SYNTHESIS OF AMPHIPHILIC FULLERODENDRIMERS AND THEIR INCORPORATION IN LANGMUIR AND LANGMUIR-BLODGETT FILMS

摘要

Amphiphilic dendrimers with a C_(60) core have been obtained by cyclization of dendritic l,3-phenylenebis(methylene)-tethered bis-malonate derivatives at the carbon sphere. The relative position of the two cyclopropane rings in the resulting bis-methanofullerene derivatives has been determined based on the molecular symmetry (C_s) deduced from the ~1H- and ~(13)C-NMR spectra. The hydrophobic/hydrophilic balance of these dendrimers has been systematically modified by changing the size of the polar head-group in order to investigate the role of the amphiphilicity at the air-water interface and during the deposition onto solid substrates. The Langmuir studies have revealed a conformational change in the dendritic structure with the size of the polar-head group. Due to a better anchoring onto the water surface, the compounds with the largest polar-head group adopt a more compact structure and the dendritic branches are forced to wrap the fullerene core. This model is nicely confirmed by the amount of fullerene-fullerene interactions within the Langmuir-Blodgett films deduced from their absorption spectra.