Photoresponsive Propeller-like Chiral AIE Copper(I) Clusters.

A pair of propeller-like chiral trinuclear Cu clusters (R/S-Cu3) with unique photoinduced fluorescence enhancement were prepared. R/S-Cu3 showed intense variable luminescence after UV light irradiation, which was attributed to the stepwise oxidation of ligand in the clusters. It exhibited typical aggregation-induced emission (AIE) (α =17.3). Mechanism studies showed that metal cluster-centered (MCC) and triplet metal-to-ligand charge-transfer ( MLCT) processes are the origin of the luminescence; the processes are regulated by a restriction of intramolecular motions mechanism in a different state. The chiral structure and AIE feature endow R/S-Cu3 with remarkable circularly polarized luminescence (g =2×10 ) in the aggregated state. It shows good capability for producing reactive oxygen species. This work enriches the kinds of atomically precise AIE clusters, gains insight into their luminescence mechanism, and offers the prospect of application in multifunctional materials.