| 摘要 |
Compounds of the formula R1-A1-Z1-A2-(Z2-A3)n-R2 I wherein Z1 denotes the group -CH2CH2CH2O- or -OCH2CH2CH2-; n stands for the number 0 or 1; R1 represents a group R3 or R3-A4-Z3-; R2 represents a group R4 or R4-A5-Z4-; Z2, Z3 and Z4 each independently are a single covalent bond. -CH2-CH2-, -CH2O-, -OCH2-, -COO-, -OOC-, -CH2CH2CH2O- or -OCH2CH2CH2-; A1, A2, A3, A4 and A5 each independently denote unsubstituted or methyl, halogen and/or cyano-substituted 1,4-phenylene, in which optionally 1-4 CH groups are replaced by nitrogen, unsubstituted or methyl- and/or cyano-substituted trans-1,4-cyclohexylene, in which optionally 2 CH2 groups are replaced by oxygen and/or sulfur, bicyclo[2.2.2]-octane-1,4-diyl, 1,3,4-thiadiazole-2,5-diyl, naphthalene-2,6-diyl, tetralin-2,6-diyl or decalin-2,6-diyl; R3 and R4 each independently represent an unsubstituted or halogen- and/or cyano-substituted alkyl or alkenyl group, in which optionally 1 CH2 group or 2 non-adjacent CH2 groups is/are replaced by -O-, -COO- and/or -OOC-, or one of the residues R3 and R4 also represents hydrogen, halogen, cyano or -NCS, as well as liquid crystalline mixtures and their use for electro-optical purposes.
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