Dresden 2009 – scientific programme

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O: Fachverband Oberflächenphysik

O 52: Metal substrates: Adsorption of organic / bio molecules VII

O 52.6: Talk

Thursday, March 26, 2009, 16:15–16:30, SCH A118

Interaction between coordinated metal ions and a metal substrate: Differently substituted cobalt porphyrins on Ag(111) — •Yun Bai, Florian Buchner, Martin Schmid, Ina Kellner, Florian Vollnhals, Hubertus Marbach, Hans-Peter Steinrück, and J. Michael Gottfried — Universität Erlangen-Nürnberg, Lehrstuhl für Physikalische Chemie II, Egerlandstr. 3, 91058 Erlangen, Germany

Adsorbed metalloporphyrins are of increasing interest due to their potential applications in heterogeneous catalysis and in sensor systems. Previous studies from our group have suggested the existence of an electronic interaction between the metal centers of the adsorbed porphyrin complexes of iron and cobalt and the underlying substrate surface, which plays an important role in modifying the electronic structure and, thereby, the reactivity of these metal centers.[1,2] However, with the previously used tetraphenylporphyrin (TPP) ligands, the adsorbed complexes undergo saddle-shape distortion, which could also influence the electronic structure. To separate the effects of distortion on the one hand and the coupling to the substrate on the other, we have studied cobalt octaethylporphyrin, which adsorbs in a flat, undistorted conformation on Ag(111). Comparison of our XPS, UPS, and STM results with previous CoTPP data [1,2] confirms that indeed the metal center plays an essential role in the electronic interaction between the porphyrin complexes and the substrate. Supported by the DFG through SFB 583.

1. T. Lukasczyk et al., J. Phys. Chem. C 111 (2007) 3090.

2. K. Flechtner et al., J. Am. Chem. Soc. 129 (2007) 12110.