Authors
Xuechao Li, Shiqi Wang, Pingo Mutombo, Chaojie Xu, Zhuoran Wang, Biao Yang, Qiang Chen, Haiming Zhang, Klaus Müllen, Pavel Jelínek, Lifeng Chi
Published in
Journal of the American Chemical Society. Nov 06, 2026. Epub Nov 06, 2026.
Abstract
On-surface synthesized nanographene and aromatic architectures featuring π-radicals have attracted widespread research interest in recent years. However, the role of delocalized π-electrons in governing the reactivity and regioselectivity of radical-involving reactions, such as cyclodehydrogenation, remains underexplored. In this manuscript, we investigated on-surface reactions of tricyclo(dimethoxy-vinyl-phenanthrene) on Au(111). Following multistep demethylation and cyclodehydrogenation, kekulene-hexaone (KeO) has been successfully synthesized. However, systematic scanning probe microscopy (SPM) and X-ray photoelectron spectroscopy (XPS) revealed an overlap between the thermal reaction windows of the initial demethylation and the first cyclodehydrogenation reactions at a remarkably low temperature of 423 K. Complementary quantum mechanics/molecular mechanics (QM/MM) simulations elucidated a π-radical-assisted mechanism for this low-temperature reaction sequence. The selective first cyclodehydrogenation can be triggered by spin density overlap between two neighboring delocalized π-radicals within a particular demethylated configuration. This configuration-dependent activation provides a fundamental atomistic basis for understanding regioselectivity in on-surface chemistry. Beyond the reaction mechanism, we demonstrated a frustrated assembly of KeO molecules which indicated a tautomerization (C═O⇌C-O·) of ortho-benzoquinone units driven by π-electron resonance. We believe this versatile electronic capability opens a novel avenue for engineering carbon-based quantum materials with exotic correlated electronic states.
PMID:
43002689
Bibliographic data and abstract were imported from PubMed on 10 Nov 2026.
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