| PATENT ASSIGNEE'S COUNTRY | Japan |
| UPDATE | 11.00 |
| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | 21.11.00 |
| PATENT TITLE |
Conjugated nitrile derivative, liquid crystal composition, and liquid crystal display elements |
| PATENT ABSTRACT |
Liquid crystalline compounds having a wide temperature range of liquid crystal phase, a high dielectric anisotropy, and a high optical anisotropy; and liquid crystal compositions and display devices containing the composition. The liquid crystalline compounds are conjugated nitrile derivatives expressed by the formula (1) ##STR1## wherein R represents an alkyl group or a fluoroalkyl group each having 1 to 10 carbon atoms, halogen atom, or cyano group provided that in the alkyl or fluoroalkyl group, one or not-adjacent two or more methylene or fluoromethylene groups may be replaced by oxygen atom or 1,2-ethenylene group; A.sub.1, A.sub.2, A.sub.3 and A.sub.4 represent 1,4-cyclohexylene group, 1,4-phenylene in which one or two hydrogen atoms on the ring may be replaced by fluorine atom, 1,3-dioxane-2,5-diyl, or pyrimidine-2,5-diyl; B.sub.1, B.sub.2, and B.sub.3 independently represent a covalent bond, 1,2-ethylene group, 1,2-ethenylene group, 1,2-ethynylene group, carbonyloxy group, methylenoxy group, or 1,4-butylene group; m, n, and p are 0 or 1; and G represents a group expressed by the formula ##STR2## |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | 28.05.99 |
| PATENT CT FILE DATE | 27.11.97 |
| PATENT CT NUMBER | This data is not available for free |
| PATENT CT PUB NUMBER | This data is not available for free |
| PATENT CT PUB DATE | 04.06.98 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT REFERENCES CITED |
Coates et al., "Effect of Light on the Liquid Crystal Transition Temperatures of 4-(4-n-Pentylphenyl)vinyl Cyanide", J.C.S. Chem. Comm., 1975, pp. 514-515. |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A conjugated nitrile derivative expressed by the general formula (1) ##STR1536## wherein rings A.sub.1, A.sub.2, A.sub.3, and A.sub.4 independently represent 1,4-cyclohexylene, 1,4-phenylene in which one or two hydrogen atoms on the ring may be replaced by fluorine atom, 1,3-dioxane-2,5-diyl, or pyrimidine-2,5-diyl; B.sub.1, B.sub.2, and B.sub.3 independently represent a covalent bond, 1,2-ethylene, 1,2-ethenylene, 1,2-ethynylene, oxymethylene, methylenoxy, carbonyloxy, or 1,4-butylene group; G represents the formula (2), (3), or (4) ##STR1537## R represents an alkyl group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, a halogen atom, or cyano group provided that in the alkyl group or fluoroalkyl group, one or not-adjacent two or more methylene groups or fluoromethylene groups may be replaced by oxygen atom or 1,2-ethenylene group; and m, n, and p are independently 0 or 1. 2. The conjugated nitrile derivative according to claim 1 wherein m=n=p=0. 3. The conjugated nitrile derivative according to claim 1 wherein m=n=0, and p=1. 4. The conjugated nitrile derivative according to claim 1 wherein m=0, and n=p=1. 5. The conjugated nitrile derivative according to claim 1 wherein m=n=p=1. 6. The conjugated nitrile derivative according to claim 3 wherein G is the group expressed by the formula (2). 7. The conjugated nitrile derivative according to claim 6 wherein A.sub.4 is 1,4-cyclohexylene. 8. The conjugated nitrile derivative according to claim 6 wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. 9. The conjugated nitrile derivative according to claim 7 wherein A.sub.3 is 1,4-cyclohexylene, and B.sub.3 is a covalent bond. 10. The conjugated nitrile derivative according to claim 3 wherein G is the group expressed by the formula (3). 11. The conjugated nitrile derivative according to claim 10 wherein A.sub.4 is 1,4-cyclohexylene. 12. The conjugated nitrile derivative according to claim 10 wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. 13. The conjugated nitrile derivative according to claim 11 wherein A.sub.3 is 1,4-cyclohexylene, and B.sub.3 is a covalent bond. 14. The conjugated nitrile derivative according to claim 12 wherein A.sub.3 is 1,4-cyclohexylene, and B.sub.3 is a covalent bond. 15. The conjugated nitrile derivative according to claim 3 wherein G is the group expressed by the formula (4). 16. The conjugated nitrile derivative according to claim 15 wherein A.sub.4 is 1,4-cyclohexylene. 17. The conjugated nitrile derivative according to claim 15 wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. 18. The conjugated nitrile derivative according to claim 16 wherein A.sub.3 is 1,4-cyclohexylene, and B.sub.3 is a covalent bond. 19. The conjugated nitrile derivative according to claim 17 wherein A.sub.3 is 1,4-cyclohexylene, and B.sub.3 is a covalent bond. 20. The conjugated nitrile derivative according to claim 4 wherein G is the group expressed by the formula (2). 21. The conjugated nitrile derivative according to claim 20 wherein A.sub.4 is 1,4-cyclohexylene. 22. The conjugated nitrile derivative according to claim 20 wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. 23. The conjugated nitrile derivative according to claim 4 wherein G is the group expressed by the formula (3). 24. The conjugated nitrile derivative according to claim 23 wherein A.sub.4 is 1,4-cyclohexylene. 25. The conjugated nitrile derivative according to claim 23 wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. 26. The conjugated nitrile derivative according to claim 4 wherein G is the group expressed by the formula (4). 27. The conjugated nitrile derivative according to claim 26 wherein A.sub.4 is 1,4-cyclohexylene. 28. The conjugated nitrile derivative according to claim 26 wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. 29. The conjugated nitrile derivative according to claim 5 wherein G is the group expressed by the formula (2). 30. The conjugated nitrile derivative according to claim 29 wherein A.sub.4 is 1,4-cyclohexylene. 31. The conjugated nitrile derivative according to claim 29 wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. 32. The conjugated nitrile derivative according to claim 5 wherein G is the group expressed by the formula (3). 33. The conjugated nitrile derivative according to claim 32 wherein A.sub.4 is 1,4-cyclohexylene. 34. The conjugated nitrile derivative according to claim 32 wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. 35. The conjugated nitrile derivative according to claim 5 wherein G is the group expressed by the formula (4). 36. The conjugated nitrile derivative according to claim 35 wherein A.sub.4 is 1,4-cyclohexylene. 37. The conjugated nitrile derivative according to claim 35 wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. 38. A liquid crystal composition comprising at least one conjugated nitrile derivative defined in any one of claims 1 through 37. 39. A liquid crystal composition, comprising, as a first component, at least one conjugated nitrile derivative defined in any one of claims 1 through 37, and comprising, as a second component, at least one compound selected from the group consisting of the compounds expressed by any one of the general formulas (5), (6), and (7) ##STR1538## wherein R.sub.3, Y.sub.1, L.sub.1, L.sub.2, Z.sub.1, and Z.sub.2 may be the same or different from one another among the formulas; R.sub.3 represents an alkyl group having 1 to 10 carbon atoms in which alkyl group, one or not-adjacent two or more methylene groups may be replaced by oxygen atom or --CH.dbd.CH--, and any hydrogen atom may be replaced by fluorine atom; Y.sub.1 represents fluorine atom, chlorine atom, OCF.sub.3, OCF.sub.2 H, CF.sub.3, CF.sub.2 H, CFH.sub.2, OCF.sub.2 CF.sub.2 H, or OCF.sub.2 CFHCF.sub.3 ; L.sub.1 and L.sub.2 independently represent hydrogen atom or fluorine atom; Z.sub.1 and Z.sub.2 independently represent 1,2-ethylene group, 1,4-butylene group, --COO--, --CF.sub.2 --, --OCF.sub.2 --, --CH.dbd.CH--, or a covalent bond; B represents trans-1,4-cyclohexylene, or 1,3-dioxane-2,5-diyl, or 1,4-phenylene in which hydrogen atom on the ring may be replaced by fluorine atom; and C represents trans-1,4-cyclohexylene, or 1,4-phenylene in which hydrogen atom on the ring may be replaced by fluorine atom. 40. A liquid crystal composition, comprising, as a first component, at least one conjugated nitrile derivative defined in any one of claims 1 through 37, and comprising, as a second component, at least one compound selected from the group consisting of the compounds expressed by the general formula (8) or (9) ##STR1539## wherein R.sub.4 and R.sub.5 independently represent an alkyl group having 1 to 10 carbon atoms in which alkyl group, one or not-adjacent two or more methylene groups may be replaced by oxygen atom or --CH.dbd.CH--, and any hydrogen atom may be replaced by fluorine atom; Y.sub.2 represents --CN group or --C.tbd.C--CN; E represents trans-1,4-cyclohexylene, 1,4-phenylene, 1,3-dioxane-2,5-diyl, or pyrimidine-2,5-diyl; G represents trans-1,4-cyclohexylene, 1,4-phenylene in which hydrogen atom on the ring may be replaced by fluorine atom, or pyrimidine-2,5-diyl; H represents trans-1,4-cyclohexylene or 1,4-phenylene; Z.sub.3 represents 1,2-ethylene group, --COO--, or a covalent bond; L.sub.3, L.sub.4, and L.sub.5 independently represent hydrogen atom and or fluorine atom; b, c, and d are independently 0 or 1. 41. A liquid crystal composition, comprising, as a first component, at least one conjugated nitrile derivative defined in any one of claims 1 through 37, comprising, as a second component, at least one compound selected from the group consisting of the compounds expressed by any one of the general formulas (5), (6), and (7) ##STR1540## wherein R.sub.3, Y.sub.1, L.sub.1, L.sub.2, Z.sub.1, and Z.sub.2 may be the same or different from one another among the formulas; R.sub.3 represents an alkyl group having 1 to 10 carbon atoms in which alkyl group, one or not-adjacent two or more methylene groups may be replaced by oxygen atom or --CH.dbd.CH--, and any hydrogen atom may be replaced by fluorine atom; Y.sub.1 represents fluorine atom, chlorine atom, OCF.sub.3, OCF.sub.2 H, CF.sub.3, CF.sub.2 H, CFH.sub.2, OCF.sub.2 CF.sub.2 H, or OCF.sub.2 CFHCF.sub.3 ; L.sub.1 and L.sub.2 independently represent hydrogen atom or fluorine atom; Z.sub.1 and Z.sub.2 independently represent 1,2-ethylene group, 1,4-butylene group, --COO--, --CF.sub.2 O--, --OCF.sub.2 --, --CH.dbd.CH--, or a covalent bond; B represents trans-1,4-cyclohexylene or 1,3-dioxane-2,5-diyl, or 1,4-phenylene in which hydrogen atom on the ring may be replaced by fluorine atom; and C represents trans-1,4-cyclohexylene, or 1,4-phenylene in which hydrogen atom on the ring may be replaced by fluorine atom, and comprising, as a third component, at least one compound selected from the group consisting of the compounds expressed by any one of the general formulas (10), (11), and (12) ##STR1541## wherein R.sub.6, R.sub.7, I, J, and K may be the same or different from one another among the formulas; R.sub.6 and R.sub.7 independently represent an alkyl group having 1 to 10 carbon atoms in which alkyl group, one or not-adjacent two or more methylene groups may be replaced by oxygen atom or --CH.dbd.CH--, and any hydrogen atom may be replaced by fluorine atom; I, J, and K independently represent trans-1,4-cyclohexylene or pyrimidine-2,5-diyl, or 1,4-phenylene in which hydrogen atom and on the ring may be replaced by fluorine atom; Z.sub.4 and Z.sub.5 independently represent --C.tbd.C--, --COO--, --CH.sub.2 CH.sub.2 --, --CH.dbd.CH--, or a covalent bond. 42. A liquid crystal composition, comprising, as a first component, at least one conjugated nitrile derivative defined in any one of claims 1 through 37, comprising, as a second component, at least one compound selected from the group consisting of the compounds expressed by the general formula (8) or (9) recited in claim 40, and comprising, as a third component, at least one compound selected from the group consisting of the compounds expressed by any one of the general formulas (10), (11), and (12) recited in claim 41. 43. A liquid crystal composition, comprising, as a first component, at least one conjugated nitrile derivative defined in any one of claims 1 through 37, comprising, as a part of a second component, at least one compound selected from the group consisting of the compounds expressed by any one of the general formulas (5), (6), and (7) recited in claim 39, comprising, as another part of the second component, at least one compound selected from the group consisting of the compounds expressed by the general formula (8) or (9) recited in claim 40, and comprising, as a third component, at least one compound selected from the group consisting of the compounds expressed by any one of the general formulas (10), (11), and (12) recited in claim 41. 44. A liquid crystal composition comprising the conjugated nitrile derivative defined in claim 1 and an optically active compound. 45. A liquid crystal display device comprising the liquid crystal composition defined in claim 44. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
TECHNICAL FIELD The present invention relates to liquid crystalline compounds and liquid crystal compositions. More specifically, the invention relates to conjugated nitrile derivatives of liquid crystalline compounds preferable as component of liquid crystal compositions; liquid crystal compositions comprising the nitrile derivative; and liquid crystal display devices fabricated by using the liquid crystal composition. BACKGROUND ART Liquid crystal display devices utilize optical (refractive) anisotropy and dielectric anisotropy of liquid crystalline compounds. Viewing from the aspect of display mode, display devices of twisted nematic (TN) type, super twisted nematic (STN) type, dynamic scattering (DS) type, guest,host (GH) type, or DAP type organized according to their electrooptical effect are known. From the aspect of driving mode, display devices of static driving mode, time shearing addressing mode, active matrix driving mode, or two-frequency addressing scheme are known. Liquid crystal substances used for the display devices are required to exhibit a liquid crystal phase in a wide temperature range and to be stable against heat, light, moisture, air, electric field, and electromagnetic radiation. However, since it is impossible to satisfy all of such requirements by a single compound at present, it is a current situation that several, or in some cases more than twenty liquid crystalline compounds are mixed and used as liquid crystal compositions. Accordingly, the liquid crystalline compounds have come to be required to exhibit excellent miscibility each other. Recently in particular, since display devices are used in many instances in sever environments such as at cryogenic temperatures, improvement of the compounds in the miscibility at low temperatures has come to be required. With the increase of demand for display devices of high quality, requests for liquid crystal composition having an improved response speed to the change in electric field, and steepness have been increased. In order to fulfil the requirements, it is required to use liquid crystal materials having a low viscosity and a large dielectric anisotropy value as component of liquid crystal compositions. In order to increase the response speed of liquid crystal compositions, it is effective to make the thickness (d) of liquid crystal cells small (thin) in addition to satisfying the requirements described above. In this case, however, it is necessary to increase optical anisotropy value (.DELTA.n) (to use liquid crystalline compounds having a large .DELTA.n as component) for the reason described below. That is, excellent display contrast and wide visual angle are found as other characteristics required of display devices. In order to achieve this end, it is necessary to maintain the product of .DELTA.n and d (.DELTA.n.multidot.d) at a certain value, and thus, when d is made small according to the measures described above, it is necessary to increase .DELTA.n. For originating liquid crystalline compounds having a large .DELTA.n, it is sufficient, for instance, to introduce ethynylene group into a liquid crystal molecule, and it is known by means of the compounds expressed by the formula (13) (Japanese Patent Publication No. Hei 3-29051) and compounds expressed by one of the formulas (14) to (16) (DE 4027458 and WO 90-13610) that the compounds can be changed into ones having a large value even in dielectric anisotropy (.DELTA..epsilon.) by altering the ethynylene group into the one having an electron attractive group, for example, CN, Cl, CHF.sub.2, or CF.sub.3 as substituent. ##STR3## wherein R represents an alkyl group. However, as to the compounds expressed by the formula (13), their electric properties are not disclosed at all in the Japanese Patent Publication No. Hei 3-29051. Compounds expressed by one of the formulas (14) to (16) are narrow in the temperature range of liquid crystal phase, and they can not be said to exhibit a sufficiently large value of either .DELTA.n and .DELTA..epsilon. besides. An object of the present invention is to solve the defects in the conventional technology. Another object of the present invention is to provide conjugated nitrile derivatives, novel liquid crystalline compounds having a sufficiently large .DELTA.n and a large .DELTA..epsilon., being excellent in miscibility with other liquid crystalline compounds, having a low viscosity, and being chemically and physically stable; to provide liquid crystal compositions comprising the nitrile derivative; and to provide liquid crystal display devices fabricated by using the liquid crystal composition. DISCLOSURE OF THE INVENTION As a result of diligent investigations by the present inventors to achieve the objects described above, compounds of a novel structure having improved characteristics compared with known liquid crystalline compounds have been found, leading to the accomplishment of the present invention. Summary of the present invention is as follows: (1) A conjugated nitrile derivative expressed by the general formula (1) ##STR4## wherein rings A.sub.1, A.sub.2, A.sub.3, and A.sub.4 independently represent 1,4-cyclohexylene, 1,4-phenylene in which one or two hydrogen atoms on the ring may be replaced by fluorine atom, 1,3-dioxane-2,5-diyl, or pyrimidine-2,5-diyl; B.sub.1, B.sub.2, and B.sub.3 independently pepresent a covalent bond, 1,2-ethylene, 1,2-ethenylene, 1,2-ethynylene, oxymethylene, methylenoxy, carbonyloxy, or 1,4-butylene group; G represents the formula (2), (3), or (4) ##STR5## R represents an alkyl group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, a halogen atom, or cyano group provided that in the alkyl group or fluoroalkyl group, one or not-adjacent two or more methylene groups or fluoromethylene groups may be replaced by oxygen atom or 1,2-ethenylene group; m, n, and p are independently 0 or 1; and each element which constitutes the compound may be selected from its isotopes. (2) The conjugated nitrile derivative recited in paragraph (1) above wherein m=n=p=0. (3) The conjugated nitrile derivative recited in paragraph (1) above wherein m=n=0, and p=1. (4) The conjugated nitrile derivative recited in paragraph (1) above wherein m=0, and n=p=1. (5) The conjugated nitrile derivative recited in paragraph (1) above wherein m=n=p=1. (6) The conjugated nitrile derivative recited in paragraph (3) above wherein G is the group expressed by the formula (2). (7) The conjugated nitrile derivative recited in paragraph (6) above wherein A.sub.4 is 1,4-cyclohexylene. (8) The conjugated nitrile derivative recited in paragraph (6) above wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. (9) The conjugated nitrile derivative recited in paragraph (7) above wherein A.sub.3 is 1,4-cyclohexylene, and B.sub.3 is a covalent bond. (10) The conjugated nitrile derivative recited in paragraph (3) above wherein G is the group expressed by the formula (3). (11) The conjugated nitrile derivative recited in paragraph (10) above wherein A.sub.4 is 1,4-cyclohexylene. (12) The conjugated nitrile derivative recited in paragraph (10) above wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. (13) The conjugated nitrile derivative recited in paragraph (11) above wherein A.sub.3 is 1,4-cyclohexylene, and B.sub.3 is a covalent bond. (14) The conjugated nitrile derivative recited in paragraph (12) above wherein A.sub.3 is 1,4-cyclohexylene, and B.sub.3 is a covalent bond. (15) The conjugated nitrile derivative recited in paragraph (3) above wherein G is the group expressed by the formula (4). (16) The conjugated nitrile derivative recited in paragraph (15) above wherein A.sub.4 is 1,4-cyclohexylene. (17) The conjugated nitrile derivative recited in paragraph (15) above wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. (18) The conjugated nitrile derivative recited in paragraph (16) above wherein A.sub.3 is 1,4-cyclohexylene, and B.sub.3 is a covalent bond. (19) The conjugated nitrile derivative recited in paragraph (17) above wherein A.sub.3 is 1,4-cyclohexylene, and B.sub.3 is a covalent bond. (20) The conjugated nitrile derivative recited in paragraph (4) above wherein G is the group expressed by the formula (2). (21) The conjugated nitrile derivative recited in paragraph (20) above wherein A.sub.4 is 1,4-cyclohexylene. (22) The conjugated nitrile derivative recited in paragraph (20) above wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. (23) The conjugated nitrile derivative recited in paragraph (4) above wherein G is the group expressed by the formula (3). (24) The conjugated nitrile derivative recited in paragraph (23) above wherein A.sub.4 is 1,4-cyclohexylene. (25) The conjugated nitrile derivative recited in paragraph (23) above wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. (26) The conjugated nitrile derivative recited in paragraph (4) above wherein G is the group expressed by the formula (4). (27) The conjugated nitrile derivative recited in paragraph (26) above wherein A.sub.4 is 1,4-cyclohexylene. (28) The conjugated nitrile derivative recited in paragraph (26) above wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. (29) The conjugated nitrile derivative recited in paragraph (5) wherein G is the group expressed by the formula (2). (30) The conjugated nitrile derivative recited in paragraph (29) above wherein A.sub.4 is 1,4-cyclohexylene. (31) The conjugated nitrile derivative recited in paragraph (29) above wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. (32) The conjugated nitrile derivative recited in paragraph (5) above wherein G is the group expressed by the formula (3). (33) The conjugated nitrile derivative recited in paragraph (32) above wherein A.sub.4 is 1,4-cyclohexylene. (34) The conjugated nitrile derivative recited in paragraph (32) above wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. (35) The conjugated nitrile derivative recited in paragraph (5) above wherein G is the group expressed by the formula (4). (36) The conjugated nitrile derivative recited in paragraph (35) above wherein A.sub.4 is 1,4-cyclohexylene. (37) The conjugated nitrile derivative recited in paragraph (35) above wherein A.sub.4 is 1,4-phenylene ring in which one or two hydrogen atoms on the ring may be replaced by fluorine atom. (38) A liquid crystal composition comprising at least one conjugated nitrile derivative recited in any one of paragraphs (1) through (37) above. (39) A liquid crystal composition, comprising, as a first component, at least one conjugated nitrile derivative recited in any one of paragraphs (1) through (37) above, and comprising, as a second component, at least one compound selected from the group consisting of the compounds expressed by any one of the general formulas (5), (6), and (7) ##STR6## wherein R.sub.3, Y.sub.1, L.sub.1, L.sub.2, Z.sub.1, and Z.sub.2 may be the same or different from one another among the formulas; R.sub.3 represents an alkyl group having 1 to 10 carbon atoms in which alkyl group, one or not-adjacent two or more methylene groups may be replaced by oxygen atom or --CH.dbd.CH--, and any hydrogen atom may be replaced by fluorine atom; Y.sub.1 represents fluorine atom, chlorine atom, OCF.sub.3, OCF.sub.2 H, CF.sub.3, CF.sub.2 H, CFH.sub.2, OCF.sub.2 CF.sub.2 H, or OCF.sub.2 CFHCF.sub.3 ; L.sub.1 and L.sub.2 independently represent hydrogen atom or fluorine atom; Z.sub.1 and Z.sub.2 independently represent 1,2-ethylene group, 1,4-butylene group, --COO--, --CF.sub.2 O--, --OCF.sub.2 --, --CH.dbd.CH--, or a covalent bond; ring B represents trans-1,4-cyclohexylene or 1,3-dioxane-2,5-diyl, or 1,4-phenylene in which hydrogen atom on the ring may be replaced by fluorine atom; ring C represents trans-1,4-cyclohexylene, or 1,4-phenylene in which hydrogen atom on the ring may be replaced by fluorine atom; and each element which constitutes the compounds of each of the general formulas may be selected from its isotopes. (40) A liquid crystal composition, comprising, as a first component, at least one conjugated nitrile derivative recited in any one of paragraphs (1) through (37) above, and comprising, as a second component, at least one compound selected from the group consisting of the compounds expressed by the general formula (8) or (9) ##STR7## wherein R.sub.4 and R.sub.5 independently represent an alkyl group having 1 to 10 carbon atoms in which alkyl group, one or not-adjacent two or more methylene groups may be replaced by oxygen atom or --CH.dbd.CH--, and any hydrogen atom may be replaced by fluorine atom; Y.sub.2 represents --CN group or --C.tbd.C--CN; ring E represents trans-1,4-cyclohexylene, 1,4-phenylene, 1,3-dioxane-2,5-diyl, or pyrimidine-2,5-diyl; ring G represents trans-1,4-cyclohexylene, 1,4-phenylene in which hydrogen atom on the ring may be replaced by fluorine atom, or pyrimidine-2,5-diyl; ring H represents trans-1,4-cyclohexylene or 1,4-phenylene; Z.sub.3 represents 1,2-ethylene group, --COO--, or a covalent bond; L.sub.3, L.sub.4, and L.sub.5 independently represent hydrogen atom or fluorine atom; b, c, and d are independently 0 or 1; and each element which constitutes the compounds of each of the general formulas may be selected from its isotopes. (41) A liquid crystal composition, comprising, as a first component, at least one conjugated nitrile derivative recited in any one of paragraphs (1) through (37) above, comprising, as a second component, at least one compound selected from the group consisting of the compounds expressed by any one of the general formulas (5), (6), and (7) described above, and comprising, as a third component, at least one compound selected from the group consisting of the compounds expressed by any one of the general formulas (10), (11), and (12) ##STR8## wherein R.sub.6, R.sub.7, I, J, and K may be the same or different from one another among the formulas; R.sub.6 and R.sub.7 independently represent an alkyl group having 1 to 10 carbon atoms in which alkyl group, one or not-adjacent two or more methylene groups may be replaced by oxygen atom or --CH.dbd.CH--, and any hydrogen atom may be replaced by fluorine atom; I, J, and K independently represent trans-1,4-cyclohexylene or pyrimidine-2,5-diyl, or 1,4-phenylene in which hydrogen atom on the ring may be replaced by fluorine atom; Z.sub.4 and Z.sub.5 independently represent --C.tbd.C--, --COO--, --CH.sub.2 CH.sub.2 --, --CH.dbd.CH--, or a covalent bond; and each element which constitutes the compounds of each of the general formulas may be selected from its isotopes. (42) A liquid crystal composition, comprising, as a first component, at least one conjugated nitrile derivative recited in any one of paragraphs (1) through (37) above, comprising, as a second component, at least one compound selected from the group consisting of the compounds expressed by the general formula (8) or (9) described above, and comprising, as a third component, at least one compound selected from the group consisting of the compounds expressed by any one of the general formulas (10), (11), and (12) described above. (43) A liquid crystal composition, comprising, as a first component, at least one conjugated nitrile derivative recited in any one of paragraphs (1) through (37) above, comprising, as a part of a second component, at least one compound selected from the group consisting of the compounds expressed by any one of the general formulas (5), (6), and (7) described above, comprising, as another part of the second component, at least one compound selected from the group consisting of the compounds expressed by the general formula (8) or (9) described above, and comprising, as a third component, at least one compound selected from the group consisting of the compounds expressed by any one of the general formulas (10), (11), and (12) described above. (44) A liquid crystal composition recited in any one of paragraphs (38) to (43) above wherein the liquid crystal composition further comprises an optically active compound. (45) A liquid crystal display device fabricated by using the liquid crystal composition recited in any one of paragraphs (38) to (44) above. As described above, the conjugated nitrile derivatives, the liquid crystalline compounds of the present invention are expressed by the general formula (1). Among them, a group of the compounds expressed by one of the formulas (1-a) to (1-n) can particularly be mentioned as preferable examples. ##STR9## wherein R and G have the same meaning as described above. Any of these compounds of the present invention exhibit a large .DELTA.n. Besides, they are low in viscosity, excellent in miscibility with other liquid crystalline compounds, and chemically and physically stable. Since particularly the compounds expressed by one of the formulas (1-k) to (1-n) further have a high clearing point, they can be used as component when liquid crystal compositions having a high upper limit temperature of liquid crystal are produced. Since the compounds expressed by one of the formulas (1-e) to (1-n), particularly the compounds expressed by the formula (1-e), (1-j), (1-k), (1-l), or (1-m) have an extremely large .DELTA.n, they are remarkably useful. All liquid crystalline compounds of the present invention expressed by the general formula (1) do not necessarily exhibit a liquid crystal phase. However, since any of the compounds is excellent in miscibility with other liquid crystalline compounds, and does not considerably lower or narrow the temperature range of nematic phase of other liquid crystalline compounds when mixed with them, it is useful as component of liquid crystal compositions even if it does not exhibit a liquid crystal phase by itself. Liquid crystal compositions of the present invention comprise, as a first component, at least one liquid crystalline compound expressed by the general formula (1). It is necessary to develop excellent characteristics that the content of the compound is 0.1 to 99.9% by weight based on the amount of the liquid crystal composition. While the liquid crystal compositions of the present invention may be composed only of the first component described above, compositions in which at least one compound selected from the group consisting of the compounds expressed by one of the general formulas (5), (6), and (7) described above (the compounds are hereinafter referred to as second component A) and/or at least one compound selected from the group consisting of the compounds expressed by the general formula (8) or (9) described above (the compounds are hereinafter referred to as second component B) are mixed as a second component in addition to the first component; or compositions in which at least one compound selected from the group consisting of the compounds expressed by one of the general formulas (10), (11), and (12) described above are additionally mixed as a third component to the first and second components are preferable. Further, an optically active compound, and known compounds for the purpose of adjusting threshold voltage, temperature range of liquid crystal phase, .DELTA.n, .DELTA..epsilon., and viscosity can be mixed as other components to the compositions. Among the second component A, compounds expressed by one of the formulas (5-1) to (5-9) can be mentioned as preferable examples of the compounds included in the general formula (5), compounds expressed by one of the formulas (6-1) to (6-69) can be mentioned as preferable examples of the compounds included in the general formula (6), and compounds expressed by one of the formulas (7-1) to (7-24) can be mentioned as preferable examples of the compounds included in the general formula (7), respectively. ##STR10## wherein R.sub.3 and Y.sub.1 have the same meaning as described above. Any compounds expressed by one of these general formulas (5) to (7) exhibit a positive .DELTA..epsilon., are considerably excellent in thermal stability and chemical stability, and are indispensable when liquid crystal compositions for TFT (AM-LCD) of which a high reliability such as a high voltage holding ratio (large specific resistivity) is required. The amount of the compound to be used is suitably in the range of 1 to 99.9% by weight based on the total amount of liquid crystal composition when liquid crystal compositions for TFT are produced, and the amount is preferably 10 to 97% by weight, and more desirably 40 to 95% by weight. In that case, the compositions may further comprise a compound expressed by one of the general formulas (10) to (12) for the purpose of adjusting viscosity. Compounds expressed by one of the general formulas (5) to (7) can be used when liquid crystal compositions for STN display mode or TN display mode are produced. However, since the compounds are relatively low in the effect of lowering threshold voltage of liquid crystal compositions, their amount to be used is preferably less than 50% by weight based on the total amount of liquid crystal composition. Next, among the second component B, compounds expressed by one of the formulas (8-1) to (8-40) can be mentioned as preferable examples of the compounds included in the general formula (8), and compounds expressed by one of the formulas (9-1) to (9-3) can be mentioned as preferable examples of the compounds included in the general formula (9), respectively. ##STR11## wherein R.sub.4, Y.sub.2, and R.sub.5 have the same meaning as described above. Compounds expressed by one of these general formula (8) or (9) have a positive and large dielectric anisotropy value .DELTA..epsilon., and used particularly for the purpose of lowering threshold voltage of liquid crystal compositions. Also, they are used for the purpose of improving the steepness of liquid crystal compositions for STN display mode or TN display mode, including for the purpose of adjusting .DELTA.n, and widening nematic range such as raising clearing point, and thus they are indispensable compounds when liquid crystal compositions for STN display mode or TN display mode are produced. As the amount of the compounds to be used is increased, threshold voltage of liquid crystal compositions can be lowered, but on the other hand, viscosity is increased. Accordingly, it is advantageous, for low voltage driving, to use a large amount of the compound so far as viscosity of liquid crystal compositions satisfies a required characteristic. According to such circumstances, when liquid crystal compositions for STN display mode or TN display mode are produced, the amount of the compounds to be used is suitably in the range of 0.1 to 99.9% by weight based on the total amount of liquid crystal composition, and the amount is preferably 10 to 97% by weight and more desirably 40 to 95% by weight. Among the third component described above, compounds expressed by one of the formula (10-1) to (10-11) can be mentioned as preferable examples of the compounds included in the general formula (10), compounds expressed by one of the formulas (11-1) to (11-18) can be mentioned as preferable examples of the compounds included in the general formula (11), and compounds expressed by one of the formulas (12-1) to (12-6) can be mentioned as preferable examples of the compounds included in the general formula (12), respectively. ##STR12## wherein R.sub.6 and R.sub.7 have the same meaning as described above. Any compound expressed by one of these general formulas (10) to (12) has a small absolute value of dielectric anisotropy .DELTA..epsilon.. Among them, compounds of the general formula (10) are used principally for the purpose of adjusting viscosity or adjusting .DELTA.n of liquid crystal compositions, and the compounds of the general formula (11) or (12) are used for the purpose of widening nematic range such as raising clearing point, and for the purpose of adjusting .DELTA.n. With the increase of the amount to be used, this compound raises threshold voltage of liquid crystal compositions, but on the other hand, reduces viscosity. Accordingly, it is desirable to use a large amount of the compound so far as threshold voltage of liquid crystal compositions satisfies a required value. According to such circumstances, when liquid crystal compositions for TFT are produced, the amount of the compound to be used is suitably less than 40% by weight based on the total amount of liquid crystal composition, and preferably less than 35% by weight. On the other hand, when liquid crystal compositions for STN display mode or TN display mode are produced, the amount of the compound to be used is suitably less than 70% by weight, and preferably less than 60% by weight. With the exception of such specific cases as liquid crystal compositions for OCB (Optically Compensated Birefringence) mode, an optically active compound, among the other components, is usually added to the liquid crystal compositions for the purpose of inducing helical structure of liquid crystal composition to adjust required twist angle and to prevent reverse twist. While the optically active compound is selected from a wide range of known compounds, the optically active compound expressed by one of the following formulas (Op-1) to (Op-8) can preferably be mentioned: ##STR13## By the addition of these optically active compounds, the pitch length of twist of liquid crystal compositions are adjusted. The pitch length of twist is preferably adjusted in the range of 40 to 200 .mu.m in the case of liquid crystal compositions for TFT or TN, and preferably adjusted in the range of 6 to 20 .mu.m in the case of liquid crystal compositions for STN. In the case for bistable TN mode, it is preferable to adjust the pitch length in the range of 1.5 to 4 .mu.m. In such cases, two or more kind of optically active compounds may be added for the purpose of adjusting the dependency of the pitch length on temperature. Liquid crystal compositions provided according to the present invention can be produced by methods which are conventional by themselves. For instance, the liquid crystal compositions are usually produced by a method in which various components are dissolved in one another at a high temperature. Further, the liquid crystal compositions of the present invention can be used as ones for guest-host (GH) mode by adding a dichroic dye such as merocyanine type, styryl type, azo type, azomethine type, azoxy type, quinophthalone type, anthraquinone type, and tetrazine type thereto. Alternatively, the liquid crystal compositions of the present invention can be used as NCAP which is prepared by the microencapsulation of a nematic liquid crystal, or as liquid crystal compositions for polymer dispersed liquid crystal display devices (PDLCD) represented by polymer net work liquid crystal display devices (PNLCD) prepared by forming a polymer of three-dimensional reticulated structure in a liquid crystal. Still further, the liquid crystal compositions of the present invention can be used as ones for electrically controlled birefringence (ECB) mode or dynamic scattering (DS) mode. While the liquid crystal compositions of the present invention are produced by such methods as described above, the following Composition Examples 1 to 46 can be mentioned as their examples: In each of the Composition Examples, compounds are designated by making a particular group or structure shown in the column of left side terminal group, bonding group, ring structure, or right side terminal group in Table 1 below correspond to the symbol shown in the same line and the same column. Designation in the case where the hydrogen atom on trans-1,4-cyclohexylene and trans,trans-bicyclohexane-4,4'-diyl group is replaced by its isotope, heavy hydrogen (deuterium) atom is shown by symbol [1D,.about.8D] after excerpting only substituted heavy hydrogen atoms, when both of the groups mentioned above are assumed to be expressed by the formula (60) and (61), respectively, and any one of hydrogen atoms L.sup.1, L.sup.2, L.sup.3, L.sup.4, L.sup.5, L.sup.6, L.sup.7, and L.sup.8 on the ring is assumed to be replaced by one of heavy hydrogen atoms 1D, 2D, 3D, 4D, 5D, 6D, 7D, and 8D. Compound No. appended to the compounds of the present invention in the following Composition Examples means that the compounds are the same as those shown in Examples described below and having the same appended Compound No.; and the content of compounds means % by weight unless otherwise specified. Further, data of characteristics in Composition Examples are indicated by T.sub.NI (phase transition temperature of nematic phase-isotropic liquid, or clearing point), T.sub.MP (crystallization temperature), .eta. (viscosity: determined at 20.0.degree. C.), An (optical anisotropy value: determined at 25.0.degree. C.), .DELTA..epsilon. (dielectric anisotropy value: determined at 25.0.degree. C.), V.sub.th (threshold voltage: determined at 25.0.degree. C.), and P (pitch: determined at 25.0.degree. C.). ##STR14## TABLE 1 |
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