Polymerizable polar compound, liquid crystal composition and liquid crystal display device

A compound, represented by formula (1):

• wherein, in formula (1),
• a and b are independently 0, 1 or 2, wherein 0≤a+b≤3,
• ring A1, ring A2, ring A3 and ring A4 are independently 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl, fluorene-2,7-diyl, phenanthrene-2,7-diyl, anthracene-2,6-diyl, perhydrocyclopenta[a]phenanthrene-3,17-diyl or 2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetradecahydrocyclopenta[a]phenanthrene-3,17-diyl, and in the rings, at least one hydrogen may be replaced by fluorine, chlorine, alkyl having 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkoxy having 1 to 11 carbons or alkenyloxy having 2 to 11 carbons, and in the groups, at least one hydrogen may be replaced by fluorine or chlorine, and when a is 2, two of ring A1 may be different, and when b is 2, two of ring A4 may be different;
• Z1, Z2, Z3, Z4 and Z5 are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one —CH2— may be replaced by —O—, —CO—, —COO—, —OCO— or —OCOO—, and at least one —(CH2)2— may be replaced by —CH═CH— or —C≡C—, and in the groups, at least one hydrogen may be replaced by halogen, in which at least one in Z2, Z3 or Z4 is —COO—, —OCO—, —CH═CHCOO—, —OCOCH═CH—, —CH═CH—, —CH═CHCO— or —COCH═CH—, and when a is 2, two Z*s may be different, and two Z5s may be different;
• Sp1 and Sp2 are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one —CH2— may be replaced by —O—, —CO—, —COO—, —OCO— or —OCOO—, and at least one —(CH2)2— may be replaced by —CH═CH— or —C≡C—, and in the groups, at least one hydrogen may be replaced by halogen;
• P1 is a group represented by any one of formulas (1b) to (1i);
• and
• P2 is a group represented by formula (1d);
• wherein, in formulas (1b) to (1i),
• M1 and M2 are independently hydrogen, halogen, alkyl having 1 to 5 carbons, or alkyl having 1 to 5 carbons in which at least one hydrogen is replaced by halogen;
• R2 is hydrogen, halogen or alkyl having 1 to 5 carbons, and in the alkyl, at least one hydrogen may be replaced by halogen, and at least one —CH2— may be replaced by —O—;
• and
• R3, R4 and R5 are independently hydrogen or alkyl having 1 to 15 carbons, and in the alkyl, at least one —CH2— may be replaced by —O— or —S—, and at least one —(CH2)2— may be replaced by —CH═CH— or —C≡C—, and in the groups, at least one hydrogen may be replaced by halogen.