| abstract |
The use of a compound of the formula I, in liquid crystal mixtures, R1(-A1)a(-M1)b(-A2)-O-CF(CF3)-COO-(-A3)(-M2)c(-A4)d-R2 Iin which the symbols and indices have the following meanings: R1 and R2 are identical or different and are hydrogen, a straight-chain or branched alkyl radical having 1 to 20 carbon atoms (with or without asymmetrical carbon atoms), where one or more -CH2- groups may also be replaced by -O-, -CO-, cyclopropane-1,2-diyl, -Si(CH3)2-, with the proviso that oxygen atoms must not be bonded directly to one another, and/or one or more H atoms of the alkyl radical may be substituted by -F; M1 and M2 are identical or different and are -CO-O-, -O-CO-, or a single bond; A1, A2, A3 and A4 are identical or different and are 1,4-phenylene, in which one or more H atoms may be replaced by F, pyrazine-2,5-diyl, in which one or two H atoms may be replaced by F, pyridazine-3,6-diyl, in which one or two H atoms may be replaced by F, pyridine-2,5-diyl, in which one or more H atoms may be replaced by F, pyrimidine-2,5-diyl, in which one or two H atoms may be replaced by F, trans-1,4-cyclohexylene, 1,3,4-thiadiazole-2,5-diyl, 1,3-dioxane-2,5-diyl, 1,3-dithiane-2,5-diyl, 1,3-thiazole-2,4-diyl, in which one H atom may be replaced by F, 1,3-thiazole-2,5-diyl, in which one H atom may be replaced by F, thiophene-2,4-diyl, in which one H atom may be replaced by F, thiophene-2,5-diyl, in which one or two H atoms may be replaced by F, naphthalene-2,6-diyl, in which one or more H atoms may be replaced by F; a, b, c and d are zero or one. |