A high-performance fluorophore-decorated bimodal scaffold as a target-specific ratiometric sensor and extractant for aluminum and mercury ions

Abstract

To protect ecological safety and public health, building a simple and efficient chemosensor to monitor and extract toxic metal ions in the environment is important. In this work, a sophisticated blue emissive ligand (PTA) was designed and developed through a rapid and one-pot condensation reaction using a sonochemical technique for the selective detection of Al³⁺ and Hg²⁺ ions. PTA was effectively used as a dual-functional colorimetric and ratiometric chemoprobe for selective and sensitive detection of Hg²⁺ and Al³⁺ ions with distinct fluorescence channels without signal crosstalk. The detection limits of PTA for Al³⁺ and Hg²⁺ ions were determined to be 3.88 nM and 3.70 nM, respectively. The binding stoichiometry of PTA–Hg²⁺ and PTA–Al³⁺ was determined using a Job's plot experiment and was further validated by NMR titration, FT-IR and HR-MS analysis. The PTA for Al³⁺/Hg²⁺ sensing showed outstanding benefits of ultra-fast response, large Stokes shift up to ∼160/188 nm, exciting circularity, excellent pH stability, and strong anti-interference ability. Interestingly, the PTA–Hg²⁺ ensemble acts as a new relay chemosensor for arginine or histidine via a demetallation reaction. In addition, we developed an effective solid-state optical sensor by combining the novel fluorescent probe (PTA) with a structurally integrated bimodal poly(ACm-co-EGDMA) membrane for selective ratiometric detection and extraction of toxic mercury and aluminium ions. The proposed work offers a simple, eco-friendly, cost-effective, and portable ratiometric solid-state sensor for the selective ratiometric recognition and extraction of Al³⁺ and Hg²⁺ ions.