Arenethiolate Monolayer-Protected Gold Clusters

Abstract

Nanometer-sized gold clusters stabilized by monolayers of arenethiolates prepared using the Brust reaction are somewhat larger (by TEM) and less thermally stable (by TGA) than those prepared under similar conditions and stabilized by alkanethiolates. Like the latter, the mean core size decreases for synthetic conditions based on larger thiol/Au ratios. The differential pulse voltammetry of the arenethiolates was especially interesting by displaying electrochemical ensemble Coulomb staircase features analogous to those recently reported, even in unfractionated cluster preparations, consistent with a smaller dispersity of core sizes than usual for alkanethiolate-protected clusters. The spacings between quantized capacitance charging features on the potential axis decrease with decreasing methylene linker chain length. TEM studies show chain/ring self-organization features. The UV−vis spectral surface plasmon bands of the arenethiolate clusters are virtually independent of the specific aryl ligands for small cluster sizes; for others a collective band feature might be due to the formation of small aggregates of MPCs.