Intermolecular Anionic Mixed-Valence and π-Dimer Complexes of ortho-Pentannulated Bisazacoronene Diimide.

Abstract

This study reports the serendipitous discovery of intermolecular anionic mixed-valence (MV) and π-dimer species in ortho-pentannulated BisAzaCoroneneDiimides (BACDs) during their electrochemical reduction in a non-aqueous solvent. A library of nitrogen-containing extended PDIs was synthesized via an aza-benzannulation reaction followed by a Pd-catalysed ortho-pentannulation reaction. Ortho-pentannulated BACDs revealed strong aggregation abilities in solution. Concentration-dependent UV/Vis absorption spectra, variable temperature 1H NMR experiments, and atomic force microscopy coupled to molecular dynamics support their self-assembly into columnar aggregates. Cyclic voltammetry experiments in dichloromethane reveal prominent splitting of the first reduction wave, attributed to the formation of unprecedented intermolecular anionic MV and π-dimers in organic solvent. These species were thoroughly characterized by real-time spectroelectrochemistry, electrochemical simulations and theoretical calculations. Remarkably, this work underscores the tuneable nature of AzaBenzannulatedPerylene Diimides (AzaBPDIs) and BACDs, emphasizing their potential as a promising scaffold for designing supramolecular materials with long-range radical anion delocalization. The observation of this phenomenon provides insights into the fundamental behaviour of supramolecular organic semiconductors, thereby paving the way for the development of novel electronic devices and electron-deficient materials.