Tb3+ tuning AIE self-assembly of copper nanoclusters for sensitively sensing trace fluoride ions

Abstract Tb3+ ions induce highly emissive copper nanoclusters (CuNCs) from weakly luminescent glutathione (GSH)-CuNCs driven by aggregation induced emission (AIE) mediated self-assemblies. The latter were fabricated via a one-step route utilizing GSH as both a reductant and a stabilizing agent. Complexation of Tb3+ with the carboxyl groups of GSH on the surface of GSH-CuNCs reduces nonradiative relation of the excited state(s) by restricting the intramolecular rotation-vibrational motion. This allows the formation of the highly red emissive Tb3+-CuNCs with over 260-fold emission increase. Moreover, the Tb3+-CuNCs exhibit increased long-term storage stability and a 14-fold increase in quantum yield relative to the GSH-CuNCs. The intense red fluorescence from Tb(III)-CuNCs is quenched by F− ions because of strong Tb3+ coordination with F−. On this basis, a new assay was constructed to selectively and sensitively detect F− ions. The limit of detection (LOD) for F− is 10 nM, which is lower than that stipulated by the World Health Organization (63.16 μM in drinking water). The Tb(III)-CuNCs-based fluorescence assay was applied to determine F− in real samples with satisfactory result.