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Large-Cavity Coronoids with Different Inner and Outer Edge Structures
journal contribution
posted on 2020-07-02, 20:29 authored by Marco Di Giovannantonio, Xuelin Yao, Kristjan Eimre, José I. Urgel, Pascal Ruffieux, Carlo A. Pignedoli, Klaus Müllen, Roman Fasel, Akimitsu NaritaCoronoids,
polycyclic aromatic hydrocarbons with geometrically
defined cavities, are promising model structures of porous graphene.
Here, we report the on-surface synthesis of C168 and C140 coronoids,
referred to as [6]- and [5]coronoid, respectively, using 5,9-dibromo-14-phenylbenzo[m]tetraphene as the precursor. These coronoids entail large
cavities (>1 nm) with inner zigzag edges, distinct from their outer
armchair edges. While [6]coronoid is planar, [5]coronoid is not. Low-temperature
scanning tunneling microscopy/spectroscopy and noncontact atomic force
microscopy unveil structural and electronic properties in accordance
with those obtained from density functional theory calculations. Detailed
analysis of ring current effects identifies the rings with the highest
aromaticity of these coronoids, whose pattern matches their Clar structure.
The pores of the obtained coronoids offer intriguing possibilities
of further functionalization toward advanced host–guest applications.