Aggregation-induced barrier to oxygen-a new AIE mechanism for metal clusters with phosphorescence

This work not only reported a series of AIE metal clusters, illustrating their multiple applications, but, more importantly, also proposed a new AIE mechanism and provided a new perspective for understanding the influence of aggregation on the phosphorescence properties of molecules. Metal clusters are useful phosphors, but highly luminescent examples are quite rare. Usually, the phosphorescence of metal clusters is hindered by ambient O-2 molecules. Transforming this disadvantage into an advantage for meaningful applications of metal clusters presents a formidable challenge. In this work, we used ligand engineering to judiciously prepare colour-tuneable and brightly emitting Cu(I) clusters that are ultrasensitive to O-2 upon dispersion in a fluid solution or in a solid matrix. When the O-2 scavenger dimethyl sulfoxide (DMSO) was used as the solvent, joint photo- and oxygen-controlled multicolour switches were achieved for the first time for metal cluster-based photopatterning and photo-anticounterfeiting. More importantly, an aggregation-induced barrier to oxygen, a new aggregation-induced emission mechanism for metal clusters, was proposed, providing a new pathway to realizing the intense emission of metal clusters in the aggregated state. These results are expected to promote the application of metal clusters and enrich the luminescence theory of metal cluster aggregates.