Uniform Gold Nanoclusters Supported on Mesoporous Polymer Beads Decorated with Polyaminophosphine Patches for the Catalytic Reduction of 4-Nitrophenol

Abstract

In the jigsaw puzzle of quality gold nanoclusters (AuNCs), those protected by weak ligands or coligands are still rarely available. Here, we provide an example in the case of supported AuNCs. Branched polyethylenimine (PEI, diameter of 1.86 nm) is introduced as discrete molecular patches onto the support of mesoporous polymer beads. Each patch is derived into polyaminophosphine with 2-(diphenylphosphino) benzaldehyde (dppb). The molecular patch is of nanoscale and uniform size. The polymer beads after PEI loading bear unimodal pores (3.9 nm), and the specific surface area is of 390 m2 g–1. AuNCs are obtained by mildly heating the mixture of the functionalized beads and aqueous chloroauric acids. Uniform AuNCs with a diameter of 1.2 ± 0.2 nm (∼53 Au atoms) are obtained when each PEI patch bears 17 dppb ligands, smaller than that of 3.5 nm in the absence of any dppb, suggesting that dppb enhances the nucleation of AuNCs. The heteroleptic AuNCs show ultrahigh catalytic performance (TOF = 391 h–1) for the reduction of 4-nitrophenol, where the dppb ligands hardly suppress the catalytic activity. The catalyst is well recoverable and durable for the reduction of 4-nitrophenol.