Ligand effects on gold-copper nanorod catalyzed aqueous organic reactions.
by Jenkins, Samir V.; Chen, Jingyi; Chen, Shutang
Among the principles of green chem. synthesis are the use of non-harzardous solvents, atom economy, and catalysis. Due to their high surface area-vol. ratio and the relative ease with which they can be recovered, nanoparticles are an attractive option for aq. catalysis of org. reactions. Morphol. control of metal nanoparticles often involves the use of surface ligands, which in turn affect the catalytic activity of nanocatalysts. The surface anchoring group, chain length, and configuration of the water-sol., polymeric ligands influence the catalytic properties of alloyed AuCu3 nanorods for metal-catalyzed org. reactions. Due to the binding affinity of the surface-anchoring groups, a thiol anchor was found to be detrimental the Au-catalyzed redn. of p-nitrophenol while the Cu-catalyzed azide-alkyne cycloaddn. was severely inhibited by amine anchors. Furthermore, the catalytic activity of nanorods increased with increased dimension of the ligands with the same anchoring group due to the redn. of graft d. Elevated temp. facilitates the mobility of surface ligands in benzonitrile hydration to benzamide, resulting in the enhancement of catalytic activity. This work highlights the paramount importance of surface ligand selection in the design of nanocatalysts for catalytic org. reactions.