Gold and silver nanoparticles functionalized by the adsorption of dialkyl disulfides

The formation of three-dimensional self-assembled monolayers (3-D SAMs) generated by the adsorption of n-octadecyl disulfide onto colloidal gold and silver nanoparticles is described. The functionalized nanoparticles were characterized by solubility, transmission electron microscopy, ultraviolet-visible spectroscopy, H-1 nuclear magnetic resonance spectroscopy, surface-enhanced Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. On gold nanoparticles, this new functionalization method affords crystalline 3-D SAMs that are indistinct from those prepared by the analogous adsorption of n-octadecanethiol. On silver nanoparticles, however, the films derived from n-octadecyl disulfide appear to be somewhat less crystalline than those prepared similarly from n-octadecanethiol, The origin of this difference is briefly explored and discussed.