Regensburg 2007 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 31: New Materials

CPP 31.4: Talk

Friday, March 30, 2007, 11:15–11:30, H40

Near-edge x-ray absorption spectroscopy of metalloporphyrins and metalloporphyrin-fullerene dyads — •Norman Schmidt¹, Jörg Dannhäuser², Thomas Strunskus³, Andreas Hirsch², and Rainer Fink¹ — ¹Universität Erlangen. Physikalische Chemie II, Erlangen, Germany — ²Universität Erlangen, Organische Chemie II, Erlangen, Germany — ³Ruhr-Universität Bochum, Physikalische Chemie I, Bochum, Germany

Metalloporphyrins are well-known as electron donors in photoinduced electron transfer processes. [60]fullerene is an excellent electron acceptor, thus stabilizing radical ion-pair states in dyads of metalloporphyrins and fullerene. In these model systems for photosynthesis, the two chromophores are forced into a rigid stacking arrangement by covalent bonding and crystal packing, which leads to an interaction of the electron density of the central metal and the fullerene π-system on both sides of the porphyin plane. Also a weak back-bonding is found.

In the current study, the electronic structure of thick films of (Mn, Fe, Co, Zn, Sn)-porphyrins and (Mn, Fe, Co)-dyads on Au-plated Si was investigated with NEXAFS spectroscopy. The presented N1s spectra reflect the electronic interaction of the central metal ion with the esurrounding N atoms. Differences in the metal 2p-edge spectra between porphyrin and dyad arise mainly from electron density in the dz²-orbital (single occupation for Fe³⁺ and Co²⁺). The measured spectra will also be compared to DFT calculations. This work was funded by DFG (SFB 583).