Incorporating Copper Nanoclusters into Metal-Organic Frameworks: Confinement-Assisted Emission Enhancement and Application for Trinitrotoluene Detection

Herein, a strategy for improving both the stability and the emission intensity of Cu nanoclusters based on their entrapment into metal-organic frameworks (MOFs) is demonstrated. The latter effect reaches 20 times and is ascribed to a confinement-assisted emission enhancement similar to the aggregation induced emission of fluorescent species in solution, evidenced by the prolonged emission lifetime. Cu nanoclusters are distributed homogeneously over the entire MOFs structure, as confirmed by combination of structural and elemental mapping studies. Toward potential applications of Cu nanocluster/MOF composites as chemical sensors, the authors demonstrate the selective quenching of their emission by 2,4,6-trinitrotoluene attributed to specific electron-withdrawing interactions with glutathione ligands on Cu clusters.