Materials for organic electroluminescent devices

A compound of formula (1)

• where the R radicals may also occur more than once and the symbols used are:
• Z is O or S;
• R* is a group of the formula (2) or (3), where the dotted bond represents the bond to the base skeleton in formula (1),
• X is the same or different at each instance and is CR or N, where not more than two X groups are N, or two adjacent X groups are a group of the following formula (4) or (5):
• where the dotted bonds indicate the linkage of this group in formula (2);
• Y is the same or different at each instance and is CR or N;
• W is the same or different at each instance and is NAr2, O, S or C(R)2;
• L is a single bond or an aromatic or heteroaromatic ring system which has 5 to 24 aromatic ring atoms and may be substituted by one or more R radicals;
• Ar1, Ar2 is the same or different at each instance and is an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms and may be substituted by one or more R radicals;
• R is the same or different at each instance and is H, D, F, Cl, Br, I, CN, NO2, OR1, SR1, COOR1, C(═O)N(R1)2, Si(R1)3, B(OR1)2, C(═O)R1, P(═O)(R1)2, S(═O)R1, S(═O)2R1, OSO2R1, a straight-chain alkyl group having 1 to 20 carbon atoms or an alkenyl or alkynyl group having 2 to 20 carbon atoms or a branched or cyclic alkyl group having 3 to 20 carbon atoms, where the alkyl, alkenyl or alkynyl group may in each case be substituted by one or more R1 radicals, where one or more nonadjacent CH2 groups may be replaced by Si(R1)2, C═O, NR1, O, S or CONR1, or an aromatic or heteroaromatic ring system which has 5 to 60 aromatic ring atoms, preferably 5 to 40 aromatic ring atoms, and may be substituted in each case by one or more R1 radicals;
• at the same time, two R radicals together may also form an aliphatic, heteroaliphatic, aromatic or heteroaromatic ring system;
• R1 is the same or different at each instance and is H, D, F, Cl, Br, I, CN, NO2, OR2, SR2, Si(R2)3, B(OR2)2, C(═O)R2, P(═O)(R2)2, S(═O)R2, S(═O)2R2, OSO2R2, a straight-chain alkyl group having 1 to 20 carbon atoms or an alkenyl or alkynyl group having 2 to 20 carbon atoms or a branched or cyclic alkyl group having 3 to 20 carbon atoms, where the alkyl, alkenyl or alkynyl group may each be substituted by one or more R2 radicals, where one or more nonadjacent CH2 groups may be replaced by Si(R2)2, C═O, NR2, O, S or CONR2 and where one or more hydrogen atoms in the alkyl, alkenyl or alkynyl group may be replaced by D, F, Cl, Br, I or CN, or an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms and may be substituted in each case by one or more R2 radicals;
• at the same time, two or more R1 radicals together may form an aliphatic ring system;
• R2 is the same or different at each instance and is H, D, F, CN or an aliphatic, aromatic or heteroaromatic organic radical, especially a hydrocarbyl radical, having 1 to 20 carbon atoms, in which one or more hydrogen atoms may also be replaced by F.