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O: Fachverband Oberflächenphysik
O 20: Focus Session: Molecular Nanostructures on Surfaces: On-Surface Synthesis and Single-Molecule Manipulation I
O 20.3: Vortrag
Dienstag, 19. März 2024, 11:15–11:30, HE 101
On-Surface Synthesis and Characterization of Pentadecacene — •Zilin Ruan1, Tim Naumann1, Jakob Schramm2, John B. Bauer3, Holger F. Bettinger3, Ralf Tonner-Zech2, and J. Michael Gottfried1 — 1Department of Chemistry, University of Marburg, 35043 Marburg (Germany) — 2Wilhelm Ostwald Institute of Physical and Theoretical Chemistry, University of Leipzig, 04103 Leipzig (Germany) — 3Institute for Organic Chemistry, University of Tübingen, 72076 Tübingen (Germany)
Acenes represent a unique class of polycyclic aromatic hydrocarbons that have fascinated chemists and physicists due to their exceptional potential for use in organic electronic applications. Here, we demonstrate the on-surface synthesis of pentadecacene, the longest acene known to date and here reported for the first time, via atom-manipulation-induced dissociation of a trietheno-bridged precursor on a Au(111) surface under ultra-high vacuum conditions. The geometric and electronic structures of the generated acene have been investigated by combined scanning tunneling microscopy/spectroscopy and non-contact atomic force microscopy. We observed an antiferromagnetic open-shell ground state electron configuration for pentadecacene from a spin-excitation feature at low bias, giving a singlet-triplet gap of around 124 meV. Alternatively, upon a thermal cracking of the trietheno-bridges at higher temperature, pentadecacene can be also generated and spontaneously forms complex structure with up to 6 gold atoms on Au(111) surface, suggesting a considerable multiradical contribution to its electronic ground state.
Keywords: scanning tunneling microscopy; non-contact atomic force microscopy; single-molecule manipulation; acene; open-shell