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Abstract

In this work it was investigated to what extent the triptycene unit can be used as a "crystallographic synthon" to induce a tight face-to-face π stacking of aromatic π systems. This arrangement is promising for high carrier mobility in semiconductors. For this purpose, triptycene end-capped Quinoxalinophenanthrophenazine (QPP) derivatives with different substituents at the peripheral phenylene unit were synthesized and their packing behavior was investigated. The influence of crystallization conditions was also tested. From nine QPP derivatives, 19 crystal structures and six donor-acceptor co-crystal structures were obtained. In 24 of these structures characteristic, tightly packed π-dimers were found. This underlines the high robustness of the "triptycene synthon" and shows that it can be used to effectively modify the π stacking behavior towards a high overlap of the π planes. The concept of triptycene end-capping was finally applied to benzothienobenzothiophen (BTBT) to show that this strategy can be used for other π systems as well. This assumption was confirmed with six crystal structures obtained. Additionally, the packing behavior of a series of cyano-substituted pyrene-fused pyrazaacenes (PPAs), which are potential n-type semiconductors due to their electron deficient nature, and Pyrene-substituted QPPs was investigated as well. In all ten crystal structures π-stacking, promising for charge transport, was found. Experimental and theoretical investigations as well as calculated charge transfer integrals indicate that some of the presented materials are promising candidates for semiconductors in organic electronics.