AGGREGATION OF C-7O IN SOLVENT MIXTURES

The unusual solvatochromism of C-70 is investigated in a variety of so lvent mixtures by optical absorption and fluorescence techniques. Dist inct reversible color change from pink to purple is seen in the solven t mixtures studied. Such changes are seen also for C-60 solutions in s ome solvent mixtures. Formation of clusters is found to be responsible for the observed optical changes. Light scattering studies are carrie d out to confirm the presence of clusters which show that the particle size varies from similar to 100 to similar to 1000 nm depending on th e concentration of the fullerene. It is found that the solubility of t he fullerene in the solubilizing solvent and that in the solvent mixtu res are the major factors governing the aggregation behavior of the fu llerene. Polarity of the solvent plays a minor role in the formation o f aggregates.