Non-reversible solvatochromism in N-methyl-2-pyrrolidone/toluene mixed solutions of fullerene C60

► Non-reversible solvatochromism from C60 fullerene in the binary solvent is observed. ► N-Methyl-2-pyrrolidone plus C60/toluene shows the classical solvatochromism. ► Toluene plus C60/N-methyl-2-pyrrolidone is characterized by a non-linear solvatochromism. ► Different solvent-solute interactions are responsible for observed solvatochromism. ► Age effect on UV-Vis spectra is concluded.