Supramolecular mixed valence assemblies exhibiting picoseconds rates of electron transfer are reported. Trinuclear ruthenium clusters of the type, [Ru3O(OAc)6(CO)(L)(pyS)] where L= 4-cyanopyridine, pyridine, and 4-dimethylaminopyridine, bound to Au nanoparticles (NPs) are electrochemically reduced to form mixed valence nanoclusters. Infrared spectroelectrochemical responses show dynamic coalescence of the ?(CO) region, indicating that electron transfer between Ru clusters attached via a p-conjugated bridge to NPs occurs on the vibrational timescale. Bloch simulation of IR ?(CO) spectra gives ket on the order of 1011- 1012 s-1. Ground state electron transfer rates exhibit strong dependence on solvent dynamics. These results suggest that solvent dynamics control electron transfer, while solvent reorganization energy, ?s, is uncoupled with ET rates. This behavior is consistent with supramolecular assemblies that lie on the nearly barrier-less, class II/III borderline of mixed valence.

Ultrafast electron transfer through gold nanoparticles: Ancilary ligand and solvent effects

243rd National Meeting (2012)

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