28 kDa Alkanethiolate-Protected Au Clusters Give Analogous Solution Electrochemistry and STM Coulomb Staircases
Roychelle S. Ingram, Michael J. Hosterler, Royce W. Murray, T. Gregory Schaaff, Joseph T. Khoury, Tobert L. Whetter, Terry P. Bigioni, Daniel K. Guthrie, and Phillip N. First

Abstract:

We report here the electron transfer (et) behavior (Figure 1) of highly purified, 28 kDa core mass, hexanethiolate-protected gold cluster molecules^1-3 and the remarkable correspondence between tip-based tunneling spectroscopy of a single Au cluster molecule physisorbed on a metal surface⁴ and cyclic and differential pulse voltammetry of ensembles of the same clusters at a metal/solution interface. This study establishes new ground in three ways: (1) the samples studied are "monodisperse" in core size and structure; thus the observed et properties can be assigned to a specific number and arrangement of gold atoms; (2) the et comparison of single molecules to a thermodynamically relevant ensemble of the same molecules demonstrates correspondence of results across these vastly different regimes; and (3) the voltammetry provides the first example of a solution-phase coulomb staircase of an ensemble of nanoparticles.

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