The Effect of Ligand Denticity in Size-Selective Synthesis of Calix[n]arene-Stabilized Gold Nanoparticles: A Multitechnique Approach

A series of gold nanoparticles (AuNPs) stabilized by monodentate, bidentate, and tridentate thiolate calix[n]arene ligands 1-3 was prepared by using the Brust Schiffrin two-phase direct synthesis and characterized with NMR spectroscopy, elemental analysis, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The experimental data show that the particular multidentate structure of calix[n]arene derivatives 2 and 3 introduces a control element in the preparation of the gold nanoparticles that allows, in the particular experimental conditions here reported, to obtain very small (approximate to 1 nm) AuNPs. These are the first experimental findings that identify a role of ligand "denticity" in the determination of the nuclearity of nanoparticles.