Interaction of Molecules in Solutions of C60 in Polar Solvents

The features of fullerene C60 in N-methyl-2-pyrrolidone (NMP) solutions and NMP/water solvents were studied using optical absorption spectroscopy, dynamic light scattering (DLS) and atomic force microscopy (AFM). When 30% distilled water was added to the C60/NMP solution, a bathochromic shift (by ~9 nm) and a hyperchromic effect for the characteristic absorption maximum (~331 nm) for the solution, as well as a relatively weak and broad new absorption region around 440 nm, were found. These optical changes are explained by the partial destruction of C60-C60 and C60-NMP complexes when water is added to the solution, and the formation of new C60-water complexes or mixed solvate shells of C60-NMP and C60-water during their reorganization. It was determined that at a constant concentration of C60 in solutions, the maximum hydrodynamic diameter of the synthesized fullerene nanoaggregates in a C60/NMP solution is ~23 nm, and in a C60/NMP/water solution is ~33 nm.