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Lateral Extension of π Conjugation along the Bay Regions of Bisanthene through a Diels–Alder Cycloaddition Reaction

Authors

  • Jinling Li,

    1. Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 (Singapore), Fax: (+65) 6779-1691
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  • Chongjun Jiao,

    1. Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 (Singapore), Fax: (+65) 6779-1691
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  • Prof. Kuo-Wei Huang,

    1. KAUST Catalysis Center and Division of Chemical and Life Sciences and Engineering, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900 (Kingdom of Saudi Arabia)
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  • Prof. Jishan Wu

    Corresponding author
    1. Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 (Singapore), Fax: (+65) 6779-1691
    • Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 (Singapore), Fax: (+65) 6779-1691
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Abstract

Diels–Alder cycloaddition reactions at the bay regions of bisanthene (1) with dienophiles such as 1,4-naphthoquinone have been investigated. The products were submitted to nucleophilic addition followed by reductive aromatization reactions to afford the laterally extended bisanthene derivatives 2 and 3. Attempted synthesis of a larger expanded bisanthene 4 revealed an unexpected hydrogenation reaction at the last reductive aromatization step. Unusual Michael addition was observed on quinone 14, which was obtained by Diels–Alder reaction between 1 and 1,4-anthraquinone. Compounds 13 exhibited near-infrared (NIR) absorption and emission with high-to-moderate fluorescent quantum yields. Their structures and absorption spectra were studied by density function theory and non-planar twisted structures were calculated for 2 and 3. All compounds showed amphoteric redox behavior with multiple oxidation/reduction waves. Oxidative titration with SbCl5 gave stable radical cations, and the process was followed by UV/Vis/NIR spectroscopic measurements. Their photostability was measured and correlated to their different geometries and electronic structures.

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