Concerning metallic nanoparticles, their surface reactivity is studied and we can observe that the 4-(3-phenylpropyl) pyridine ligand is fixed to the metallic surface of ruthenium nanoparticles with bidentate coordination by π interaction of the two aromatic groups.
The catalytic reactivity of these nanoparticles was studied in hydrogenation reactions by DOSY NMR and NOE experiments. The intra- and inter- molecular NOE effects observed indicate the coordination of the substrate and the formed product after hydrogenation (Top. Catal. 2013, 56, 1253).
Modifications of stabilizers, especially ligands, during the synthesis of the metal nanoparticles (MNPs) could be demonstrated by analysis of the organic phases (GC, MS, NMR) as well as obtained PdNPs (IR, TEM, XRD, XPS). Thioether phosphines undergo changes by activation of Calkyle–S, C-aryle-S and Caryle-P bonds promoted by palladium clusters formed during the synthesis, leading to 30% degradation of the ligand (Dalton Trans. 2014, 43, 9038). This is mitigated by an ionic liquid medium (work done in collaboration with the team of E. Martin in Mexico).
The ongoing collaboration with Pr. G. Muller's team (University of Barcelona) allows us to have access to a wide range of P-chiral phosphine, with the ability to modulate. Recently, we have isolated Ru and Pd nanoparticles with homogeneous shape and size, wherein the ligands show a remarkable robustness without being modified after synthesis (according to the conventional bottom-up methodology by decomposition of molecular precursors). The small size of these nanoparticles allows us to follow their formation by NMR, taking advantage of insignificant the Knight shift of these metals. These results lead us to enantioselective catalysis applications, where NPs are still rarely used and the results are controversial.