Bimesogenic compounds and mesogenic media

Bimesogenic compounds of formula

• wherein
• R11 and R12 are each independently H, halogen, CN, NO2 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, wherein one or more non-adjacent CH2 groups may 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,
• MG11 and MG12 are each independently a mesogenic group,
• at least one of
• MG11 and MG12 contains at least one fused ring group selected from alicyclic, aromatic and condensed groups made up of 7 to 23 carbon atoms, wherein one or two non-adjacent CH groups each may be replaced by an N-atom and/or one or two non-adjacent CH2 groups, independently of each other, may be replaced by an O- or an S-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, wherein the mesogenic group can also contain 0 to 3 six membered rings selected from 1,4-phenylene, wherein in addition one or more CH groups may be replaced by N, trans-1,4-cyclo-hexylene in which, in addition, one or two non-adjacent CH2 groups may be replaced by O and/or S, 1,4-cyclohexenylene, 1,4-bicyclo-(2,2,2)-octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydro-naphthalene-2,6-diyl, 1,2,3,4-tetrahydro-naphthalene-2,6-diyl, cyclobutane-1,3-diyl, spiro[3.3]heptane-2,6-diyl or dispiro[3.1.3.1] decane-2,8-diyl, it being possible for all these groups to be unsubstituted, mono-, di-, tri- or tetrasubstituted with F, Cl, CN or alkyl, alkenyl, alkoxy, alkenyloxy, alkylcarbonyl or alkoxycarbonyl groups, wherein one or more H atoms may be substituted by F or Cl,
• Sp1 is a spacer group comprising 1, 3 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, no 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,
• X11 and X12 are independently from one another a linking group selected from —CO—, —CO—O—, —O—CO—, —O—, —CH═CH—, —C≡C—, —CO—S—, —S—CO—, —CS—S—, —S—, —CF2—, —CF2—O—, —O—CF2—and a single bond,
• however under the condition that X11and X12 are not both —O— and under the condition that X11 and X12 are both not a single bond, and under the condition that in —X11-Sp1—X12— no two O-atoms are adjacent to one another, no two —CH═CH— groups are adjacent to each other and no two groups selected from —O—CO—, —S—CO—, —O—CO—O—, —CO—S—, —CO—O—, —CF2—O—, —O—CF2— and —CH═CH— are adjacent to each other.