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Abstract

The focus of the presented work lies on the introduction of novel structural motifs into the solid state structure of functionalized N-heteroacenes by synthesis and quantum chemistry. Additionally literature known (aza-)acenes were studied in terms of transfer integrals and it was tried to optimize the crystal packing of tetraazapentacene derivatives regarding their transfer integrals. Di-iso-propylethylsilyl- and cyclopropyldi-iso-propylsilyl groups were introduced as slightly smaller and larger silyl groups respectively than TIPS. Transfer integrals showed a concentration on one of the two overlap regions instead of balanced values for both. A series of diazadioxaacenes, which are analogous to the N,N‘-dihydroazaacenes, were synthesized and their optical, electronic and morphologic properties were examined. Doing attempts for incorporating seven-membered rings into the acene backbone, acetyl quinoxaline derivatives and quinoxalotropones were obtained as products of oxidation reactions. Ethynylated benzoquinoxalotropone shows a low LUMO energy, a highly symmetric crystal packing, and thus interesting properties for application in organic thin-film transistors. Since large azaacenes tend to stabilize via dimerization or reduction, a conjugative link between smaller acene units can help with the building of large structures. Therefore the incorporation of cyclobutadiene rings into the acene backbone was computationally studied for symmetrical and non-symmetrical biphenylene derivatives. The symmetrical compound and its hydrogenation products show interesting structural and electronic properties. The question concerning aromaticity was discussed. The non-symmetrical azaacenes were examined for the electronics and compared to the corresponding pure azaacenes.