Glutathione-capped gold nanoclusters: photoinduced energy transfer and singlet oxygen generation §

Abstract

Abstract: Glutathione-capped gold clusters prepared in an aqueous medium are known to exhibit excellent photosensitizing properties. We have now successfully transferred these gold clusters in an organic medium while retaining all the characteristic excited state properties. These gold clusters can be further modified with organic ligands such as 2-Phenylethanethiol (PET). The gold clusters in organic medium exhibit enhanced emission yield (Φ f= 0.15) compared to that in an aqueous medium (Φ f= 0.08). The excited state lifetimes of 3.7μs (untreated) and 1.5μs (PET treated) in toluene are also greater than the lifetime observed in aqueous solution (0.77μs). By employing laser flash photolysis we are able to induce triplet energy transfer to β -carotene and oxygen. A singlet oxygen generation with the efficiency of 13% was observed in these experiments. The excited state properties of glutathione-capped gold clusters further shows its importance as a photosensitizer in light energy conversion and biomedical applications Graphical Abstract: SYNOPSIS A few atom gold clusters modified with organic ligands exhibit high photoactivity by generating singlet oxygen with 13% quantum efficiency. [Figure not available: see fulltext.].