Wydział Chemii

Rafał Zuzak

Arseni Borissov

Mads Engelund

Ewelina Janiga-Janocha

Marcin Stępień

Szymon Godlewski

2026

Angewandte Chemie - International Edition

65

e3729447/1-e3729447/11

10.1002/anie.3729447

Naukowa

Angielski

Artykuł

Surface-assisted reactions on nonmetallic substrates remain much less developed than their counterparts on metals, especially for heteroatom-doped precursors and intermolecular coupling processes. Here we show that TiO₂(110) can support not only cyclodehydrogenation of a nitrogen-rich nanographene precursor but also annulative intermolecular coupling on a semiconducting oxide surface. Under ultrahigh vacuum, hexapyrrolylbenzene (HPB) undergoes cyclodehydrogenation on rutile TiO₂(110) to give unsubstituted hexapyrrolohexaazacoronene (HPHAC, 1). Upon further annealing, 1 undergoes dehydrogenative dimerization to form a cyclooctatetraene-annulated HPHAC dimer (2), as supported by scanning tunneling microscopy and spectroscopy (STM/STS), density functional theory (DFT), and simulated STM images. The dimer, but not the monomer, undergoes single-electron transfer to the substrate to form [2]^•+, consistent with STM/STS observations, its lower ionization threshold, and computed frontier orbital energies. Gas-phase calculations are consistent with a plausible arenium-type pathway for annulative dimer formation and further indicate that oxidation increases global aromatic character across the fused framework.

azacoronene, cyclodehydrogenation, nanographene, on-surface synthesis, titanium dioxide

http://dx.doi.org/10.1002/anie.3729447

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