2—, —CH2O— or a single bond.

According to a tenth aspect of the present invention, there is provided a liquid crystal composition comprising at least one liquid crystalline compound according to any of the first through fourth aspects as a first component, at least one compound selected from a group consisting of compounds represented by general formulas (7), (8) and (9) as a second component and at least one compound selected from a group consisting of compounds represented by general formulas (10), (11) and (12) as a third component.
According to an eleventh aspect of the present invention, there is provided a liquid crystal composition comprising at least one liquid crystalline compound according to any of the first through fourth aspects as a first component, at least one compound selected from a group consisting of compounds represented by general formulas (2), (3) and (4) as a second component and at least one compound selected from a group consisting of compounds represented by general formulas (7), (8) and (9) as a third component.
According to a twelfth aspect of the present invention, there is provided a liquid crystal composition comprising at least one liquid crystalline compound according to any of the first through fourth aspects as a first component, at least one compound selected from a group consisting of compounds represented by general formulas (5) and (6) as a second component and at least one compound selected from a group consisting of compounds represented by general formulas (7), (8) and (9) as a third component.
According to a thirteenth aspect of the present invention, there is provided a liquid crystal composition comprising at least one liquid crystalline compound according to any of the first through fourth aspects as a first component, at least one compound selected from a group consisting of compounds represented by general formulas (2), (3) and (4) as a second component, at least one compound selected from a group consisting of compounds represented by general formulas (5) and (6) as a third component, and at least one compound selected from a group consisting of compounds represented by general formulas (7), (8) and (9) as a fourth component.
According to a fourteenth aspect of the present invention, there is provided a liquid crystal composition according to any of the fifth through thirteenth aspects further comprising one or more optically active compounds.
According to a fifteenth aspect of the present invention, there is provided a liquid crystal display device constituted from a liquid crystal composition according to any of the fifth through fourteenth aspects.
The liquid crystalline compounds of the present invention represented by the general formula (1) are compounds having two to four rings and characterized by containing an alkenyl group and 2,3-difluorophenyl group simultaneously. These liquid crystalline compounds not only exhibit physical and chemical stability under conditions where liquid crystal display devices are used, but also have a wide liquid crystal phase temperature range, a large negative Δε, and low viscosity, enable an increase in the K33/K11 value, and are highly soluble in liquid crystal compositions even at low temperature.
Although, as described in the description of the Background Art, compounds having 2,3-difluoro-1,4-phenylene group in respective partial structures have been disclosed in patent gazettes or other references, the present inventors are the first to discover that compounds having both an alkenyl group and the above structure have the above features. In the compounds of the present invention, desired properties can be adjusted by suitable selection of the ring structures, or the structures of bonding groups or side chains among the elements constituting a molecule. Therefore, when the compounds of the present invention ate used as the components of liquid crystal compositions, nemetic liquid crystal compositions having the following preferable properties can be prepared.
1) Since the liquid crystal phase temperature range is wide, the usable temperature range is expanded.
2) Since the compositions have large negative Δε and low viscosity, response time is improved and driving voltage is lowered in IPS and VA systems. 3) Since the K33/K11 value can be increased and Δε/ε⊥ can be decreased in the STN system, the steepness of the V-T (voltage-transmissivity) curve is improved.

4) Stable nematic liquid crystal compositions can be prepared without the precipitation of crystals and the appearance of a smectic phase, even at extremely low temperature.

Thus, there can be provided novel liquid crystal compositions and liquid crystal display devices which are stable in usage environments, which realize the expansion of usable temperature range, and which have a low driving voltage and high response speed and provide high contrast.

Although all compounds of the present invention have favorable properties, a liquid crystal composition meeting the requirements of specific applications can be prepared by use of compounds in which R1, ring A1, ring A2, ring A3, X1, Y1, l, m and n in general formula (1) have been properly selected.
If a compound having a large negative Δε is desired, 2,3-difluoro-1,4-phenylene group may be bonded at the site of ring A1, ring A2, or ring A3; if the liquid crystal phase temperature range is required to be on the low-temperature side, a two-ring compound (m=n=0) may be selected; if the liquid crystal phase temperature range is required to be on the high-temperature side, a three-ring or four-ring compound (m+n=1 or m+n=2) may be selected; and if a large refractive index of anisotropy is required, 1,4-phenylene group may be bonded at the site of ring A1, ring A2 or ring A3. The compound in which a hydrogen atom on the 1,4-phenylene group is substituted by a fluorine atom has especially excellent solubility at low temperature.
Among the compounds represented by the general formula (1), examples of especially favorable compounds are those represented by the following general formulas (1-1) through (1-7):




where, ring A1, ring A2, ring A3, and Y1 have the same meanings as described above, and R has the following structure;





where, R1 and X1 have the same meanings as described above.

In general formulas (1-1) through (1-7), R represents an alkenyl group or an alkenyloxy group having 2 to 15 carbon atoms, among which vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 2-propenyloxy, 2-butenyloxy, 2-pentenyloxy and 4-pentenyloxy groups are particularly preferable; and Y1 represents hydrogen, an alkyl group having 1 to 15 carbon atoms or an alkoxy group, among which methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, and octyloxy groups are particularly preferable.
The liquid crystal composition of the present invention will be described below. In order to exhibit favorable properties, the liquid crystal composition of the present invention preferably contains at least one of the compounds represented by the general formula (1) in a total amount of 0.1 to 99.9% by weight.
More specifically, the liquid crystal composition of the present invention comprises a first component containing at least one of the compounds represented by general formula (1) and a second component comprising a compound selected from the group of compounds represented by general formulas (2) through (12) according to the purpose of the liquid crystal composition.
Among the compounds represented by general formulas (2) through (4), compounds represented by the following general formulas (2-1) through (4-24) are particularly preferred, where R2 and Y2 have the same meanings as described above:














































The compounds represented by general formulas (2) through (4) are compounds having positive values of dielectric anisotropy, and excellent thermal and chemical stability, and are particularly useful for preparing liquid crystal compositions for TFT (AM-LCD) displays which require high reliability; for example, a high voltage holding ratio or high specific resistance.
In preparing a liquid crystal composition for TFT displays, the compounds represented by general formulas (2) through (4) may be contained in a total amount of 0.1 to 99.9% by weight, preferably 10 to 97% by weight, and more preferably 40 to 95% by weight. In this case, compounds represented by general formulas (7) through (9) maybe further added for the adjustment of viscosity.
In preparing a liquid crystal composition for STN or TN displays, the compounds represented by general formulas (2) through (4) can also be used. Since the compounds represented by general formulas (2) through (4) have a weaker effect in lowering the threshold voltage of the liquid crystal composition than do the compounds represented by general formulas (5) and (6), the compounds represented by general formulas (2) through (4) are preferably contained in a total amount of 50% by weight or less.
Among the compounds represented by general formulas (5) and (6) are compounds represented by the following general formulas (5-1) through (6-3) are particular preferred; where, R3, R4 and Y3 have the same meanings as described above.






















The compounds represented by general formulas (5) and (6) have large positive values of dielectric anisotropy, and are particularly useful for lowering the threshold voltage of liquid crystal compositions. These compounds are also used for expanding the nematic range such as for adjusting values of refractive index anisotropy and elevating clearing points. Furthermore, these compounds are used for improving the steepness of the V-T (voltage-transmissivity) curve of liquid crystal compositions for STN or TN displays.
The compounds represented by general formulas (5) and (6) are particularly useful for preparing liquid crystal compositions for STN or TN displays.
Increasing the quantity of the compounds represented by general formulas (5) and (6) has the effect of lowering the threshold voltage of the liquid crystal composition and increasing its viscosity. Therefore, use of a large amount of these compounds is advantageous for producing display element having low driving voltage, so long as the viscosity of the liquid crystal composition satisfies requirements. In preparing liquid crystal compositions for STN or TN displays, the total content of the compounds represented by general formulas (5) and (6) may be 0.1 and 99.9% by weight, preferably 10 to 97% by weight, and more preferably 40 to 95% by weight.
Among the compounds represented by general formulas (7) through (9), compounds represented by the following general formulas (7-1) through (9-6) are particularly preferred: where, R5 and R6 have the same meanings as described above.













The compounds represented by general formulas (7) through (9) have small absolute values of dielectric anisotropy, and are nearly neutral. The compounds represented by the general formula (7) are mainly used for adjusting the viscosity or refractive index of anisotropy of liquid crystal compositions. The compounds represented by the general formulas (8) and (9) are used for expanding the nematic range by, for example, elevating the clearing point of liquid crystal composition, or for adjusting the refractive index of anisotropy.
Increase in the content of the compounds represented by general formulas (7) through (9) has the effects of increasing the threshold voltage and decreasing the viscosity of liquid crystal compositions. Therefore, these compounds are preferably used in a large amount, so long as the threshold voltage of liquid crystal compositions satisfy requirements.
When a liquid crystal composition for TFT displays is prepared, the content of the compounds represented by general formulas (7) through (9) is preferably 40% by weight or less, more preferably 35% by weight or less with respect to the liquid crystal composition. When a liquid crystal composition for STN or TN displays is prepared, the content of the compounds represented by general formulas (7) through (9) is preferably 70% by weight or less, more preferably 60% by weight or less with respect to the entirety of the liquid crystal composition.
Among the compounds represented by general formulas (10) through (12), compounds represented by the following general formulas (10-1) through (12-3) are particularly preferred; where, R7 and R8 have the same meanings as described above.







The compounds represented by general formulas (10) through (12) have negative values of dielectric anisotropy. The compounds represented by the general formula (10) are two-ring compounds, and are mainly used for adjusting threshold voltage, viscosity, and refractive index of anisotropy. The compounds represented by general formula (11) are used for expanding the nemetic range; for example, for raising the clearing point, or for adjusting refractive index of anisotropy. The compounds represented by general formula (12) are used for expanding the nemetic range, as well as for lowering threshold voltage and increasing refractive index of anisotropy.
Although the compounds represented by general formulas (10) through (12) are used in N-type compositions (i.e., composition having a negative value of dielectric anisotropy Δε), increase in their content has the effect of lowering the threshold voltage of the composition and increasing viscosity. Therefore, these compounds are preferably used in small amounts, so long as the threshold voltage of the liquid crystal composition satisfies requirements. However, since these compounds have absolute values of dielectric anisotropy of 5 or smaller, attaining a low driving voltage may become impossible if the content is less than 40% by weight.
When an N-type liquid crystal composition for TFT displays is prepared, the total content of the compounds represented by general formulas (10) through (12) is preferably 40% by weight or more, more preferably 50 to 95% by weight.
The compounds represented by general formulas (10) through (12) may also be added to a P-type liquid crystal composition (i.e., a compound having a positive value of dielectric anisotropy Δε) for controlling the elastic modulus of the liquid crystal composition, and for controlling the voltage-transmissivity curve (V-T curve). In such a case, the total content of the compounds represented by general formulas (10) through (12) is preferably 30% by weight or less.
In the liquid crystal composition of the present invention, an optically active compound is added so as to induce the helical structure of the liquid crystal composition for adjustment of twist angle and prevention of reverse twist, except for special cases such as liquid crystal compositions for OCB (optically compensated birefringence) mode displays. Although the optically active compounds added to the liquid crystal compositions of the present invention may be any known optically active compounds used for such a purpose, preferred examples include the following optically active compounds:







These optically active compounds are usually added to the liquid crystal composition of the present invention so as to adjust the pitch of the twist. The pitch of the twist is preferably adjusted within a range of 40 to 200 μm for liquid crystal compositions for TFT and TN displays, and within a range of 6 to 20 μm for liquid crystal compositions for STN displays. In the case of bistable TN-mode displays, the pitch of the twist is preferably adjusted within a range of 1.5 to 4 μm. Two or more optically active compounds may be added for adjustment of the temperature dependence of the pitch.
The liquid crystal composition of the present invention itself is prepared by conventional methods. In a typically adopted method, various components are mutually dissolved at high temperature.
The liquid crystal composition used according to the present invention can also be used as a liquid crystal composition for Guest-Host-mode (GH) displays by addition of merocyanine-, styryl-, azo-, azomethine-, azoxy-, quinophthalone-, anthraquinone-, or tetrazine-based dichroic colorants. It can also be used as the liquid crystal composition for NCAP produced by the micro-encapsulation of nematic liquid crystals, or for a Polymer Dispersed Liquid Crystal Display device (PDLCD) in which a three-dimensional polymer matrix is formed in liquid crystals. In addition, it can also be used as liquid crystal compositions for Electrically Controlled Birefringence mode (ECB) or Dynamic Scattering mode (DS) liquid crystal displays.
Method for Preparation of the Compounds
The compounds represented by the general formula (1) can be prepared easily by using of typical methods for synthesizing organic chemicals. For example, the compounds can be synthesized by selection and combination of well-known reactions described in literatures or magazines such as Organic Synthesis, Organic Reactions and Shin Zikken Kagaku Koza. Typical routes of synthesis will be described with reference to the following reaction formulas.
In the following reaction formulas, each of MSG1 through MSG5 independently represents a residual group of an organic compound; Hal represents Cl, Br or I; ring A represents trans-1,4-cyclohexylene group, 1,4-phenylene group in which one or more hydrogen on the six-member ring may be substituted by halogen, pyrimidine-2,5-diyl group, pyridine-2,5-diyl group, 1,3-dioxane-2,5-diyl group, tetrahydropyrane-2,5-diyl group, 1,3-dithiane-2,5-diyl group or tetrahydrothiopyrane-2,5-diyl group; Q1 represents hydrogen, an alkyl group having 1 to 13 carbon atoms in which each of optional nonadjacent methylene groups may be substituted by oxygen or an alkenyl group having 2 to 13 carbon atoms; and p represents 0 or 1.
In order to introduce an alkenyl group into a molecule, the following method can be used. That is, Wittig's reagent (12) is allowed to react with a ketone derivative or an aldehyde derivative (11) in the presence of a base such as sodium methylate, potassium-t-butoxide (t-BuOK), and butyl lithium, in an ether-based solvent such as tetrahydrofuran (abbreviated as THF) or diethyl ether to form a compound (13). When Q1 is an alkyl group or an alkenyl group described above, a trans-type isomer (14) can be formed by isomerizing the compound (13) with a benzenesulfinate or p-toluenesulfinate.
In order to introduce an alkenyl group of a desired chain length in a molecule, the following method can be used. In the same manner as described above, Wittig's reagent (16) is allowed to react with a ketone derivative (15) in an ether-based solvent in the presence of a base to form a compound (17). Next, the compound (17) is allowed to react with a mineral acid such as hydrochloric acid or sulfuric acid, or an organic acid such as formic acid or p-toluene sulfonic acid to form an aldehyde derivative (18).
Furthermore, in the same manner as described above, Wittig's reagent (20) is allowed to react with a ketone derivative (19) in the presence of a base to form a compound (21). Next, the compound (21) is subjected to hydrogen reduction in a toluene/Solmix mixed solvent in the presence of a metallic catalyst such as palladium/carbon or Raney nickel, and is allowed to react with a mineral acid such as hydrochloric acid or sulfuric acid, or an organic acid such as formic acid or p-toluene sulfonic acid to form an aldehyde derivative (22) These processes may be repeated as required.
The thus-obtained aldehyde derivative (18) or aldehyde derivative (22) is subjected to the same procedures for obtaining the compound (14) from the aldehyde derivative (11) to form a compound having an alkenyl group of a desired chain length.




In order to introduce 2,3-difluoro-1,4-phenylene group in a molecule, the following reactions can be utilized.
When 2,3-difluoro-1,4-phenylene group is introduced into a benzene derivative MSG4 at the 4-position, a difluorobenzene derivative (31) is sequentially allowed to react with n-butyl lithium or sec-butyl lithium, then with zinc chloride, in an ether-based solvent such as THF and diethyl ether, and further subjected to a coupling reaction with 2,3-difluoro-1-bromobenzene in the presence of a metallic catalyst of palladium (0) to form a compound (32).
When a 2,3-difluoro-1,4-phenylene group is introduced into the ketone site of a cyclohexanone derivative having MSG4 at the 4-position, the cyclohexanone derivative (33) is allowed to react with a Grignard reagent (34) to cause a Grignard reaction, dehydrated in the presence of an acid catalyst, and subjected to hydrogen reduction to form a compound (35).




Compounds represented by general formula (1) in which rings A1, A2 and A3 are silacyclohexane rings can be prepared by methods disclosed in Japanese Patent Application Laid Open Nos. 7-70148, 7-112990, and 7-149770; that is, a method in which a silacyclohexane compound is subjected to a coupling reaction with a corresponding organic metal reagent, or a method in which a metal is allowed to react with a compound having both a corresponding silane site and a halogen site to cause reaction in which a silicon-carbon bond is formed within the molecule.
The compound (1) described in the present application can be formed by appropriate selection of the above reactions.


EXAMPLES
The present invention will be described in further detail referring to examples; however, the present invention is by no means limited by these examples. The structures of compounds were identified by nuclear magnetic resonance spectrometry or mass spectrometry (abbreviated as MS). In these examples, M+ in MS represents the molecular ion peak, C represents the crystal phase, SA the smectic A phase, SB the smectic B phase, N the nematic phase, Iso the isotropic liquid phase, and ( ) indicate the monotropic liquid crystal phase. All phase transition temperatures are expressed in terms of ° C.
Example 1
Synthesis of 2,3-difluoro-1-ethoxy-4-(trans-4-(3-butenyl)-cyclohexyl) benzene (compound (No. 8) represented by general formula (1) in which each of R1 and X1 is hydrogen, ring A1 is trans-1,4-cyclohexylene group, Y1 is ethoxy group, 1 is 2, and each of m and n is 0)
Step 1
Under a nitrogen flow, 141 mmol of 1-ethoxy-2,3-difluorobenzen was dissolved in 200 ml of THF, and the resultant solution was cooled to −70° C. While the same temperature was maintained, 130 ml of sec-butyl lithium (1.3 M, cyclohexane solution) was added dropwise, and the resultant solution was stirred for 1 hour at the same temperature. A solution of 128 mmol of 1,4-cyclohexanedione monoethlylene acetal dissolved in 200 ml of THF was added dropwise while the same temperature was maintained, and the resultant solution was further stirred for 1 hour at the same temperature. The reaction temperature was then gradually elevated to room temperature, after which the solution was stirred for 2 hours at room temperature. The reaction was terminated by gradual addition of the reaction mixture into 500 ml of water. The water layer was extracted by 500 ml of toluene, and the organic layer was washed with 500 ml of water three times and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure, the residue was dissolved in 300 ml of toluene, 1.5 g of p-toluenesulfonic acid monohydride was added, and the solution was heated to reflux for 1 hour. The organic layer was washed three times with 300 ml of water, and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure, the residue was subjected to silica gel column chromatography (eluent: a mixed solvent of ethyl acetate/toluene=3/7), and the solvent was distilled off under reduced pressure. The residue was dissolved in 200 ml of a mixed solvent of toluene/ethanol (1/1), 4.0 g of 5-wt %-palladium/carbon catalyst, and the solution was stirred for 6 hours at room temperature under a hydrogen pressure of 1–2 kg/cm2. After the catalyst was filtered off, the solvent was distilled off from the filtrate under reduced pressure, the residue was subjected to silica gel column chromatography (eluent: ethyl acetate/toluene=3/7), and the solvent was distilled off under reduced pressure, to form crude 4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexane monoethylene acetal.
Step 2
Crude 4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexanone monoethylene acetal (50.3 mmol) obtained in Step 1 was dissolved in 200 ml of toluene, 87% formic acid (503 mmol) was added, and the solution was heated to reflux for 4 hours. The reaction solution was washed twice with 100 ml of a saturated aqueous solution of sodium hydrogen carbonate, then three times with 100 ml of water, and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure, to form crude 4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexanone (50.3 mmol).
Step 3
A mixture of 2-(1,3-dioxane-2-yl)-ethyltriphenyl phosphonium bromide (60.4 mmol) and 30 ml of THF was cooled down to −30° C. by use of a refrigerant under a nitrogen flow. To this mixture, t-BuOK (60.4 mmol) was added, and the mixture was stirred for one hour. A solution of the crude 4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexanone (50.3 mmol) dissolved in 100 ml of THF was added dropwise to this mixture while temperature was maintained at −30° C. or below. After completion of the addition, the reaction temperature was gradually elevated to room temperature, and the mixture was stirred for 2 hours. The reaction mixture was filtered with celite, the solvent was distilled off under reduced pressure, the residue was subjected to silica gel column chromatography (eluent: a mixed solvent of ethyl acetate/toluene=3/7), the solvent was distilled off under reduced pressure, and the product was re-crystallized from heptane to form 2-(2-(4-(2,3-difluoro-4-ethoxyphenyl)cyclohexylidene)-ethyl)-1,3-dioxane (36.9 mmol).
Step 4
The 2-(2-(4-(2,3-difluoro-4-ethoxyphenyl)cyclohexylidene)-ethyl)-1,3-dioxane (36.9 mmol) obtained by the reaction of Step 3 was dissolved in 100 ml of a mixed solvent of toluene/ethanol (1/1), 4.0 g of 5-wt %-palladium/carbon catalyst was added, and the solution was stirred for 7 hours at room temperature under a hydrogen pressure of 1–2 kg/cm2. After the catalyst was filtered off, the solvent was distilled off from the filtrate under reduced pressure, the residue was subjected to silica gel column chromatography (eluent: a mixed solvent of ethyl acetate/toluene=3/7), the solvent was distilled off under reduced pressure, and the product was re-crystallized from ethanol to form 2-(2-(trans-4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexyl)-ethyl)-1,3-dioxane (36.9 mmol).
Step 5
The 2-(2-(trans-4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexyl)-ethyl)-1,3-dioxane (19.8 mmol) obtained by the reaction of Step 4 was dissolved in 100 ml of toluene, 87% formic acid (198 mmol) was added, and the solution was heated to reflux for 4 hours. The reaction solution was twice washed with 50 ml of a saturated aqueous solution of sodium hydrogen carbonate, then three times with 50 ml of water, and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure, to form crude 3-(trans-4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexyl)-propanal (19.8 mmol).
Step 6
A mixture of methyltriphenyl phosphonium bromide (23.8 mmol) and 50 ml of THF was cooled to −30° C. by use of a refrigerant under a nitrogen flow. To this mixture, t-BuOK (23.8 mmol) was added and the mixture was stirred for one hour. A solution of the crude 3-(trans-4-(2,3-difluoro-4-ethoxyphenyl)-cyclohexyl)-propanal (19.8 mmol) and dissolved in 50 ml of THF was added dropwise to this mixture while temperature was maintained at −30° C. or below. After the addition was completed, the reaction temperature was gradually elevated to room temperature, and the mixture was stirred for 2 additional hours. The reaction mixture was filtered with celite, the solvent was distilled off under reduced pressure, the residue was subjected to silica gel column chromatography (eluent: a mixed solvent of ethyl acetate/heptane=1/1), the solvent was distilled off under reduced pressure, and the product was re-crystallized from ethanol to form the target compound (9.51 mmol).
Various spectra confirmed the structure of this product.

    
    
        MS:m/e=294 (M+)
        Phase transition temperature: C 39.4 Iso
    
    


In the similar processes as with Example 1, the following compounds can be prepared.














compoundNO.1






 


compoundNO.2






 


compoundNO.3




C 34.0 Iso(° C.)


 


compoundNO.4






 


compoundNO.5






 


compoundNO.6




C 40.8 Iso(° C.)


 


compoundNO.7






 


compoundNO.8




C 39.4 Iso(° C.)


 


compoundNO.9






 


compoundNO.10






 


compoundNO.11




C 27.1 Iso(° C.)


 


compoundNO.12






 


compoundNO.13




C 22.7 Iso(° C.)


 


compoundNO.14






 


compoundNO.15






 


compoundNO.16






 


compoundNO.17






 


compoundNO.18






 


compoundNO.19






 


compoundNO.20






 


compoundNO.21






 


compoundNO.22






 


compoundNO.23






 


compoundNO.24






 


compoundNO.25






 


compoundNO.26






 


compoundNO.27






 


compoundNO.28






 


compoundNO.29






 


compoundNO.30






 


compoundNO.31




C 86.7 N 162.8Iso(° C.)


 


compoundNO.32






 


compoundNO.33




C 76.8 (SB 62.0)N 172.0 Iso(° C.)


 


compoundNO.34






 


compoundNO.35






 


compoundNO.36




C 80.6 N 169.2Iso(° C.)


 


compoundNO.37






 


compoundNO.38




C 80.0 (SB 71.8)N 184.8 Iso(° C.)


 


compoundNO.39






 


compoundNO.40






 


compoundNO.41






 


compoundNO.42






 


compoundNO.43




C 55.7 SB 98.3N 172.5 Iso(° C.)


 


compoundNO.44






 


compoundNO.45






 


compoundNO.46




C 42.6 N 145.5Iso(° C.)


 


compoundNO.47






 


compoundNO.48






 


compoundNO.49






 


compoundNO.50






 


compoundNO.51






 


compoundNO.52






 


compoundNO.53






 


compoundNO.54






 


compoundNO.55






 


compoundNO.56






 


compoundNO.57






 


compoundNO.58






 


compoundNO.59






 


compoundNO.60






 


compoundNO.61






 


compoundNO.62






 


compoundNO.63






 


compoundNO.64






 


compoundNO.65






 


compoundNO.66






 


compoundNO.67






 


compoundNO.68






 


compoundNO.69






 


compoundNO.70






 


compoundNO.71






 


compoundNO.72






 


compoundNO.73






 


compoundNO.74






 


compoundNO.75






 


compoundNO.76






 


compoundNO.77






 


compoundNO.78






 


compoundNO.79






 


compoundNO.80






 


compoundNO.81






 


compoundNO.82






 


compoundNO.83






 


compoundNO.84






 


compoundNO.85






 


compoundNO.86






 


compoundNO.87






 


compoundNO.88






 


compoundNO.89






 


compoundNO.90






 


compoundNO.91






 


compoundNO.92






 


compoundNO.93






 


compoundNO.94






 


compoundNO.95






 


compoundNO.96






 


compoundNO.97






 


compoundNO.98






 


compoundNO.99






 


compoundNO.100






 


compoundNO.101






 


compoundNO.102






 


compoundNO.103






 


compoundNO.104






 


compoundNO.105






 


compoundNO.106






 


compoundNO.107






 


compoundNO.108






 


compoundNO.109






 


compoundNO.110






 


compoundNO.111






 


compoundNO.112






 


compoundNO.113






 


compoundNO.114






 


compoundNO.115






 


compoundNO.116






 


compoundNO.117






 


compoundNO.118






 


compoundNO.119






 


compoundNO.120






 


compoundNO.121






 


compoundNO.122






 


compoundNO.123






 


compoundNO.124






 


compoundNO.125






 


compoundNO.126






 


compoundNO.127






 


compoundNO.128






 


compoundNO.129






 


compoundNO.130






 


compoundNO.131






 


compoundNO.132






 


compoundNO.133






 


compoundNO.134






 


compoundNO.135






 


compoundNO.136






 


compoundNO.137






 


compoundNO.138






 


compoundNO.139






 


compoundNO.140






 


compoundNO.141






 


compoundNO.142






 


compoundNO.143






 


compoundNO.144






 


compoundNO.145






 


compoundNO.146






 


compoundNO.147






 


compoundNO.148






 


compoundNO.149






 


compoundNO.150






 


compoundNO.151






 


compoundNO.152






 


compoundNO.153






 


compoundNO.154






 


CompoundNO.155






 


compoundNO.156






 


compoundNO.157






 


compoundNO.158






 


compoundNO.159






 


compoundNO.160






 


compoundNO.161






 


compoundNO.162






 


compoundNO.163






 


compoundNO.164






 


compoundNO.165






 


compoundNO.166






 


compoundNO.167






 


compoundNO.168






 


compoundNO.169






 


compoundNO.170






 


compoundNO.171






 


compoundNO.172






 


compoundNO.173






 


compoundNO.174






 


compoundNO.175






 


compoundNO.176






 


compoundNO.177






 


compoundNO.178






 


compoundNO.179






 


compoundNO.180






 


compoundNO.181






 


compoundNO.182






 


compoundNO.183






 


compoundNO.184






 


compoundNO.185






 


compoundNO.186






 


compoundNO.187






 


compoundNO.188






 


compoundNO.189






 


compoundNO.190






 


compoundNO.191






 


compoundNO.192






 


compoundNO.193






 


compoundNO.194






 


compoundNO.195






 


compoundNO.196






 


compoundNO.197






 


compoundNO.198






 


compoundNO.199






 


compoundNO.200






 


compoundNO.201






 


compoundNO.202






 


compoundNO.203






 


compoundNO.204






 


compoundNO.205






 


compoundNO.206






 


compoundNO.207






 


compoundNO.208






 


compoundNO.209






 


compoundNO.210






 


compoundNO.211






 


compoundNO.212






 


compoundNO.213






 


compoundNO.214






 


compoundNO.215






 


compoundNO.216






 


compoundNO.217






 


compoundNO.218






 


compoundNO.219






 


compoundNO.220






 


compoundNO.221






 


compoundNO.222






 


compoundNO.223






 


compoundNO.224






 


compoundNO.225






 


compoundNO.226






 


compoundNO.227






 


compoundNO.228






 


compoundNO.229






 


compoundNO.230






 


compoundNO.231






 


compoundNO.232






 


compoundNO.233






 


compoundNO.234






 


compoundNO.235






 


compoundNO.236






 


compoundNO.237






 


compoundNO.238






 


compoundNO.239






 


compoundNO.240






 


compoundNO.241






 


compoundNO.242






 


compoundNO.243






 


compoundNO.244






 


compoundNO.245






 


compoundNO.246






 


compoundNO.247






 


compoundNO.248






 


compoundNO.249






 


compoundNO.250






 


compoundNO.251






 


compoundNO.252






 


compoundNO.253






 


compoundNO.254






 


compoundNO.255






 


compoundNO.256






 


compoundNO.257






 


compoundNO.258






 


compoundNO.259






 


compoundNO.260






 


compoundNO.261






 


compoundNO.262






 


compoundNO.263






 


compoundNO.264






 


compoundNO.265






 


compoundNO.266






 


compoundNO.267






 


compoundNO.268






 


compoundNO.269






 


compoundNO.270






 


compoundNO.271






 


compoundNO.272






 


compoundNO.273






 


compoundNO.274






 


compoundNO.275






 


compoundNO.276






 


compoundNO.277






 


compoundNO.278






 


compoundNO.279






 


compoundNO.280






 


compoundNO.281






 


compoundNO.282






 


compoundNO.283






 


compoundNO.284






 


compoundNO.285






 


compoundNO.286






 


compoundNO.287






 


compoundNO.288






 


compoundNO.289






 


compoundNO.290






 


compoundNO.291






 


compoundNO.292






 


compoundNO.293






 


compoundNO.294






 


compoundNO.295






 


compoundNO.296






 


compoundNO.297






 


compoundNO.298






 


compoundNO.299






 


compoundNO.300






 


compoundNO.301




C 50.44 Iso(° C.)


 


compoundNO.302






 


compoundNO.303






 


compoundNO.304






 


compoundNO.305






 


compoundNO.306






 


compoundNO.307






 


compoundNO.308






 


compoundNO.309






 


compoundNO.310






 


compoundNO.311






 


compoundNO.312






 


compoundNO.313






 


compoundNO.314






 


compoundNO.315













Examples of nematic liquid crystal compositions containing Examples of nematic liquid crystal compositions containing the liquid crystalline compounds of the present invention are shown below. In these example compositions, the notations of the compounds follow the definitions shown in Table 1, and their proportions are shown in terms of percent by weight.
Viscosity (η) was measured at 20.0° C., and refraction index of anisotropy (Δn), value of dielectric anisotropy (Δε), threshold voltage (Vth), and twist pitch (P) were measured at 25.0° C.
Neither appearance of the smectic phase nor precipitation of crystals was observed in any of the following compounds, even after the compounds were allowed to stand for 40 days in a freezer at a temperature of −20° C.







TABLE 1





Description method of compounds using marks.


R—(A1)—Z1— - - - —Zn—(An)—X


















1) Left end groups R—
Marks







CnH2n+1—
n-



CnH2n+1O—
nO—



CnH2n+1OCmH2m—
nOm-



CH2═CH—
V-



CH2═CHCnH2n—
Vn-



CnH2n+1CH═CHCmH2m—
nVm-



CnH2n+1CH═CHCmH2mCH═CHCkH2k—
nVmVk-



CF2═CH—
VFF-







2) Ring structures —(A1)—, —(An)—
Marks











B



 







B(F)



 







B(2F)



 







B(2F,3F)



 







B(2F,5F)



 







B(2CN,3CN)



 







B(F,F)



 







H



 







Py



 







Pr(F)







3) Bonding groups —Z1—, —Zn—
Marks







—C2H4—
2



—C4H8—
4



—COO—
E



—C≡C—
T



—CH═CH—
V



—CF2O—
CF2O



—OCF2—
OCF2







4) Right end groups —X—
Marks







—F
—F



—Cl
—CL



—CN
—C



—CF3
—CF3



—OCF3
—OCF3



—OCF2H
—OCF2H



—CnH2n+1
-n



—OCnH2n+1
—On



—COOCH3
—EMe



—CnH2nCH═CH2
-n V



—CmH2mCH═CHCnH2n+1
-mVn



—CmH2mCH═CHCnH2nF
-mVnF



—CH═CF2
-VFF



—CnH2nCH═CF2
-nVFF











5) Examples of description





Example 1 3-H2B(F,F)B(F)-F








 


Example 2 3-HB(F)TB-2








 


Example 3 1V2-BEB(F,F)-C















Example 2
Composition Example 1

















V-HB(2F,3F)-O2
(No. 6)
15.0%



3-HEB-O2

12.9%



3-HEB-O4

20.7%



4-HEB-O2

15.5%



5-HEB-O1

15.5%



3-HEB-O2

10.4%



TNI = 60.0 (° C.)



η = 20.0 (mPa · C.)



Δn = 0.085



Δε = −2.0










Example 3
Composition Example 2

















V2-HB(2F,3F)-O2
(No. 8)
15.0%



3-HEB-O2

12.9%



3-HEB-O4

20.7%



4-HEB-O2

15.5%



5-HEB-O1




3-HEB-O2

10.4%



TNI = 64.0 (° C.)



η = 20.1 (mPa · s)



Δn = 0.086



Δε = −2.1










Example 4
Composition Example 3

















V-HB(2F,3F)-O3
(No. 11)
15.0%



3-HEB-O2

12.9%



3-HEB-O4

20.7%



4-HEB-O2

15.5%



5-HEB-O1

15.5%



3-HEB-O2

10.4%



TNI = 58.6 (° C.)



η = 20.1 (mPa · s)



Δn = 0.082



Δε = −2.0










Example 5
Composition Example 4

















V-HHB(2F,3F)-O1
(No. 31)
15.0%



3-HEB-O2

12.9%



3-HEB-O4

20.7%



4-HEB-O2

15.5%



5-HEB-O1

15.5%



3-HEB-O2

10.4%



TNI = 82.1 (° C.)



η = 22.4 (mPa · s)



Δn = 0.090



Δε = −2.1










Example 6
Composition Example 5

















V2-HHB(2F,3F)-O1
(No. 33)
15.0%



3-HEB-O2

12.9%



3-HEB-O4

20.7%



4-HEB-O2

15.5%



5-HEB-O1

15.5%



3-HEB-O2

10.4%



TNI = 83.3 (° C.)



η = 22.0 (mpa · s)



Δn = 0.089



Δε = −2.0










Example 7
Composition Example 6

















V-HHB(2F,3F)-O2
(No. 36)
15.0%



3-HEB-O2

12.9%



3-HEB-O4

20.7%



4-HEB-O2

15.5%



5-HEB-O1

15.5%



3-HEB-O2

10.4%



TNI = 84.7 (° C.)



η = 21.7 (mPa · s)



Δn = 0.092



Δε = −2.0










Example 8
Composition Example 7

















V2-HHB(2F,3F)-O2
(No. 38)
15.0%



3-HEB-O2

12.9%



3-HEB-O4

20.7%



4-HEB-O2

15.5%



5-HEB-O1

15.5%



3-HEB-O2

10.4%



TNI = 87.1 (° C.)



η = 21.4 (mPa · s)



Δn = 0.092



Δε = −1.7










Example 9
Composition Example 8

















VFF-HB(2F,3F)-O2
(No. 301)
15.0%



3-HEB-O2

12.9%



3-HEB-O4

20.7%



4-HEB-O2

15.5%



5-HEB-O1

15.5%



3-HEB-O2

10.4%



TNI = 62.0 (° C.)



η = 21.3 (mpa · s)



Δn = 0.084



Δε = −1.9










Example 10
Composition Example 9

















V2-HB(2F,3F)-O2
(No. 8)
14.0%



V2-HHB (2F, 3F)-O1
(No. 33)
14.0%



4-HEB-O2

20.0%



5-HEB-O1

20.0%



3-HEB-O2

18.0%



5-HEB-O2

14.0%



TNI = 79.7 (° C.)



η = 22.7 (mPa · s)



Δn = 0.097



Δε = −2.5










Example 11
Composition Example 10

















V-HB(2F,3F)-O3
(No. 11)
8.0%



V2-HB(2F,3F)-O2
(No. 8)
8.0%



V2-HHB(2F,3F)-O2
(No. 38)
8.0%



3-HH-2

5.0%



3-HH-4

6.0%



3-HH-O1

4.0%



3-HH-O3

5.0%



5-HH-O1

4.0%



3-HB(2F,3F)-O2

12.0%



5-HB(2F,3F)-O2

11.0%



3-HHB(2F,3F)-O2

14.0%



5-HHB(2F,3F)-O2

15.0%



TNI = 71.7 (° C.)



Δn = 0.079



Δε = −4.4










Example 12
Composition Example 11

















V-HHB(2F,3F)-O1
(No. 31)
4.0%



V-HHB(2F,3F)-O2
(No. 36)
4.0%



3-HH-4

5.0%



3-HH-5

5.0%



3-HH-O1

6.0%



3-HH-O3

6.0%



3-HB-O1

5.0%



3-HB-O2

5.0%



3-HB(2F,3F)-O2

10.0%



5-HB(2F,3F)-O2

10.0%



3-HHB(2F,3F)-O2

12.0%



5-HHB(2F,3F)-O2

13.0%



3-HHEH-3

5.0%



3-HHEH-5

5.0%



4-HHEH-3

5.0%



TNI = 89.1 (° C).



Δn = 0.079



Δε = −3.3










Example 13
Composition Example 12

















V-HHB(2F,3F)-O1
(No. 31)
4.0%



3-BB(2F,3F)-O2

12.0%



3-BB(2F,3F)-O4

10.0%



5-BB(2F,3F)-O4

10.0%



2-BB(2F,3F)B-3

25.0%



3-BB(2F,3F)B-5

13.0%



5-BB(2F,3F)B-5

14.0%



5-BB(2F,3F)B-7

12.0%



TNI = 73.9 (° C.)



Δn = 0.194



Δε = −3.5










Example 14
Composition Example 13

















V-HB(2F,3F)-O2
(No. 6)
6.0%



3-BB(2F,3F)-O2

10.0%



5-BB-5

9.0%



5-BB-O6

9.0%



5-BB-O8

8.0%



3-BEB-5

6.0%



5-BEB-5

3.0%



3-HEB-O2

20.0%



5-BBB(2F,3F)-7

9.0%



3-H2BB(2F)-5

20.0%



TNI = 71.6 (° C.)



Δn = 0.146



Δε = −3.3










Example 15
Composition Example 14

















V-HB(2F,3F)-O3
(No. 11)
5.0%



V2-HB(2F,3F)-O2
(No. 8)
5.0%



V-HHB(2F,3F)-O2
(No. 36)
5.0%



3-HB-O2

6.0%



3-HEB(2F,3F)-O2

9.0%



4-HEB(2F,3F)-O2

9.0%



5-HEB(2F,3F)-O2

9.0%



2-BB2B-O2

6.0%



3-BB2B-O2

6.0%



5-BB2B-O1

6.0%



5-BB2B-O2

6.0%



1-B2BB(2F)-5

7.0%



3-B2BB(2F)-5

7.0%



5-B(F)BB-O2

7.0%



3-BB(2F,3F)B-3

7.0%



TNI = 81.6 (° C.)



η = 29.0 (mPa · s)



Δn = 0.162



Δε = −2.7










Example 16
Composition Example 15

















V2-HB(2F,3F)-O2
(No. 8)
9.0%



V-HHB(2F,3F)-O2
(No. 36)
9.0%



3-HB-O2

9.0%



2-BTB-O1

5.0%



1-BTB-O2

5.0%



3-BTB(2F,3F)-O2

13.0%



5-BTB(2F,3F)-O2

13.0%



3-B(2F,3F)TB(2F,3F)-O4

4.0%



5-B(2F,3F)TB(2F,3F)-O4

4.0%



3-HBTB-O1

5.0%



3-HBTB-O2

5.0%



3-HBTB-O3

5.0%



3-HHB(2F,3F)-O2

6.0%



5-HBB(2F,3F)-O2

5.0%



5-BPr(F)-O2

3.0%



TNI = 95.0 (° C.)



η = 30.2 (mpa · s)



Δn = 0.223










Example 17
Composition Example 16

















V-HB(2F,3F)-O3
(No. 11)
10.0%



V2-HB(2F,3F)-O2
(No. 8)
6.0%



V-HHB(2F,3F)-O1
(No. 31)
5.0%



V2-HHB(2F,3F)-O1
(No. 33)
6.0%



V2-HHB(2F,3F)-O2
(No. 38)
6.0%



3-HB-O2

4.0%



5-HB-3

8.0%



5-BB(2F,3F)-O2

10.0%



5-HB(2F,3F)-O2

8.0%



5-HHB(2F,3F)-O2

4.0%



5-HHB(2F,3F)-1O1

4.0%



3-HHB(2F,3F)-1

5.0%



3-HBB-2

6.0%



3-BB(2F,3F)B-3

8.0%



5-B2BB(2F,3F)-O2

10.0%



TNI = 72.3 (° C.)



Δn = 0.128



Δε = −4.2










Example 18
Composition Example 17

















V-HB(2F,3F)-O2
(No. 6)
9.0%



V-HHB(2F,3F)-O2
(No. 36)
3.0%



V2-HHB(2F,3F)-O1
(No. 33)
3.0%



V2-HHB(2F,3F)-O2
(No. 38)
7.0%



3-HB-O2

20.0%



1O1-HH-3

6.0%



1O1-HH-5

5.0%



3-HH-EMe

12.0%



5-HEB-O1

8.0%



3-HHB-1

6.0%



3-HHB-3

6.0%



3-HEB(2CN,3CN)-O5

4.0%



4-HEB(2CN,3CN)-O5

3.0%



5-HEB(2CN,3CN)-O5

2.0%



2-HBEB(2CN,3CN)-O2

2.0%



4-HBEB(2CN,3CN)-O4

4.0%



TNI = 75.8 (° C.)



η = 33.2 (mPa · s)



Δn = 0.087



Δε = −6.3










Example 19
Composition Example 18

















V-HB(2F,3F)-O2
(No. 6)
5.0%



V2-HHB(2F,3F)-O2
(No. 38)
3.0%



1V2-BEB(F,F)-C

5.0%



3-HB-C

20.0%



V2-HB-C

6.0%



2-BTB-1

10.0%



1O1-HH-3

3.0%



3-HH-4

11.0%



3-HHB-1

11.0%



3-H2BTB-2

4.0%



3-H2BTB-3

4.0%



3-H2BTB-4

4.0%



3-HB(F)TB-2

6.0%



3-HB(F)TB-3

5.0%



3-HHB-C

3.0%



TNI = 89.0 (° C.)



η = 17.3 (mPa · s)



Δn = 0.154



Δε = 6.7



Vth = 2.19 (V)










The pitch of the composition produced by adding 0.8 part by weight of an optically active compound CM33 to 100 parts by weight of the above composition was, P=11.3 μm.
Example 20
Composition Example 19

















V-HHB(2F,3F)-O1
(No. 31)
3.0%



V-HHB(2F,3F)-O2
(No. 36)
3.0%



2O1-BEB(F)-C

5.0%



3O1-BEB(F)-C

12.0%



5O1-BEB(F)-C

4.0%



1V2-BEB(F,F)-C

10.0%



3-HEB-O4

4.0%



3-HH-EMe

6.0%



3-HB-O2

18.0%



7-HEB-F

2.0%



7-HHEB-F

2.0%



5-HHEB-F

2.0%



3-HBEB-F

4.0%



2O1-HBEB(F)-C

2.0%



3-HB(F)EB(F)-C

2.0%



3-HBEB(F,F)-C

2.0%



3-HHB-F

4.0%



3-HHB-O1

4.0%



3-HHB-3

3.0%



3-HEBEB-F

2.0%



3-HEBEB-1

2.0%



3-HHB(F)-C

4.0%



TNI = 76.4 (° C.)



η = 38.0 (mPa · s)



Δn = 0.117



Δε = 23.9



Vth = 1.12 (V)










Example 21
Composition Example 20

















V-HB(2F,3F)-O2
(No. 6)
5.0%



V-HB(2F,3F)-O3
(No. 11)
5.0%



V-HHB(2F,3F)-O1
(No. 31)
4.0%



V2-HHB(2F,3F)-O1
(No. 33)
4.0%



1V2-BEB(F,F)-C

6.0%



3-HB-C

18.0%



2-BTB-1

10.0%



5-HH-VFF

20.0%



1-BHH-VFF

8.0%



1-BHH-2VFF

11.0%



3-H2BTB-2

5.0%



3-HHB-1

4.0%



TNI = 71.8 (° C.)



η = 16.8 (mPa · s)



Δn = 0.123



Δε = 5.3



Vth = 2.51 (V)










Example 22
Composition Example 21

















V2-HHB(2F,3F)-O2
(No. 38)
10.0%



5-HB-F

12.0%



6-HB-F

9.0%



7-HB-F

7.0%



2-HHB-OCF3

7.0%



3-HRB-OCF3

7.0%



4-HHB-OCF3

7.0%



5-HHB-OCF3

5.0%



3-HH2B-OCF3

4.0%



5-HH2B-OCF3

4.0%



3-HHB(F,F)-OCF3

5.0%



3-HBB(F)-F

10.0%



3-HH2B(F)-F

3.0%



3-HB(F) BH-3

3.0%



5-HBBH-3

3.0%



3-HHB(F,F)-OCF2H

4.0%



TNI = 92.1 (° C.)



η = 15.8 (mPa · s)



Δn = 0.091



Δε = 3.3



Vth = 2.73 (V)










Example 23
Composition Example 22

















V-HHB(2F,3F)-O2
(No. 36)
5.0%



7-HB(F,F)-F

5.0%



3-H2HB(F,F)-F

12.0%



4-H2HB(F,F)-F

6.0%



3-HHB(F,F)-F

10.0%



3-HBB(F,F)-F

10.0%



3-HHEB(F,F)-F

10.0%



4-HHEB(F,F)-F

3.0%



5-HHEB(F,F)-F

3.0%



2-HBEB(F,F)-F

3.0%



3-HBEB(F,F)-F

5.0%



5-HBEB(F,F)-F

3.0%



3-HGB(F,F)-F

15.0%



3-HBCF2OB(F,F)-F

4.0%



3-HHBB(F,F)-F

6.0%



TNI = 80.1 (° C.)



η = 33.6 (mPa · s)



Δn = 0.087



Δε = 12.8



Vth = 1.51 (V)










The pitch of the composition produced by adding 0.3 part by weight of an optically active compound CN to 100 parts by weight of the above composition was, P=77.0 μm.
Example 24
Composition Example 23

















V-HHB(2F,3F)-O1
(No. 31)
5.0%



V2-HHB(2F,3F)-O1
(No. 33)
5.0%



2-HHB(F)-F

2.0%



3-HHB(F)-F

2.0%



5-HHB(F)-F

2.0%



2-HBB(F)-F

6.0%



3-HBB(F)-F

6.0%



2-H2BB(F)-F

9.0%



3-H2BB(F)-F

9.0%



3-HBB(F,F)-F

25.0%



5-HBB(F,F)-F

19.0%



1O1-HBBH-4

5.0%



1O1-HBBH-5

5.0%



TNI = 101.0 (° C.)



η = 35.8 (mPa · s)



Δn = 0.134



Δε = 6.1



Vth = 2.17 (V)










The pitch of the composition produced by adding 0.2 part by weight of an optically active compound CM43L to 100 parts by weight of the above composition was, P=77.7 μm.
Example 25
Composition Example 24

















V-HB(2F,3F)-O3
(No. 11)
15.0%



V2-HB(2F,3F)-O2
(No. 8)
15.0%



V-HHB(2F,3F)-O1
(No. 31)
10.0%



V2-HHB(2F,3F)-O1
(No. 33)
10.0%



V2-HHB(2F,3F)-O2
(No. 38)
10.0%



3-HH-EMe

25.0%



5-HH-EMe

15.0%










Example 26
Composition Example 25

















V-HB(2F,3F)-O3
(No. 11)
13.0%



V2-HB(2F,3F)-O2
(No. 8)
13.0%



V2-HHB(2F,3F)-O1
(No. 33)
10.0%



V2-HHB(2F,3F)-O2
(No. 38)
10.0%



3-HH-EMe

20.0%



5-HH-EMe

10.0%



3-HH-4

10.0%



3-HB-O2

5.0%



3-HHB-1

9.0%










Example 27
Composition Example 26

















V-HB(2F,3F)-O3
(No. 11)
12.0%



V2-HB(2F,3F)-O2
(No. 8)
12.0%



V-HHB(2F,3F)-O2
(No. 31)
8.0%



V2-HHB(2F,3F)-O1
(No. 33)
8.0%



3-HH-EMe

12.0%



5-HH-EMe

5.0%



3-HEB-O2

6.0%



3-HEB-O4

8.0%



4-HEB-O2

6.0%



5-HEB-O1

6.0%



5-HEB-O2

4.0%



3-HHB-1

13.0%










INDUSTRIAL APPLICABILITY
As seen from the above examples, the compound of the present invention which has two to four rings with containing an alkenyl group and 2,3-difluorophenyl group, has the following features:

    1) Exhibits a wide liquid crystal phase temperature range, as well as frequent appearance of the nematic phase;
    2) Significantly improves response speeds and lowers driving voltages in IPS and VA systems because of large negative Δε and low viscosity;
    3) Increases K33/K11 values and decreases Δε/ε⊥, improving the steepness of the V-T curve in the STN system; and
    4) Stable nematic liquid crystal compositions can be prepared therefrom without the precipitation of crystals or the appearance of the smectic phase even at extremely low temperature.


The compound of the present invention exhibits the above features 1) through 4), and provides novel liquid crystal compositions and liquid crystal diaplay devices that are stable against under the outside environment, and that can realize expansion of the usable temperature range, low voltage driving, and high response speed.

## Claims

1. A liquid crystal composition comprising at least two components, characterized by containing at least one liquid crystalline compound represented by the following general formula (1):




wherein
R1 represents hydrogen, fluorine, an alkyl group having 1 to 4 carbon atoms, or an alkenyl group having 2 to 4 carbon atoms;
each of rings A1, A2 and A3 independently represents trans-1,4-cyclohexylene group, 1,4-cyclohexenylene group, trans-1,4-silacyclohexylene group, 1,4-phenylene group, 2,3-difluoro-1,4-phenylene group, 2-fluoro-1,4-phenylene group, 3-fluoro-1,4-phenylene group, 1,3-dioxane-2,5-diyl group, tetrahydropyrane-2,5-diyl group, 1,3-dithiane-2,5-diyl group, or tetrahydro-thiopyrane-2,5-diyl group;
X1 represents hydrogen or fluorine;
Y1 represents hydrogen or an alkyl group having 1 to 10 carbon atoms, in which each of optional nonadjacent methylene groups (—CH2—) may be substituted by oxygen; λ represents an integer from 0 to 4, in which each of optional nonadjacent methylene groups in (—CH2—)l may be substituted by oxygen; and
each of m and n independently represents 0 or 1;
with the proviso that when Y1 represents ethoxy, one of m and n is 1 and the other is 0, A1 represents trans-1,4-cyclohexylene, A2 and A3 are 2,3-difluoro-1,4-phenylene or 3-fluoro-1,4-phenylene, X1 represents hydrogen, λ is 0 or 2, then R1 represents neither hydrogen nor methyl;
when Y1 represents ethoxy, one of m and n is 1 and the other is 0, A1 represents trans-1,4-cylclohexylene, A2 and A3 are 2-fluoro-1,4-phenylene, X1 represents hydrogen, R1 represents methyl, then λ is neither 0 nor 2; and
when ring A1 represents 1,4-phenylene group, 2,3-difluoro-1,4-phenylene group, 2-fluoro-1,4-phenylene, or 3-fluoro-1,4-phenylene group, λ is 1 to 4.

2. A liquid crystalline compound represented by the following general formula (1):




wherein
R1 represents hydrogen, fluorine, an alkyl group having 1 to 4 carbon atoms, or an alkenyl group having 2 to 4 carbon atoms;
each of rings A1, A2 and A3 independently represents trans-1,4-cyclohexylene group, 1,4-cyclohexenylene group, trans-1,4-silacyclohexylene group, 1,4-phenylene group, 2,3-difluoro-1,4-phenylene group, 2-fluoro-1,4-phenylene group, 3-fluoro-1,4-phenylene group, 1,3 -dioxane-2,5-diyl group, tetrahydropyrane-2,5-diyl group, 1,3-dithiane-2,5-diyl group, or tetrahydro-thiopyrane-2,5-diyl group;
X1 hydrogen or fluorine;
Y1 represents hydrogen or an alkyl group having 1 to 10 carbon atoms, in which each of optional nonadjacent methylene groups (—CH2—) may be substituted by oxygen; Λ represents an integer from 0 to 4, in which each of optional nonadjacent methylene groups in (—CH2—), may be substituted by oxygen; and each of m and n independently represents 0 or 1;
with the proviso that
when Y1 represents ethoxy, one of m and n is 1 and the other is 0, A1 represents trans-1,4-cyclohexylene, A2 and A3 are 2,3-difluoro-1,4-phenylene or 3-fluoro-1,4-phenylene, X1 represents hydrogen, Λ is 0 or 2, then R1 represents neither hydrogen nor methyl;
when Y1 represents ethoxy, one of m and n is 1 and the other is 0, A1 represents trans-1,4-cylclohexylene, A2 and A3 are 2-fluoro-1,4-phenylene, X1 represents hydrogen, R1 represents methyl, then Λ is neither 0 nor 2;
when both rings A1 and A2 represents 1,4-cyclohexylene, l is 2, m is 1, n is 0, both R1 and X1 represent hydrogen, then Y1 represents hydrogen or an alkyl group having 2 to 10 carbon atoms, in which each of optional nonadjacent methylene groups (—CH2—) may be substituted by oxygen; and
when ring A1 represents 1,4-phenylene group, 2,3-difluoro-1,4-phenylene group, 2-fluoro-1,4-phenylene group, or 3-fluoro-1,4-phenylene group, Λ is 1 to 4.

3. A liquid crystalline compound according to claim 2, wherein each of the rings A1 and A2 in general formula (1) is independently trans-1,4-cyclohexylene group, 2,3-difluoro-1,4-phenylene group or 1,3-dioxane-2,5-diyl group; m is 1; and n is 0.

4. A liquid crystal composition comprising at least one liquid crystalline compound according to claim 2 as a first component and at least one compound selected from a group consisting of compounds represented by the following general formulas (7), (8) and (9) as a second component;




where
each of R5 and R6 independently represents an alkyl group having 1 to 10 carbon atoms, in which each of optional nonadjacent methylene groups may be substituted by oxygen or vinylene group and in which each of optional hydrogen in these methylene may be substituted by fluorine;
each of rings G, I and J independently represents trans-1,4-cyclohexylene group, pyrimidine-2,5-diyl group or 1,4-phenylene group in which hydrogen may be substituted by fluorine; and
each of Z4 and Z5 independently represents 1,2-ethylene group, vinylene group, —COO—, —C≡C— or a single bond.

5. A liquid crystal composition comprising at least one liquid crystalline compound according to claims 2 as a first component; at least one compound selected from a group consisting of compounds represented by the following general formulas (7), (8) and (9):




as a second component, where
each of R5 and R6 independently represents an alkyl group having 1 to 10 carbon atoms, in which each of optional nonadjacent methylene groups may be substituted by oxygen or vinylene group and in which each of optional hydrogen in these methylene may be substituted by fluorine;
each of rings G, I and J independently represents trans-1,4-cyclohexylene group, pyrimidine-2,5-diyl group or 1,4-phenylene group in which hydrogen may be substituted by fluorine; and
each of Z4 and Z5 independently represents 1,2-ethylene group, vinylene group, —COO—, —C≡C— or a single bond; and
at least one compound selected from a group consisting of compounds represented by the following general formulas (10), (11) and (12):





as a third component, where
each R7 and R8 independently represents an alkyl group having 1 to 10 carbon atoms, in which each of optional adjacent methylene groups may be substituted by oxygen or vinylene group, and in which each of optional hydrogen in these methylene groups may be substituted by fluorine;
each of rings K and M independently represents trans-1,4-cyclohexylene group or 1,4-phenylene group;
each L6 and L7 independently represents hydrogen or fluorine, but L6 and L7 are not both hydrogen simultaneously; and
each Z6 and Z7 independently represents —CH2CH2—, —CH2— or a single bond.

6. A liquid crystal composition comprising at least one liquid crystalline compound according to claim 2 as a first component; at least one compound selected from a group consisting of compounds represented by the following general formulas (2), (3) and (4):




as a second component, where
R2 represents an alkyl group having 1 to 10 carbon atoms, in which each of optional nonadjacent methylene groups may be substituted by oxygen or —CH═CH— group, and in which each of optional hydrogen in these methylene groups may be substituted by fluorine;
Y2 represents fluorine, chlorine, —OCF3, —OCF2H, —CF3, —CF2H, —CFH2, —OCF2CF2H or —OCF2CFHCF3;
each L1 and L2 independently represents hydrogen or fluorine; p1 each Z1 and Z2 independently represents 1,2-ethylene group, vinylene group, 1,4-butylene group, —COO—, —CF2O—, —OCF2 or a single bond;
ring B represents trans-1,4-cyclohexylene group, 1,3-dioxane-2,5-diyl group or 1,4-phenylene group, in which each of hydrogen may be substituted by fluorine; and
ring C represents trans-1,4-cyclohexylene group or 1,4-phenylene group, in which each of hydrogen may be substituted by fluorine; and
at least one compound selected from a group consisting of compounds represented by the following general formulas (7), (8) and (9):





as a third component, where
each of R5 and R6 independently represents an alkyl group having 1 to 10 carbon atoms, in which each of optional nonadjacent methylene groups may be substituted by oxygen or vinylene group and in which each of optional hydrogen in these methylene may be substituted by fluorine;
each of rings G, I and J independently represents trans-1,4-cyclohexylene group, pyrimidine-2,5-diyl group or 1,4-phenylene group in which hydrogen may be substituted by fluorine; and
each of Z4 and Z5 independently represents 1,2-ethylene group, vinylene group, —COO—, —C≡C— or a single bond.

7. A liquid crystal composition comprising at least one liquid crystalline compound according to claim 2 as a first component; at least one compound selected from a group consisting of compounds represented by the following general formulas (5) and (6):




as a second component, where
each of R3 and R4 independently represents an alkyl group having 1 to 10 carbon atoms, in which each of optional nonadjacent methylene groups may be substituted by oxygen or vinylene group, and in which each of optional hydrogen in these methylene groups may be substituted by fluorine;
Y3 represents —CN or —C≡C—CN;
ring D represents trans-1,4-cyclohexylene group, 1,4-phenylene group, pyrimidine-2,5-diyl group or 1,3-dioxane-2,5-diyl group;
ring E represents trans-1,4-cyclohexylene group or 1,4-phenylene group, in which each of optional hydrogen may be substituted by fluorine or pyrimidine-2,5-diyl group;
ring F represents trans-1,4-cyclohexylene group or 1,4-phenylene group;
Z3 represents 1,2-ethylene group, —COO— or a single bond;
each L3, L4 and L5 independently represents hydrogen or fluorine; and
each a, b and c independently represents 0 or 1; and
at least one compound selected from a group consisting of compounds represented by the following general formulas (7), (8) and (9):





as a third component, where
each of R5 and R6 independently represents an alkyl group having 1 to 10 carbon atoms, in which each of optional nonadjacent methylene groups may be substituted by oxygen or vinylene group and in which each of optional hydrogen in these methylene may be substituted by fluorine;
each of rings G, I and J independently represents trans-1,4-cyclohexylene group, pyrimidine-2,5-diyl group or 1,4-phenylene group in which hydrogen may be substituted by fluorine; and
each of Z4 and Z5 independently represents 1,2-ethylene group, vinylene group, —COO—, —C≡C— or a single bond.

8. A liquid crystal composition comprising at least one liquid crystalline compound according to claim 2 as a first component; at least one compound selected from a group consisting of compounds represented by the following general formulas (2), (3) and (4):




as a second component, where
R2 represents an alkyl group having 1 to 10 carbon atoms, in which each of optional nonadjacent methylene groups may be substituted by oxygen or —CH═CH— group, and in which each of optional hydrogen in these methylene groups may be substituted by fluorine;
Y2 represents fluorine, chlorine, —OCF3, —OCF2H, —CF3, —CF2H, —CFH2, —OCF2CF2H or —OCF2CFHCF3;
each L1 and L2 independently represents hydrogen or fluorine;
each Z1 and Z2 independently represents 1,2-ethylene group, vinylene group, 1,4-butylene group, —COO—, —CF2O—, —OCF2 or a single bond;
ring B represents trans-1,4-cyclohexylene group, 1,3-dioxane-2,5-diyl group or 1,4-phenylene group, in which each of hydrogen may be substituted by fluorine; and
ring C represents trans-1,4-cyclohexylene group or 1,4-phenylene group, in which each of hydrogen may be substituted by fluorine;
at least one compound selected from a group consisting of compounds represented by the following general formulas (5) and (6):





as a third component, where
each of R3 and R4 independently represents an alkyl group having 1 to 10 carbon atoms, in which each of optional nonadjacent methylene groups may be substituted by oxygen or vinylene group, and in which each of optional hydrogen in these methylene groups may be substituted by fluorine;
Y3 —CN or —C≡C—CN;
ring D represents trans-1,4-cyclohexylene group, 1,4-phenylene group, pyrimidine-2,5-diyl group or 1,3-dioxane-2,5-diyl group;
ring E represents trans-1,4-cyclohexylene group or 1,4-phenylene group, in which each of optional hydrogen may be substituted by fluorine or pyrimidine-2,5-diyl group;
ring F represents trans-1,4-cyclohexylene group or 1,4-phenylene group;
Z3 represents 1,2-ethylene group, —COO— or a single bond;
each L3, L4 and L5 independently represents hydrogen or fluorine; and
each a, b and c independently represents 0 or 1; and
at least one compound selected from a group consisting of compounds represented by the following general formulas (7), (8) and (9):





as a fourth component, where
each of R5 and R6 independently represents an alkyl group having 1 to 10 carbon atoms, in which each of optional nonadjacent methylene groups may be substituted by oxygen or vinylene group and in which each of optional hydrogen in these methylene may be substituted by fluorine;
each of rings G, I and J independently represents trans-1,4-cyclohexylene group, pyrimidine-2,5-diyl group or 1,4-phenylene group in which hydrogen may be substituted by fluorine; and
each of Z4 and Z5 independently represents 1,2-ethylene group, vinylene group, —COO—, —C≡C— or a single bond.

9. A liquid crystal composition according to claim 1 further comprising one or more optically active compounds.

10. A liquid crystal display device constituted from a liquid crystal composition according to claim 1.