Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 65: Poster: Molecular Nanostructures on Surfaces
O 65.1: Poster
Mittwoch, 20. März 2024, 18:00–20:00, Poster C
On surface synthesis of a Dicaesium Tetraphenylporphyrin Complex: A combined TPR, XPS, STM and DFT study — •Kassandra Zoltner, Leonard Neuhaus, Florian Münster, Lukas Heuplick, Jan Herritsch, and J. Michael Gottfried — Department of Chemistry, University of Marburg, 35043 Marburg, Germany
Tetrapyrroles such as porphyrins and their metal complexes exhibit interesting chemical and optoelectronic properties leading to numerous potential applications in photosensor technology and organic electronics. While the surface chemistry of transition metal-porphyrin complexes has been extensively studied, there is a growing interest in exploring complexes with alkali metals. This study focuses on the on-surface reaction of tetraphenylporphyrin (H2TPP) with caesium in the multilayer and monolayer regime on Ag(111). The reaction product was conclusively identified by temperature programed desorption mass spectrometry (TPD-MS) as Cs2TPP, where both aminic hydrogens were replaced by caesium ions. The data also indicate that Cs2TPP is thermally stable up to 700 K. Upon annealing up to 400 K the N1s X-ray photoelectron spectrum revealed a complete metalation to Cs2TPP in the monolayer, whereas in the multilayer a partial conversion is already observed at room temperature. DFT calculations indicate that Cs2TPP exhibits a bipyramidal structure with Cs ions on both sides of the molecular plane. The conducted study sheds light on the on-surface coordination chemistry of heavy alkali metal tetrapyrrole complexes potentially leading to further improvement and advancements in modern technologies.
Keywords: On-surface synthesis; Metalation reaction; TPD; XPS; Porphyrins