A simple large-scale synthesis of nearly monodisperse gold and silver nanoparticles with adjustable sizes and with exchangeable surfactants

Oleylamine-ligated gold and silver nanoparticles can be conveniently synthesized by reaction of tetrachloroauric acid or silver acetate with oleylamine in refluxing toluene, hexane, or 1,2-dichlorobenzene. The sizes of the colloids can be controlled with the solvent, reaction temperature, and reaction time. The gold nanoparticles spontaneously organize into micrometer-size colloidal crystals. Reactions of the gold and silver nanoparticles with aliphatic and carboxylic acid-functionalized thiols affords the ligand-exchanged nanoparticles as colloids that, depending on the surfactants, can be soluble in aqueous or nonaqueous solvents.