Size Matters: Influence of Gold‐to‐Ligand Ratio and Sulfur‐Sulfur Distance of Linear Thioether Heptamers on the Size of Gold Nanoparticles

A systematic investigation of two parameters steering the size of linear octadentate heptamer‐coated gold nanoparticles (Au NP s) is presented, being i ) the chemical structure (sulfur‐sulfur distance) of the coating thioether heptamer ligand and ii ) the ratio of ligand to tetrachloroauric acid ( HA uCl 4 ) reduced during the formation of the Au NP s. For this purpose, a novel terphenyl‐based thioether heptamer ( Ter ) is synthesized via an end‐capping oligomerization strategy, comprising an increased distance between neighboring sulfur atoms in the ligand backbone compared to the meta ‐xylene‐ ( Xyl ) and tetraphenylmethane‐ ( TPM ) based heptamers. While for both investigated parameters a clear trend to various‐sized NP s is shown, a stronger influence in the resulting sizes is observed by alteration of ligand to gold‐ratio. Remarkable processability‐ and long‐term stability‐features were observed for Au NP s stabilized by the bulky tetraphenylmethane‐based heptamer ( TPM ).