Fluorinated polycycles and their use in liquid-crystal mixtures

摘要

Compounds of the formula (I) where: R¹, R² are each independently a) H b) -M¹-A¹-R⁵ c) a straight-chain or branched alkyl radical having from 1 to 16 carbon atoms or a straight-chain or branched alkenyl radical having from 2 to 16 carbon atoms, where c1) one or more nonadjacent and nonterminal CH₂ groups may be replaced by -O-, -C(-O)O-, -O-C(-O)-, -O-C(-O)-O-, -C(-O)- or -Si(CH₃)₂-, and/or c2) one CH₂ group may be replaced by -C≡C-, cyclopropane-1,2-diyl, cyclobutane-1,3-diyl, cyclohexane-1,4-diyl or phenylene-1,4-diyl, and/or c3) one or more hydrogen atoms may be replaced by F and/or Cl, p, q, r are each independently 0 or 1 M¹-is -CO-O-, -O-CO-, -CH₂-O-, -O-CH₂-, -CF₂-O-, -O-CF₂-, -CH-CH-, -CF-CF-, -C≡C-, -CH₂-CH₂-CO-O-, -O-CO-CH₂-CH₂-, -CH₂-CH₂-, -CF₂-CF₂-, -(CH₂)₄-, -OC(-O)CF-CF- or a single bond, A¹ is 1,4-phenylene where one or two hydrogen atoms may be replaced by F, Cl, CN and/or OCF₃, or up to three hydrogen atoms may be replaced by fluorine, 1,4-cyclohexylene where one or two hydrogen atoms may be replaced by CH₃ and/or F, 1-cyclohexene-1,4-diyl where one hydrogen atom may be replaced by CH₃ or F, or 1,3-dioxane-2,5-diyl, R⁵ has the same possible definitions as R¹ and R² with the exception of -M¹-A¹-R⁵, with the provisos that: a) at least one of p, q, r is 1 b) R¹ and R² must not at the same time be H are used in liquid-crystal mixtures.