Compound of the formula I where A and B in each case, independently of one another, denote a radical selected from the following groups: a) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene and 1,4'-bicyclohexylene, in which, in addition, one or two non-adjacent CH 2 groups may be replaced by -O- and/or -S- and in which, in addition, one or more H atoms may be replaced by F, b) the group consisting of 1,4-phenylene and 1,3-phenylene, in which, in addition, one or two non-adjacent CH groups may be replaced by N and in which, in addition, one or more H atoms may be replaced by L, and c) the group consisting of where, in addition, one or more H atoms in these radicals may be replaced by L, and/or one or more double bonds may be replaced by single bonds, and/or one or more CH groups may be replaced by N, i and j in each case, independently of one another, denote 0 or 1, Z 0 denotes a single bond, -CH 2 -, -CF 2 -, -CO-, -O-, -NH-, -NH- -, -CH 2 CH 2 -, -CH=CH-, -CF 2 O-, -OCF 2 -, -CH 2 O-, -OCH 2 -, -COO-, -OCO-, -C 2 F 4 - or -CF=CF-, and L on each occurrence, identically or differently, denotes F, Cl, CN or straight-chain or branched, in each case optionally fluorinated alkyl, alkoxy, arylalkyl or alkylarylalkyl having 1 to 15 C atoms, in which, in addition, one or more non-adjacent CH 2 groups may be replaced by -O- and/or -S-, and where Sp 1 and Sp 2 in each case, independently of one another, denote alkylene having 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl or CN, and in which, in addition, one or more non-adjacent CH 2 groups may in each case be replaced, independently of one another, by -O-, -S-, -NH-, -CH=CH- or -C≡C-, where no two O atoms in the compound are connected directly to one another. A and B in each case, independently of one another, denote a radical selected from the following groups: a) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene and 1,4'-bicyclohexylene, in which, in addition, one or two non-adjacent CH 2 groups may be replaced by -O- and/or -S- and in which, in addition, one or more H atoms may be replaced by F, b) the group consisting of 1,4-phenylene and 1,3-phenylene, in which, in addition, one or two non-adjacent CH groups may be replaced by N and in which, in addition, one or more H atoms may be replaced by L, and c) the group consisting of where, in addition, one or more H atoms in these radicals may be replaced by L, and/or one or more double bonds may be replaced by single bonds, and/or one or more CH groups may be replaced by N, a) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene and 1,4'-bicyclohexylene, in which, in addition, one or two non-adjacent CH 2 groups may be replaced by -O- and/or -S- and in which, in addition, one or more H atoms may be replaced by F, b) the group consisting of 1,4-phenylene and 1,3-phenylene, in which, in addition, one or two non-adjacent CH groups may be replaced by N and in which, in addition, one or more H atoms may be replaced by L, and c) the group consisting of i and j in each case, independently of one another, denote 0 or 1, Z 0 denotes a single bond, -CH 2 -, -CF 2 -, -CO-, -O-, -NH-, -NH- -, -CH 2 CH 2 -, -CH=CH-, -CF 2 O-, -OCF 2 -, -CH 2 O-, -OCH 2 -, -COO-, -OCO-, -C 2 F 4 - or -CF=CF-, L on each occurrence, identically or differently, denotes F, Cl, CN or straight-chain or branched, in each case optionally fluorinated alkyl, alkoxy, arylalkyl or alkylarylalkyl having 1 to 15 C atoms, in which, in addition, one or more non-adjacent CH 2 groups may be replaced by -O- and/or -S-, Sp 1 and Sp 2 in each case, independently of one another, denote alkylene having 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl or CN, and in which, in addition, one or more non-adjacent CH 2 groups may in each case be replaced, independently of one another, by -O-, -S-, -NH-, -CH=CH- or -C≡C-, where no two O atoms in the compound are connected directly to one another.