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 <i>via</i> dehalogenation, and then into covalent tetramers and cyclic pentamers <i>via</i> 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.