Synthesis and Characterization of Water Soluble Gold Nanoclusters of Varied Core Size

A series of water soluble gold nanoclusters of variable core size were prepared and characterized. The clusters were synthesized using a ligand substitution reaction between CH₃(OCH₂CH₂)₃SH and hexanethiol encapsulated gold nanoclusters, and characterized using NMR, FTIR, and UV/Vis spectroscopy, as well as TGA, DSC, and TEM. Conductivity values were obtained for the clusters and increased as expected along with the gold core size. The substitution reaction used in the synthesis was followed by ¹H NMR and found to produce only partial ligand substitution after 24 h, consistent with solubility observations and necessitating use of a two-step preparation scheme.