Stimuli‐Responsive Fluorescent Nanoswitches: Solvent‐Induced Emission Enhancement of Copper Nanoclusters

Abstract Copper nanoclusters (CuNCs) as a new class of fluorescent materials have attracted a great deal of interest due to their outstanding fluorescence properties. In this work, a variety of organic solvents were used to induce self‐assembly of glutathione‐capped CuNCs (GSH‐CuNCs) to form ordered assemblies with enhanced fluorescence properties. Assemblies with multicolor fluorescence emission were constructed on the basis of the aggregation‐induced emission (AIE) of GSH‐CuNCs and the solvent effect. The fluorescence emission from these GSH‐CuNCs assemblies can also be tuned from yellow to purple by changing the organic solvent. A possible mechanism based on the size of the assemblies and electron transfer was explored to explain the solvent effects on GSH‐CuNCs. Stimuli‐responsive nanoswitches with excellent reversibility can be controlled by changing the type of organic solvent and the ratio of the organic solvent to the aqueous solution of GSH‐CuNCs. As the CuNCs assemblies exhibit strong, stable, and color‐tunable fluorescence, they were employed as color‐conversion materials for recognizing different organic solvents.