Self-assembling of gold nanoparticles directed by fullerenes-based nodes
Résumé
Development of new catalysts to improve industrially important chemical reactions in terms of activity and selectivity, in environmentally more acceptable means and economical matter is one of the most important needs in research. Heterogeneous catalysis has shown its potential over the last years with the discovery of new catalysts easy to separate from the reaction medium. Today, nanoparticles, and particulary gold clusters, are considered as the most exciting materials in heterogeneous catalysis due to their high surface/volume ratio allowing for a high numbers of catalytically active sites. Nevertheless, the main problem associated with the use of nanoparticles-based catalysts is their dispersion. When particles form stable colloidal solution, they show good activity and dispersion, but once exhausted, they are difficult to regenerate. In contrast, when nanoparticles are immobilized on a support they are easier to regenerate and still remain in a dispersed state, but these composites exhibit a lower accessible surface area, due to the support, that thus limits their inherent effectivity and in general the support effect is not negligible. To overcome these limitations, we develop new nanostructured materials by using the concept of self-assembly of nanoparticles directed by organic linkers to generate multifunctional hybrid materials with a high number of catalytic centers. To connect gold nanoparticles and prevent their aggregation, we use functionalized hexa-adduct fullerenes as 3D rigid and defined nodes.[1,2] Our recent results show that thiocyanate-functionnalized hexaadduct fullerenes can be coupled by direct reaction from chlorauric acid and LiBH4 as a reducing agent and in the presence of 4-aminothiophenol. This new material has been characterized by small angles XR scattering, TEM and spectroscopy and show the formation of a network with monodisperse 2 nm gold particles and an interparticular distance of 4 nm corresponding to the functionalized fullerene molecules (figure 1). In this presentation we will also discuss the influence of the terminal functions of the hexaadduct fullerenes and the different synthetic pathways on the formation of the networks. 1)Fortgang, P.; Maisonhaute, E.; Amatore, C.; Delavaux-Nicot, B.; Lehl , J.; Nierengarten, J.-F. Angew. Chem. Int. Ed., 2011, 50, 2364. 2) Lehl, J.; Nierengarten, J.-F.; Harriman, A.; Bura, T.; Ziessel, R. J. Am. Chem. Soc., 2012, 134, 988.