On-Surface Synthesis of a π-Extended Diaza[8]circulene

K. Nakamura, Q.-Q. Li, O. Krejčí, A. S. Foster,* K. Sun, S. Kawai,* S. Ito*
J. Am. Chem. Soc. 2020, 142, 11363–11369. DOI: 10.1021/jacs.0c02534

Abstract: Heterocyclic [8]circulenes are an important class of polycyclic aromatic hydrocarbon molecules because of their unique structural properties and promising applications. However, synthesis of heterocyclic [8]circulenes is still limited and thus is an important synthetic challenge. Here we describe the first example of a π-extended diaza[8]circulene bearing six hexagons and two pentagons, which was successfully synthesized only by a combined in-solution and on-surface synthetic strategy. State-of-the-art scanning tunneling microscopy with a CO functionalized tip and density functional theory calculations revealed its planar confor-mation and a unique electronic structure.

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