Magic-Numbered Aun Clusters Protected by Glutathione Monolayers (n = 18, 21, 25, 28, 32, 39): Isolation and Spectroscopic Characterization

Abstract
Small gold clusters (18(SG)11, Au21(SG)12, Au25±1(SG)14±1, Au28(SG)16, Au32(SG)18, and Au39(SG)23. Their optical absorption spectra are highly structured with clear absorption onsets, which shift toward higher energies with reduction of the core size. These molecular-like gold clusters exhibit visible photoluminescence. The results reported herein provide helpful guidelines or starting points for further experimental and theoretical studies on structures, stabilities, and optical properties of monolayer-protected gold clusters.