Reversible ligand exchange of triphenylphosphine with thiols on gold nanoparticles for Janus modification and catalyst recycling

作者：Li, Degui; Liu, Tong; Luo, Yujia; Zhuge, Xiangqun; Luo, Kun^*; Luo, Zhihong^*; Liu, Xiaoteng; Zhang, Kui^*

来源：SEPARATION AND PURIFICATION TECHNOLOGY, 2023, 322: 124154.

DOI：10.1016/j.seppur.2023.124154

• Gold nanoparticle
• Ligand exchange
• Janus modification
• Catalyst recycling
• Reduction of 4-nitrophenol

Separation and regeneration of ultrafine catalysts in reaction system still remain challenging. In this study, we demonstrate a simple route to recycle gold nanoparticle (Au NP) catalysts by alternating surface wettability. Hydrophilic Au NPs protected with 3-mercapto-1,2-propanediol (MPD) were applied to catalyze the reduction of 4-nitrophenol (4-NP) using sodium borohydride as reductant, and were then separated from the suspension by interfacial ligand exchange with a toluene solution containing triphenylphosphine (TPP), led to amphiphilic Janus Au NPs with both MPD and TPP ligands at the toluene-water interface. The catalyst was regenerated by a reversible ligand exchange with a MPD aqueous solution. Experiments show that interfacial ligand exchange between phosphines and thiols on gold surface is reversible, although the forward and backward rates are different. As a result, the Au NP catalyst capped with MPD exhibited an excellent catalytic activity with an apparent rate constant (k) of 2.79 min-1, and the performance could be maintained for more than 10 regener-ation cycles. The facile conversion between hydrophilic and amphiphilic Janus Au NPs provides a new pathway to explore monophasic and multiphasic reactions with convenient catalyst separation and regeneration.

• 单位
  常州大学; 桂林理工大学; 1; 浙江大学