On-surface synthesis and characterization of anti-aromatic cyclo[12]carbon and cyclo[20]carbon.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39223168.
- Also identified by DOI 10.1038/s41467-024-52115-w and PMC identifier 11369269.
- Licence recorded as CC BY-NC-ND.
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Abstract
Cyclo[n]carbons have recently attracted significant attention owing to their geometric and electronic structures remaining largely unexplored in the condensed phase. In this work, we focus on two anti-aromatic cyclocarbons, namely C<sub>12</sub> and C<sub>20</sub>. By designing two fully halogenated molecular precursors both including 4-numbered rings, we further extend the on-surface retro-Bergman ring-opening reaction, and successfully produce C<sub>12</sub> and C<sub>20</sub>. The polyynic structures of C<sub>12</sub> and C<sub>20</sub> are unambiguously revealed by bond-resolved atomic force microscopy. More importantly, subtly positioning the C<sub>20</sub> molecule into an atomic fence formed by Cl clusters allows us to experimentally probe its frontier molecular orbitals, yielding a transport gap of 3.8 eV measured from scanning tunneling spectroscopy. Our work may advance the field by easier synthesis of a series of cyclocarbons via on-surface retro-Bergman ring-opening strategy.