Clarifying Ligand Effects in Metal Nanocluster Catalysis by Theoretical Calculations and Single-Molecule Junctions

Investigating structure-property relationships remains a central focus in the study of metal nanoclusters. However, the widespread reliance on ensemble-level techniques for these molecule-like materials poses significant challenges to achieving a deep understanding. Herein, we employ single-molecule junction techniques combined with theoretical calculations to elucidate ligand effects in cluster catalysis. We examine isostructural Cu 25 clusters that share an identical metal core framework but differ in their surface ligands (thiolate versus selenolate). A pronounced difference in catalytic activity is observed for hydrogenation reactions: Cu 25 -Se exhibits high activity, whereas Cu 25 -S is nearly inactive. Theoretical calculations reveal that the substrate adsorption capability is strongly influenced by the surface ligands, which modulate the charge states of the surface metal centers. Single-molecule conductance measurements indicate that there is a significant difference in the charge transport efficiencies of the two clusters, which explains the observation for their divergent catalytic performances. This study not only elucidates the fundamental influence of ligands on cluster catalysis but, more importantly, establishes single-molecule conductance measurement as a strategy for probing structure-catalysis relationships in metal nanoclusters. Investigating the structure-property relationships of metal nanoclusters at the single-molecule level will offer crucial guidance for the design of nanocluster materials.