Self-Metalation of Phthalocyanine Molecules with Silver Surface Atoms by Adsorption on Ag(110)

Abstract

We report that metal-free phthalocyanine (H2Pc) molecules with a central cavity are able to incorporate Ag atoms from an Ag(110) surface thus creating silver-phthalocyanine (AgPc). The reaction was investigated by means of scanning tunneling microscopy (STM) under ultrahigh vacuum, and the metalation of \ce{H2Pc} at the interface was confirmed with X-ray photoelectron spectroscopy. Three different kinds of molecules were found on the surface that are assigned to H2Pc, the corresponding dehydrogenated molecules (Pc) and AgPc. The relative amounts of Pc and AgPc increase with increasing annealing temperature. We suggest that the reaction with Ag atoms from the steps of the surface occurs favorably only for already dehydrogenated molecules; thus, the metalation of H2Pc is likely limited by the heat-induced dehydrogenation. Density functional theory simulations of the reaction path are presented to corroborate this hypothesis.