Reactive mesogens with high birefringence

A compound of formula I

• wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings
• P a polymerisable group,
• Sp a spacer group or a single bond,
• Sp1 a spacer group or a single bond,
• R11 H, F, Cl, CN, CH═CH2, alkyl, alkoxy, thioalkyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy with 1 to 6 C atoms which is optionally fluorinated or chlorinated, or P-Sp,
• A, B phenylene-1,4-diyl, naphthalene-1,4-diyl, naphthalene-2,6-diyl, fluorene-2,7-diyl, dibenzothiophene-2,7-diyl, dibenzofuran-2,7-diyl, benzo[1,2-b:4,5-b′]dithiophene-2,5-diyl, indole-4,7-diyl, benzothiophene-4,7-diyl, 9,10-dihydro-phenanthrene-2,7-diyl or 1,2,3,4-tetrahydronaphthalene-5,8-diyl where, in addition, one or more CH groups in these groups may be replaced by N, all of which are optionally substituted by one or more groups L or P-Sp-,
• C phenylene-1,4-diyl or naphthalene-2,6-diyl, preferably phenylene-1,4-diyl or naphthalene-2,6-diyl, in which, in addition, one or more CH groups in these groups may be replaced by N, and which are optionally substituted by one or more groups L or P-Sp-,
• provided that not more than one of A, B and C may denote naphthalene-1,4-diyl,
• L F, Cl, —CN, —SCN, P-Sp-, or straight chain alkyl having 1 to 25 C atoms or branched or cyclic alkyl having 3 to 25 atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, CR0═CR00—, —C≡C—,
• in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by P-Sp-, F or Cl, or two substituents L that are connected to directly adjacent C atoms may also form a cycloalkyl or cycloalkenyl group with 5, 6, 7 or 8 C atoms,
• Z11 —O—, —S—, —CO—, —COO—, —OCO—, —S—CO—, —CO—S—, —O—COO—, —CO—NR0—, —NR0—CO—, —NR0—CO—NR00, —NR0—CO—O—, —O—CO—NR0—, —OCH2—, —CH2O—, —SCH2—, —CH2S—, —CF2O—, —OCF2—, —CF2S—, —SCF2—, —CH2CH2—, —(CH2)n1, —CF2CH2—, —CH2CF2—, —CF2CF2—, —CH═N—, —N═CH—, —N═N—, —CH═CR0—, —CY1═CY2—, —C≡C—, —CH═CH—COO—, —OCO—CH═CH— or a single bond, preferably —COO—, —OCO—, —C≡C—, or a single bond,
• n1 1, 2, 3 or 4,
• s 0, 1, 2 or 3,
• R0, R00 H or alkyl having 1 to 12 C atoms,
• Y1, Y2 H, F, Cl, NCS, or CN,
• m 0 or 1,
• n 0, 1, 2, 3 or 4.