Compounds and liquid-crystalline medium
Compounds of the formula I, and liquid-crystalline media, preferably having a nematic phase and negative dielectric anisotropy, comprising a) one or more compounds of the formula I and one or more compounds selected from b) one or more compounds of formula II and/or c) one or more compounds selected from compounds of formulae III-1 to III-4 and formula B Methods for making and using these liquid-crystalline media in electro-optical displays, particularly in active-matrix displays based on the VA, ECB, PALC, FFS or IPS effect and the displays which contain these media. Methods for stabilizing liquid-crystalline media with compounds of formula I, where the liquid-crystalline media comprise one or more compounds of the formula II and one or more compounds selected from compounds of the formulae III-1 to III-4 and formula B.
1. A liquid crystalline medium comprising
a. one or more compounds of the formulae I-9, I-10 or I-11
2. A medium according to claim 1 , wherein the total concentration of the one or more compounds of the formulae I-9, I-10 or I-11 in the medium as a whole is from 1 ppm to 2500 ppm.
3. A medium according to claim 1 , which further comprises a compound of the formula II
in which
R 22 denotes an unsubstituted alkenyl radical having 2 to 7 C atoms
and R 21 denotes n-propyl and R 22 denotes vinyl.
4. A medium according to claim 3 , wherein the total concentration of the compounds of the formula II in the medium as a whole is from 25% to 45%.
5. A medium according to claim 1 , which further comprises one or more compounds of the formula III-4
in which
R 31 denotes an unsubstituted alkyl radical having 1 to 7 C atoms,
R 32 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkoxy radical having 1 to 6 C atoms.
6. A medium according to claim 1 , which additionally comprises one or more chiral compounds.
7. A compound of the formulae I-9, I-10 or I-11
8. An electro-optical display electro-optical component, which contains a liquid-crystalline medium according to claim 1 .
9. A display according to claim 8 , which utilize a IPS, FFS, VA or ECB effect.
10. A display according to claim 8 , which contains an active-matrix addressing device.
11. A method which comprises including a compound of claim 7 in a liquid-crystalline medium.
12. A method which comprises including a liquid-crystalline medium according to claim 1 in an electro-optical display or in an electro-optical component.
13. A process for the preparation of a liquid-crystalline medium according to claim 1 , comprising mixing one or more compounds of the formulae I-9, I-10 or I-11 with one or more compounds of the formula B
in which
R B1 and R B2 each, independently of one another, denote an unsubstituted alkyl radical, alkoxy radical, oxaalkyl radical or alkoxyalkyl radical having 1 to 7 C atoms, or an alkenyl radical or alkenyloxy radical having 2 to 7 C atoms, and
L B1 and L B2 each, independently of one another, denote F or Cl.
14. A process for the stabilization of a liquid-crystalline medium which comprises adding to said liquid-crystalline medium one or more compounds of claim 7 , and optionally one or more compounds of the formulae OH-1 to OH-6,
15. A process for the preparation of a compound according to claim 7 , which comprises hydrogenating the corresponding 2,2,6,6-tetramethylpiperidine 1-oxyl or 1-benzyl precursor.
16. A process for the preparation of a liquid-crystalline medium according to claim 3 , comprising mixing one or more compounds of the formulae I-9, I-10 or I-11 with one or more compounds of the formula B
in which
R B1 and R B2 each, independently of one another, denote an unsubstituted alkyl radical, alkoxy radical, oxaalkyl radical or alkoxyalkyl radical having 1 to 7 C atoms, or an alkenyl radical or alkenyloxy radical having 2 to 7 C atoms, and
L B1 and L B2 each, independently of one another, denote F or Cl and one or more compounds of the formula II.
17. A process for the preparation of a liquid-crystalline medium according to claim 5 , comprising mixing one or more compounds of the Formulae I-9, I-10 or I-11 with one or more compounds of the formula B
in which
R B1 and R B2 each, independently of one another, denote an unsubstituted alkyl radical, alkoxy radical, oxaalkyl radical or alkoxyalkyl radical having 1 to 7 C atoms, or an alkenyl radical or alkenyloxy radical having 2 to 7 C atoms, and
L B1 and L B2 each, independently of one another, denote F or Cl
and one or more compounds of the formula III-4.
18. A medium according to claim 3 , which further comprises a compound of the formula II and one or more compounds of formula B,
in which
R B1 and R B2 each, independently of one another, denote an unsubstituted alkyl radical, alkoxy radical, oxaalkyl radical or alkoxyalkyl radical having 1 to 7 C atoms, or an alkenyl radical or alkenyloxy radical having 2 to 7 C atoms, and
L B1 and L B2 each, independently of one another, denote F or Cl.