Solution behaviour of C60 fullerene in N-Methylpyrrolidinone/toluene mixtures

The aggregation of C60 and C70 fullerenes in solution of some solvent mixtures was determined by the polarity of the medium. Solute-solute interactions were favored with respect to solute-solvent interactions, resulting in the fullerenes aggregation. It was observed that when added to fullerene solutions in toluene, the color of the solutions was observed to gradualy change with time from the typical violet toward yellow. It was found that a much larger number of interactions occured in solvent mixtures like toluene/NMP that were specifically NMP-toluene, fullerene-fullerene, NMP-fullerene and toluene-fullerene interactions.