Synthesis of highly stable gold nanoparticles using conventional and geminal ionic liquids

Highly stable and hydrophilic ionic liquid-capped gold nanoparticles were synthesized by in situ reduction of HAuCl4 with NaBH4 in an aqueous medium. Two kinds of ionic liquids (ILs) were used in this work: namely, 1-dodecyl-3-methylimidazolium chloride [C12mim][Cl] and a geminal-IL (GIL), 1,4-bis(methylimidazolium-1yl)dodecane bromide, with two hydrophilic head groups. Prepared gold nanoparticles were characterized by UV–vis spectra, transmission electron microscopy (TEM), dynamic light scattering (DLS) analysis and FTIR spectroscopy. To the best of our knowledge this is the first report on using these types of ILs in gold nanoparticle synthesis. The results showed the synthesis of low polydispersed and stable gold nanoparticles with sizes about 10 nm. The IL ([C12mim][Cl]) capped gold nanoparticles were stable for at least 8 months.