The significance of bromide in the Brust-Schiffrin synthesis of thiol protected gold nanoparticlesElectronic supplementary information (ESI) available. See DOI: 10.1039/c7sc03266h

• Main Authors: Booth, S. G, Uehara, A, Chang, S.-Y, La Fontaine, C, Fujii, T, Okamoto, Y, Imai, T, Schroeder, S. L. M, Dryfe, R. A. W
• Format: Journal Article
• Published: 20.11.2017
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c7sc03266h

The mechanism of the two-phase Brust-Schiffrin synthesis of alkane thiol protected metal nanoparticles is known to be highly sensitive to the precursor species and reactant conditions. In this work X-ray absorption spectroscopy is used in conjunction with liquid/liquid electrochemistry to highlight the significance of Br − in the reaction mechanism. The species [AuBr 4 ] − is shown to be a preferable precursor in the Brust-Schiffrin method as it is more resistant to the formation of Au( i ) thiolate species than [AuCl 4 ] − . Previous literature has demonstrated that avoidance of the Au( i ) thiolate is critical to achieving a good yield of nanoparticles, as [Au( i )X 2 ] − species are more readily reduced by NaBH 4 . We propose that the observed behavior of [AuBr 4 ] − species described herein explains the discrepancies in reported behavior present in the literature to date. This new mechanistic understanding should enable nanoparticle synthesis with a higher yield and reduce particle size polydispersity. The mechanism of the two-phase Brust-Schiffrin synthesis of alkane thiol protected metal nanoparticles has been shown to be highly sensitive to the precursor species and reactant conditions.