Patent ID: 8148551

Claim:
A tricyclic aromatic compound of formula I: in which A 1 , A 2 , A 3 , A 4 are each, independently of one another, a 1,4-cyclohexylene, 1,4-cyclohexenylene or 1,4-cyclohexadienylene radical which is unsubstituted or substituted by one to four F atoms and in which, in each case independently of one another, one or two CH 2 groups may be replaced by —O— or —S —in such a way that heteroatoms are not linked directly to one another, a 1,4-phenylene radical, which may be substituted by one or two fluorine or chlorine atoms and in which, in addition, one or two CH groups may be replaced by N, or a 1,4-bicyclo[2.2.2]octylene radical or 2,6-spiro[3.3]heptylene radical, Q 1 -Q 2 denotes O—CH 2 or O—CF 2 , R 1 , R 2 are each, independently of one another, an alkyl radical having 1 to 12 C atoms which is unsubstituted or at least monosubstituted by halogen and in which one or more non-adjacent CH 2 groups may each, independently of one another, be replaced by —O—, —S — or —CO—, two adjacent CH 2 groups may each be replaced by —CH═CH—, —CF═CF—, —COO—, —OOC—, —C≡C— or a 1,2-cyclopropanylene radical or three adjacent CH 2 groups may be replaced by a 1,3-cyclobutanylene radical, or denote F, Cl, —OCF 3 , —OCHF 2 , —CN, —NCS or H, with the proviso that either only R 1 or only R 2 may be H, X 1 , X 2 X 3 each, independently of one another, denote H, F or Cl, Z 1 , Z 2 , Z 3 , Z 4 are each, independently of one another, a single bond, —CH 2 CH 2 —, —CH 2 O—, —OCH 2 —, —CH 2 CF 2 —, —CF 2 CH 2 —, —CF 2 O—, —OCF 2 —, —COO—, —OOC—, —CH═CH—, —CF═CF—, —C≡C—, and q, r, s, t, u are each, independently of one another, 0 or 1.