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7,7,8,8‐Tetraaryl‐ o ‐quinodimethane Stabilized by Dibenzo Annulation: A Helical π‐Electron System That Exhibits Electrochromic and Unique Chiroptical Properties
Author(s) -
Suzuki Takanori,
Sakano Yuto,
Iwai Tomohiro,
Iwashita Shinichi,
Miura Youhei,
Katoono Ryo,
Kawai Hidetoshi,
Fujiwara Kenshu,
Tsuji Yasushi,
Fukushima Takanori
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201203092
Subject(s) - dication , stacking , chemistry , intramolecular force , circular dichroism , crystallography , electrochromism , diastereomer , annulation , steric effects , chirality (physics) , photochemistry , electron transfer , piperidine , trimer , molecule , stereochemistry , dimer , organic chemistry , nambu–jona lasinio model , chiral symmetry breaking , physics , electrode , quantum mechanics , quark , catalysis
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.