Chiral esters of alpha-substituted carboxylic acids and mesogeneous pyrimidine-5-yl-phenols, and their use as dopants in liquid-crystal phases

摘要

The novel compounds are chiral esters formed from alpha -substituted carboxylic acids and mesogenic hydroxyl compounds of the general formula (I) IMAGE (I) in which the symbols have the following meaning: MO=molecular radical of a mesoganic hydroxyl compound MOH after removing an H, the radial MO being expressed by the general formula (II): R2-(A1)n1-(B-)(n2(A2)(n3-O(II) where the meaning of R2 is a straight-chain or branched (C1-C12)alkyl or alkenyl, it being possible for one or two nonadjacent CH2 groups to be replaced by O and/or S atoms, or if n1=1, also F, Cl, Br or CN, A1, A2 are, independently of each other, 1,4-phenylene, pyrimidine-2,5-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 said groups to be substituted at least singly by F, Cl, Br, CN and/or (C1-C12)alkyl (optionally, one or two nonadjacent CH2 groups are replaced by O and/or S atoms), B is CO-O, O-CO, CH2-CH2, OCH2, CH2O, CH=N, N=CH, N=N N(O)=N, n1, n2, n3 are, independently of each other, 0, 1 or 2, n1 and n3 not being simultaneously 0, Y is F, Cl, Br, CN or CF3, and R1 is branched, (C3-C9)alkyl, benzyl or phenyl, the compounds having R1=branched (C3-C7)alkyl, benzyl or phenyl, Y=F, Cl or Br, R2=(C1-C11)alkoxy, A1, A2= n1, n3=1 and n2=0 being excluded. The compounds preferably find application in tilted smectic liquid-crystalline phases which they transform into ferroelectric liquid-crystalline phases; they have high values of spontaneous polarization.