Local adsorption structure and bonding of porphine on Cu(111) before and after self-metalation

Journal of Chemical Physics 150, 094702 (2019)

Local adsorption structure and bonding of porphine on Cu(111) before and after self-metalation

D. A. Duncan,P.Casado Aguilar,M.Paszkiewicz1,K. Diller,F. Bondino,E. Magnano,F.Klappenberger,I.Píš,A. Rubio,J. V. Barth,A. Pérez Paz, F. Allegretti

We have experimentally determined the lateral registry and geometric structure of free-base porphine (2H-P) and coppermetalated porphine (Cu-P) adsorbed on Cu(111), by means of energy-scanned photoelectron diffraction (PhD), and compared the experimental results to density functional theory (DFT) calculations that included van der Waals corrections within the Tkatchenko-Scheffler approach. Both 2H-P and Cu-P adsorb with their center above a surface bridge site. Consistency is obtained between the experimental and DFT-predicted structural models, with a characteristic change in the corrugation of the four N atoms of the molecule’s macrocycle following metalation. Interestingly, comparison with previously published data for cobalt porphine adsorbed on the same surface evidences a distinct increase in the average height of the N atoms above the surface through the series 2H-P, Cu-P, and cobalt porphine. Such an increase strikingly anti-correlates the DFT-predicted adsorption strength, with 2H-P having the smallest adsorption height despite the weakest calculated adsorption energy. In addition, our findings suggest that for these macrocyclic compounds, substrate-to-molecule charge transfer and adsorption strength may not be univocally correlated.

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This work was supported by the Munich-Centre for Advanced Photonics (MAP), the ERC Advanced Grants MolArt (Project No. 247299) and QSpec-NewMat (Project No. 694097), the German Research Foundation (DFG) via KL 2294/3-1, and Grupos Consolidados UPV/EHU (IT578-13). D.A.D. acknowledges funding from the Alexander von Humboldt Foundation and the Marie Curie Intra-European Fellowship for Career Development (SiliNano, Project No. 626397). The authors gratefully acknowledge the computing resources provided by the Leibniz Supercomputing Centre (www.lrz.de) and the STFC Scientific Computing Department’s SCARF cluster. We would also like to thank Elettra Sincrotrone Trieste for the award of beam time and Willi Auwärter for helpful discussions.

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