A novel calixfullerene 1, in which a homooxacalixarene moiety conjugates with a fullerene moiety through a triethylene glycol chain, exhibits interesting self-complexation-decomplexation properties in response to the solvent polarity. In CDCl3, 1 exists predominantly as conformer I with a free fullerene moiety and the open calixarene cavity. In CHCl3/CH3CN (1:1, v/v), however, 1 exists predominantly as the self-inclusion conformer II with the 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 CHCl3/CH3CN (24:1, v/v) at 27 °C].
|ジャーナル||European Journal of Organic Chemistry|
|出版ステータス||出版済み - 9 2000|
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