Liquid-crystal compound, liquid-crystal medium comprising same, and electro-optical liquid-crystal display

A nematic liquid-crystal medium, comprising at least one compound of formula I

• wherein
• R11 and R12 are each independently, H, an alkyl group having 1 to 15 carbon atoms which is monosubstituted by CN or CF3 or at least monosubstituted by halogen, in which at least one or more CH2 group is optionally, independently replaced by —O—, —S—, —CH═CH—,
• —CO—, —CO—O—, —O—CO— or —O—CO—O— in such a way that O atoms are not linked directly to one another,
• Z11, Z12 and Z13 are each independently, —CH2—CH2—, —CH═CH—, —C≡C—, —COO—, —OCO—, —CH2O—, —OCH2—, —CF2O—, —OCF2—, —(CH2)4—, —CF═CF—, —CH═CF—, —CF═CH— or a single bond,
• are each independently,
• (e) trans-1,4-cyclohexylene, in which one or two non-adjacent CH2 groups are optionally independently replaced by —O— or —S—,
• (f) 1,4-cyclohexenylene,
• (g) 1,4-phenylene, in which one or two OH groups are optionally replaced by N, or
• (h) 1,4-bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl,
• whereby in any of rings (e) to (h) at least one hydrogen atom bound to a carbon atom may be replaced by a fluorine atom and
• n11 and n12 are each 0, 1 or 2, and
• n11+n12 is 1, 2 or 3,
• and at least one compound of formula II1
• wherein
• R21 and R22 are each independently, as defined for R11 in formula I,
• Z21 and Z22 are each independently, as defined for Z11 in formula I,
• and
• I is 0 or 1.

A liquid-crystal medium, comprising at least one compound of formula I

• wherein
• R11 and R12 are each independently, H, an alkyl group having 1 to 15 carbon atoms which is monosubstituted by CN or CF3 or at least monosubstituted by halogen, in which at least one or more CH2 group is optionally, independently replaced by —O—, —S—, —CH═CH—,
• —CO—, —CO—O—, —O—CO— or —O—CO—O— in such a way that O atoms are not linked directly to one another,
• Z11, Z12 and Z13 are each independently, —CH2—CH2—, —CH═CH—, —C≡C—, —COO—, —OCO—, —CH2O—, —OCH2—, —CF2O—, —OCF2—, —(CH2)4—, —CF═CF—, —CH═CF—, —CF═CH— or a single bond,
• are each independently,
• (i) trans-1,4-cyclohexylene, in which one or two non-adjacent CH2 groups are optionally independently replaced by —O— or —S—,
• (j) 1,4-cyclohexenylene,
• (k) 1,4-phenylene, in which one or two CH groups are optionally replaced by N, or
• (I) 1,4-bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl,
• whereby in any of rings (e) to (h) at least one hydrogen atom bound to a carbon atom may be replaced by a fluorine atom, and
• n11 and n12 are each 0, 1 or 2, and
• n11+n12 is 1, 2 or 3,
• with the provisos that Z12 is not a single bond and/or n12 is 1 or 2, and if n11 is 0, Z13 is not a single bond.

A compound of formula I

• wherein
• R11 and R12 are each independently, H, an alkyl group having 1 to 15 carbon atoms which is monosubstituted by CN or CF3 or at least monosubstituted by halogen, in which at least one CH2 group is optionally independently replaced by —O—, —S—, —CH═CH—,
• —CO—, —CO—O—, —O—CO— or —O—CO—O—in such a way that O atoms are not linked directly to one another,
• Z11, Z12 and Z13 are each independently, —CH2—CH2—, —CH═CH—, —C≡C—, —COO—, —OCO—, —CH2O—, —OCH2—, —CF2O—, —OCF2—, —(CH2)4—, —CF═CF—, —CH═CF—, —CF═CH— or a single bond,
• are each independently,
• (m) trans-1,4-cyclohexylene, in which, one or two non-adjacent CH2 groups are optionally independently replaced by —O— or —S—,
• (n) 1,4-cyclohexenylene,
• (o) 1,4-phenylene, in which, one or two CH groups are optionally replaced by N, or
• (p) 1,4-bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl,
• whereby in any of rings (a) to (d) at least one hydrogen atom bound to a carbon atom is optionally replaced by a fluorine atom, and
• n11 and n12 are each 0, 1 or 2, and
• n11+n12 is 1, 2 or 3,
• with the provisos that Z12 is not a single bond and/or n12 is 1 or 2, and if n11 is 0, Z13 is not a single bond.