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Synthesis and Stability of N,N′-Dialkyl-1,13-dimethoxyquinacridinium (DMQA+): A [4]Helicene with Multiple Redox States

Authors

  • Dr. Thomas Just Sørensen,

    1. Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø (Denmark), Fax: (+45) 35-32-02-14
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  • Dr. Merete F. Nielsen,

    1. Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø (Denmark), Fax: (+45) 35-32-02-14
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  • Dr. Prof. Bo W. Laursen

    Corresponding author
    1. Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø (Denmark), Fax: (+45) 35-32-02-14
    • Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø (Denmark), Fax: (+45) 35-32-02-14

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Abstract

N,N′-Dialkyl-1,13-dimethoxyquinacridinium (DMQA+) is a configurationally locked [4]helicene, a stable carbenium ion and a potent near-infrared emitter. The versatile synthesis and resolution into M and P enantiomers has made DMQA+ and its congener helicenium derivatives attractive chiral dyes and building blocks. In the present study, electrochemical and spectroscopic studies showed that several redox states of DMQA+ are accessible and stable. The cation stability towards nucleophiles is determined and it is shown that the addition of OH proceeds with a surprisingly low rate of reaction. The synthetic methodologies leading to DMQA+ are described, and the chemistry occurring from the different redox states of DMQA is identified. This [4]helicene is shown to be a unique molecular framework that is stable as a neutral radical and very stable as a carbenium ion.

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