Highly Selective Dimerization of 3-Trioxotriangulene Mediated by Delocalized π-Radical Character on Au(111)

Radical-mediated coupling reactions serve as powerful tools for chemical bond formation, leveraging the high reactivity of radical intermediates to achieve reactions inaccessible through traditional ionic pathways. However, achieving radical-mediated multisite coupling remains a significant challenge. Here, we report an on-surface synthesis strategy of delocalized π-radical-mediated multisite cooperative coupling for the highly selective synthesis of oxygen-doped nanographene. Initially, dehydrogenation of the hydroxyl group on the molecule generates a σ-radical, which simultaneously transforms into a delocalized π-radical due to orbital rehybridization. Subsequently, electron delocalization induced by the π-radical gives rise to the spin-density distribution along the entire periphery of the molecule, enabling multisite C-O and C-C coupling between two monomer units. Owing to the high regioselectivity imposed by steric hindrance between the carbonyl groups, high-yield (>95.6%) π-conjugated oxygen-doped nanographene is synthesized. Our work establishes a novel paradigm of cooperative multibond formation mediated by delocalized π-radicals, opening a promising avenue for the precise bottom-up synthesis of extended π-conjugated systems.