Extending Chain Length of PNP Pincer Ligands Triggers Catalytic Activity of Gold-Copper Nanoclusters in Aerobic Oxidations.

Structural isomerism of organic ligand-protected atomically precise metal nanoclusters constitutes an ideal model for revealing the structure-activity relationship of nano-catalysts at the atomic level, while purposefully designing and synthesizing catalytically active metal nanocluster structural isomers remains a central challenge. Herein, we developed a generalizable strategy toward the construction of isomeric metal nanoclusters by varying the chain length of PNP pincer ligands. A pair of metal nanocluster structural isomers 2C-Au10Cu6 and 3C-Au10Cu6 has been successfully synthesized and crystallographically characterized. The structural isomerism phenomenon originating from one atomic Au/Cu shuttle in the kernel and the resulted surface ligand arrangement was uncovered at the atomic level based on their precise structures. The structural isomerism leads to the significantly different electron transfer and surface activation ability of 2C-Au10Cu6 and 3C-Au10Cu6, thus triggering the superior activity of 3C-Au10Cu6 in catalyzing aerobic oxidations. This work would be enlightening for precisely regulating the metal kernel and surface structures of metal nanoclusters for efficient catalysis, and also be inspiring for the rational design of metal nanocluster structural isomers.