abstract

• We have performed semi-empirical as well as density functional theory calculations in order to analyse the hydration properties of both bare C 60 and highly hydroxylated C60(OH)26 fullerenes. In all of our calculations, a total of 42 and 98 water molecules are always surrounding our here-considered carbon nanostructures. We found different wetting properties as a function of the chemical composition and structure of the OH-molecular over-layer covering the fullerene surface. In the case of bare C60, water adsorption reveals that the H2O species are not uniformly arranged around the carbon network but rather forms water droplets of different sizes, clearly revealing the hydrophobic nature of the C60 structure. In contrast, in the polyhydroxylated C 60(OH)26 fullerenes, the degree of wetting is strongly influenced by the precise location of the hydroxyl groups. We found that different adsorbed configurations for the OH-molecular coating can lead to the formation of partially hydrated or completely covered C60(OH) 26 compounds, a result that could be used to synthesize fullerene materials with different degrees of wettability. By comparing the relative stability of our hydroxylated structures in both bare and hydrated conditions we obtain that the energy ordering of the C60(OH)26 isomers can change in the presence of water. The radial distribution function of our hydrated fullerenes reveals that water near these kinds of surfaces is densely packed. In fact, by counting the number of H2O molecules which are adsorbed, by means of hydrogen bonds, to the surface of our more stable C 60(OH)26 isomer, we found that it varies in the range of 5-10, in good agreement with experiments. Finally, by comparing the calculated optical absorption spectra of various C60(OH)26 structures in the presence and absence of water molecules, we note that only slight variations in the position and intensity of the electronic excitations are found, indicating that their vacuum optical properties are more or less preserved in aqueous environments. © 2011 IOP Publishing Ltd.

authors

• Barajas-Barraza R.E.
• Guirado López Ricardo Alberto
• Padilla-Osuna I.
• Rodríguez-Zavala J.G.

publication date

• 2011-01-01

published in

• Journal of Physics B: Atomic, Molecular and Optical Physics  Journal

keywords

• Aqueous environment; Carbon Nanostructures; Carbon network; Chemical compositions; Density functional theory calculations; Different sizes; Electronic excitation; Energy orderings; Fullerene surfaces; Hydration properties; Hydrophobic nature; Hydroxyl groups; Presence of water; Radial distribution functions; Relative stabilities; Semi-empirical; Water adsorption; Water droplets; Water molecule; Wetting property; Adsorption; Density functional theory; Distribution functions; Electromagnetic wave absorption; Fluidized beds; Hydration; Hydrogen bonds; Hydroxylation; Isomers; Lead compounds; Molecules; Optical properties; Surfaces; Water absorption; Wetting; Fullerenes

Digital Object Identifier (DOI)

• 10.1088/0953-4075/44/20/205104

start page

end page

volume

• 44

issue

• 20