Patent ID: 7744968

Claim:
A compound of formula I in which, in each case independently of one another, identically or differently, R 1 is a group of the formula R 2 is hydrogen, an alkanyl, alkoxy, alkenyl or alkynyl having up to 15 carbon atoms which is unsubstituted or mono- or polysubstituted by F, in which one or more CH 2 groups are optionally replaced, independently of one another, by —O—, —S—, —SO 2 —, —CO—, —(CO)O—, —O(CO)— or —O(CO)—O— in such a way that heteroatoms are not linked directly, or a group of the formula A 1 , A 2 , A 3 and A 4 denote 1,4-cyclohexylene, in which one or two CH 2 are optionally replaced by O, 1,4-phenylene, which may be unsubstituted or mono- or disubstituted by F, or a group of the formula Z 1 , Z 2 , Z 3 and Z 4 denote a single bond, —CF 2 O—, —OCF 2 —, —CH 2 CH 2 —, —CF 2 CF 2 —, —CF 2 CH 2 —, —CH 2 CF 2 —, —CHF—CHF—, —(CO)O—, —O(CO)—, —CH 2 O—, —OCH 2 —, —CF═CH—, —CH═CF—, —CF═CF—, —CH═CH— or —C≡C—, a, b, c and d denote 0, 1 or 2, and n and m denote 0 or 1.