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

Stepwise growth of fullerene nanoparticles ( n C x ; 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 n C x in the presence of poly(ethylene glycol) (PEG) in water. Fullerenes expelled from the γ‐CD hosts by PEG were piled on the original n C x , resulting in growth of n C x . This process could be repeated and the size of n C x 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 C 60 /C 70 core/shell fullerene nanoparticles, which had the ability to photogenerate active oxygen, 1 O 2 .