Silver nanocluster-based fluorescent probes for detection of trace water in organic solvents with potential application in reaction monitoring

Confined silver nanoclusters within the pores of zeolites can bring about fascinating luminescent composites with high stability. The open structure of zeolites endues the materials with excellent fluorescence sensing performance, making them suitable for application in sensor fields. In LTA zeolites, Ag₄²⁺ clusters can form [Ag₄(H₂O)_<i>m</i>]²⁺ in the hydrated state exhibiting green emission or form [Ag₆(O)_<i>n</i>]²⁺ with red emission in the dehydration state, leading to reversible emission. Herein, we prepared a luminescent detector based on Ag-zeolites for trace amounts of water in organic solvents through a simple, cost-effective and environmentally friendly method. With the incorporation of water, the materials display a remarkable reversible optical switch from red to green owing to the reversible Ag₄²⁺ cluster structure of [Ag₄(H₂O)_<i>m</i>]²⁺ ↔ [Ag₆(O)_<i>n</i>]²⁺ in zeolites. The luminescent material features a low detection limit (0.2% v/v) for water and can be used for detecting trace amounts of water in organic solvents.