7,7,8,8-Tetraaryl-o-quinodimethane Stabilized by Dibenzo Annulation: A Helical π-Electron System That Exhibits Electrochromic and Unique Chiroptical Properties

Authors

  • Prof. Takanori Suzuki,

    Corresponding author
    1. Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810 (Japan), Fax: (+81) 11-706-2714
    • Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810 (Japan), Fax: (+81) 11-706-2714
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  • Yuto Sakano,

    1. Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810 (Japan), Fax: (+81) 11-706-2714
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  • Dr. Tomohiro Iwai,

    1. Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810 (Japan), Fax: (+81) 11-706-2714
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  • Dr. Shinichi Iwashita,

    1. Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810 (Japan), Fax: (+81) 11-706-2714
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  • Dr. Youhei Miura,

    1. Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810 (Japan), Fax: (+81) 11-706-2714
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  • Dr. Ryo Katoono,

    1. Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810 (Japan), Fax: (+81) 11-706-2714
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  • Prof. Hidetoshi Kawai,

    1. Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810 (Japan), Fax: (+81) 11-706-2714
    2. Present address: Department of Chemistry, Faculty of Science, Tokyo University of Science, 1–3 kagurazaka, Shinjuku-ku, Tokyo, 162-8601 (Japan)
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  • Prof. Kenshu Fujiwara,

    1. Department of Chemistry, Faculty of Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo, 060-0810 (Japan), Fax: (+81) 11-706-2714
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  • Prof. Yasushi Tsuji,

    1. Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510 (Japan)
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  • Prof. Takanori Fukushima

    1. Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8503 (Japan)
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Abstract

When two benzene rings are fused to a tetraaryl-o-quinodimethane skeleton, sterically hindered helical molecules 1 acquire a high thermodynamic stability. Because the tetraarylbutadiene subunit contains electron-donating alkoxy groups, 1 undergo reversible two-electron oxidation to 22+, which can be isolated as deeply colored stable salts. Intramolecular transfer of the point chirality (e.g., sec-butyl) on the aryl groups to helicity induces a diastereomeric preference in dications 2 b2+ and 2 c2+, which represents an efficient method for enhancing circular-dichroism signals. Thus, those redox pairs can serve as new electrochiroptical response systems. X-ray analysis of dication 22+ revealed π–π stacking interaction of the diarylmethylium moieties, which is also present in solution. The stacking geometry is the key contributor to the chirosolvatochromic response.

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