Effect of Ionic Liquid (emim BF₄) on the Dispersion of Gold Nanoparticles

A simple method has been described for the design of hybrid materials made of 1-ethyl- 3-methylimidazolium tetrafluoroborate (emim BF₄) stabilized gold (0) nanoparticles providing clear evidence about the coordination and stabilization behavior of imidazolium ionic liquids. The monodispersed gold nanoparticles were thoroughly verified by steady state spectroscopy and TEM microscopy, the hybrid material in comparison with the bare Au nanoparticles. This study revealed enhanced emission and a red-shifted absorption band which is attributed to charge transfer from IL to gold nanoparticles.TEM images of the nanoparticles corroborated the steady state results and showed similar particle sizes furthermore the nanoparticles appear often surrounded by IL layers. Based on the experiment results, which favor the interaction between IL anions instead of IL cations, we suggest the existence of an Au - F interaction and anionic Au-BF₄ stabilization in the fluorine- containing ILs.