Liquid crystal compounds, liquid crystal compostions containing the compounds, and liquid crystal display devices made by using the compositions

A liquid crystalline compound expressed by the general formula (1)

• wherein R1 and Y1 represent an alkyl group having 1 to 20 carbon atoms one or more non-adjacent methylene groups in the alkyl group may be replaced by oxygen atom, sulfur atom, or vinylene group;
• X1, X2, and X3 independently represent single bond, 1,2-ethylene group, vinylene group, —COO—, —CF2O—, or —OCF2— provided that at least one of X1, X2, and X3 represents —CF2O— or —OCF2—;
• ring A1, ring A2, ring A3, and ring A4 independently represent trans-1,4-cyclohexylene group CH2 group on which ring may be replaced by oxygen atom, or 1,4-phenylene group one or more hydrogen atoms of which may be replaced by fluorine atom or chlorine atom;
• and m and n are independently 0 or 1;
• provided that at least one ring among A1, ring A2, ring A3, and ring A4 represents 1,4-phenylene group at least one hydrogen atom in which group is replaced by fluorine atom or chlorine atom;
• and
• when m=n=0, and X1 represents —CF2O or —OCF2, then ring A1 or ring A4 represents trans-1,4-cyclohexylene group;
• when m+n≧1 and at least two among X1, X2, and X3 are bonding groups selected from —CF2O— or —OCF2—, then at least one of rings which bond directly to the carbon atom in the —CF2O— or —OCF2— is trans-1,4-cyclohexylene group.