Compounds of the formula I in which one of A 2 and A 3 denotes or the other of A 2 and A 3, A 1, A 4 and A 5, independently of one another, denote a) 1,4-phenylene, in which one or more CH groups may be replaced by N, b) a radical of the formula c) trans-1,4-cyclohexylene or cyclohexenylene, in which, in addition, one or two non-adjacent CH 2 groups may be replaced by -O-and/or -S-, or d) a radical from the group 1,4-bicyclo[2.2.2]octylene, cyclobutane-1,3-diyl, spiro[3.3]heptane-2,6-diyl, thiophene-2,5-diyl, furan-2,5-diyl, and in which, in the groups a), b), c) and d), one or more H atoms are optionally replaced, independently, by in each case one group Y, Y denotes Br, Cl, F, CN, -NCS, -SCN, SF 5, C 2 -C 10 alkenyl, C 1 -C 10 alkoxy, C 3 -C 6 cycloalkyl, C 3 -C 6 cycloalkenyl or a mono- or polyfluorinated C 1 -C 10 alkyl or alkoxy group, R 1 and R 2 denote a straight-chain alkyl radical having 1 to 15 C atoms, where, in addition, one or more CH 2 groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CH=CH-, - O-, -O -, - -, -O- in such a way that O atoms are not linked directly to one another, R 3 denotes C 1 -C 10 alkyl, C 2 -C 10 alkenyl, C 1 -C 10 alkoxy, C 3 -C 6 cycloalkyl, C 3 -C 6 cycloalkenyl or a mono- or polyfluorinated C 1 -C 10 alkyl or alkoxy group, Z 1, Z 2 and Z 3 denote a single bond, and m, n and o, independently of one another, denote 0 or 1, where (m + n + o) is 2 or 3. one of A 2 and A 3 denotes or the other of A 2 and A 3, A 1, A 4 and A 5, independently of one another, denote a) 1,4-phenylene, in which one or more CH groups may be replaced by N, b) a radical of the formula c) trans-1,4-cyclohexylene or cyclohexenylene, in which, in addition, one or two non-adjacent CH 2 groups may be replaced by -O-and/or -S-, or d) a radical from the group 1,4-bicyclo[2.2.2]octylene, cyclobutane-1,3-diyl, spiro[3.3]heptane-2,6-diyl, thiophene-2,5-diyl, furan-2,5-diyl, and in which, in the groups a), b), c) and d), one or more H atoms are optionally replaced, independently, by in each case one group Y, a) 1,4-phenylene, in which one or more CH groups may be replaced by N, b) a radical of the formula c) trans-1,4-cyclohexylene or cyclohexenylene, in which, in addition, one or two non-adjacent CH 2 groups may be replaced by -O-and/or -S-, or d) a radical from the group 1,4-bicyclo[2.2.2]octylene, cyclobutane-1,3-diyl, spiro[3.3]heptane-2,6-diyl, thiophene-2,5-diyl, furan-2,5-diyl, Y denotes Br, Cl, F, CN, -NCS, -SCN, SF 5, C 2 -C 10 alkenyl, C 1 -C 10 alkoxy, C 3 -C 6 cycloalkyl, C 3 -C 6 cycloalkenyl or a mono- or polyfluorinated C 1 -C 10 alkyl or alkoxy group, R 1 and R 2 denote a straight-chain alkyl radical having 1 to 15 C atoms, where, in addition, one or more CH 2 groups in these radicals may each be replaced, independently of one another, by -C≡C-, -CH=CH-, - O-, -O -, - -, -O- in such a way that O atoms are not linked directly to one another, R 3 denotes C 1 -C 10 alkyl, C 2 -C 10 alkenyl, C 1 -C 10 alkoxy, C 3 -C 6 cycloalkyl, C 3 -C 6 cycloalkenyl or a mono- or polyfluorinated C 1 -C 10 alkyl or alkoxy group, Z 1, Z 2 and Z 3 denote a single bond, and m, n and o, independently of one another, denote 0 or 1, where (m + n + o) is 2 or 3.