Synthesis of Tetraoctylammonium-Protected Gold Nanoparticles with Improved Stability

Abstract

This paper shows that an introduction of thiosulfate anions in place of bromide anions greatly improves both chemical and thermal stability of tetraoctylammonium-protected gold nanoparticles. Tetraoctylammonium thiosulfate [(Oct)4N+-O3SS]-protected gold nanoparticles are synthesized by the reduction of (Oct)4N+-AuCl4 to Au(I)-SSO3-, followed by the addition of sodium borohydride. The presence of thiosulfate anions instead of bromide anions on the surface of gold nanoparticles results in a significant dampening of the surface plasmon band of gold at 526 nm due to the strong interaction between thiosulfate and the gold nanoparticle surface. Cyanide decomposition and heating treatment studies suggest that (Oct)4N+-O3SS-protected nanoparticles have much higher overall stability compared to (Oct)4N+-Br-protected gold nanoparticles.

Short-time preparation and electrochemical properties of a single layer of tetraoctylammonium bromide capped Au nanoparticles on dithiol self-assembled monolayer-modified Au electrode

“…Although the kinetics of immobilization of TOAB-AuNPs were not studied in the past, it has been reported that binding of TOAB ions with AuNPs is labile and can be easily exchanged by other molecules [35,36].…”

Chemical and heating treatments of ionic monolayer-protected clusters (IMPCs) with different surface counter anions

“…1) [11]. Herein, we report through investigations of the stability of both Oct 4 N +− O 3 SS-IMPCs and Oct 4 N +− BrIMPCs upon chemical treatments and solid-phase heating treatments.…”

“…However, the unsatisfactory long-term stability of ionic surfactant-protected gold nanoparticles has limited the broader use of these nanomaterials. The removal of solvents from solution containing ionic monolayer protected nanoparticles caused a complete agglomeration of particles and resulted in the formation of insoluble materials [8,10,11]. In addition, these particles decomposed by heating treatments at moderately low temperature [11].…”

“…The removal of solvents from solution containing ionic monolayer protected nanoparticles caused a complete agglomeration of particles and resulted in the formation of insoluble materials [8,10,11]. In addition, these particles decomposed by heating treatments at moderately low temperature [11]. Citrate reduction of HAuCl 4 in water led to citrate-capped gold nanoparticles with core sizes ranging from 9 to 120 nm [12].…”

Reactive Template Method to Synthesize Gold Nanoparticles with Controllable Size and Morphology Supported on Shells of Polymer Hollow Microspheres and Their Application for Aerobic Alcohol Oxidation in Water

“…[1] Recently, a great deal of methods have been developed to prepare stable gold nanoparticles with controllable size. The synthesized gold nanoparticles are always capped with a certain stabilizer, which involves alkanethiols, [2] amines, [3] nucleotides, [4] and polymers, [5] to avoid the aggregation of gold nanoparticles resulting from Van der Waals attractions. [6] One recent research activity regarding the application of gold nanoparticles focuses on their catalytic activity for many reactions, such as glucose oxidation, [7] alcohol oxidation, [8] CO oxidation, and propylene expoxidation.…”