Two-phase Brust-Schiffrin method (BSM) has been a predominant procedure for synthesizing thiolate-protected gold (Au) nanoparticles (NPs) since 1994. The long-held belief was that the addition of thiol to the organic layer of Au (III) and tetraoctylammonium bromide (TOAB) reduced Au (III) to polymeric [Au(I)SR]n species, which is the intermediate for the formation of Au NPs. However, Goulet et al showed recently that [TOA]+[AuX2]- complex was formed instead when aqueous phase is present. Furthermore, Li et al demonstrated that such formed [TOA]+[AuX2]- complex is actually part of inverse micelles of [TOA]+ encapsulating gold ions together with water. The amount of water in the inverse micelles had a profound effect on the formation of Au NPs, leading to dramatic changes in the size of Au NPs. However, the low solubility of water in the organic solvent does not enable an easy control of the size of micelle by which the quality of NP synthesis may be further improved. In this presentation, we report our investigation of using ethanol instead of water as a solvent for Au (III) salt in the Brust-Schiffrin type of synthesis of Au NPs. The effect of how the encapsulated ethanol can influence sizes of the formed Au NPs will be demonstrated. We will also discuss the characterizations of the intermediates formed prior to the addition of reducing agent NaBH4 by analyzing the Raman spectra, of the size of the formed inverse micelles by NMR, and of the Au NPs by TEM.

On using ethanol solution of Au[III] Salt in the Brust-Schiffrin synthesis of thiolate-protected gold NPs

244th National Meeting (2012)

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