(189cd) Thermodynamic Stability of Thiolate-Protected Gold Nanoclusters: From Molecular to Metallic Systems

Thiolate-protected atomically-precise gold nanoclusters (NCs) have generated strong interest due to their nonlinear optical properties, making them great candidates for applications in catalysis, chemical sensing, and energy conversion. Many gold NCs of distinct sizes have been successfully synthesized experimentally, yet there is still a lack of understanding when it comes to their stability. Two main questions that arise are why only certain size and compositions of gold NCs are stable and what role the ligands play in their stability. A promising approach to answer these questions is the newly developed thermodynamic stability theory¹, which revealed a parity between core cohesive energy (CE) and shell-to-core binding energy (BE) for every experimentally synthesizable nanocluster. Herein we use Density Functional Theory calculations to demonstrate that the theory can be extended to larger NCs, namely Au₁₄₆(SR)₅₇ and Au₂₇₉(SR)₈₄. Of the two NCs, the latter is of significance due to its metallic properties, which indicates that the theory can accurately predict stability independent of molecular or metallic NC behavior. The two NCs have also been found to match stoichiometric predictions between number of core metal atoms and number of ligands, thus demonstrating that one can accurately predict the exact stoichiometry of experimentally accessible NCs. We additionally address the effect of the type of ligands on the CE and BE contributions and on the overall thermodynamic stability of the NCs.

1. Taylor, M. G.; Mpourmpakis, G., Thermodynamic stability of ligand-protected metal nanoclusters. Nat Commun 2017, 8, 15988.