Atomically Precise Preorganization of Open Metal Sites on Gold Nanoclusters with High Catalytic Performance

Gold nanoclusters with surface open sites are crucial for practical applications in catalysis. We have developed a surface geometric mismatch strategy by using mixed ligands of different type of hindrance. When bulky phosphine Ph3P and planar dipyridyl amine (Hdpa) are simultaneously used, steric repulsion between the ligands will reduce the ligand coverage of gold clusters. A well-defined access granted gold nanocluster [Au-23(Ph3P)(10)(dpa)(2)Cl](SO3CF3)(2) (Au-23, dpa=dipyridylamido) has been successfully synthesized. Single crystal structural determination reveals that Au-23 has eight uncoordinated gold atoms in the shape of a distorted bicapped triangular prism. The accessibility of the exposed Au atoms has been confirmed quantitatively by luminescent titration with 2-naphthalenethiol. This cluster has excellent performance toward selective oxidation of benzyl alcohol to benzaldehyde and demonstrates excellent stability due to the protection of negatively charged multidentate ligand dpa.

Automated summary

A gold nanocluster with well-defined access has been successfully synthesized using a surface geometric mismatch strategy with mixed ligands. This cluster shows excellent performance in selective oxidation reactions and demonstrates good stability due to the protection of a negatively charged multidentate ligand.