Structural and Optical Properties of Isolated Noble Metal–Glutathione Complexes: Insight into the Chemistry of Liganded Nanoclusters

Abstract

Gold(I)– and silver(I)–thiolate oligomers generated under nanoparticle growth conditions have been suggested to play an important role in the growth mechanism of thiolate-protected noble metal clusters. In this work, we explore the formation of isolated noble metal–glutathione complexes by complementing electrospray mass spectrometry and optical action spectroscopy with TDDFT calculations. We have isolated and recorded action spectra of [Au+GSH–2H]−, [Ag+GSH–2H]−, and [3Ag+2GSH–4H]− complexes. Competition between photofragmentation and photodetachment channels related to electron binding energies was observed. Our findings show that, although structural properties of silver and gold metal–glutathione oligomers are similar, their optical properties in the UV range differ substantially. The experimental spectra were interpreted and assigned by comparison with TDDFT simulations, which allowed us to identify the key role of O–metal–S subunits and characterize their optical properties depending on the choice of metal.