On-surface reaction of tetraphenylporphyrins with Os3(CO)12 precursors and Os clusters: A scanning tunnelling microscopy investigation

Abstract

The ability of porphyrin molecules to incorporate metal atoms into the cavity of the macrocycle is the primary factor that enables the plethora of their applications. The fabrication and characterisation of surface confined metal-organic architectures by employing porphyrins promise unique technical applications in the field of nanotechnology. Here we report on the efforts to use triosmium dodecacarbonyl as a metal precursor for the on-surface Os functionalisation of porphyrins under ultra-high vacuum conditions. We address the effects of the temperature treatment of mixtures of tetraphenylporphyrins and the Os precursor molecules, which can decompose to yield Os clusters, on Ag(111) via scanning tunnelling microscopy, a technique that provides real-space visualisation of the reaction products formed. It is shown that free base porphyrins can be metallated to osmium porphyrins. Furthermore the presence of Os on the Ag(111) surface catalyses intramolecular cyclodehydrogenations in tetraphenylporphyrins, as well as intermolecular tetraphenylporphyrin polymerisation.