Three-ring liquid crystal compound having lateral fluorine, liquid crystal composition, and liquid crystal display device

1. A liquid crystal compound represented by formula (a-1):

wherein

R 1 and R 2 are each independently hydrogen, alkyl having 1 to 10 carbons, alkenyl having 2 to 10 carbons, alkoxy having 1 to 9 carbons, alkoxyalkyl having 2 to 9 carbons or alkenyloxy having 2 to 9 carbons;

ring A 1 is trans-1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl or pyridine-2,5-diyl;

L 1 , L 2 , L 3 and L 4 are each independently hydrogen or fluorine, and at least three of them are fluorine; and

Z 1 is a single bond, —(CH 2 ) 2 —, —CH═CH—, —C≡C—, —CH 2 O— or —OCH 2 — when ring A 1 is trans-1,4-cyclohexylene, 1,4-cyclohexenylene, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl or pyridine-2,5-diyl, and Z 1 is —(CH 2 ) 2 —, —CH═CH—, —C≡C—, —CH 2 O— or —OCH 2 -when ring A 1 is 1,4-phenylene.

2. The compound according to claim 1 , wherein in formula (a-1),

R 1 and R 2 are each independently alkyl having 1 to 10 carbons, alkenyl having 2 to 10 carbons, alkoxy having 1 to 9 carbons, alkoxyalkyl having 2 to 9 carbons or alkenyloxy having 2 to 9 carbons;

ring A 1 is 1,4-phenylene; and

Z 1 is —(CH 2 ) 2 —, —CH═CH—, —C≡C—, —CH 2 O— or —OCH 2 —.

3. The compound according to claim 1 , wherein in formula (a-1),

R 1 and R 2 are each independently alkyl having 1 to 10 carbons, alkenyl having 2 to 10 carbons, alkoxy having 1 to 9 carbons, alkoxyalkyl having 2 to 9 carbons or alkenyloxy having 2 to 9 carbons; and

ring A 1 is trans-1,4-cyclohexylene.

4. The compound according to claim 1 , wherein the compound is represented by formula (a-2) or (a-3):

wherein,

R 3 and R 4 are each independently alkyl having 1 to 10 carbons, alkenyl having 2 to 10 carbons, alkoxy having 1 to 9 carbons, alkoxyalkyl having 2 to 9 carbons or alkenyloxy having 2 to 9 carbons;

L 5 , L 6 , L 7 and L 8 are each independently hydrogen or fluorine, and at least three of them are fluorine; and

Z 2 is a single bond, —(CH 2 ) 2 —, —CH═CH—, —CH 2 O— or —OCH 2 —.

5. The compound according to claim 1 , wherein the compound is represented by any one of formulas (a-4) to (a-13):

wherein

R 5 and R 6 are each independently alkyl having 1 to 10 carbons, alkenyl having 2 to 10 carbons, alkoxy having 1 to 9 carbons, alkoxyalkyl having 2 to 9 carbons or alkenyloxy having 2 to 9 carbons; and

Z 3 is —(CH 2 ) 2 —, —CH═CH—, —CH 2 O— or —OCH 2 —.

6. The compound according to claim 5 , wherein in formulas (a-4) to (a-13), Z 3 is —OCH 2 —.

7. The compound according to claim 5 , wherein in formulas (a-4) to (a-13), Z 3 is —(CH 2 ) 2 —.

8. A liquid crystal composition which has negative dielectric anisotropy, comprising a first component consisting of at least one compound selected from the group of compounds represented by formula (a-1), (a-2) or (a-3), and a second component consisting of at least one compound selected from the group of compounds represented by formulas (e-1) to (e-3):

wherein

R 1 and R 2 are each independently hydrogen, alkyl having 1 to 10 carbons, alkenyl having 2 to 10 carbons, alkoxy having 1 to 9 carbons, alkoxyalkyl having 2 to 9 carbons or alkenyloxy having 2 to 9 carbons;

ring A 1 is trans-1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl or pyridine-2,5-diyl;

L 1 , L 2 , L 3 and L 4 are each independently hydrogen or fluorine, and at least three of them are fluorine; and

Z 1 is a single bond, —(CH 2 ) 2 —, —CH═CH—, —C≡C—, —CH 2 O— or —OCH 2 — when ring A 1 is trans-1,4-cyclohexylene, 1,4-cyclohexenylene, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl or pyridine-2,5-diyl, and Z 1 is —(CH 2 ) 2 —, —CH═CH—, —C≡C—, —CH 2 O— or —OCH 2 — when ring A 1 is 1,4-phenylene,

wherein,

R 3 and R 4 are each independently alkyl having 1 to 10 carbons, alkenyl having 2 to 10 carbons, alkoxy having 1 to 9 carbons, alkoxyalkyl having 2 to 9 carbons or alkenyloxy having 2 to 9 carbons;

L 5 , L 6 , L 7 and L 8 are each independently hydrogen or fluorine, and at least three of them are fluorine; and

Z 2 is a single bond, —(CH 2 ) 2 —, —CH═CH—, —CH 2 O— or —OCH 2 —,

wherein

Ra 11 and Rb 11 are each independently alkyl having 1 to 10 carbons, and in the alkyl, arbitrary —CH 2 — may be nonadjacently replaced by —O—, and arbitrary —(CH 2 ) 2 — may be nonadjacently replaced by —CH═CH—, and arbitrary hydrogen may be replaced by fluorine;

ring A 11 , ring A 12 , ring A 13 and ring A 14 are each independently trans-1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl; and

Z 11 , Z 12 and Z 13 are each independently a single bond, —CH 2 —CH 2 —, —CH═CH—, —C≡C—, —COO— or —CH 2 O—.

9. A liquid crystal composition which has negative dielectric anisotropy, comprising a first component consisting of at least one compound selected from the group of compounds represented by formulas (a-4) to (a-13), and a second component consisting of at least one compound selected from the group of compounds represented by formulas (e-1) to (e-3):

wherein

R 5 and R 6 are each independently alkyl having 1 to 10 carbons, alkenyl having 2 to 10 carbons, alkoxy having 1 to 9 carbons, alkoxyalkyl having 2 to 9 carbons or alkenyloxy having 2 to 9 carbons; and

Z 3 is —(CH 2 ) 2 —, —CH═CH—, —CH 2 O— or —OCH 2 —,

wherein

Ra 11 and Rb 11 are each independently alkyl having 1 to 10 carbons, and in the alkyl, arbitrary —CH 2 — may be nonadjacently replaced by —O—, and arbitrary —(CH 2 ) 2 — may be nonadjacently replaced by —CH═CH—, and arbitrary hydrogen may be replaced by fluorine;

ring A 11 , ring A 12 , ring A 13 and ring A 14 are each independently trans-1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl; and

Z 11 , Z 12 and Z 13 are each independently a single bond, —CH 2 —CH 2 —, —CH═CH—, —C≡C—, —COO— or —CH 2 O—.

10. The liquid crystal composition according to claim 8 , wherein the content ratio of the first component is in the range of 5% to 60% by weight and the content ratio of the second component is in the range of 40% to 95% by weight, based on the total weight of the liquid crystal composition.

11. The liquid crystal composition according to claim 8 , further comprising a third component consisting of at least one compound selected from the group of compounds represented by formulas (g-1) to (g-6), in addition to the first and second components:

wherein

Ra 21 and Rb 21 are each independently hydrogen or alkyl having 1 to 10 carbons, and in the alkyl, arbitrary —CH 2 — may be nonadjacently replaced by —O—, and arbitrary —(CH 2 ) 2 — may be nonadjacently replaced by —CH═CH—, and arbitrary hydrogen may be replaced by fluorine;

ring A 21 , ring A 22 and ring A 23 are each independently trans-1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl;

Z 21 , Z 22 an Z 23 are each independently a single bond, —CH 2 —CH 2 —, —CH═CH—, —C≡C—, —OCF 2 —, —CF 2 O—, —OCF 2 CH 2 CH 2 —, —CH 2 CH 2 CF 2 O—, —COO—, —OCO—, —OCH 2 — or —CH 2 O—;

Y 1 Y 2 , Y 3 and Y 4 are each independently fluorine or chlorine;

q, r and s are each independently 0, 1 or 2, q+r is 1 or 2, and q+r+s is 1, 2 or 3; and

t is 0, 1 or 2.

12. The liquid crystal composition according to claim 11 , wherein the third component is at least one compound selected from the group of compounds represented by formulas (h-1) to (h-7):

wherein

Ra 22 and Rb 22 are each independently straight-chain alkyl having 1 to 8 carbons, straight-chain alkenyl having 2 to 8 carbons or straight-chain alkoxy having 1 to 7 carbons;

Z 24 , Z 25 and Z 26 are each independently a single bond, —CH 2 CH 2 —, —CH 2 O— or —OCH 2 —; and

Y 1 and Y 2 are simultaneously fluorine, or one of Y 1 and Y 2 is fluorine and the other is chlorine.

13. A liquid crystal composition which has negative dielectric anisotropy, comprising a first component consisting of at least one compound selected from the compounds represented by formulas (a-4) to (a-13), a second component consisting of at least one compound selected from the group of compounds represented by formulas (e-1) to (e-3), and a third component consisting of at least one compound selected from the group of compounds represented by formulas (h-1) to (h-7):

wherein

R 5 and R 6 are each independently alkyl having 1 to 10 carbons, alkenyl having 2 to 10 carbons, alkoxy having 1 to 9 carbons, alkoxyalkyl having 2 to 9 carbons or alkenyloxy having 2 to 9 carbons; and

Z 3 is —(CH 2 ) 2 —, —CH═CH—, —CH 2 O— or —OCH 2 ,

wherein

Ra 11 and Rb 11 are each independently alkyl having 1 to 10 carbons, and in the alkyl, arbitrary —CH 2 — may be nonadjacently replaced by —O—, and arbitrary —(CH 2 ) 2 — may be nonadjacently replaced by —CH═CH—, and arbitrary hydrogen may be replaced by fluorine;

ring A 11 , ring A 12 , ring A 13 and ring A 14 are each independently trans-1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl; and

Z 11 , Z 12 and Z 13 are each independently a single bond, —CH 2 —CH 2 —, —CH═CH—, —C≡C—, —COO— or —CH 2 O—,

wherein

Ra 22 and Rb 22 are each independently straight-chain alkyl having 1 to 8 carbons, straight-chain alkenyl having 2 to 8 carbons or straight-chain alkoxy having 1 to 7 carbons;

Z 24 , Z 25 and Z 26 are each independently a single bond, —CH 2 CH 2 — —CH 2 O— or —OCH 2 —; and

Y 1 and Y 2 are simultaneously fluorine, or one of Y 1 and Y 2 is fluorine and the other is chlorine.

14. The liquid crystal composition according to claim 13 , wherein the content ratio of the first component is in the range of 5% to 60% by weight, the content ratio of the second component is in the range of 20% to 75% by weight, and the content ratio of the third component is in the range of 20% to 75% by weight, based on the total weight of the liquid crystal composition.

15. A liquid crystal display device comprising the liquid crystal composition according to claim 8 .

16. The liquid crystal display device according to claim 15 , wherein the operating mode thereof is a VA mode or an IPS mode, and the driving mode thereof is an active matrix mode.