Bimesogenic compounds and mesogenic media

Bimesogenic compounds of formula I

• wherein
• R11 and R12 are each independently H, F, Cl, CN, NCS or a straight-chain or branched alkyl group with 1 to 25 C atoms, which may be unsubstituted, mono- or polysubstituted by halogen or CN, it being also possible for one or more non-adjacent CH2 groups to be replaced, in each occurrence independently from one another, by —O—, —S—,
• —NH—, —N(CH3)—, —CO—, —COO—, —OCO—, —O—CO—O—, —S—CO—, —CO—S—, —CH═CH—, —CH═CF—, —CF═CF— or —C≡C— in such a manner that oxygen atoms are not linked directly to one another, a straight-chain or branched alkyl group with 1 to 25 C atoms which may be unsubstituted, mono- or polysubstituted by halogen or CN,
• MG11 and MG12 are each independently a mesogenic group,
• at least one of
• MG11 and MG12 comprises one, two or more 5-atomic and/or 6-atomic rings, in case of comprising two or more 5- and/or 6-atomic rings at least two of these may be linked by a 2-atomic linking group, and
• CG1 is a central group, wherein the total number of atoms connecting the groups MG11 and MG12 is an odd integer in the range from three to 17, the central atom of these atoms connecting the groups MG11 and MG12 is an O atom, preferably CG1 is X11-J-O—K—X12—, wherein
• J and K are each —(CH2—)n-,
• wherein in n is an integer in the range from 1 to 8, and wherein one or more H atoms optionally may be replaced by an F atom,
• X11 and X12 are either both a single bond or both an O atom or are independently of one another selected from —CO—O— and —O—CO—.