From ligand-stabilized gold nanoparticles to hybrid organic-inorganic superstructures

Gold nanoparticles (Au NPs) have many potential applications including nanoelectronics, catalysts and sensors. These future devices depend on stable and monodisperse NPs and their directed assembly. Herein we review our efforts to develop oligomeric thioether ligands able to direct the synthesis of Au NPs and their surface functionalization. A screening of different oligomeric thioethers indicates that the NPs become more stable and monodisperse with increasing length of the thioether oligomer. The heptameric benzylic thioether 4 stabilizes monodisperse NPs with a diameter of 1 nm and excellent long-term stability in solution. It is further monofunctionalized with a central protected acetylene. After NP formation in the presence of the ligands we utilize the peripheral functionality to interlink the NPs. A mild oxidative diacetylene coupling protocol is used to covalently bind these 'artificial molecules'. This wet-chemical procedure leads to the formation of hybrid organic-inorganic superstructures.