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Updated: Jun 9, 2025
Preparation and Characterization of C60/Graphene Hybrid Nanostructures
Published on: May 15, 2018
Dibenzo-peri-Heptacene: A Stable Open-Shell Graphene Fragment With a Balanced Combination of Armchair and Zigzag Edge
Qing Jiang1, Yi Han1, Shaofei Wu1
1Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore.
Abstract:
Atomically precise open-shell graphene fragments, such as extended peri-acenes, hold significant interest for electronics and spintronics. However, their inherent high reactivity poses challenges for synthesis and application. In this study, a novel approach is introduced: the fusion of a zigzag-edged peri-tetracene with an all-armchair-edged hexa-peri-hexabenzocoronene (HBC) via two shared benzene rings to produce a stable open-shell hydrocarbon, named dibenzo-peri-heptacene (DBPH). The DBPH derivative 1 exhibits considerably enhanced stability, with a half-life (t1/2) of 46 days in toluene solution under ambient conditions. This improved stability is attributed to peri-benzannulation, enhanced aromatic stabilization, and kinetic protection of the reactive sites along the zigzag edges. The structure of 1 is unequivocally verified through single-crystal X-ray diffraction analysis. With a balanced combination of armchair and zigzag edge structures, derivative 1 displays a diradical character of 39.2% and a singlet-triplet gap of ≈-3.16 kcal mol-1. It features a narrow electrochemical energy gap (0.87 eV) and exhibits amphoteric redox behavior. Notably, its dication and dianion states manifest a closed-shell singlet ground state, representing doubly charged structures where a HBC unit is fused with a benzo[f]tetraphene moiety. This research paves the way for synthesizing novel open-shell graphene fragments with adjustable electronic properties and exceptional stability.
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