Unraveling the Impact of Gold(I)-Thiolate Motifs on the Aggregation-Induced Emission of Gold Nanoclusters

Aggregation-induced emission (AIE) provides an efficient strategy to synthesize highly luminescent metal nanoclusters (NCs), however, rational control of emission energy and intensity of metal NCs is still challenging. This communication reveals the impact of surface Au-I-thiolate motifs on the AIE properties of Au NCs, by employing a series of water-soluble glutathione (GSH)-coordinated Au complexes and NCs as a model ([Au10SR10], [Au15SR13], [Au18SR14], and [Au25SR18](-), SR=thiolate ligand). Spectroscopic investigations show that the emission wavelength of Au NCs is adjustable from visible to the near-infrared II (NIR-II) region by controlling the length of the Au-I-SR motifs on the NC surface. Decreasing the length of Au-I-SR motifs also changes the origin of cluster luminescence from AIE-type phosphorescence to Au-0-core-dictated fluorescence. This effect becomes more prominent when the degree of aggregation of Au NCs increases in solution.