2,3-difluorophenyl derivative having negative dielectric anisotropy, liquid crystal composition, and liquid crystal display device

Abstract

The invention is to provide liquid crystalline compounds having a negative and extremely large dielectric anisotropy value and a small optical anisotropy value at the same time; liquid crystal compositions comprising the compound; and liquid crystal display devices fabricated by using the liquid crystal composition; the liquid crystalline compounds have 2,3-dihalogenophenylene moiety and are expressed by formula (1) wherein Ra and Rb each independently represents a linear or branched alkyl having 1 to 10 carbon, any methylene in the alkyl may be replaced by —O—, —S—, —CH═CH—, or —C≡C—, but —O— is not successive, and any hydrogen in the alkyl may be replaced by halogen; rings A1 to A4 each independently represents trans-1,4-cyclohexylene, cyclohexene-1,4-diyl, pyridine-1,4-diyl, pyrimidine-2,5-diyl, or 1,4-phenylene, wherein at least one hydrogen in these rings may be replaced by halogen, and any nonadjacent methylene in cyclohexane ring may be replaced by —O—; Y1 and Y2 each independently represents F or Cl; Z1, Z2 and Z3 each independently represents a single bond, —CH2CH2—, —(CH2)4—, —COO—, —OCO—, —CH2O—, —OCH2—, —CF2O—, or —OCF2—; and l, m and n each independently is 0, 1 or 2, and the sum of l+m+n is 3 and less.

Dependencies are inferred from the claim text.