Fluorinated phenantrene derivatives for liquid crystal mixtures

A fluorinated phenanthrene derivative of the formula (I)

• in which the symbols and indices have the following meanings:
• G is —CHF—CH2— or —CF═CH—;
• E1, E2, E3, E4, E5 and E6 are identical or different and are
• —CH—, —CF— or —N—, with the proviso that E4 and E5 cannot simultaneously be —N—;
• R1 and R2 are identical or different and are
• a) hydrogen, —F, —Cl, —CF3, —OCF3 or —CN,
• b) a straight-chain or branched alkyl radical (with or without an asymmetric carbon atom) having 1 to 20 carbon atoms, where
• b1) one or more nonadjacent and nonterminal CH2 groups can be replaced by —O—, —S—, —CO—O—, —O—CO—, —O—CO—O— or —Si(CH3)2—, and/or
• b2) one or more CH2 groups can be replaced by —CH═CH—, —C≡C—, cyclopropane-1,2-diyl, 1,4-phenylene, 1,4-cyclohexylene or 1,3-cyclopentylene, and/or
• b3) one or more H atoms can be replaced by F and/or Cl, and/or
• b4) the terminal CH3 group can be replaced by one of the following chiral groups (optically active or racemic):
• with the proviso that only one of the radicals R1, R2 can be hydrogen, —F, —Cl, —CF3, —OCF3 or —CN;
• R3, R4, R5, R6 and R7 are identical or different and are
• a) hydrogen,
• b) a straight-chain or branched alkyl radical (with or without an asymmetric carbon atom) having 1 to 16 carbon atoms, where
• b1) one or more nonadjacent and nonterminal CH2 groups can be replaced by —O—, and/or
• b2) one or two CH2 groups can be replaced —CH═CH—,
• c) R4 and R5 together are alternatively —(CH2)4— or —(CH2)5—, if they are attached to an oxirane, dioxolane, tetrahydrofuran, tetrahydropyran, butyrolactone or valerolactone system;
• M1, M2, M3 and M4 are identical or different and are
• —CO—O—, —O—CO—, —CO—S—, —S—CO—, —CS—O—, —O—CS—, —CH2—O—, —O—CH2—, —CH2—S—, —S—CH2—, —CH═CH—, —C≡C—, —CH2—CH2—CO—O—, —O—CO—CH2—CH2— 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 can be replaced by F, Cl and/or CN, pyrazine-2,5-diyl, in which one or two H atoms can be replaced by F, Cl and/or CN, pyridazine-3,6-diyl in which one or two H atoms can be replaced by F, Cl and/or CN, pyridine-2,5-diyl in which one or more H atoms can be replaced by F, Cl and/or CN, pyrimidine-2,5-diyl in which one or two H atoms can be replaced by F, Cl and/or CN, 1,4-cyclohexylene in which one or two H atoms can be replaced by CN, F and/or CH3, 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 can be replaced by F, Cl and/or CN, 1,3-thiazole-2,5-diyl in which one H atom can be replaced by F, Cl and/or CN, thiophene-2,4-diyl, in which one H atom can be replaced by F, Cl and/or CN, thiophene-2,5-diyl in which one or two H atoms can be replaced by F, Cl and/or CN, piperazine-1,4-diyl piperazine-2,5-diyl or 1-(C1-C4)alkyl-1-silacyclohexylene-1,4-diyl;
• a, b, c and d are zero or one,
• with the proviso that the compound of the formula (I) may contain no more than four ring systems having five or more members.