Chiral compounds, cholesteric and ferroelectric liquid crystal compositions comprising these chiral compounds, and liquid crystal displays comprising these liquid crystal compositions

A chiral liquid crystal compound of the general formula (1):

• in which
• R1=Y—(CH2)n—(O)m—(CH2)k—(O)l—(CH2)p—, or
• Y—(CH2)n—CH═CH—(CH2)p—(O)m—, or
• Y—(CH2)n—CHYl—(O)m—(CH2)k—(O)l—CHY2—(CH2)p—Y3, or
• Y—(CH2)n—CHY1—(O)m—(CH2)k—(O)l—(CH2)p—Y3, or
• fluorinated alkyl or fluorinated alkoxy groups where the fluorinated alkyl or fluorinated alkoxy group has from 1 to 20 carbon atoms;
• R2=Y3—(CH2)n—CHY4—(O)m—(CH2)k—(O)l—CHY5—(CH2)p—Y, or
• Y3—(CH2)n—(O)m—(CH2)k—(O)l—CHY5—(CH2)p—Y,
• where
• R2 is a chiral substituent, and R1 is a non-chiral linear or branched alkyl residue having from 6 to 25 carbon atoms, and where
• Y denotes, in each occurrence, and independently of each other, one of the atoms H, F, and Cl, or one of the groups —CN, —S—CN, —O—CF3, —CF3, —CO—CH3, —CiH2i+1, —O—CiCH2i+1, —CO—O—CiCH2i+1, or —O—CO—CiH2i+1;
• Y1 and Y2 denote, in each occurrence, and independently of each other, one of the atoms F and Cl or one of the groups —CN, —CF3, —CjH2j+1, —CO—O—CjH2j+1, —O—CO—CjH2j+1 or nonsimultaneously the atom H, or simultaneously the atom H;
• Y3 denotes in each occurrence, and independently of each other, one of a single bond or the atom —O—,
• Y4 and Y5 denote, in each occurrence, and independently of each other, one of the atoms F, Cl or one of the groups —CN, —CF3, —ChH2h+1, —O—ChH2h+1, —CO—O—ChH2h+1, —O—CO—ChH2h+1 or nonsimultaneously the atom H;
• n, p, k, j, i, h each assume values, independently for each of n, p, k, j, i, and h, from 0 to 7;
• m and l independently denote 0 or 1;
• and if l=m=0, then i+k+n+p is at least 6
• with the proviso that Y, Y1, Y2, Y3, Y4, Y5, h, i, j, k, l, m, n, and p are chosen such that R2 is a chiral substituent having at least one center of chirality,
• K denotes a single bond or a six-membered ring system selected from the group consisting of cyclohexane, cyclohexene, benzene, pyridine, pyrimidine, tetrazine, 1,3,2-dioxaborinane, hexahydropyridine, hexahydropyrimidine, hexahydropyridazine, hexahydropyrazine, the isomers of hexahydrotriazine, tetrahydrooxazine, cyclobutane, cyclopentane, cycloheptane, and cyclooctane rings, and from at least partially unsaturated ring compounds derived from any of these ring compounds, wherein the number of atoms in these rings or ring systems between the two atoms forming a part of the chemical bond to the next ring, or to the substituent R1 does not differ by more than one if counted in the clockwise, and if counted in the counter-clockwise sense, starting from the same atom in each case;
• where A and A1 assume value 0 or 1, and in the case when K is single bond, only one of A and A1 is 0,
• K1-5 independently of each other denote each a six-membered ring system selected from the group consisting of benzene, pyridine, pyrimidine, tetrazine, 1,3,2-dioxaborinane, hexahydropyridine, hexahydropyrimidine, hexahydropyridazine, hexahydropyrazine, the isomers of hexahydrotriazine, tetrahydrooxazine, and of the at least partially unsaturated ring compounds derived from any of these ring compounds,
• X1-20 denote, independently of each other, alkyl, or alkoxy, or fluorinated alkyl, or fluorinated alkoxy groups, or the atom H, or one of the halogen atoms, or one of the alkyl, alkoxy, fluorinated alkyl, and fluorinated alkoxy groups having, in each case independently of each other, from 1 to 20 carbon atoms,
• wherein the outer of the consecutive rings, (the rings that carry the substituents R1 and R2, respectively), do not carry substituents in the 2, 3, 5, and 6 positions
• and wherein at least three consecutive rings of the rings from K1, K2, K3, K4 and K5 are aromatic or heteroaromatic rings selected independently from each other from the group of rings consisting of benzene, pyridine, pyrimidine, and tetrazine, consecutive rings meaning rings that are directly bonded to each other, with one atom which is a member of the one ring being directly bonded to one atom which is a member of the next ring.