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O: Fachverband Oberflächenphysik

O 20: Focus Session: Molecular Nanostructures on Surfaces: On-Surface Synthesis and Single-Molecule Manipulation I

O 20.6: Vortrag

Dienstag, 19. März 2024, 12:00–12:15, HE 101

On-surface Synthesis of Nitrogen-Doped Carbon Nanostructures — •Tim Naumann¹, Zilin Ruan¹, Olaf Kleykamp¹, Alix Kaczmarek², Eugen Sharikow¹, Jörg Sundermeyer¹, Doreen Mollenhauer², and J. Michael Gottfried¹ — ¹Department of Chemistry, University of Marburg, 35043 Marburg, Germany — ²Department of Chemistry, University of Giessen, 35392 Giessen, Germany

The electronic and magnetic properties of carbon-based nanomaterials can be tailored by altering the topology, introducing defect sites like vacancies, or doping with heteroatoms. Here, we present an on-surface synthesis route to a variety of nitrogen-containing 0D and 1D carbon nanostructures starting from one single precursor. Annealing 4-([1,1'-biphenyl]-2-yl)-2,6-dibromopyridine on Au(111) leads to Ullmann-coupling of the precursor molecules followed by dehydrocyclization to yield cycloarenes with different cavity sizes as well as a nitrogen-doped gulf-edge graphene nanoribbon. Ring formation of six precursor molecules leads to a flat cycloarene, which can host a metal atom in its central cavity. Filling the cavity causes an energetic shift of the cycloarene's frontier orbitals. The direction of the shift depends on the metal used. A curved cycloarene emerges from a ring formed by five precursor molecules, whereas a higher surface coverage favors chain formation. The electronic and geometric properties of the products were investigated by low-temperature scanning tunneling microscopy/spectroscopy (STM/STS) and non-contact atomic force microscopy (nc-AFM).

Keywords: Carbon Nanostructures; Cycloarenes; On-surface Synthesis; Scanning Probe Microscopy; Ultra-high Vacuum