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

Abstract

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

Introduction of Fullerenes into Hydrogels via Formation of Fullerene Nanoparticles

“…These results are in good agreement with the UV−vis spectra, in which the characteristic peak of solvated fullerene red shifts from 331 to 343 nm. The red shift of the peak at 331 nm usually indicates an increase in the size of the fullerene nanoparticles . Notably, the histogram of C 60 −gel ( 30 ) clearly shows the presence of small nanoparticles similar to those observed in C 60 −gel ( 10 ) (Figure f).…”

“…The average nanoparticle diameters are 26, 40, and 51 nm for reaction times of 30, 60, and 120 min, respectively. This indicates that the fullerene nanoparticles in the gel gradually grow by using C 60 molecules supplied by the C 60 −γ‐CD complex . The histograms of the diameters of the nanoparticles determined from the TEM images are shown in Figure e−h.…”

“…We recently reported that PEG accelerates decomposition of the fullerene−γ‐CD complex and formation of fullerene nanoparticles ,. Thus, we believe that gelatin polymer might also affect the stability of the fullerene−γ‐CD complex and induce fullerene nanoparticle formation (Figure ).…”

“…However, for growth of C 60 nanoparticles, the nucleation and growth processes are both very fast because of the very low solubility of C 60 in water . Therefore, the probabilities of formation of new nuclei and growth of seed crystals are the same, which supports formation of small fullerene nanoparticles during the fullerene transfer reaction.…”

Fullerene–porphyrin hybrid nanoparticles that generate activated oxygen by photoirradiation

“…11 In this method, C 60 -g-CD complexes can exist as stable isolated molecules in water, enabling the precise size control and step-wise growth of C 60 NPs. 12,13 Herein, the preparation of hybrid NPs comprising C 60 and hydrophobic porphyrin molecules are reported. C 60 -g-CD and porphyrin-trimethyl-b-cyclodextrin (por-TMe-b-CD) complexes are mixed in water in the presence of PEG.…”