Benchmark Models for Elucidating Ligand Effects: Thiols Ligated Isostructural Cu₆ Nanoclusters

Area of Science:

• Materials Science
• Nanotechnology
• Catalysis

Background:

• Atomically precise copper nanoclusters (Cu NCs) show great application potential but their growth mechanisms and properties are poorly understood.
• The role of ligands in Cu NCs is largely unexplored at the atomic level due to a lack of suitable models.
• Understanding ligand effects is crucial for designing efficient Cu NCs-based catalysts.

Purpose of the Study:

• To synthesize isostructural copper nanoclusters (Cu NCs) with varying mono-thiol ligands to investigate the intrinsic role of ligands.
• To elucidate the atom-by-atom structural evolution process of Cu NCs during synthesis.
• To explore how subtle atomic differences in ligands affect Cu NC properties and catalytic activity.

Main Methods:

• Synthesis of three isostructural Cu6 nanoclusters ligated with 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, and 2-mercaptobenzoxazole.
• Mass spectrometry (MS) to map the atom-by-atom structural evolution process.
• Ion-molecule reactions and density functional theory (DFT) calculations to investigate ligand defect contributions.

Main Results:

• Ligands with only atomic differences (NH, O, S) significantly influence the building-up processes, chemical properties, and atomic structures of Cu NCs.
• Catalytic activities of Cu NCs are profoundly affected by the choice of ligand.
• Defective sites on ligands were found to significantly contribute to the activation of molecular oxygen.

Conclusions:

• This study provides fundamental insights into the ligand effect on copper nanoclusters.
• Subtle atomic variations in ligands can be leveraged to tune Cu NC properties and catalytic performance.
• Defect engineering in ligands is a promising strategy for developing highly efficient Cu NC catalysts, particularly for oxygen activation.