Patent ID: 7326447

Claim:
A compound of formula I wherein Y is —CO—, —CS—, —CH 2 —, —CF 2 — or —CHF—, L 1 and L 2 are each, independently of one another, H, F, Cl or —CN, are each, independently of one another, and, if present more than once, also independently of one another, (a) a trans-1,4-cyclohexylene radical, in which, one or two non-adjacent CH 2 groups are optionally replaced by —O— and/or —S—, (b) a 1,4-cyclohexenylene radical, (c) a 1,4-phenylene radical, in which, one or two non-adjacent CH groups are optionally replaced by N, or (d) 1,4-bicyclo[2.2.2]octylene, 1,3-bicyclo[1.1.1]pentylene, spiro[3.3]heptane-2,4-diyl, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl, R 1 and R 2 are each, independently of one another, H, halogen, —CN, —SCN, —SF 5 , —CF 3 , —CHF 2 , —CH 2 F, —OCF 3 , —OCHF 2 , or an alkyl group having 1 to 15 carbon atoms which is monosubstituted by CN or CF 3 or at least monosubstituted by halogen, and in which one or more CH 2 groups each, independently of one another, are optionally replaced by —O—, —S—, —CH═CH—, —CF═CF—, —CF═CH—, —CH═CF—, —CO—, —CO—O—, —O—CO— or —O—CO—O— in such a way that neither O nor S atoms are linked directly to one another, Z 1 and Z 2 are each, independently of one another, —CH 2 —CH 2 —, —CF 2 —CF 2 —, —CF 2 —CH 2 —, —CH 2 —CF 2 —, —CH═CH—, —CF═CF—, —CF═CH—, —CH═CF—, —C═C—, —COO—, —OCO—, —CH 2 O—, —OCH 2 —, —CF 2 O—, or —OCF 2 —, or a combination of two of these groups, where no two O atoms are bonded to one another, and n and m are each 0, 1 or 2, where n+m is 0, 1, 2 or 3, with the proviso that, if Y is —CO—, at least one of L 1 and L 2 is not H.