Size-Dependent Photoluminescence from Thiolate-Protected Water-Soluble Cobalt Nanoclusters

摘要

abstract_textpThe luminescence property of highly oxidative transition metal nanostructures using Co, Ni and Cu are being challenging. Due to their high susceptibility for oxidation and non-existence of appropriate synthesis methodologies and lack of efficient mechanism to confirm their luminescence properties. To overcome these shortcomings, herein we report a new synthesis strategy to develop a novel tripeptide thiolate ligand i. e., glutathione (GS) protected ultrasmall water-soluble cobalt nanoclusters, Co-n(GS)(m.) As achieved Co-n(GS)(m) clusters were isolated from the crude CoGS using polyacrylamide gel electrophoresis (PAGE) technique. The PAGE separation for the crude CoGS sample resulted in three bands of varying sizes i. e., 2-5 nm (band 1), 6-18 nm (band 2) and 13-28 nm (band 3), which exhibits size-dependent luminescence with quantum yields of 10 , 7.5 and 5.8 respectively. Among them, the maximum quantum yield for the ultrasmall Co-n(GS)(m) nanoclusters from the band 1 exhibits a blue emission which could be as result of synergetic behaviour from the aggregation induced emission (AIE) and ligand-metal-metal charge transfer (LMMCT) relaxations offered by the triplet state of Co-n(GS)(m) nanoclusters. This significant results for the water-soluble, highly robust and luminescent Co-n(GS)(m) nanoclusters confirm their potential ability to act as an alternative to expensive metal nanoparticles and conventional fluorescent materials for the technological and bioimaging applications./p/abstract_text