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 the 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 C60 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.