Understanding the Solubility Behavior of Atomically Precise Gold Nanoclusters

Over the last two decades, ligand-protected gold nanoclusters (Au NCs) have experienced continued interest because of their controlled synthesis with atomic precision and unique, tunable properties. Despite the success in the synthesis of a series of Au NCs, their solubility behavior as a function of size, shape, and type of ligands on their surface is not well understood. Herein, we use density functional theory calculations to systematically investigate key physicochemical properties that affect Au NC solubility in organic media. We focus on 10 experimentally determined NCs ranging from 21 to 133 Au atoms, exhibiting various shapes and stabilized by five different aprotic thiolate ligands. Our results reveal that the NC symmetry (shape) and charge state dictate the NC dipole moment and polarizability, which in turn regulate the overall solubility behavior. Our computational results are in excellent agreement with experimental observations rationalizing solubility trends across a wide range of NC sizes. Furthermore, we demonstrate how our methodology can elucidate the atypical solubility behavior of specific Au NCs, such as Au 30 (S-Adm) 18 .