Highly Sensitive and Selective Recognition of Zn²⁺ and Fe²⁺ Ions Using a Novel Thiophene-Derived Hydrazone Dual Fluorometric Sensor

The selective detection of Zn²⁺ and Fe²⁺ ions is critical in environmental and biological studies. Schiff base chemosensors hold promise, but exploration of thiophene-derived variants remains limited. This work introduces a novel thiophene-derived Schiff base sensor (TBH), synthesized through the condensation reaction of thiophene-2-carboxaldehyde with benzil-bis-hydrazone, for the selective detection of Zn²⁺ and Fe²⁺ ions. TBH exhibits remarkable selectivity, with a significant 185-fold fluorescence enhancement for Zn²⁺ and complete quenching 99% for Fe²⁺, allowing for distinct detection of both ions. Notably, TBH demonstrates high binding affinity towards Zn²⁺ and Fe²⁺, even in the presence of competing cations, forming stable 1:1 complexes. This finding is supported by absorption and emission titration studies and FT-IR analysis as well. This easily synthesized, rapid and cost-effective sensor offers a promising approach for sensitive and differentiated dual detection of Zn²⁺ and Fe²⁺ in environmental and biological systems.