An object of the present invention is to provide novel liquid crystalline compounds having a negative and extremely large dielectric anisotropy value and a small optical anisotropy value together, to provide liquid crystal compositions comprising the liquid crystalline compound, and to provide liquid crystal display devices fabricated by using the liquid crystal composition; the liquid crystalline compounds have 2,3-difluorophenyl moiety and are expressed by the general formula (1)
wherein Ra and Rb each independently represent a straight chain or branched alkyl group having 1 to 20 carbon atoms in which group any methylene group may be replaced by -O-, -CH=CH-, or -C≡C-, but there is not a case wherein -O- continues; ring A1 represents cyclohexane-1,4-diyl in which ring any methylene group may be replaced by -O-; ring A2 represents 2,3-difluoro-1,4-phenylene in which phenylene hydrogen atoms at 5-position and 6-position may each independently be replaced by methyl groups or fluorine atoms; Z1 and Z2 represent single bond or -CH2CH2-; Xa, Xb, Xc, and Xd represent hydrogen atom, fluorine atom, or chlorine atom, but at least one of Xa, Xb, Xc, and Xd is fluorine atom or chlorine atom.
本发明的目的是提供新型液晶化合物,其介电常数各向异性值为负且极大,光学各向异性值较小,提供包含该液晶化合物的液晶组合物,并提供使用该液晶组合物制造的液晶显示设备;该液晶化合物具有 2,3-二
氟苯基分子,由通式 (1) 表示
其中 Ra 和 Rb 各自独立地代表具有 1 至 20 个碳原子的直链或支链烷基,在该基团中,任何亚甲基可被 -O-、-CH=CH- 或 -C≡C- 取代,但不存在 -O- 继续存在的情况;环 A1 代表
环己烷-1,4-二基,在该环中,任何亚甲基可被 -O- 取代;环 A2 代表 2,3-二
氟-1,4-亚苯基,其中 5 位和 6 位的亚苯基氢原子可各自独立地被甲基或
氟原子取代; Z1 和 Z2 代表单键或-CH2CH2-; Xa、Xb、Xc 和 Xd 代表氢原子、
氟原子或
氯原子,但 Xa、Xb、Xc 和 Xd 中至少有一个是
氟原子或
氯原子。