O-Doped Nanographenes: The Pyrano/Pyrylium Route Towards Semiconducting Cationic Mixed-Valence Complexes

摘要

Herein we report an efficient synthesis to prepare O-doped nanographenes derived from the pi-extension of pyrene. The derivatives are highly fluorescent and feature low oxidation potentials. Using electrooxidation, crystals of cationic mixed-valence (MV) complexes were grown in which the organic salts organize into face-to-face pi-stacks, a favorable solid-state arrangement for organic electronics. Variable-temperature electron paramagnetic resonance (EPR) measurements and relaxation studies suggest a strong electron delocalization along the longitudinal axis of the columnar pi-stacking architectures. Electric measurements of single crystals of the MV salts show a semiconducting behavior with a remarkably high conductivity at room temperature. These findings support the notion that pi-extension of heteroatom-doped polycyclic aromatic hydrocarbons is an attractive approach to fabricate nanographenes with a broad spectrum of semiconducting properties and high charge mobilities.