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, preferably a polar group, more preferably F, Cl, CN, OCF3, CF3,
• MG11 and MG12 are each independently a mesogenic group, which comprises one, two or more 6-atomic rings, in case of comprising two or more 6-atomic rings at least two of these may be linked by a 2-atomic linking group,
• MG11 is a or comprises one 1,3-phenylene, wherein optionally one or two non-adjacent CH groups each may be replaced by an N-atom, and which optionally is substituted by one or more halogen atoms and/or by one or more alkyl group(s) each independently having 1 to 9 C atoms and/or by one more alkoxy group(s) each independently having 1 to 9 C atoms,
• Sp1 is a spacer group comprising 1, 2, 3, 4 or 5 to 40 C atoms, wherein one or more non-adjacent and non-terminal CH2 groups may also be replaced by —O—, —S—, —NH—, —N(CH3)—, —CO—, —O—CO—, —S—CO—, —O—COO—, —CO—S—, —CO—O—, —CH(halogen)-, —CH(CN)—, —CH═CH— or —C≡C—, however in such a way that no two O-atoms are adjacent to one another, now two —CH═CH— groups are adjacent to each other and no two groups selected from —O—CO—, —S—CO—, —O—COO—, —CO—S—, —CO—O— and —CH═CH— are adjacent to each other, wherein one or more H atoms in —(CH2)n— may independently of each other optionally be replaced by F or CH3 and/or one or more non-adjacent —CH2— groups may be replaced by —O—, and
• X11 and X12 are each independently of one another a group selected from —CH═CH—, —C≡C—, —O—, —CF2—O—, —O—CF2—, —CO—O—, —O—CO—, —O—CO—O—, —S—, —CS—S—, —S—CS—, —CO—S—, —S—CO—, —S—CO—S— and —S—CS—S— or a single bond, however under the condition that in —X11-Sp1-X12— no two O-atoms are adjacent to one another, now two —CH═CH— groups are adjacent to each other and no two groups selected from —O—CO—, —S—CO—, —O—COO—, —CO—S—, —CO—O— and —CH═CH— are adjacent to each other.