| abstract |
Liquid crystal compounds have the formula (I), in which R denotes H, an alkyl or alkylene residue which is unsubstituted or monosubstituted by CN or by CF3, or at least monosubstituted by halogen, having 1 to 15 carbon atoms, then that in these residues one or more CH2 groups can also be substituted, independently of each other, by -O-, -S-, - $ (1,3) $ -, -CO-O-, -O-CO- or -O-CO-O-, so that the O atoms are not directly bonded to each other; Z1 and Z represent independently of each other -CH2CH2-, -CH = CH-, -C = C- or a single bond, while one of the residues Z1 or Z can also represent - (CH2) 4- or -CH = CH-CH2CH2-; A and A1 independently of one another represent trans-1,4-cyclohexylene, in which one or two non-adjacent CH2 groups may also be substituted by -O-, or 1,4-phenylene unsubstituted or substituted a or twice with fluorine and / or Cl atoms, one or two CH groups which may also be substituted by N in 1,4-phenylene; m is 0, 1, 2, or 3; o + s equals 0, 1 or 2, while (s + o) 2; W denotes -O-, -COO- or a single bond; Q denotes -O-, -CH = CH- or a single bond; r is between 1 and 7; t is between 0 and 7; and Y denotes F, Cl, CF3, OCF3, CHF2, OCHF2 or OCH2F. These compounds are useful as components of liquid crystal media. |