| 摘要 |
A liquid crystal (LC) compound having generally required physical properties, low viscosity, proper optical anisotropy, proper dielectric anisotropy and good compatibility with other LC compounds is described. An LC composition including the compound and an LCD device including the composition are also described. The compound is expressed by formula (1a): wherein the ring A<SUP>1 </SUP>and the ring A<SUP>2 </SUP>are independently 1,4-phenylene, pyridine-2,5-diyl, pyrimidine-2,5-diyl or naphthalene-2,6-diyl, in which any hydrogen can be replaced by halogen; Z<SUP>1</SUP>, Z<SUP>2 </SUP>and Z<SUP>3 </SUP>are independently a single bond, -(CH<SUB>2 </SUB>)<SUB>2</SUB>-, -(CH<SUB>2 </SUB>)<SUB>4</SUB>-, -CH-CH-, -C≡C-, -CF<SUB>2</SUB>O-, -OCF<SUB>2</SUB>-, -COO- or -OCO-; X<SUP>a</SUP>, X<SUP>b</SUP>, X<SUP>c</SUP>, X<SUP>d</SUP>, X<SUP>e </SUP>and X<SUP>f </SUP>are independently hydrogen or fluorine; Y is -OCH<SUB>2</SUB>F, -OCHF<SUB>2</SUB>, -OCF<SUB>3</SUB>, -SCH<SUB>2</SUB>F, -SCHF<SUB>2</SUB>, -SCF<SUB>3</SUB>, -CH<SUB>2</SUB>F, -CHF<SUB>2</SUB>, -CF<SUB>3</SUB>, fluorine or chlorine; L<SUP>a </SUP>and L<SUP>b </SUP>are independently hydrogen or fluorine; and "l" and "m" are independently equal to 0 or 1.
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