Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 40: Organic Molecules at Surfaces 4: Chemistry on Surfaces
O 40.1: Vortrag
Mittwoch, 7. September 2022, 10:30–10:45, S051
On-surface synthesis of planar π-extended cycloparaphenylenes featuring an all-armchair edge topology — Feifei Xiang1, Sven Maisel2, Sumit Beniwal1, Vladimir Akhmetov2,3, Cordula Ruppenstein3, Mirunalini Devarajulu1, Andreas Dörr1, Olena Papaianina3, Andreas Görling2, Konstantin Amsharov2,3, and •Sabine Maier1 — 1FAU Erlangen-Nürnberg, Dept. of Physik — 2FAU Erlangen-Nürnberg, Dept. of Chemistry and Pharmacy — 3Institute for Chemistry, University Halle-Wittenberg
[n]cycloparaphenylenes ([n]CPPs) have attracted significant attention due to their unique cyclic structure and highly effective para-conjugation leading to a myriad of fascinating (opto-)electronic properties. However, their strained topology prevents the π-extension of CPPs to convert them either into armchair nanobelts or planarized CPP macrocycles. We have successfully tackled this long-standing challenge and present the bottom-up synthesis and characterization of atomically precise in-plane π-extended [12]CPP on Au(111) by low-temperature scanning probe microscopy/spectroscopy combined with density functional theory.[1] The planar π-extended CPP represents the first nanographene with an all-armchair edge topology. The exclusive para-conjugation at the periphery yields delocalized electronic states and the planarization maximizes the overlap of p-orbitals, which both reduce the bandgap compared to conventional CPP. Calculations predict ring currents and global aromaticity in the doubly charged system.
[1] F. Xiang et al., Nat. Chem. 2022, doi: 10.1038/s41557-022-00968-3.