S,N-Heteroacenes Up to a Tridecamer

Herein, syntheses of extended pi-conjugated ladder S,N-heteroacenes from the octamer to the tridecamer and their physical properties are described. Motivated by previous results on shorter members of this family, we further extended the number of annulated thiophene and pyrrole rings in our S,N-heteroacene series up to 13. The synthetic strategy to achieve the heteroacene scaffolds comprised multiple ring closures by transition metal-catalyzed C-S and C-N coupling/cyclization reactions, leading to fused thiophene or pyrrole rings, respectively. The extended S,N-heteroacenes comprising varying sequences of heteroatoms were fully characterized by NMR, high-resolution mass spectrometry, UV-vis and fluorescence spectroscopy, and cyclic voltammetry. Furthermore, stable radical cations and dications were formed by controlled oxidation of the heteroacenes and optically characterized. Valuable structure-property relationships concerning the optoelectronic properties were deduced.