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A Novel [60]Fullerene‐Calixarene Conjugate Which Facilitates Self‐Inclusion of the [60]Fullerene Moiety into the Homooxacalix[3]arene Cavity
Author(s) -
Ikeda Atsushi,
Nobukuni Shigeki,
Udzu Hiromi,
Zhong Zhenlin,
Shinkai Seiji
Publication year - 2000
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200010)2000:19<3287::aid-ejoc3287>3.0.co;2-r
Subject(s) - moiety , chemistry , calixarene , conformational isomerism , fullerene , intramolecular force , nuclear magnetic resonance spectroscopy , stereochemistry , photochemistry , crystallography , molecule , organic chemistry
A novel calixfullerene 1 , in which a homooxacalix[3]arene moiety conjugates with a [60]fullerene moiety through a triethylene glycol chain, exhibits interesting self‐complexation−decomplexation properties in response to the solvent polarity. In CDCl 3 , 1 exists predominantly as conformer I with a free [60]fullerene moiety and the open calixarene cavity. In CHCl 3 /CH 3 CN (1:1, v/v), however, 1 exists predominantly as the self‐inclusion conformer II with the [60]fullerene moiety capped by the intramolecular calixarene moiety. This is a unimolecular event but not an aggregate formation event because the concentration effect on the stoichiometry in the 1 H NMR spectroscopy and molecular weight determination in vapor pressure osmometry are all commensurate with a unimolecular process. The complexation−decomplexation exchange rate is slower than the NMR time scale, which has enabled us to estimate the equilibrium constant [conformer II/conformer I = 0.72 in CHCl 3 /CH 3 CN (24:1, v/v) at 27 °C].