Issue 7, 2010

Strong anion effects on gold nanoparticle formation in ionic liquids

Abstract

Ionic liquids (ILs) have attracted tremendous interest in the recent past for their potential in many chemical fields. The current report explores the effects of a set of ILs based on the 1-ethyl-3-methyl-imidazolium cation and different anions on the formation of gold nanoparticles. X-Ray diffraction finds face-centered cubic gold in all cases, but transmission electron microscopy (TEM) shows that there are distinct differences in particle formation and stabilization with the ethyl sulfate (ES), trifluoromethanesulfonate (TfO) and methanesulfonate (MS) anions. With the MS anion, nanoparticles with diameters between 5 and 7 nm form, which increasingly aggregate at higher reaction temperatures. With TfO, also small 5 to 7 nm particles form, but only at low temperatures. Above ca. 160 °C, large, ill-defined and aggregated particles form. With ES, polydisperse samples form at all temperatures except 160 °C. In this case the nanoparticles appear often surrounded by an IL film, which appears to stabilize individual, ca. 15 to 20 nm particles. Dynamic light scattering and UV/Vis spectroscopy further show that in suspension the particles are, much like seen in the TEM, more strongly aggregated with higher reaction temperatures. In summary, the results suggest that there are very specific IL–gold interactions that are responsible for the formation of gold particles with an IL-specific shape, size, and aggregation behavior.

Graphical abstract: Strong anion effects on gold nanoparticle formation in ionic liquids

Article information

Article type
Paper
Submitted
24 Aug 2009
Accepted
12 Nov 2009
First published
14 Dec 2009

J. Mater. Chem., 2010,20, 1332-1339

Strong anion effects on gold nanoparticle formation in ionic liquids

V. Khare, Z. Li, A. Mantion, A. A. Ayi, S. Sonkaria, A. Voelkl, A. F. Thünemann and A. Taubert, J. Mater. Chem., 2010, 20, 1332 DOI: 10.1039/B917467B

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