Photoluminescence and temperature dependent emission studies of Au₂₅ clusters in the solid state

Abstract

Effect of ligand exchange on the optical and photoluminescence properties of Au₂₅SG₁₈ (SG-glutathione thiolate) clusters was investigated. A fluorescein-based dye, 5-((2-(and-3)-S-(acetylmercapto)succinoyl)amino)-fluorescein (SAMSA) was anchored on water soluble Au25SG18 clusters by the place exchange reaction and the solid-state emission of the exchange product was studied. Inherent fluorescence image of these clusters was mapped. Organic soluble Au₂₅(SC₂H₄Ph)₁₈ clusters were synthesized as a model system which also showed temperature-dependent solid-state emission, in good agreement with the results from water soluble Au₂₅ clusters.