Long-Lived Charge Separation in Gold Nanoparticles Encapsulated inside Cucurbit[7]uril and Its Relevance for Photocatalysis

Gold nanoparticles (average size 1 urn) encapsulated inside cucurbit[7]uril exhibit, upon 532 rim excitation in water, an intense transient absorption spectrum. The temporal profiles of the signals were different depending on the monitoring wavelength and extended beyond 1.2 ms. Quenching experiments using electron donors and acceptor molecules support that the transient spectra correspond to species arising from electron ejection from gold clusters to the solution. Photochemical generation of positive gold clusters has been advantageously used to effect the catalytic dimerization of phenylacetylene and to minimize the spurious decomposition of H2O2 promoted by Au@CB[7] in the dark.