Porphyrin picking-up substrate metal atoms: metalation of 2H-TPP on Fe and Ni

Here we demonstrate, using high-resolution x-ray spectroscopy and density functional theory calculations that by depositing a (sub)monolayer of more complex molecules, like 2H-TPP, on Fe(110) and Ni(111) surfaces at room temperature, the macrocycle binds directly to an ad-atom of the metallic substrate that metalates the porphyrin, forming Fe-TPP and Ni-TPP respectively. Using high-resolution x-ray spectroscopy and density functional theory calculations,we have shown that 2H-tetraphenyl-porphyrins metalate at room temperature by incorporating a surface metal atom when a (sub)monolayer is deposited on 3d magnetic substrates, like Fe(110) and Ni(111). For the most critical case, Ni(111), the calculations demonstrate that the redox metalation reaction would be exothermic with an energy gain of 0.89 eV upon embedding Ni adatom in the macrocycle.

 This attactive interaction with substrate atoms enables the formation of metallo-organic complexes simplifying the synthesis of the metalation process and certainly improving the interaction with the substrate. 

We believe that the described reaction should be relevant for chemisorption of different free-base macrocyclic molecules on other reactive surfaces.

The achievement of a complete metalation by Fe and Ni can be regarded as a test case for a successful preparation of spintronic devices by means of molecular based magnets (orgamometallic nanostructures) and inorganic magnetic substrates.

Room temperature metalation of 2H-TPP monolayer on Fe and Ni surfaces by picking-up substrate metal atoms

Andrea Goldoni, Carlo A. Pignedoli, Giovanni Di Santo, Carla Castellarin-Cudia, Elena Magnano, Federica Bondino, Alberto Verdini, Daniele Passerone

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