Open Access Nano Express

Controlled reduction for size selective synthesis of thiolate-protected gold nanoclusters Aun(n = 20, 24, 39, 40)

Xiangming Meng1, Zhao Liu1, Manzhou Zhu1* and Rongchao Jin12*

Author Affiliations

1 Department of Chemistry, Anhui University, Hefei, Anhui, 230026, People’s Republic of China

2 Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, 15213, USA

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Nanoscale Research Letters 2012, 7:277  doi:10.1186/1556-276X-7-277

Published: 30 May 2012

Abstract

This work presents a controlled reduction method for the selective synthesis of different sized gold nanoclusters protected by thiolate (SR = SC2H4Ph). Starting with Au(III) salt, all the syntheses of Aun(SR)m nanoclusters with (n, m) = (20, 16), (24, 20), (39, 29), and (40, 30) necessitate experimental conditions of slow stirring and slow reduction of Au(I) intermediate species. By controlling the reaction kinetics for the reduction of Au(I) into clusters by NaBH4, different sized gold nanoclusters are selectively obtained. Two factors are identified to be important for the selective growth of Au20, Au24, and Au39/40 nanoclusters, including the stirring speed of the Au(I) solution and the NaBH4 addition speed during the step of Au(I) reduction to clusters. When comparing with the synthesis of Au25(SC2H4Ph)18 nanoclusters, we further identified that the reduction degree of Au(I) by NaBH4 also plays an important role in controlling cluster size. Overall, our results demonstrate the feasibility of attaining new sizes of gold nanoclusters via a controlled reduction route.

Keywords:
Gold nanoclusters; Size selective synthesis; Controlled reduction