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Register a new userSelf-Metalation of Phthalocyanine Molecules with Silver Surface Atoms by Adsorption on Ag(110)
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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.
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We have experimentally determined the lateral registry and geometric structure of free-base porphine (2H-P) and copper-metalated 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 molecules 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, 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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Organometallic nanostructures are promising candidates for applications in optoelectronics, magnetism and catalysis. Our bottom-up approach employs a cyano-functionalized terminal alkyne species (CN-DETP) on the Ag(110) surface to fabricate 2D domains of regularly stacked Ag-acetylide nanowires. We unravel their adsorption properties and give evidence to their organometallic character with the aid of complementary surface-sensitive techniques, i.e. scanning tunneling microscopy, X-ray photoelectron spectroscopy and near-edge X-ray absorption fine-structure spectroscopy. Guided by the anisotropic (110) surface, highly oriented nanowires form in two enantiomorphic domains of regularly stacked trans isomers, whereby the bifunctional design of CN-DETP gives rise to orthogonal bonding motifs. Based on STM imaging, we find high thermal stability of the Ag-bis-acetylide wires, without conversion into graphdiyne chains. Our approach based on orthogonal bifunctionalization and selective functional group recognition extends the toolbox of creating alkyne-based nanostructures at interfaces.
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