Study of self-aggregation and insertion into vesicular systems of amphiphilic C60 fullerene derivatives

Hydrophilic monoadducts of C60 fullerene have been the object of interest for their practical applications in the biological field1. Though the attachment of (only) a single hydrophylic addend promotes water solubility, these derivatives tend to form clusters2 in aqueous solutions or in organic/aqueous solvents rather than to dissolve as monomers. This communication presents a comparative study on the experimental conditions used for the formation of aggregates in aqueous solutions and in organic/aqueous mixtures of the following monoderivatives of fullero(C60)pyrrolidine, DF1 2-Acetyl-carnitine (5-(Fulleropyrrolidin-1-yl)-3-oxapentan-1-yl) Ester; DF2 1-{N,N-bis-[acetamido-N-(2,5,8-trioxadecane)]}amino,2-Fullero[2-(2,5,8-trioxanonanoyl)pyrrolidin-1-yl)]ethane. Aqueous solutions of aggregates can be prepared by following a suitably designed experimental protocol. Partition experiments between n-octanol and water have been used to evaluate the hydrophobic vs. hydrophilic components within the molecular structures and to compare the hydrofobicity of the two fullerene derivatives. The insertion of DF1, DF2 and the fullerene C60 into the bilayer of vesicles from cationic double-chained surfactants has been observed spectrophotometrically. The rates of breakdown of the above vescicles in the presence and in the absence of fullerenes, induced by addition of some single chained surfactants, have been compared.