Patent ID: 8202584

Claim:
A liquid-crystalline medium of negative dielectric anisotropy which comprises a) 2-80% by weight of a first dielectrically negative component A, which comprises of one or more compounds of formula I in which R 11 and R 12 each, independently of one another, denote H, an unsubstituted alkyl or alkenyl radical having up to 15 C atoms, in which one or more CH 2 groups may be replaced by —O—, —S—, —C≡C—, —CF 2 —O—, —O—CF 2 —, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, one of the rings present denotes and the others, if present, in each case independently of one another, denote Z 11 and Z 12 each, independently of one another, denote —CH 2 —CH 2 —, —CH═CH—, —C≡C—, —CH 2 —O—, —O—CH 2 —, —CO—O—, —O—CO—, —CF 2 —O—, —O—CF 2 —, —CF 2 —CF 2 — or a single bond, X 1 denotes S, Se or Te, m and n, independently of one another, denote 0 or 1, and b) 2-80% by weight of a second dielectrically negative component B, which comprises one or more compounds of formula II, III and/or IV: in which R 21 , R 22 , R 31 , R 32 , R 41 and R 42 each, independently of one another, denote H, an unsubstituted alkyl or alkenyl radical having up to 15 C atoms, in which one or more CH 2 groups may be replaced by —O—, —S—, —C≡C—, —CF 2 —O—, —O—CF 2 —, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, one of the rings present denotes L 21 and L 22 , independently of one another, denote ═C(X 2 )— and one of L 21 and L 22 alternatively also denotes ═N—, X 2 denotes F, Cl, OCF 3 , CF 3 , CH 3 , CH 2 F, or CHF 2 , and the other rings, if present, in each case independently of one another, denote one of the rings present denotes and the others, if present, in each case independently of one another, denote where L 31 and L 32 , independently of one another, denote ═C(X 3 )— and one of L 31 and L 32 alternatively also denotes ═N—, and X 3 denotes F, Cl, OCF 3 , CF 3 , CH 3 , CH 2 F, or CHF 2 , or together denote a single bond, one of the rings present denotes and the others, if present, in each case independently of one another, denote together denote a single bond, Z 21 to Z 23 , Z 31 to Z 33 and Z 41 to Z 43 each, independently of one another, denote —CH 2 —CH 2 —, —CH═CH—, —C≡C—, —CH 2 —O—, —O—CH 2 —, —CO—O—, —O—CO—, —CF 2 —O—, —O—CF 2 —, —CF 2 —CF 2 — or a single bond, r and s each, independently of one another, denote 0 or 1, t and u each, independently of one another, denote 0 or 1, l and o each, independently of one another, denote 0 or 1.