Chirality in bare and passivated gold nanoclusters

Abstract

Chiral structures have been found as the lowest-energy isomers of bare $({\mathrm{Au}}_{28}$ and ${\mathrm{Au}}_{55})$ and thiol-passivated $[{\mathrm{Au}}_{28}({\mathrm{SCH}}_{3}{)}_{16}$ and ${\mathrm{Au}}_{38}({\mathrm{SCH}}_{3}{)}_{24}]$ gold nanoclusters. The degree of chirality existing in the chiral clusters was calculated using the Hausdorff chirality measure. We found that the index of chirality is higher in the passivated clusters and decreases with the cluster size. These results are consistent with the observed chiroptical activity recently reported for glutahione-passivated gold nanoclusters, and provide theoretical support for the existence of chirality in these compounds.