Molecular electron-transfer properties of Au-38 clusters

The electron transfer (ET) behavior of molecule-like Au38 clusters, protected by a phenyethanethiolate monolayer, Au38(SR)24, was studied on glassy carbon and platinum electrodes in N,N-dimethylformamide and dichloromethane. The kinetic parameters corresponding to the two first oxidation states (+1/0 and +2/+1) and the first reduction state (0/-1) were obtained by using cyclic voltammetric theory, convolution analysis, and global analysis. The ET properties of the anion electrogenerated from Au38(SR)24 were studied by homogeneous redox catalysis and using diphenyl disulfide as the acceptor, in comparison with ET results obtained by using conventional radical-anion donors. Both the heterogeneous and the homogeneous analyses point to a remarkably fast ET behavior typical of the formation and reactivity of delocalized ionic species in which solvent reorganization is the main factor controlling the intrinsic barrier.