Patent ID: 8580146

Claim:
A compound represented by formula (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 , ring A 2 and ring A 3 are each independently 1,4-cyclohexylene, 1,4cyclohexenylene, 1,4-phenylene or 2,3-difluoro-1,4-phenylene; at least one of ring A 2 and ring A 3 is 1,4-cyclohexenylene when ring A l is 1,4-cyclohexylene; Z 1 is —(CH 2 ) 2 —CH═CH— or —CH═CH—(CH 2 ) 2 —; l is 1 or 2, m and n are each independently 0, 1 or 2, the sum of m and n is 1 or 2, and the sum of 1, m and n is 2 or 3; when l and m are 1, n is 0, ring A 1 is 1,4-phenylene or 2,3-difluoro-1,4-phenylene and ring A 2 is 1,4-cyclohexylene or 1,4-cyclohexenylene, and when l is 2, m is 1 and n is 0, if one ring A 1 is 1,4-cyclohexylene or 1,4-cyclohexenylene, then the other ring A 1 is 1,4-phenylene, and ring A 2 is 1,4-phenylene.