Crystal structure and Hirshfeld surfaces analysis of Heterocyclic-and circulenes

The crystal structure of the new diazatrioxa[9]circulene and tetrahydro-diazatetraoxa[10]circulene which represent the first synthesized representatives of “higher” hetero[n]circulenes with n>8, was analyzed in details. Hirshfeld surface analyses, the dnorm surfaces and two-dimensional fingerprint plots were used to verify the contributions of the different intermolecular interactions within the crystal structure of diazatrioxa[9]circulene and tetrahydro-diazatetraoxa[10]circulene. The Hirshfeld surface analysis of the crystal structure clarifies that the most important contribution for crystal packing is from H∙∙∙H and C∙∙∙H intermolecular interactions for both circulenes. The shape-index surface shows that in the case of diazatrioxa[9]circulene two sides of the molecules are involved with the same contacts in neighbouring molecules and curvedness plots show flat surface patches that are characteristic of planar stacking. Such face-to-face structural organization provides the main charge transfer pathway in [9]circulene. In the case of [10]circulene, the area involved in the same contacts is much less, however, two types of intermolecular packing modes can form such flat surface patches at curvedness plots which is useful for more efficient charge transfer.