Use of compounds of formula I in which the individual radicals have the following meanings: A 1, A 3 independently of each other denote 1,4-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl, wherein in all of these groups one or more CH groups are optionally replaced by N, A 2 denotes 1,4-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl, wherein in all of these groups one or more CH groups are optionally replaced by N, cyclohexane-1,4-diyl, wherein one or more non-adjacent CH 2 -groups are optionally replaced by O and/or S, 1,4-cyclohexenylene, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, piperidine-1,4-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, indane-2,5-diyl or octahydro-4,7-methano-indane-2,5-diyl, wherein all of these groups are unsubstituted or mono- or polysubstituted by L, Z 1, Z 2 and Z 3 are selected from the group consisting of -O-, -CO-O-, -OCO-, -OCH 2 -, -CH 2 O-, -CF 2 O-, -OCF 2 -, -CH 2 CH 2 -, -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, single bond, L denotes P-, P-Sp-, OH, CH 2 OH, F, Cl, Br, I, -CN, -NO 2,-NCO, -NCS, -OCN, -SCN, -C(=O)N(R x) 2, -C(=O)Y 1,-C(=O)R x, -N(R x) 2, optionally substituted silyl, optionally substituted aryl or heteroaryl having 5 to 20 ring atoms, or straight-chain or branched alkyl having 1 to 25, particularly preferably 1 to 10, C atoms, in which, in addition, one or more non-adjacent CH 2 groups may each be replaced, independently of one another, by -C(R 00)=C(R 000)-, -C≡C-, -N(R 00)-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and/or S atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by F, Cl, CN, P- or P-Sp-, R 00 and R 000 each, independently of one another, denote H or alkyl having 1 to 12 C atoms, P 1, P 2, P 3 independently of each other denote a polymerisable group, Sp 1, Sp 2, Sp 3 independently of each other denote a spacer group or a single bond, Y 1 is halogen, R x denotes P-, P-Sp-, H, halogen, straight chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein one or more non-adjacent CH 2 -groups are optionally replaced by -O-,-S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are optionally replaced by F, Cl, P- or P-Sp-, optionally substituted aryl, aryloxy, heteroaryl or heteroaryloxy having 5 to 20 ring atoms, X 1, X 2, X 3 independently of each other denote O, S, -C -, -OC -, -C O-, -CF 2 O-, or a single bond, n is 0, 1 or 2, m and o are independently of each other 1 or 2, t is 0, 1, 2 or 3, in liquid-crystal media and LC displays. A 1, A 3 independently of each other denote 1,4-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl, wherein in all of these groups one or more CH groups are optionally replaced by N, A 2 denotes 1,4-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl, wherein in all of these groups one or more CH groups are optionally replaced by N, cyclohexane-1,4-diyl, wherein one or more non-adjacent CH 2 -groups are optionally replaced by O and/or S, 1,4-cyclohexenylene, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, piperidine-1,4-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, indane-2,5-diyl or octahydro-4,7-methano-indane-2,5-diyl, wherein all of these groups are unsubstituted or mono- or polysubstituted by L, Z 1, Z 2 and Z 3 are selected from the group consisting of -O-, -CO-O-, -OCO-, -OCH 2 -, -CH 2 O-, -CF 2 O-, -OCF 2 -, -CH 2 CH 2 -, -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, single bond, L denotes P-, P-Sp-, OH, CH 2 OH, F, Cl, Br, I, -CN, -NO 2,-NCO, -NCS, -OCN, -SCN, -C(=O)N(R x) 2, -C(=O)Y 1,-C(=O)R x, -N(R x) 2, optionally substituted silyl, optionally substituted aryl or heteroaryl having 5 to 20 ring atoms, or straight-chain or branched alkyl having 1 to 25, particularly preferably 1 to 10, C atoms, in which, in addition, one or more non-adjacent CH 2 groups may each be replaced, independently of one another, by -C(R 00)=C(R 000)-, -C≡C-, -N(R 00)-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and/or S atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by F, Cl, CN, P- or P-Sp-, R 00 and R 000 each, independently of one another, denote H or alkyl having 1 to 12 C atoms, P 1, P 2, P 3 independently of each other denote a polymerisable group, Sp 1, Sp 2, Sp 3 independently of each other denote a spacer group or a single bond, Y 1 is halogen, R x denotes P-, P-Sp-, H, halogen, straight chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein one or more non-adjacent CH 2 -groups are optionally replaced by -O-,-S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are optionally replaced by F, Cl, P- or P-Sp-, optionally substituted aryl, aryloxy, heteroaryl or heteroaryloxy having 5 to 20 ring atoms, X 1, X 2, X 3 independently of each other denote O, S, -C -, -OC -, -C O-, -CF 2 O-, or a single bond, n is 0, 1 or 2, m and o are independently of each other 1 or 2, t is 0, 1, 2 or 3,