Organotin chemistry for the preparation of fullerene-rich nanostructures
ABSTRACT 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.
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ABSTRACT: C60 derivatives bearing either terminal alkyne or azide functional groups have been prepared and used as building blocks under the copper mediated Huisgen 1,3-dipolar cycloaddition conditions. In general, the reactivity of C60 toward azides does not significantly compete with the cycloaddition leading to the desired 1,2,3-triazole derivatives and good yields can be obtained when fullerene derivatives with reasonable solubility are used as starting materials. The electrochemical properties of the new fullerene derivatives have also been investigated by cyclic voltammetry (CV) and Osteryoung Square Wave Voltammetry (OSWV).Tetrahedron 12/2008; 64(50):11409-11419. DOI:10.1016/j.tet.2008.09.047 · 2.82 Impact Factor
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ABSTRACT: Owing to their peculiar electronic properties, fullerene derivatives are attractive building blocks for dendrimer chemistry. Whereas, for the main part, the fullerene-containing dendrimers reported so far have been prepared with a C(60) core, dendritic structures with fullerene units at their surface or with C(60) spheres in the dendritic branches have been more scarcely considered. This is mainly associated with the difficulties related to the synthesis of fullerene-rich molecules. In this review, the most recent developments on the molecular engineering of fullerene-rich dendrons and dendrimers are presented to illustrate the current state-of-the-art of fullerene chemistry for the preparation of new dendritic materials.Australian Journal of Chemistry 01/2009; 62(7). DOI:10.1071/CH09163 · 1.64 Impact Factor
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ABSTRACT: Dendrimers containing up to 16 fullerene peripheral subunits have been prepared by a divergent synthetic approach based on the functionalization of polypropyleneimine (PPI) dendrimers with a C60 derivative bearing an activated carboxylic acid function. The absorption and fluorescence properties of these compounds are substantially identical in toluene and benzonitrile. Enhanced absorption in the region between 350 and 500 nm is detected by increasing the generation number, attributable to intramolecular interactions. A size-dependent trend of decreasing singlet lifetimes (−16%) and fluorescence quantum yields (−18%) is observed. The fullerene triplet state of the dendrimers was monitored via laser flash-photolysis in toluene and benzonitrile. In both media the transient absorption signal intensity is decreased with the molecular size and the effect is more pronounced in oxygen-free solution (−60%) compared to air-equilibrated samples (−37%). In toluene the triplet decay kinetics is unchanged for the whole series, ruling out the possibility of self-quenching effects, whereas in benzonitrile a triplet lifetime increase is recorded as a consequence of fullerene self-protection towards oxygen quenching. No amine→fullerene photoinduced electron transfer is detected because the complex molecular architecture does not allow the establishment of favourable donor–acceptor distances.New Journal of Chemistry 02/2009; 33(2):337-344. DOI:10.1039/B816336G · 3.16 Impact Factor