Liquid crystal compound having xanthene skeleton and exhibiting negative dielectric anisotropy, liquid crystal composition and liquid crystal display device

1. A compound represented by formula (1-A) or (1-B):

wherein, in formula (1-A) or (1-B),

R 1 and R 2 are independently alkyl having 1 to 15 carbons, and in the alkyl, at least one of —CH 2 — may be replaced by —O—, at least one of —(CH 2 ) 2 — may be replaced by —CH═CH—, and in the groups, at least one of hydrogen may be replaced by halogen;

ring A 1 and ring A 2 are independently 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, 1,4-phenylene in which at least one of hydrogen is replaced by fluorine, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl; and

Z 1 and Z 2 are independently a single bond, —(CH 2 ) 2 —, —CH═CH—, —COO—, —OCO—, —CH 2 O—, —OCH 2 —, —CF 2 O—, or —OCF 2 —.

2. The compound according to claim 1 , wherein at least one of ring A 1 and ring A 2 is tetrahydropyran-2,5-diyl.

3. The compound according to claim 1 , represented by any one of formulas (1-A-1) to (1-A-6) and formulas (1-B-1) to (1-B-6):

wherein, in formulas (1-A-1) to (1-A-6) and formulas (1-B-1) to (1-B-6), R 1 and R 2 are independently alkyl having 1 to 10 carbons, alkenyl having 2 to 10 carbons or alkoxy having 1 to 9 carbons, and Y 1 , Y 2 , Y 3 and Y 4 are independently hydrogen or fluorine.

4. The compound according to claim 1 , represented by any one of formulas (1-A-7) to (1-A-12) and formulas (1-B-7) to (1-B-12):

wherein, in formulas (1-A-7) to (1-A-12) and formulas (1-B-7) to (1-B-12), R 1 and R 2 are independently alkyl having 1 to 10 carbons, alkenyl having 2 to 10 carbons or alkoxy having 1 to 9 carbons.

5. A liquid crystal composition, containing at least one of the compounds according to claim 1 .

6. The liquid crystal composition according to claim 5 , further containing at least one compound selected from the group of compounds represented by formulas (6) to (12):

wherein, in formulas (6) to (12),

R 13 is alkyl having 1 to 10 carbons or alkenyl having 2 to 10 carbons, and in the alkyl and the alkenyl, at least one of —CH 2 — may be replaced by —O— and at least one of hydrogen may be replaced by fluorine;

R 14 is alkyl having 1 to 10 carbons, and in the alkyl, at least one of —CH 2 — may be replaced by —O— and at least one of hydrogen may be replaced by fluorine;

R 15 is hydrogen, fluorine, alkyl having 1 to 10 carbons or alkenyl having 2 to 10 carbons, and in the alkyl and the alkenyl, at least one of —CH 2 — may be replaced by —O— and at least one of hydrogen may be replaced by fluorine;

S 11 is hydrogen or methyl;

X is —CF 2 —, —O— or —CHF—;

ring D 1 , ring D 2 , ring D 3 and ring D 4 are independently 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene in which at least one of hydrogen may be replaced by fluorine, tetrahydropyran-2,5-diyl or decahydronaphthalene-2,6-diyl;

ring D 5 and ring D 6 are independently 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, tetrahydropyran-2,5-diyl or decahydronaphthalene-2,6-diyl;

Z 15 , Z 17 and Z 18 are independently a single bond, —CH 2 CH 2 —, —COO—, —CH 2 O—, —OCF 2 — or —OCF 2 CH 2 CH 2 —;

L 15 and L 16 are independently fluorine or chlorine; and

j, k, m, n, p, q, r and s are independently 0 or 1, a sum of k, m, n and p is 1 or 2, a sum of q, r and s is 0, 1,2 or 3, and t is 1,2 or 3.

7. The liquid crystal composition according to claim 5 , further containing at least one compound selected from the group of compounds represented by formulas (13) to (15):

wherein, in formulas (13) to (15),

R 16 and R 17 are independently alkyl having 1 to 10 carbons or alkenyl having 2 to 10 carbons, and in the alkyl or the alkenyl, at least one of —CH 2 — may be replaced by —O— and at least one of hydrogen may be replaced by fluorine;

ring E 1 , ring E 2 , ring E 3 and ring E 4 are independently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 2,5-difluoro-1,4-phenylene or pyrimidine-2,5-diyl; and

Z 19 , Z 20 and Z 21 are independently a single bond, —CH 2 CH 2 —, —CH═CH—, or —COO—.

8. The liquid crystal composition according to claim 5 , further containing at least one compound selected from the group of compounds represented by formulas (2) to (4):

wherein, in formulas (2) to (4),

R 11 is alkyl having 1 to 10 carbons or alkenyl having 2 to 10 carbons, and in the alkyl and the alkenyl, at least one of hydrogen may be replaced by fluorine and at least one of —CH 2 — may be replaced by —O—;

X 11 is fluorine, chlorine, —OCF 3 , —OCHF 2 , —CF 3 , —CHF 2 , —CH 2 F, —OCF 2 CHF 2 or —OCF 2 CHFCF 3 ;

ring B 1 , ring B 2 and ring B 3 are independently 1,4-cyclohexylene, 1,4-phenylene in which at least one of hydrogen may be replaced by fluorine, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl or pyrimidine-2,5-diyl;

Z 11 , Z 12 and Z 13 are independently a single bond, —CH 2 CH 2 —, —CH═CH—, —C≡C—, —COO—, —CF 2 O—, —OCF 2 —, —CH 2 O— or —(CH 2 ) 4 —; and

L 11 and L 12 are independently hydrogen or fluorine.

9. The liquid crystal composition according to claim 5 , further containing at least one compound selected from the group of compounds represented by formula (5):

wherein, in formula (5),

R 12 is alkyl having 1 to 10 carbons or alkenyl having 2 to 10 carbons, and in the alkyl and alkenyl, at least one of hydrogen may be replaced by fluorine and at least one of —CH 2 — may be replaced by —O—;

X 12 is —C≡N or —C≡C—C≡N;

ring C 1 is 1,4-cyclohexylene, 1,4-phenylene in which at least one of hydrogen may be replaced by fluorine, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl or pyrimidine-2,5-diyl;

Z 14 is a single bond, —CH 2 CH 2 —, —COO—, —CF 2 O—, —OCF 2 — or —CH 2 O—;

L 13 and L 14 are independently hydrogen or fluorine; and

i is 1, 2, 3 or 4.

10. The liquid crystal composition according to claim 5 , further containing at least one optically active compound and/or at least one polymerizable compound.

11. The liquid crystal composition according to claim 5 , further containing at least one antioxidant and/or at least one ultraviolet light absorber.

12. A liquid crystal display device, including the liquid crystal composition according to claim 5 .