In-situ metalation of Tetraphenylporphyrin

In-situ metalation of porphyrin is of great interest for the characterization of pure species in a controlled environment. We have followed the formation of pure 2H-TPP and Fe-TPP layers on Ag(111) single crystal. Core level absorption spectra indicate the flat conformation. Photoemission points out that the interaction between Fe d_z-states and Ag bands increases the monolayer metallic character already induced by the charge transfer from the substrate.

G. Di Santo et al., J. Phys. Chem. C 115, 4155 (2011)

In this experiment we characterized the electronic states and the molecules' geometrical adaptation during the formation of pure 2H-5,10,15,20-tetraphenylporphyrin (2H-TPP) and Fe- tetraphenylporphyrin (Fe-TPP) layers on Ag(111) single crystal. Core level absorption spectra indicate the flat conformation of the monolayer suggesting an adatom hopping instead of a surface mediated dopant diffusion for the metalation process. Photoemission points out that the interaction between Fe dz-states and Ag bands increases the monolayer metallic character already induced by the charge transfer from the substrate.

The NEXAFS spectra, taken in s and p light polarization at N and C K-edges, put in evidence the flat configuration for the macrocycle and showed that the phenyl groups lie flat in the case of the monolayer while having nonflat orientation in the multilayer. The multilayer Fe metalation favors a macrocycle N distortion, while in the monolayer, the conformation of the phenyl legs and the interaction with the substrate reduce the degrees of freedom of the macrocycle toward the already reached lowest energy situation.     The influence of the Fe metallic center in the porphyrin core has only minor structural effects in the monolayer. Both core level and valence band photoemission results give evidence that the charge injection from the substrate is more likely confined to the first monolayer. The metallic state of the first layer evolves with Fe complexation because of d state hybridization with the s−p bands of the substrate.

Retrieve article Conformational Adaptation and Electronic Structure of 2H-Tetraphenylporphyrin on Ag(111) during Fe Metalation G. Di Santo, C. Castellarin-Cudia, M. Fanetti, B. Taleatu, P. Borghetti, L. Sangaletti, L. Floreano, E. Magnano, F. Bondino, and A. Goldoni J. Phys. Chem. C, 2011, 115 (10), pp 4155–4162 DOI: 10.1021/jp111151n Publication Date (Web): February 22, 2011 Copyright © 2011 American Chemical Society