Liquid crystalline medium
The invention relates to a liquid-crystalline medium which comprises at least one compound of the formula I, and to the use thereof for an active-matrix display, in particular based on the VA, PSA, PS-VA, PALC, FFS or IPS effect.
1. A liquid-crystalline medium comprising a mixture of polar compounds, said mixture comprises at least one compound of the formula I,
in which
R 1 and R 1* each, independently of one another, denote an alkyl or alkoxy Radical having 1 to 15 C atoms, wherein one or more CH 2 groups in these radicals is optionally replaced, independently of one another, by —C≡C—, —CF 2 O—, —CH═CH—,
—O—, —CO—O—, —O—CO— in such a way that O atoms are not linked directly to one another, and wherein one or more H atoms may be replaced by halogen, and
L 1 and L 2 each, independently of one another, denote F, Cl, CF 3 or CHF 2 .
2. The liquid-crystalline medium according to claim 1 , further comprising one or more compounds of formulae IIA, IIB and IIC,
in which
R 2A , R 2B and R 2C each, independently of one another, denote H, an alkyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, wherein one or more CH 2 groups in these radicals is optionally replaced by —O—, —S—,
—CH═CH—, —C≡C—, —CF 2 O—, —OCF 2 —, —OC—O— or —O—CO— in such a way that O atoms are not linked directly to one another,
L 1-4 each, independently of one another, denote F or Cl,
Z 2 and Z 2′ each, independently of one another, denote a single bond, —CH 2 CH 2 —, —CH═CH—, —CF 2 O—, —OCF 2 —, —CH 2 O—, —OCH 2 —, —COO—, —OCO—, —C 2 F 4 —, —CF═CF—, —CH═CHCH 2 O—,
n denotes 0 or 1,
p denotes 1 or 2,
q denotes 0 or 1, and
v denotes 1 to 6.
3. The liquid-crystalline medium according to claim 1 , further comprising one or more compounds of the formula III,
in which
R 31 and R 32 each, independently of one another, denote a straight-chain alkyl, alkoxyalkyl or alkoxy radical having up to 12 C atoms, and
denotes
Z 3 denotes a single bond, —CH 2 CH 2 —, —CH═CH—, —CF 2 O—, —OCF 2 —, —CH 2 O—, —OCH 2 —, —COO—, —OCO—, —C 2 F 4 —, —C 4 H 9 —, —CF═CF—.
4. The liquid-crystalline medium according to claim 1 , comprising at least compound of the formulae I-1 to I-10,
in which
alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms,
alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms,
alkoxy and alkoxy* each, independently of one another, denote a straight-chain alkoxy radical having 1-6 C atoms, and
L 1 and L 2 each, independently of one another, denote F or Cl.
5. The liquid-crystalline medium according to claim 1 , further comprising at least one compound of the formulae L-1 to L-11,
in which
R, R 1 and R 2 each, independently of one another, denote H, an alkyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, wherein one or more CH 2 groups in these radicals is optionally replaced by —O—, —S—,
—C≡C—, —CF 2 O—, —OCF 2 —, —OC—O— or —O—CO— in such a way that O atoms are not linked directly to one another,
alkyl denotes an alkyl radical having 1-6 C atoms,
n denotes 0 or 1, and
s denotes 1 or 2.
6. The liquid-crystalline medium according to claim 1 , further comprising one or more terphenyls of the formulae T-1 to T-21,
in which
R denotes a straight-chain alkyl or alkoxy radical having 1-7 C atoms,
x denotes 0-4,
n denotes 0 or 1,
m denotes 1-6.
7. The liquid-crystalline medium according to claim 1 , further comprising one or more compounds of the formulae O-1 to O-16,
in which
R 1 and R 2 each, independently of one another, denote H, an alkyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, wherein one or more CH 2 groups in these radicals is optionally replaced by —O—, —S—,
—C≡C—, —CF 2 O—, —OCF 2 —, —OC—O— or —O—CO— in such a way that O atoms are not linked directly to one another.
8. The liquid-crystalline medium according to claim 1 , further comprising one or more indane compounds of the formula In,
in which
R 11 , R 12 , R 13 denote a straight-chain alkyl, alkoxy, alkoxyalkyl or alkenyl radical having 1-5 C atoms,
R 12 and R 13 can also denote halogen,
denotes
i denotes 0, 1 or 2.
9. The liquid-crystalline medium according to claim 1 , having a proportion of compounds of the formula I in the mixture as a whole is ≧1% by weight.
10. A process for the preparation of a liquid-crystalline medium according to claim 1 , comprising mixing at least one compound of the formula I with at least one further liquid-crystalline compound, and additives are optionally added.
11. An electro-optical display, comprising a liquid-crystalline medium according to claim 1 .
12. An electro-optical display having active-matrix addressing, comprising, as dielectric, a liquid-crystalline medium according to claim 1 .
13. An electro-optical display according to claim 12 , that is a VA, PSA, PS-VA, PALC, FFS or IPS display.
14. A compound, which is one of the following compounds