Theoretical study on the effects of ligand on the ligand-protected gold nanoclusters.

Ligand-protected gold nanoclusters have emerged as important functional nanomaterials, yet the rational selection of optimal stabilizing ligands remains challenging. This study systematically investigates 11 representative ligands (thiolates, alkynyls, and phosphines) to establish fundamental design principles for gold cluster stabilization. Using density functional theory, we characterize their binding geometries with Au atoms/Au7 clusters, hydrogen dissociation energies, binding strengths, and electronic properties. Key findings reveal that linear thiolates (C12H26S and C6H13S) exhibit superior stabilization capability, combining high binding energies, large HOMO-LUMO gaps, and minimal steric hindrance. In contrast, alkynyls' strong binding is offset by high dehydrogenation barriers, while phosphines require auxiliary stabilizers due to weak interactions. The molecular origins of these differences are elucidated through electronic structure analysis. This work provides crucial insights into ligand-cluster interactions, offering a theoretical framework for designing stable, functional gold nanoclusters.