Regensburg 2007 – scientific programme

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O: Fachverband Oberflächenphysik

O 26: Organic, Polymeric, and Biomolecular Films II

O 26.3: Talk

Tuesday, March 27, 2007, 11:45–12:00, H42

Surface-confined coordination chemistry with metalloporphyrins: In-situ metalation and axial coordination — •Ken Flechtner, Yun Bai, Sven Schöffel, Marie-Madeleine Walz, Liam Bradshaw, J. Michael Gottfried, and Hans-Peter Steinrück — Universität Erlangen-Nürnberg, Lehrstuhl für Physikalische Chemie II, Egerlandstr. 3, 91058 Erlangen, Germany

Metalloporphyrins represent the reactive centers in various biological and chemical systems, in which axial coordination of molecules on the central metal ion is essential for their specific functionalities as an enzyme, catalyst, or sensor. Here, we applied and extended concepts of solution-based coordination chemistry to surface reactions of metalloporphyrins adsorbed on an Ag(111) surface. Employing photoelectron spectroscopy and complementary techniques, we focused on: (A) Synthesis of adsorbed metalloporphyrins by direct metalation of porphyrin monolayers with iron, cobalt, and zinc. Also, we demonstrated that adsorbed porphyrins "pick up" pre-deposited Zn atoms from the Ag surface [1]. (B) The electronic interaction between porphyrin-coordinated metal ions and a metal surface in well-defined distances, which were adjusted with different spacer substituents. (C) Axial coordination of small molecules such as NO on the metal centers of the adsorbed porphyrins, resulting in competition between the newly formed coordinate bond and the bond between ion and surface (trans effect). Supported by the Deutsche Forschungsgemeinschaft through SFB 583.

[1] A. Kretschmann et al., Chem. Commun. 2007, DOI: 10.1039/b614427f.