Dresden 2014 – scientific programme
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O: Fachverband Oberflächenphysik
O 55: Focussed Session: Towards a Quantitative Understanding of Complex Adsorption Structures: Surface Science goes Organic I
O 55.9: Talk
Wednesday, April 2, 2014, 18:30–18:45, TRE Phy
Self-metalation of 2HTPP on Cu(111) studied with XSW: Influence of the central metal atom on the bonding distance — Christoph Bürker1, •Antoni Franco-Cañellas1, Katharina Broch1, Tien-Lin Lee2, Alexander Gerlach1, and Frank Schreiber1 — 1Institut für Angewandte Physik, Universität Tübingen, Tübingen, Germany — 2Diamond Light Source, UK
Recently, the self-metalation reaction of 2H-tetraphenylporphyrin (2HTPP) on Cu(111) to copper(II)-tetraphenylporphyrin (CuTPP) induced by annealing to 500 K was reported [1]. We present a systematic X-ray standing wave (XSW) study of both molecules, performed at the Diamond Light Source, to investigate the influence of the central metal atom on the adsorption geometry. The measured small bonding distance of both molecules on Cu(111) indicates strong interaction with the substrate [2]. Comparison between the average bonding distance of the carbon atoms and nitrogen atoms reveal a distorted molecule, as the nitrogen atoms adsorb at lower bonding distances. The two chemically equivalent types of nitrogen atoms (iminic and aminic) of 2HTPP exhibit a distorted porphyrin ring. After the chemical reaction to CuTPP no change of the bonding distance of the carbon skeleton is seen, but the entire molecule becomes flattened. The results are compared to a similar scenario for metal-free phthalocyanine H2Pc and copper-phthalocyanine (CuPc) [3].
[1] J. Xiao et al., J. Phys. Chem C 116 (2012), 12275.
[2] G. Heimel et al., Nature Chem. 5 (2013) 187.
[3] A. Gerlach et al., Phys. Rev. B 71 (2005), 205425.