Meta-Phenylenediamine-Derived Silver-Containing Nanoporous Hyper-Cross-Linked Polymer: An Innovative Fluorescence Probe for S₂O₃²⁻ ion Detection in Aqueous Media

The meta-phenylenediamine polymer, when hyper-cross-linked, exhibits a minimal fluorescence intensity. However, the introduction of silver ions induces a significant increase in intensity, attributed to the plasmonic effect. This heightened intensity is selectively increased more upon the addition of thiosulfate ions. Capitalizing on this property, a fluorescence probe was developed. The correlation between fluorescence intensity reduction and S₂O₃²⁻ concentration follows a linear and consistent pattern. The precursor’s response to diverse anions such as SO₄²⁻, CO₃²⁻, HPO₄²⁻, Cr₂O₇²⁻, F⁻, Cl⁻, Br⁻, I⁻, H₂PO₄⁻, CH₃COO⁻, NO₃⁻, ClO⁻, and HCO₃⁻ was also examined. Under optimal conditions, the probe exhibited a linear range of 0.5-3 µM with a detection limit of 0.01 µM. Its effectiveness was demonstrated in measuring thiosulfate concentrations in aqueous media.