General Multistage Programmable Assembled Strategy for Highly Luminescent Metal Nanoclusters Originating from AIE-Type Rational Synthesis and Its Application in Extending the Dynamic Range of Assays

Luminescent enhancement of metal nanoclusters (MNCs) has been generally adopted in several strategies. However, little progress on cascading multiple approaches has been made owing to remarkable diversity of their sizes, compositions, metallic core, and surface ligands. Herein, the well-defined MNCs is prepared by controlling the precursor ratio of ligand to metal ions, whose structure significantly influence on incorporating aggregation-induced emission (AIE) with MNC-encapsulated into zeolitic imidazolate frameworks (ZIFs). Interestingly, glutathione-decorated copper nanoclusters (CuNCs) with AIE behavior are synthesized at a lower ratio between ligands and Cu2+, and then Zn2+ brings CuNCs to generate assembly (CZA) followed by the in situ formation of the ZIF shell. Finally, CuNCs encapsulated in ZIFs (CuNCs@ZIFs) are obtained. Notably, the photoluminescence quantum yield of CuNCs is increased from 0.9 to 20.3% for CZA and to 24.5% for CuNCs@ZIFs. Oppositely, the emission of CuNCs synthesized from the higher ratio between ligands and Cu2+ is quenched by Zn2+ accompanying the failure formation of ZIFs. This strategy is also applied for six other nanoclusters. Furthermore, CuNCs-based assemblies are screened for extending the dynamic range of quantification in H2O2 and glucose assay. Our results can guide the construction of nanocluster assemblies with excellent photoluminescence and stability, accelerating their utilization in real applications.