Nitrogen-containing hetreocycles for organic electroluminescent devices

A compound comprising at least one structure of the formula (I)

• wherein:
• Za is the same or different at each instance and is Ar, Rc, L1-Q, or L1-N(Ar)2;
• Q is the same or different at each instance and is an electron transport group;
• L1 is the same or different at each instance and is a bond or an aromatic or heteroaromatic ring system which has 5 to 60 aromatic ring atoms and may be substituted by one or more R radicals;
• Ra is the same or different at each instance and is a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 10 carbon atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 10 carbon atoms, each of which may be substituted by one or more R2 radicals, or an aromatic or heteroaromatic ring system having 5 to 20 aromatic ring atoms, which may be substituted in each case by one or more R2 radicals, where two or more substituents Ra together may form a ring system;
• Rb is the same or different at each instance and is H, D, straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 10 carbon atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 10 carbon atoms, each of which may be substituted by one or more R2 radicals, or an aromatic or heteroaromatic ring system which has 5 to 20 aromatic ring atoms and may be substituted in each case by one or more R2 radicals, where two substituents Rb together may form a ring system;
• Ar is the same or different at each instance and is an aromatic or heteroaromatic ring system which has 5 to 60 aromatic ring atoms and may be substituted by one or more R radicals, where it is possible for two Ar radicals bonded to the same nitrogen atom also to be bridged to one another by a single bond or a bridge selected from B(R), C(R)2, Si(R)2, C═O, C═NR, C═C(R)2, RC═CR, O, S, S═O, SO2, N(R), P(R), P(═O)R and an ortho-linked phenylene group that may be substituted by one or more R radicals;
• R, Rc, Rd is the same or different at each instance and is H, D, OH, F, Cl, Br, I, CN, NO2, N(Ar′)2, N(R1)2, C(═O)N(Ar′)2, C(═O)N(R1)2, C(Ar′)3, C(R1)3, Si(Ar′)3, Si(R1)3, B(Ar′)2, B(R1)2, C(═O)Ar′, C(═O)R1, P(═O)(Ar′)2, P(═O)(R1)2, P(Ar′)2, P(R1)2, S(═O)Ar′, S(═O)R1, S(═O)2Ar′, S(═O)2R1, OSO2Ar′, OSO2R1, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 40 carbon atoms or an alkenyl or alkynyl group having 2 to 40 carbon atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 20 carbon atoms, where the alkyl, alkoxy, thioalkoxy, 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 R1C═CR1, C≡C, Si(R1)2, C═O, C═S, C═Se, C═NR1, —C(═O)O—, —C(═O)NR1—, NR1, P(═O)(R1), —O—, —S—, SO or SO2, or an aromatic or heteroaromatic ring system which has 5 to 60 aromatic ring atoms and may be substituted in each case by one or more R1 radicals, or an aryloxy or heteroaryloxy group which has 5 to 60 aromatic ring atoms and may be substituted by one or more R1 radicals, where two R, Rd radicals together or one R, Rd radical together with a further group, especially an Rc radical, may also form a ring system;
• Ar′ is the same or different at each instance and is an aromatic or heteroaromatic ring system which has 5 to 60 aromatic ring atoms and may be substituted by one or more R radicals, where it is possible for two Ar′ radicals bonded to the same carbon atom, silicon atom, nitrogen atom, phosphorus atom or boron atom also to be bridged to one another by a single bond or a bridge selected from B(R1), C(R1)2, Si(R1)2, C═O, C═NR1, C═C(R1)2, O, S, S═O, SO2, N(R1), P(R1) and P(═O)R1;
• R1 is the same or different at each instance and is H, D, F, Cl, Br, I, CN, NO2, N(Ar″)2, N(R2)2, C(═O)Ar″, C(═O)R2, P(═O)(Ar″)2, P(Ar″)2, B(Ar″)2, B(R2)2, C(Ar″)3, C(R2)3, Si(Ar″)3, Si(R2)3, a straight-chain alkyl, alkoxy or thioalkoxy group having 1 to 40 carbon atoms or a branched or cyclic alkyl, alkoxy or thioalkoxy group having 3 to 40 carbon atoms or an alkenyl group having 2 to 40 carbon atoms, each of which may be substituted by one or more R2 radicals, where one or more nonadjacent CH2 groups may be replaced by —R2C═CR2—, —C≡C—, Si(R2)2, C═O, C═S, C═Se, C═NR2, —C(═O)O—, —C(═O)NR2—, NR2, P(═O)(R2), —O—, —S—, SO or SO2, and where one or more hydrogen atoms may be replaced by D, F, Cl, Br, I, CN or NO2, or an aromatic or heteroaromatic ring system which has 5 to 60 aromatic ring atoms and may be substituted in each case by one or more R2 radicals, or an aryloxy or heteroaryloxy group which has 5 to 60 aromatic ring atoms and may be substituted by one or more R2 radicals, or an aralkyl or heteroaralkyl group which has 5 to 60 aromatic ring atoms and may be substituted by one or more R2 radicals, or a combination of these systems, where two or more R1 radicals together may form a ring system, where one or more R1 radicals may form a ring system with another part of the compound;
• Ar″ is the same or different at each instance and is an aromatic or heteroaromatic ring system which has 5 to 30 aromatic ring atoms and may be substituted by one or more R2 radicals, where it is possible for two Ar″ radicals bonded to the same carbon atom, silicon atom, nitrogen atom, phosphorus atom or boron atom also to be bridged to one another by a single bond or a bridge selected from B(R2), C(R2)2, Si(R2)2, C═O, C═NR2, C═C(R2)2, O, S, S═O, SO2, N(R2), P(R2) and P(═O)R2;
• R2 is the same or different at each instance and is selected from the group consisting of H, D, F, CN, an aliphatic hydrocarbyl radical having 1 to 20 carbon atoms or an aromatic or heteroaromatic ring system which has 5 to 30 aromatic ring atoms and in which one or more hydrogen atoms may be replaced by D, F, Cl, Br, I or CN and which may be substituted by one or more alkyl groups each having 1 to 4 carbon atoms, where two or more substituents R2 together may form a ring system.