The first example of synthesis Au-nanoparticles with amidine derivatives of closo-decaborate anion as stabilizing ligand

In this work, we report the one-pot aqueous synthesis of AuNPs using novel amidine derivatives of the closo-decaborate anion, functionalized with pendant thiol groups, as combined reducing and stabilizing agents. A comprehensive characterization using transmission electron microscopy (TEM) revealed the formation of nanoparticles with a distinctive and unusual hollow-core/dense-shell architecture, where a gold-rich shell encapsulates a low-Z element core. This unique morphology accounts for the observed absence of a characteristic surface plasmon resonance (SPR) band in the UV-Vis spectra, distinguishing these materials from classical solid-core AuNPs. X-ray photoelectron spectroscopy (XPS) confirmed the covalent attachment of the ligands via Au-S bonds and the integrity of the boron cage on the nanoparticle surface. The synthesis was optimized, establishing a 1:6 (Au:Ligand) molar ratio as ideal for achieving a narrow particle size distribution.