Liquid crystal compound, liquid crystal composition and liquid crystal display device

A compound represented by formula (1):

• wherein, in formula (1),
• R1 is alkyl having 1 to 15 carbons, and in the alkyl, at least one of —CH2— may be replaced by —O— or —S—, at least one of —(CH2)2— may be replaced by —CH═CH—, and in the groups, at least one of hydrogen may be replaced by halogen;
• ring A1, ring A2, ring A3 and ring A4 are independently 1,4-cyclohexylene, 1,4-cyclohexenylene, 1,4-phenylene, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, 2,6,7-trioxabicyclo[2.2.2]octane-1,4-diyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl, and at least one of hydrogen directly bonded to the rings thereof may be replaced by halogen;
• W1 is a group represented by formula (1a) or formula (1b);
• wherein, in formula (1a),
• Y1 and Y2 are independently fluorine or chlorine;
• in formula (1b),
• Y3, Y4 and Y5 are independently hydrogen, fluorine or chlorine, and at least two of Y3, Y4 and Y5 are fluorine or chlorine;
• and
• in formula (1),
• W2 is a group represented by formula (1c) or formula (1d);
• wherein, in formula (1c) and (1d),
• L1, L2, L3, L4 and L5 are independently hydrogen, fluorine or chlorine;
• and
• in formula (1),
• X1 is fluorine, —C≡N, —N═C═S, or alkyl having 1 to 10 carbons in which at least one of hydrogen is replaced by fluorine, alkenyl having 2 to 10 carbons in which at least one of hydrogen is replaced by fluorine, alkoxy having 1 to 9 carbons in which at least one of hydrogen is replaced by fluorine, or alkenyloxy having 2 to 9 carbons in which at least one of hydrogen is replaced by fluorine;
• a, b, c and d are independently 0 or 1, and a sum of a, b, c and d is 0, 1, 2 or 3;
• Z1, Z2, Z3, Z4 and Z5 are independently a single bond, —(CH2)2—, —CH2O—, —OCH2—, —COO—, —OCO—, —(CH2)4—, —(CH2)2CF2O—, —OCH2CF2O—, —(CH2)3O—, —O(CH2)3— or —(CH2)2COO—;
• at least one of Z1 when a is 1, Z2 when b is 1, Z3 when c is 1, Z4 when d is 1 and Z5 is —(CH2)2—, —CH2O—, —OCH2—, —COO—, —OCO—, —(CH2)4—, —(CH2)2CF2O—, —OCH2CF2O—, —(CH2)3O—, —O(CH2)3— or —(CH2)2COO—;
• when Z5 is —COO—, ring W1 is a group represented by formula (1a) and ring W2 is a group represented by formula (1c), X1 is fluorine, or alkyl having 1 to 10 carbons in which at least one of hydrogen is replaced by fluorine, alkenyl having 2 to 10 carbons in which at least one of hydrogen is replaced by fluorine, alkoxy having 1 to 9 carbons in which at least one of hydrogen is replaced by fluorine, or alkenyloxy having 2 to 9 carbons in which at least one of hydrogen is replaced by fluorine;
• when Z5 is —COO—, ring W1 is a group represented by formula (1a), ring W2 is a group represented by formula (1c), a sum of a and b is 1, a sum of c and d is 0, ring A1 when a is 1 or ring A2 when b is 1 is 1,4-phenylene, Z1 when a is 1 or Z2 when b is 1 is a single bond, both Y1 and Y2 are fluorine and X1 is fluorine, both L1 and L2 are hydrogen or fluorine;
• and
• when Z5 is —COO—, ring W1 is a group represented by formula (1a), ring W2 is a group represented by formula (1c), a sum of a, b, c and d is 0, both Y1 and Y2 are fluorine and X1 is —CF3, at least one of L1 and L2 is fluorine.