Gold and silver nanoparticles functionalized by the adsorption of dialkyl disulfides

The formation of three-dimensional self-assembled monolayers (3-D SAMs) gen erated by the adsorption of n-octadecyl disulfide onto colloidal gold and s ilver nanoparticles is described. The functionalized nanoparticles were cha racterized by solubility, transmission electron microscopy, ultraviolet-vis ible spectroscopy, H-1 nuclear magnetic resonance spectroscopy, surface-enh anced Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ra y photoelectron spectroscopy. On gold nanoparticles, this new functionaliza tion method affords crystalline 3-D SAMs that are indistinct from those pre pared by the analogous adsorption of n-octadecanethiol. On silver nanoparti cles, however, the films derived from n-octadecyl disulfide appear to be so mewhat less crystalline than those prepared similarly from n-octadecanethio l, The origin of this difference is briefly explored and discussed.