Stepwise Growth of Fullerene Nanoparticles through Guest Exchange of γ-Cyclodextrin Complexes in Water.

Stepwise growth of fullerene nanoparticles (nCx ; x=60 or 70) was performed through guest exchange of a γ-cyclodextrin (γ-CD) complex. Fullerenes bicapped by γ-CD were mixed with presynthesized nCx in the presence of poly(ethylene glycol) (PEG) in water. Fullerenes expelled from the γ-CD hosts by PEG were piled on the original nCx , resulting in growth of nCx . This process could be repeated and the size of nCx increased according to the number of growth steps. The growth of fullerene nanoparticles was confirmed by UV/Vis absorption spectroscopy, dynamic light scattering measurements, and TEM observations. The stepwise growth method also enabled the preparation of C60 /C70 core/shell fullerene nanoparticles, which had the ability to photogenerate active oxygen, 1 O2 .