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Metal–Ligand Complexation through Redox Assembly at Surfaces Characterized by Vibrational Spectroscopy

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journal contribution
posted on 01.06.2017, 00:00 by Christopher G. Williams, Miao Wang, Daniel Skomski, Christopher D. Tempas, Larry L. Kesmodel, Steven L. Tait
The formation of metal–organic complexes on metal surfaces is a research topic of high interest to develop tunable functional surfaces. One such focus of this research is the formation of single site metal centers that have uniform ligand environments and thus uniform chemistry. We report the complexation of Pt and Ag with the ligand dipyridyl-tetrazine (DPTZ) on Ag(111) and of Pt with DPTZ on the reconstructed Au(100) surface. Each metal atom binds two DPTZ molecules resulting in one-dimensional supramolecular chains across the surface. Pt complexation occurs immediately after Pt deposition at room temperature on either surface. This complexation is improved with annealing to 170 °C on Au(100). DPTZ forms complexes with Ag atoms from the Ag(111) substrate when annealed to 110 °C. No similar complexation with substrate atoms is seen on Au(100). This metal–organic complexation with substrate atoms on Ag(111) takes place even when the DPTZ is already complexed to Pt, demonstrating a Pt replacement reaction by Ag at 80 °C, which has not been reported previously. The metal–organic complexes are characterized by high-resolution electron energy loss spectroscopy (HREELS), scanning tunneling microscopy (STM), and X-ray photoelectron spectroscopy (XPS). This research is among the few to use HREELS to characterize the formation of extended metal organic networks on a surface formed through the redox of the organic species into an anionic state.