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O: Fachverband Oberflächenphysik
O 7: Focus Session: Functional Molecules at Surfaces I
O 7.5: Vortrag
Montag, 16. März 2020, 11:45–12:00, TRE Ma
Selective on-surface synthesis of oxygen heterocycles on metals — •Andreas Doerr1, Nemanja Kocić1, Konstantin Amsharov2, and Sabine Maier1 — 1Department of Physics, Erwin-Rommel Straße 1, 91052 Erlangen — 2Institute for Chemistry, Kurt-Mothes-Straße 2, 06099 Halle (Saale)
Heterocycles with nitrogen, oxygen, or sulfur atoms are the basic units to incorporate chemical functionalization into carbon scaffolds. For oxygen-doped nanographenes, furan[1] and pyran - having five- and six-membered rings, respectively - are the most common ones. However, their on-surface synthesis via cyclomerization reactions remains elusive so far. Here we present a low-temperature scanning tunneling microscopy study to understand the on-surface synthesis of furan and pyran derivatives from ketone-functionalized precursors on metal surfaces. We use thermally induced CH-activation reactions to fuse two ketone-derivatives in either cis- and trans-configuration selectively. Finally, cyclomerization reactions towards furan and pyran moieties are observed after further annealing. These results are highly unexpected because ketone derivatives are mostly known to convert to cyclic trimers or tetramers in solution-based chemistry. On the surface, however, the strong interaction of the ketones with the metal surface opens up new reaction pathways.
References
[1] L. Liu, H. Klaasen, A. Timmer, H.Y. Gao, D. Barton. H. Mönig, J. Neugebauer, H. Fuchs, A. Studer: J. Am. Chem. Soc. 2018, 140, 18, 6000-6005