Ligand-Conformation Energy Landscape of Thiolate-Protected Gold Nanoclusters

Although several thiolate-protected Au nanoclusters have yielded to total-structure determination, the ligand-conformation energy landscapes and how they affect the relative stability of the whole clusters are not well understood. In this work, we employ a force-field-based approach to perform the ligand-conformation search for isolated thiolate-protected Au nanoclusters using Au-25(SR)(18) (R = C2H4Ph) as an example. We find that the ligand-conformation energy landscape of Au-25(SC2H4Ph)(18) comprises multiple low-energy funnels of similar stability instead of a single global minimum. In fact, we find slightly more stable conformations of isolated Au-25(SC2H4Ph)(18) than those observed in the experiment from a crystalline state, indicating that specific environments such as crystal packing and solvents may all affect the ligand conformation. This work reveals the role of ligand conformation in the cluster energy landscape.