Organotin chemistry for the preparation of fullerene-rich nanostructures
Résumé
Hexameric organostannoxane derivatives 3 and 4 have been prepared by treatment of 2-phenoxyacetic acid (1) and benzoic acid (2), respectively, with n-BuSn(O)OH. The drum-like structure of these compounds, made up of a prismatic Sn6O6 core, has been confirmed by 119Sn NMR spectroscopy and single-crystal X-ray diffraction analysis. The reaction conditions used for the preparation of 3 and 4 have been applied to dendritic branches with one, two or four methanofullerene subunits at the periphery and a carboxylic acid function at the focal point to produce fullerene-rich nanostructures with a stannoxane core in almost quantitative yields. These compounds have been characterized by 1H, 13C, and 119Sn NMR spectroscopy. Their electrochemical properties have been investigated by cyclic voltammetry. The central stannoxane cage has been shown not to affect the electrochemical properties of the assembled fullerenes. Indeed, each C60 moiety behaves independently, just like the parent fullerene compounds.