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International @ MATERIAUX+CLA:ATU:ADM; International audience; Recently, atomically well defined thiolate-capped gold nanoclusters (denoted Aun(SR)m with (10,10) < (n,m) < (333,79)) have been successfully isolated and few structures have been solved. Thus, these monodispersed functionalized clusters, with precise atomic positions and gold core less than 2 nm, hold promises as a new generation of catalysts. More importantly, these nanoclusters permit in-depth studies on the subtle correlation of the structure, core diameter, thiolate ligands effect and electronic state of gold nanoparticles with their catalytic activity. New clusters made of 4-aminothiophenol (HSPhNH2) have been isolated, such as Au25(SPhNH2)17, and fully characterized by mass spectrometry, X-ray diffraction and XPS.3 Moreover these clusters exhibit absorption bands related to their molecular state. Those clusters have then be used to investigate in aerobic oxidations reactions and compared to the Au25(SC2H4Ph)18 cluster, having the same Au core but different thiolate ligand. They have been deposited on silica supports (hydrophobic 16 nm-SiO2 nanoparticles and SBA-15 mesoporous silica) and by properly selecting the support to maximize clusters/support interactions, it was possible to prepare materials with ultra-small gold particles (

International @ MATERIAUX+GUR:CLA:ADM:SMR:JEC; International audience; 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.

International @ MATERIAUX+CLA:ATU:ADM; International audience; Gold nanoparticles exhibit a catalytic activity in many chemical processes.1 Most of the reactions are size-dependant, i. e. the specific activity depends on the average gold particle size. Generally, the activity increases when the particle size decreases, with a marked increase below 5 nm, which strongly supports the role of surface gold atoms in the reactions. But for sub-2 nm particles, the origin of the catalytic power is still unclear and under intense debate. Fundamental investigations on the structure-catalytic activity relationships still lag behind, partly due to the polydispersity issue of gold nanoparticles. Indeed, polydisperse particles obscure the interesting size-dependent catalytic activity of nanogold and preclude an in-depth understanding of the origin of this size dependence. Recently, atomically well defined thiolate-capped Au nanoclusters (denoted as Aun(SR)m) have been successfully isolated and their catalytic properties have been demonstrated.2 These monodispersed functionalized clusters, with gold core between less than 1 nm and more than 2 nm, hold promises as a new generation of catalysts. More importantly, these nanoclusters permit in-depth studies on the subtle correlation of structure and catalytic activity, since they are well defined and their crystallographic structures start to be solved.3 To investigate the influence of the size, the type of ligands at the surface and also the support effect, different nanoclusters have been synthesized. New clusters made of 4-aminothiophenol (HSPhNH2) have been synthesized, such as Au25(SPhNH2)17, and fully characterized by mass spectrometry, X-ray diffraction and XPS.4 Moreover these clusters exhibit absorption bands and paramagnetic behaviour related to their molecular state. Catalytic activity for oxidation of alkene and alcohol derivatives of these colloidal or supported clusters were investigated and compared to the commonly used Aun(SCH2CH2Ph)m nanoclusters. At the opposite of the bare gold nanoparticles, the presence of the ligands around the clusters leads to a much better selectivity of the product. (1) Hashmi, A. S. K.; Hutchings, G. J. Angew. Chem.-Int. Edit. 2006, 45, 7896. (2) Jin, R. C.; Zhu, Y.; Qian, H. Chem. Eur. J. 2011, 17, 6584. (3) Zhu, Y.; Qian, H. F.; Zhu, M. Z.; Jin, R. C. Adv. Mater. 2010, 22, 1915. (4) Lavenn, C.; Albrieux, F.; Bergeret, G.; Chiriac, R.; Delichčre, P.; Tuel, A.; Demessence, A. Nanoscale DOI: 10.1039/C2NR32367B.

National @ MATERIAUX+CLA:ADM:ATU; International audience; Gold nanoparticles exhibit catalytic activity in many chemical processes.1 However, fundamental investigations on the structure-catalytic activity relationships still lag behind, partly due to the polydispersity issue of gold nanoparticles. Indeed polydisperse particles obscure the interesting size-dependent catalytic activity of nanogold and preclude an in-depth understanding of the origin of this size dependence. Recently, atomically monodisperse, thiolate-capped Au nanoclusters (denoted as Aun(SR)m) have been successfully isolated and their catalytic properties have been demonstrated.2 These well-defined gold clusters hold promises as a new generation of catalysts and, more importantly, permit in-depth studies on the subtle correlation of structure and catalytic activity, since these nanoclusters are atomically well defined and some of their structures have been solved by single crystal X-ray diffraction.3 To investigate the influence of the size, the type of ligands at the surface and also the support effect, different nanoclusters have been synthesized. Here we present the synthesis of new clusters made of 4-aminothiophenol (HSPhNH2). Among them Au10(SPhNH2)9/10 and Au25(SPhNH2)17 have been isolated and fully characterized by mass spectrometry, X-ray diffraction and XPS.4 Moreover these clusters exhibit characteristic absorption behaviors related to their molecular state. Catalytic activity for oxidation of alkene derivatives of these colloidal or supported clusters were investigated and compared to commonly used Aun(SCH2CH2Ph)m nanoclusters or bared nanoparticles. (1) Hashmi, A. S. K.; Hutchings, G. J. Angew. Chem.-Int. Edit. 2006, 45, 7896. (2) Jin, R. C.; Zhu, Y.; Qian, H. Chem. Eur. J. 2011, 17, 6584. (3) Zhu, Y.; Qian, H. F.; Zhu, M. Z.; Jin, R. C. Adv. Mater. 2010, 22, 1915. (4) Lavenn, C.; Albrieux, Bergeret, G.; F.; Chiriac, R., Delichčre P.; Tuel, A.; Demessence, A. Nanoscale , 2012, 4, 7334.