Regensburg 2025 – scientific programme
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O: Fachverband Oberflächenphysik
O 62: Focus Session Molecular Nanostructures on Surfaces: On-Surface Synthesis and Single-Molecule Manipulation III
O 62.1: Talk
Wednesday, March 19, 2025, 10:30–10:45, H24
Selective On-Surface Synthesis of Isokekulene Facilitated by Strong Molecule-Substrate Interaction — Qitang Fan1, Alexander Reichmann2, Zilin Ruan1, Faming Kang1, Tim Naumann1, Simon Werner1, Olaf Kleykamp1, Jose Martinez3, Felix Lüpke3, François C. Bocquet3, Christian Kumpf3, Serguei Soubatch3, Jörg Sundermeyer1, Peter Puschnig2, F. Stefan Tautz3, J. Michael Gottfried1, and •Sabine Wenzel1,3 — 1Fachbereich Chemie, Philipps-Universität Marburg — 2Institute of Physics, University of Graz — 3Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich
The role of different facets of metal nanoparticles in steering reaction pathways is crucial for the design of heterogeneous catalysts with superior selectivity. Transition-metal-catalyzed C-H bond activation is widely used for the synthesis of different chemicals. Here, we report orthogonal selectivity in intramolecular cyclodehydrogenation of a nonplanar cyclic precursor steered by different facets of a copper single crystal. On Cu(110), the previously unknown cycloarene isokekulene is formed with a high selectivity of 92 %, while reaction on Cu(111) is known to result in kekulene (> 99 %). Combining scanning tunneling microscopy with CO-functionalized tips and density functional theory, we identify two adsorption geometries of the precursor which react to the respective products. The isokekulene molecule appears in two nonplanar adsorption configurations and shows a strong molecule-substrate interaction including charge transfer, which accounts for the more favorable energetics of isokekulene on Cu(110).
Keywords: on-surface synthesis; scanning tunneling microscopy; density functional theory; molecule-substrate interaction