Amphiphilic diblock dendrimers with a fullerene core.
Amphiphilic dendrimers with a C(60) core have been obtained by cyclization of dendritic 1,3-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 (1)H and (13)C NMR spectra. The hydrophobic-hydrophilic balance of these dendrimers has been systematically modified by changing the size of the polar headgroup in order to investigate the role of the amphiphilicity both at the air-water interface and during deposition onto solid substrates. Langmuir studies have revealed a conformational change in the dendritic structure with the size of the polar headgroup. Because of a better anchoring onto the water surface, the compounds with the largest polar headgroup 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 as deduced from their absorption spectra.
Zhang
Sheng
S
Groupe des Matériaux Organiques, Institut de Physique et Chimie des Matériaux de Strasbourg, Université Louis Pasteur et CNRS, UMR 7504, 23 rue du Loess, B.P. 43, 67034 Strasbourg Cedex 2, France.
Rio
Yannick
Y
Cardinali
François
F
Bourgogne
Cyril
C
Gallani
Jean-Louis
JL
Nierengarten
Jean-François
JF