Fullerene-functionalized gold nanoparticles: Electrochemical and spectroscopic properties

Fullerene (C-60)-tethered gold nanoparticles were synthesized by the coupling of the fullerene molecules with peripheral amine moieties on the particle surface. The particle composition was determined by thermogravimetric analysis and FT-IR spectroscopy. The resulting particles exhibited unique optical and electrochemical properties. UV-visible measurements showed that the C-60 characteristic absorption remained practically invariant whereas the fluorescence demonstrated rather drastic enhancement of emission efficiency as compared to tire behaviors of C-60 monomers. Tethering of C-60 on the particle surface has virtually no effect on the particle molecular capacitance when C-60 is in neutral state, whereas when C-60 is electroreduced, the particle effective capacitance increases drastically, reflected in the quantized capacitance charging measurements. The strong affinity of C-60 to amine moieties was also exploited to assemble multilayers of C-60 and gold particle nanocomposite structures. Quartz crystal microbalance measurements showed quite efficient adsorption of C-60 and particles up to two repeated cycles. However, the voltammetric responses of the surface-confined C-60 and gold particle composite structures were found to be complicated by the inaccessibility of electrolyte counterions due to the compact nature of the surface assemblies.