It is of common knowledge that fullerenes form colloids in polar solvents. However, the coagulation via electrolytes and the origin of the negative charge of species are still unexplored. Using a 'radical scavenger' and electrospray ionization spectroscopy (ESI), we proved the formation of ion-radical C60˙(-) and its (probable) transformation into C60(2-) or (C60)2(2-). The coagulation of C60 organosols by NaClO4 and other perchlorates and nitrates in acetonitrile and its mixture with benzene obeys the Schulze-Hardy rule. At higher Ca(ClO4)2 and La(ClO4)3 concentrations, instead of coagulation, stable re-charged colloidal particles appeared, up to a zeta-potential of +(20-42) mV, as compared with -(33-35) mV of the initial organosols. The influence of both HClO4 and CF3SO3H was similar. This phenomenon is attributed to poor solvation of inorganic cations in cationo- and protophobic acetonitrile, which was proven using [2.2.2] cryptand. Further increasing the concentration of Ca(ClO4)2 led again to coagulation, thus demonstrating a novel type of 'coagulation zones'.
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