Angew Chem Int Ed - 2022 - Ong - Azulene‐Fused Acenes_removed.pdf
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KAUST DepartmentChemical Science Program
KAUST Catalysis Center (KCC)
Physical Science and Engineering (PSE) Division
Embargo End Date2023-07-13
Permanent link to this recordhttp://hdl.handle.net/10754/679673
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AbstractNon-alternant non-benzenoid π-conjugated polycyclic hydrocarbons (PHs) are expected to exhibit very different electronic properties from the all-benzenoid PHs. Herein, we report the synthesis and physical properties of three azulene-fused acene molecules ( 1 , 2 and 3 ), which are isoelectronic to the pentacene, hexacene and heptacene, respectively. X-ray crystallographic analysis, NMR spectra, and theoretical calculations reveal a localised aromatic backbone comprising of all the six- and five-membered rings while the seven-membered ring remains non-aromatic. They display properties of both azulene and acenes and are much more stable than the respective acenes. The dications of 1 , 2 and 3 were formed by chemical oxidation. Notably, 3 2+ exhibited an open-shell diradical character (y 0 = 30.2%) as confirmed by variable-temperature NMR and ESR measurements, which can be explained by recovery of aromaticity of an 2,6-anthraquinodimethane unit annulated with two aromatic tropylium rings.
CitationOng, A., Tao, T., Jiang, Q., Han, Y., Ou, Y., Huang, K.-W., & Chi, C. (2022). Azulene-Fused Acenes. Angewandte Chemie International Edition. Portico. https://doi.org/10.1002/anie.202209286
SponsorsThis work was supported by MOE Tier 1 grant (R-143-000-B62-114) and Tier2 grant (MOE-MOET2EP10120-0006). We also thank Ms. Tan Geok Kheng from National university of Singapore for the crystallographic analysis.
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