Amphiphilic Fullerene-Cholesterol Derivatives: Synthesis and Preparation ofLangmuir andLangmuir-Blodgett Films

Amphiphilic fullerene bis-adducts 11 and 14 containing two and four cholesterol moieties, respectively, were prepared starting from the corresponding bis-malonate derivatives. In a systematic study, their spreading behavior at the air-water interface was compared to that of bis-adduct 6 with no polar head-group. Compared to 6, for which some three-dimensional aggregation occurs, the polar head-group in 11 and 14 is responsible for an attractive interaction with the aqueous subphase, forcing the molecules towards the water surface into a two-dimensional arrangement. Even if homogeneous Langmuir films were obtained with both 11 and 14, only the films of 14 show a reversible compression/expansion behavior. This suggests that, by increasing the number of cholesterol subunits, the encapsulation of the C-sphere in its addend is more efficient, thus preventing fullerene-fullerene interactions and aggregation phenomena. The Langmuir films of 11 and 14 were also efficiently transferred onto hydrophilic quartz slides, yielding Langmuir-Blodgett films.