A compound of formula I R 1 -(A 1 -Z 1) r -B 1 -Z L -A 2 -(Z 3 -A 3) s -G in which R 1 denotes a straight chain or branched alkyl or alkoxy radical having 1 to 20 C atoms, where one or more CH 2 groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CH=CH-, -O-, -S-, -CF 2 O-, -OCF 2 -, -CO-O-, -O-CO-, -SiR 0 R 00 -, -NH-, -NR 0 - or -SO 2 - in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, CN, SCN or SF 5, or alternatively, R 1 denotes a group Dia-Z D, Dia denotes a diamondoid radical, Z D has one of the meanings of Z 1 and Z 3 or denotes a straight chain or branched spacer group, Z 1, Z 3 on each occurrence, identically or differently, denote a single bond, -CF 2 O-, -OCF 2 -, -CF 2 S-, -SCF 2 -, -CH 2 O-, -OCH 2 -, -C O-, -OC -, -C S-, -SC -, -(CH 2) n1 -, -(CF 2) n2 -, -CF 2 -CH 2 -, -CH 2 -CF 2 -, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -(CH 2) n3 O-, -O(CH 2) n4 -, -C≡C-, -O-, -S-, -CH=N-, -N=CH-, -N=N-, -N=N -, -N =N- or -N=C-C=N-, n1, n2, n3, n4 identically or differently, are 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, Z L denotes -O-, -S-, -CH 2 -, -C -, -CF 2 -, -CHF-, -C(R x) 2 -, -S - or -SO 2 -, R 0, R 00, identically or differently, denote an alkyl or alkoxy radical having 1 to 15 C atoms, in which one or more H atoms may be replaced by halogen, A 1, A 3 on each occurrence, identically or differently, denote an aromatic, heteroaromatic, alicyclic or heteroaliphatic ring having 4 to 25 ring atoms, which may also contain condensed rings and which may be mono- or polysubstituted by Y, A 2 -Z L denotes or Y, Y 3 and Y 4 on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF 5 or straight-chain or branched, in each case optionally fluorinated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, or cycloalkyl or alkylcycloalkyl each having 3 to 12 C atoms, preferably methyl, ethyl, isopropyl, cylopropyl, cyclobutyl, cyclopentyl, cyclohexyl, trifluoromethyl, methoxy or trifluoromethoxy, B 1 denotes where the groups may be oriented in both directions, L 1 to L 5, independently of one another, denote F, C!, Br, I, CN, SF 5, CF 3 or OCF 3, preferably Cl or F, where L 3 alternatively denotes H, G denotes -CH=CH 2, -OH, -CH(CH 2 OH) 2, -C(CH 2 OH) 3, B 2, -SH, -SO 2 OH, -OP 2, -PO 2, -C (PO 2) 2, -COOH, -Si(OR x) 3 or -SiCl 3, -SO 2 OR V, -OP (OR V) 2, -PO(OR V) 2, -C (PO(OR V) 2) 2, -COOR V, -Si(OR V) 3, R V denotes an alkyl having 1 to 20 C atoms, preferably a secondary or tertiary alkyl having 3 to 10 C atoms, R x denotes a straight-chain or branched alkyl having 1 to 6 C atoms, and r is 0, 1 or 2, s is 0, 1 or 2, where r + s ≤ 4. R 1 denotes a straight chain or branched alkyl or alkoxy radical having 1 to 20 C atoms, where one or more CH 2 groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CH=CH-, -O-, -S-, -CF 2 O-, -OCF 2 -, -CO-O-, -O-CO-, -SiR 0 R 00 -, -NH-, -NR 0 - or -SO 2 - in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, CN, SCN or SF 5, or alternatively, R 1 denotes a group Dia-Z D, Dia denotes a diamondoid radical, Z D has one of the meanings of Z 1 and Z 3 or denotes a straight chain or branched spacer group, Z 1, Z 3 on each occurrence, identically or differently, denote a single bond, -CF 2 O-, -OCF 2 -, -CF 2 S-, -SCF 2 -, -CH 2 O-, -OCH 2 -, -C O-, -OC -, -C S-, -SC -, -(CH 2) n1 -, -(CF 2) n2 -, -CF 2 -CH 2 -, -CH 2 -CF 2 -, -CH=CH-, -CF=CF-, -CF=CH-, -CH=CF-, -(CH 2) n3 O-, -O(CH 2) n4 -, -C≡C-, -O-, -S-, -CH=N-, -N=CH-, -N=N-, -N=N -, -N =N- or -N=C-C=N-, n1, n2, n3, n4 identically or differently, are 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, Z L denotes -O-, -S-, -CH 2 -, -C -, -CF 2 -, -CHF-, -C(R x) 2 -, -S - or -SO 2 -, R 0, R 00, identically or differently, denote an alkyl or alkoxy radical having 1 to 15 C atoms, in which one or more H atoms may be replaced by halogen, A 1, A 3 on each occurrence, identically or differently, denote an aromatic, heteroaromatic, alicyclic or heteroaliphatic ring having 4 to 25 ring atoms, which may also contain condensed rings and which may be mono- or polysubstituted by Y, A 2 -Z L denotes or Y, Y 3 and Y 4 on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF 5 or straight-chain or branched, in each case optionally fluorinated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, or cycloalkyl or alkylcycloalkyl each having 3 to 12 C atoms, preferably methyl, ethyl, isopropyl, cylopropyl, cyclobutyl, cyclopentyl, cyclohexyl, trifluoromethyl, methoxy or trifluoromethoxy, B 1 denotes where the groups may be oriented in both directions, L 1 to L 5, independently of one another, denote F, C!, Br, I, CN, SF 5, CF 3 or OCF 3, preferably Cl or F, where L 3 alternatively denotes H, G denotes -CH=CH 2, -OH, -CH(CH 2 OH) 2, -C(CH 2 OH) 3, B 2, -SH, -SO 2 OH, -OP 2, -PO 2, -C (PO 2) 2, -COOH, -Si(OR x) 3 or -SiCl 3, -SO 2 OR V, -OP (OR V) 2, -PO(OR V) 2, -C (PO(OR V) 2) 2, -COOR V, -Si(OR V) 3, R V denotes an alkyl having 1 to 20 C atoms, preferably a secondary or tertiary alkyl having 3 to 10 C atoms, R x denotes a straight-chain or branched alkyl having 1 to 6 C atoms, and r is 0, 1 or 2, s is 0, 1 or 2,