Pathway regulation of an on-surface stepwise reaction through a metal coordination template

Herein, we have demonstrated a pathway regulation of a stepwise reaction on Cu(111), including both debrominative and dehydrogenative couplings, facilitated by a persistent template effect from the metal-organic coordination motif of Cu-N. Using scanning tunneling microscopy, in combination with density functional theory calculations, we revealed that the compound 2-bromo-1,8-naphthyridine on Cu(111) initially transformed into C-Cu organometallic dimeric intermediates via dehalogenation, and then into covalent tetramers and cyclic pentamers via dehydrogenation upon successive thermal annealing treatments. The cisoid species was predominant in all reaction steps, demonstrating the persistent template effect of Cu-N coordination. Our results present a new opportunity to precisely control stepwise on-surface reactions, potentially enabling the bottom-up engineering of functional organic nanostructures.