Bimesogenic compounds and mesogenic media

A bimesogenic compound of formula I

• wherein
• R11 is F, CN, NCS or a straight-chain or branched alkyl group with 1 to 25 C atoms which are unsubstituted, mono- or polysubstituted by halogen or CN, wherein optionally one or more non-adjacent CH2 groups are 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,
• R12 is F, Cl, CN, NCS or a straight-chain or branched alkyl group with 1 to 25 C atoms which are unsubstituted, mono- or polysubstituted by halogen or CN, wherein optionally one or more non-adjacent CH2 groups are 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,
• Sp1 is a spacer group containing 5 to 40 C atoms, wherein one or more non-adjacent and non-terminal CH2 groups are optionally 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 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 the group consisting of —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 groups are independently of each other optionally replaced by F or CH3,
• X11 is —CH═CH—, —C≡C—, —CF2—O—, —O—CF2—, —CO—O—, —O—CO—, —O—CO—O—, —S—, —CS— S—, —S—CS—, —CO—S—, —S—CO—, —S—CO—S—, —S—CS—S— or a single bond, under the condition that in —X11—Sp1-X2— 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 the group consisting of —O— CO—, —S—CO—, —O—COO—, —CO—S—, —CO—O— and —CH═CH— are adjacent to each other,
• X12 is —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—, —S—CS—S— or a single bond, 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 the group consisting of —O— CO—, —S—CO—, —O—COO—, —CO—S—, —CO—O— and —CH═CH— are adjacent to each other,
• MG11 has formula II*
• -A*11-(Z*11-A*12)k- II*
• MG12 is selected
• from the group consisting of formulae II-1 to II-26 and their mirror images
• -Phe-Z-Phe- II-1
• -Phe-Z-Cyc- II-2
• -Cyc-Z-Cyc- II-3
• -Phe-Z-PheL- II-4
• -PheL-Z-Phe- II-5
• -PheL-Z-Cyc- II-6
• -PheL-Z-PheL- II-7
• -Phe-Z-Phe-Z-Phe- II-8
• -Phe-Z-Phe-Z-Cyc- II-9
• -Phe-Z-Cyc-Z-Phe- II-10
• -Cyc-Z-Phe-Z-Cyc- II-11
• -Phe-Z-Cyc-Z-Cyc- II-12
• -Cyc-Z-Cyc-Z-Cyc- II-13
• -Phe-Z-Phe-Z-PheL- II-14
• -Phe-Z-PheL-Z-Phe- II-15
• -PheL-Z-Phe-Z-Phe- II-16
• -PheL-Z-Phe-Z-PheL- II-17
• -PheL-Z-PheL-Z-Phe- II-18
• -PheL-Z-PheL-Z-PheL- II-19
• -Phe-Z-PheL-Z-Cyc- II-20
• -Phe-Z-Cyc-Z-PheL- II-21
• -Cyc-Z-Phe-Z-PheL- II-22
• -PheL-Z-Cyc-Z-PheL- II-23
• -PheL-Z-PheL-Z-Cyc- II-24
• -PheL-Z-Cyc-Z-Cyc- II-25
• -Cyc-Z-PheL-Z-Cyc- II-26
• wherein
• Cyc is 1,4-cyclohexylene,
• Phe is 1,4-phenylene or alkyl-1,4-phenylene,
• PheL is 1,4-phenylene, which is substituted by one, two or three fluorine atoms, by one or two Cl atoms, by one Cl atom and one F atom or by one alkyl or alkoxy group having 1 to 9 C-atoms, and
• Z is a single bond, —COO—, —OCO—, —O—CO—O—, —OCH2—, —CH2O—, —OCF2—, —CF2O—, —CH2CH2—, —(CH2)4—, —CF2CF2—, —CH═CH—, —CF═CF—, —CH═CH—COO—, —OCO— CH═CH— or —C≡C—
• Z*11 is a single bond, —COO—, —OCO—, —O—CO—O—, —OCH2—, —CH2O—, —OCF2—, —CF2O—, —CH2CH2—, —(CH2)4—, —CF2CF2—, —CH═CH—, —CF═CF—, —CH═CH—COO—, —OCO—CH═CH— or —C≡C—,
• A*11 present in MG11 is 1,3-phenylene, wherein optionally one or two non-adjacent CH groups each are 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,
• A*12 if present in MG11 is 1,4-phenylene, wherein one or more CH groups are optionally replaced by N, trans-1,4-cyclo-hexylene in which one or two non-adjacent CH2 groups are optionally replaced by O and/or S, 1,4-cyclohexenylene, 1,4-bicyclo-(2,2,2)-octylene, 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, wherein all these groups are unsubstituted, mono-, di-, tri- or tetrasubstituted with F, Cl, CN or alkyl, alkoxy, alkylcarbonyl or alkoxycarbonyl groups with 1 to 7 C atoms, wherein one or more H atoms are optionally substituted by F or Cl, and
• k is 1, 2, 3 or 4.