Liquid crystal compounds

A compound of formula (I)

• wherein
• A and B each independently from each other represents an unsubstituted or substituted carbocyclic or heterocyclic aromatic group selected from a monocyclic ring of five or six atoms, two adjacent monocyclic rings of five or six atoms, a bicyclic ring system of eight, nine or ten atoms, or a tricyclic ring system of thirteen or fourteen atoms;
• SP1, SP2 and SP3 each independently from each other represents a substituted or unsubstituted, straight-chain or branched C3-C18 alkylene group, in which one, two, three or four more CH2, CH or C groups are unreplaced or replaced by groups selected from the group consisting of —CH═CH—, —C≡C—, —O—, —S—, —NR′CO—, —COO—, —OOC—, —CONR′—, —OCOO—, —OCONR′ with the proviso that the spacer group does not contain two adjacent heteroatoms;
• X1, X2, X3 and X4 each independently from each other is selected from the group consisting of —O—, —S—, —NR′—, —CO—, —COO—, —OOC—, —CONR′—, —OCOO—, —OCONR′ and a single bond;
• R′ is selected from the group consisting of hydrogen, a C1-C18alkyl group;
• BP1 and BP2 each independently from each other represents a polymerizable group,
• A1, A2, A3 and A4 each independently from each other are selected from the group consisting of hydrogen, —OR, —COOR, —OCOR, —CONR, —OCOOR, —OCONR and a C1-C18alkyl group, wherein
• R is selected from the group consisting of hydrogen, an unsubstituted or substituted carbocyclic or heterocyclic aromatic group selected from a monocyclic ring of five or six atoms, two adjacent monocyclic rings of five or six atoms, a bicyclic ring system of eight, nine or ten atoms, or a tricyclic ring system of thirteen or fourteen atoms;
• a substituted or unsubstituted, straight-chain or branched C3-18alkyl group, in which one, two, three or four more CH2, CH or C groups are unreplaced or replaced by groups selected from the group consisting of —CH═CH—, —C≡C—, —O—, —S—, —NR″CO—, —COO—, —OOC—, —CONR″—, —OCOO—, —OCONR″ with the proviso that the spacer group does not contain two adjacent heteroatoms, wherein R″ is selected from the group consisting of hydrogen, a C1-C18alkyl group.