Rational size control of gold nanoparticles employing an organometallic precursor [Au-C≡C- t-Bu]4 and tunable thiolate-functionalized ionic liquids in organic medium

Gold nanoparticles (Au NPs) stabilized with six different thiolate-functionalized ionic liquids (TFILs) were synthesized in an organic solvent. The size and optical properties of the TFIL-stabilized Au NPs can be rationally controlled by altering the N-alkyl chain length and (or) the counteranion of the TFIL-stabilizing ligand. Au NPs were prepared from the reduction of a gold precursor (HAuCl4 or [Au-C≡C-t-Bu]4) employing NaBH4 in the presence of the different disulfide precursors. A model, based on Israelachvili theory, is proposed to account for the dependence of NP size on the N-alkyl chain length and the counteranion of the surfactantlike TFIL stabilizers.