Theoretical calculations of the structure and UV-vis absorption spectra of hydrated C60 fullerene

A combined Monte Carlo simulation with semiempirical quantum mechanics calculations has been performed to investigate the structure of hydrated fullerene (C₆₀HyFn) and the influence of hydration on its UV-vis spectra. The statistical information of the C₆₀ fullerene aqueous solution (C₆₀FAS) is obtained from NPT ensemble including one C₆₀ fullerene immerses in 898 water molecules. To obtain an efficient ensemble average, the auto-correlation function of the energy has been calculated. The analyzed center-of-mass pair-wise radial distribution function indicates that, on average, there are 65 and 151 water molecules around the first and second hydration shells, respectively, of a single C₆₀ molecule. To calculate the average UV-vis transition energies of C₆₀HyFn, only the statistically uncorrelated configurations are used in the quantum mechanical calculations (INDO/CIS). These involve hundreds of supramolecular structures containing one C₆₀ fullerene surrounded by the first hydration shell. The calculated average transitions at 268 and 350 nm are in very good agreement with the experimental prediction.