Design of new N,O hybrid pyrazole derived ligands and their use as stabilizers for the synthesis of Pd nanoparticles.

We describe the stabilization studies of new palladium nanoparticles (Pd NPs) with a family of hybrid ligands. For this purpose, two new N,O-hybrid pyrazole derived ligands, as well as other previously reported, have been used as NP stabilizing agents following an organometallic approach. A comparison with corresponding palladium complexes has been carried out. We have also studied the superstructures formed by the agglomeration of NPs. To evaluate the scope of the system, different parameters have been studied such as the structure of the ligand, the ligand/metal ratio, the nature of the solvent, the concentration and the reaction time. The colloidal materials resulting from the different syntheses were all characterized by IR, transmission electron microscopy techniques at low or high resolution (TEM and HR-TEM), and scanning electron microscopy (SEM-FEG). All these observations have allowed us to better understand the coordination modes of the different ligands onto the surface of the NPs.