Insights into the Structural and Thermodynamic Properties of Fullerols [C60(OH)n, n = 12, 14, 16, 18, 20, 22, 24] in Aqueous Media

Abstract In recent years, fullerenes and their amphiphilic derivatives fullerols [C60(OH)n] have received considerable attention of researchers worldwide because of their unique structural and electronic properties that enables numerous industrial and medicinal applications. Because of surface hydroxylation in fullerols [C60(OH)n], one might expect a different behaviour of these hydrophobic-hydrophilic solutes in water. In the present study, we have performed classical molecular dynamics simulations of three different isomers of fullerols [C60(OH)n, where n = 12-24]. Hydration shells of water around these nanoparticles are characterized with the help of radial distribution functions (RDFs) and hydrogen bonding. RDFs indicate the presence of two hydration shells around the central solute molecule for all the isomers. Hydrogen bonding studies reveal that with uniform distribution of hydroxyl groups on fullerene cage, the average number of solute-solvent hydrogen bond increases with an increasing number of hydroxyl groups. The hydration free energy for the isomer with uniform distribution of hydroxyl group is found to be highly negative compared to all other isomers for all the fullerols, which suggests that the effect of surface hydroxylation is more dominant where the hydroxyl groups are uniformly distributed on the fullerene cage.