A general approach combining diazonium salts and click chemistries for gold surface functionalization by nanoparticle assemblies.

This paper describes a general stepwise strategy combining diazonium salt and click chemistries for an efficient gold surface functionalization by gold nanoparticles. The procedure first involves the strong covalent bonding to gold electrodes of OH-terminated aryl layers derived from the electroreduction of the parent diazonium salts. The following step consists in transforming the OH end-groups to azides in order to obtain "clickable"-active gold surfaces, which could further be used as versatile platforms for the subsequent grafting of acetylene-bearing molecules. The practical interest of the gold surfaces functionalized by this stepwise strategy was evidenced through the self-assembly of surface-enhanced Raman scattering (SERS)-active gold nanoparticles. SERS activity was shown to be amplified by the presence of a very strong local electric field confinement between the particles and the gold surface.