Regensburg 2022 – scientific programme

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O: Fachverband Oberflächenphysik

O 55: Poster Wednesday: Organic Molecules at Surfaces 2

O 55.13: Poster

Wednesday, September 7, 2022, 18:00–20:00, P4

On-Surface Transmetalation of a Lead-Porphyrin on the Cu(111) surface — •Jan Herritsch, Stefan R. Kachel, Qitang Fan, Mark Hutter, Lukas J. Heuplick, Florian Münster, and J. Michael Gottfried — Philipps-Universität Marburg

Starting from porphyrin complexes, highly ordered nanostructures can be assembled on surfaces in which reactive metal centers are firmly anchored in a defined environment. Such structures have enormous potential in various areas of modern technology. A reaction in which there is an exchange of the central atom by another element leads to a drastic change in the properties of the functionalized surface. Here, we report on a thermally induced Pb/Cu metal exchange of lead(II)-tetraphenylporphyrin (Pb(TPP)) on the Cu(111) surface. Using temperature-dependent XPS, we were able to track this exchange reaction and the accompanying change of the Pb oxidation state by probing the Pb 4f level. The reaction starts already below 380 K and is completed at 600 K. In parallel, partial desorption of a monolayer occurs above 430 K. In a temperature-programmed reaction experiment (TPR), the desorbing species are unambiguously identified as the product, Cu(TPP), of the metal exchange by mass spectrometry. By STM, the adsorbate structure of Pb(TPP) on Cu(111) were revealed and individual free Pb atoms, which are formed in the course of the Pb/Cu metal exchange, were observed. Moreover, side-reactions of the peripheral phenyl substituents occur due to dehydrogenative coupling reactions.