Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 54: Organic Molecules on Inorganic Substrates III: Magnetism, Doping and Interfaces
O 54.2: Vortrag
Mittwoch, 3. April 2019, 10:45–11:00, H24
Aromaticity of Contracted Porphyrins: Surface Reactivity of an Adsorbed Corrole — •Jan Herritsch1, Jan-Niclas Luy1, Malte Zugermeier1, Falk Niefind1, Benedikt P. Klein1, Martin Schmid1, Peter Schweyen2, Martin Bröring2, Ralf Tonner1, and J. Michael Gottfried1 — 1Fachbereich Chemie, Philipps-Universität Marburg, Germany — 2Institut für Anorganische und Analytische Chemie, TU Braunschweig, Germany
Corroles belong to the family of cyclic tetrapyrroles. As such, they are related to the well-studied porphyrins, from which they differ by one missing methine bridge and a direct pyrrole-pyrrole link. Thus, they can be described as contracted porphyrins. This small structural difference results in substantial changes, in particular of the delocalized π-electron system. Here, we present a study of the on-surface dehydrogenation reaction of corroles. We have investigated monolayers of an octaalkyl-substituted free-base corrole on Ag(111) and Cu(111) surfaces. The adsorbed molecule contains one labile pyrrolic N-H bond, which dissociates already below 230 K on Ag(111). The barrier of this dehydrogenation was estimated by DFT calculations and is consistent with our experimental results. The valence electronic structure was further characterized by UPS and compared to DFT calculations. The dehydrogenated species, although formally a radical, has almost no remaining spin density in the adsorbed state. By applying the fundamental concepts of aromaticity and electron delocalization, this finding can be explained by charge transfer from the surface to the molecule, so that the aromatic 18π electron system is retained.