title: β,β-(1,4-Dithiino)subporphyrin Dimers Capturing Fullerenes with Large Association Constants.
abstract: β,β-(1,4-Dithiino)subporphyrin dimers 7-syn and 7-anti were synthesized by the nucleophilic aromatic substitution reaction of 2-bromo-3-(4-methoxyphenylsulfonyl)subporphyrin 4 with 2,3-dimercaptosubporphyrin 5 under basic conditions followed by axial arylation. Additions of C60 or C70 to a dilute solution of 7-anti (ca. 10(-6)  m) in toluene did not cause appreciable UV/Vis spectral changes, while similar additions to a concentrated solution (ca. 10(-3)  m) resulted in precipitation of complexes. In contrast, dimer 7-syn captured C60 and C70 in different complexation stoichiometries in toluene; a 1:1 manner and a 2:1 manner, respectively, with large association constants; Ka =(1.9±0.2)×10(6)  m(-1) for C60 @7-syn, and K1 =(1.6±0.5)×10(6) and K2 =(1.8±0.9)×10(5)  m(-1) for C70 @(7-syn)2 . These association constants are the largest for fullerenes-capture by bowl-shaped molecules reported so far. The structures of C60 @7-anti, C70 @7-anti, C60 @7-syn, and C70 @7-syn have been determined by single-crystal X-ray diffraction analysis.
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.
authors.forename: Kota
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan. osuka@kuchem.kyoto-u.ac.jp.
authors.forename: Atsuhiro
authors.initials: A
authors.lastname: Osuka
keywords: bowl-shaped molecules; dimers; fullerene; subporphyrins; supramolecular chemistry