Tunable Oxygen Connectivity in Carbaporphyrinoid Polymers on Metal Surfaces

Abstract

ABSTRACT Controlling oxygen‐mediated connectivity at metal surfaces offers a powerful route to engineer covalent and metal–organic architectures with atomic precision. Here, we demonstrate tunable oxygen‐based connectivity in carbaporphyrinoid polymers on Au(111) under ultrahigh vacuum (UHV) conditions. Initial thermal activation of hydroxyl‐functionalized dicarbahemiporphyrazine precursors induces carbon–carbon coupling via a [3+3] cycloaromatization, affording one‐dimensional polymers equipped with hydroxyl‐terminated units. From this intermediate two distinct oxygen‐based linkages can be achieved: further annealing induces dehydrogenative coupling of adjacent polymers through the hydroxyls groups to yield dibenzo‐p‐dioxane (O‐heterocyclic) bridges that covalently connect the carbaporphyrinoid macrocycles, whereas dosing cobalt produces extended metal–organic networks stabilized by two‐fold O···Co···O coordination motifs accompanied by cobalt‐metalated macrocycles. Scanning tunneling microscopy (STM) and non‐contact atomic force microscopy (nc‐AFM) directly resolve both the coordinated networks and the O‐heterocyclic bridging motifs. Complementary DFT and Free energy calculations elucidate the reaction pathways, while x‐ray photoelectron spectroscopy (XPS) reveals characteristic chemical shifts that account for C–O–C formation and suggest Co···O coordination. This controllable oxygen‐based connectivity provides a versatile platform to tune structure and electronic properties in porphyrinoid‐based polymers.