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 Yuto Sakano Dr Tomohiro Iwai Dr Shinichi Iwashita Dr Youhei Miura Dr Ryo Katoono Prof Hidetoshi Kawai Prof Kenshu Fujiwara Prof Yasushi Tsuji Prof Takanori Fukushima |
| |
| Institution: | 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);3. Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615‐8510 (Japan);4. Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori‐ku, Yokohama, 226‐8503 (Japan) |
| |
| 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 2 2+, 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 b 2+ and 2 c 2+, 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 2 2+ 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. |
| |
| Keywords: | chirality circular dichroism electrochromism helical structures redox chemistry |
|
|
