Structural reorganization of fullerene C70_{70} in N-methyl-2-pyrrolidone/toluene mixtures

The changes in the cluster state of fullerene C$_{70}$ dissolved in N-methyl-2-pyrrolidone/toluene mixture after toluene addition have been studied. In order to measure the wide range of particle sizes, including sub-single-molecule region and respectively large clusters, the Small-Angle X-ray Scattering, Dynamic Light Scattering were used. The main task was to find out correlation between the fullerene clusterization state and a volume concentration of the second nonpolar solvent. It was observed a common dependence of the structure state of fullerene C$_{70}$ on the polarity of the liquid medium; an increase in toluene content led to further dissolution of existing large agglomerates. The obtained data were analyzed in comparison with the previous results on the inverse colloidal system, C$_{70}$/toluene/N-methyl-2-pyrrolidone, and also with semi-empirical calculations, UV–vis spectroscopy measurements and experimental measurements on similar solutions based on fullerene C$_{60}$