| abstract |
The novel compounds are chiral esters of alpha -substituted phenylalkanoic acids and mesogenic hydroxy compounds, the symbols in the general formula (I) <IMAGE> (I) being defined as follows: MO=molecular radical of a mesogenic hydroxy compound MOH after removal of one H, the radical MO being expressed by the general formula (II) R2-(A1)n1-(B-)n2(A2)n3-O (II) where R2=straight-chain or branched (C1-C12)-alkyl, it being possible for one or two non-adjacent CH2 groups to be replaced by O and/or S atoms, or, if n1=1, also F, Cl, Br, CN or CF3, A1, A2=independently of one another 1,4-phenylene, diazine-2,5-diyl, diazine-3,6-diyl, 1,4-cyclohexylene, 1,3-dioxane-2,5-diyl, 1,3-dithiane-2,5-diyl or 1,4-bicyclo(2,2,2)octylene, it being possible for these groups also to be at least monosubstituted by F, Cl, Br, CN, CF3 and/or (C1-C12)-alkyl (one or two non-adjacent CH2 groups may be replaced by O and/or S atoms), B=CO-O, O-CO, CH2-CH2, OCH2, CH2O, CH=N, N=CH, N=N, N(O)=N, n1, n2, n3=independently of one another 0, 1 or 2, n1 and n3 not being 0 simultaneously, Y=an electron-attracting substituent, Z=H or an electron-attracting substituent, but not identical with Y, and R1=benzyl or phenyl, it being possible for these groups to be substituted in the aromatic moiety in the same way as A1 and A2, with the exception of the compounds with Z=H, Y=F, Cl or Br, R2=(C1-C11)-alkoxy, A1 and A2=phenyl, n1, and n3=1 and n2=0. The compounds are preferably used in tilted smectic liquid crystal phases, which are converted into ferroelectric liquid crystal phases by these compounds; they show high values of spontaneous polarization. |