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 1-3 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 SbCl 5 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. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
|Original language||English (US)|
|Number of pages||9|
|Journal||Chemistry - A European Journal|
|State||Published - Nov 14 2011|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: J. W. acknowledges financial support from Singapore DSTA DIRP Project (DSTA-NUS-DIRP/2008/03), the NRF Competitive Research Program (R-143-000-360-281), and A*Star BMRC grant (No. 10/1/21/19/642). K.-W. H. acknowledges financial support from KAUST.
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