Gold-copper alloyed nanorods for metal-catalyzed organic reactions: implication of surface ligands on nanoparticle-based heterogeneous catalysis

Recent advances in nanoparticle synthesis have created new potential avenues for aqueous catalysis of organic reactions. Morphological control of metal nanoparticles often involves the use of surface ligands, which in turn affect the catalytic activity of nanocatalysts. This Letter demonstrates that surface anchoring group, chain length, and configuration of the water-soluble, polymeric ligands influence the catalytic properties of alloyed AuCu3 nanorods for metal-catalyzed organic reactions. Due to the binding affinity of the surface-anchoring groups, a thiol anchor was found to be detrimental the Au-catalyzed reduction of p-nitrophenol while the Cu-catalyzed azide-alkyne cycloaddition 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 reduction of graft density. Elevated temperature 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 organic reactions. (C) 2015 Elsevier Ltd. All rights reserved.