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

A compound, represented by formula (1):

• wherein, in formula (1),
• R1 is hydrogen, -Sp2-P2, -Sp3-P3 or alkyl having 1 to 15 carbons, and in the alkyl, at least one piece of —CH2— may be replaced by —O—, —S— or —NH—, and at least one piece of —CH2CH2— may be replaced by —CH═CH— or —C≡C—, and in the groups, at least one hydrogen may be replaced by halogen;
• ring A1, ring A4 and ring A5 are independently cyclohexylene, cyclohexenylene, phenylene, naphthylene, decahydronaphthylene, tetrahydronaphthylene, tetrahydropyrandiyl, 1,3-dioxanediyl, pyrimidinediyl or pyridinediyl, 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 12 carbons or alkenyloxy having 2 to 11 carbons, and in the groups, at least one hydrogen may be replaced by fluorine or chlorine;
• ring A2 and ring A3 are independently cyclohexylene or phenylene, 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 12 carbons or alkenyloxy having 2 to 11 carbons, and in the groups, at least one hydrogen may be replaced by fluorine or chlorine;
• Z1, Z4 and Z5 are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one piece of —CH2— may be replaced by —O—, —CO—, —COO—, —OCO— or —OCOO—, and at least one piece of —CH2CH2— may be replaced by —CH═CH— or —C≡C—, and in the groups, at least one hydrogen may be replaced by fluorine or chlorine;
• Sp2 and Sp3 are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one piece of —CH2— may be replaced by —O—, —COO—, —OCO— or —OCOO—, and at least one piece of —CH2CH2— may be replaced by —CH═CH— or —C≡C—, and in the groups, at least one hydrogen may be replaced by fluorine or chlorine;
• and
• P2 and P3 are independently a polymerizable group represented by formula (P-1);
• wherein, in formula (P-1),
• 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;
• and
• R4 is a group selected from groups represented by any one of formulas (1a), (1b) and (1c);
• wherein, in formulas (1a), (1b) and (1c),
• Sp5 and Sp6 are independently a single bond or alkylene having 1 to 10 carbons, and in the alkylene, at least one piece of —CH2— may be replaced by —O—, —NH—, —CO—, —COO—, —OCO— or —OCOO—, and at least one piece of —CH2CH2— may be replaced by —CH═CH— or —C≡C—, and in the groups, at least one hydrogen may be replaced by halogen;
• S1 is >CH— or >N—;
• S2 is >C< or >Si<;
• X1 is a group represented by —OH, —NH2, —OR5, —N(R5)2, —COOH, —SH, —B(OH)2 or —Si(R5)3, in which R5 is hydrogen or alkyl having 1 to 10 carbons, and in the alkyl, at least one piece of —CH2— may be replaced by —O—, and at least one piece of —CH2CH2— may be replaced by —CH═CH—, and in the groups, at least one hydrogen may be replaced by halogen;
• a, b and c are independently 0, 1, 2, 3 or 4;
• d and e are independently 0, 1, 2, 3 or 4;
• and
• a sum of d and e is 2, 3 or 4.