Reassessing the Adsorption Behavior and on-Surface Reactivity of a Brominated Porphyrin on Cu(111)

On-surface coupling reactions and molecular conformation are essential processes for building tailored functional molecular nanostructures. Here, we study the thermal debromination and reactivity of free-base tetra­(4-bromophenyl)­porphyrin (H₂TBrPP) on Cu(111) as a function of the substrate temperature. It has been previously reported in the literature that C–Br bonds remain intact at room temperature (RT) and that the Br···Cu(111) interaction induces a drastic surface reconstruction around the molecule periphery and a distortion in the adsorbate itself. However, based on a combination of STM and XPS experiments, supported by density functional theory (DFT) calculations, we instead demonstrate that debromination readily occurs at RT, leading to a new interpretation of both the adsorption behavior and the molecular coupling of H₂TBrPP on Cu(111). For the molecules deposited on the metallic substrate held above RT, our STM measurements show the growth of ordered 2D metal–organic frameworks (MOFs).