An Acylhydrazone-Based Fluorescent Sensor for Sequential Recognition of Al3+ and H2PO4−

Abstract

A novel acylhydrazone-based fluorescent sensor <b>NATB</b> was designed and synthesized for consecutive sensing of Al³⁺ and H₂PO₄^-. <b>NATB</b> displayed fluorometric sensing to Al³⁺ and could sequentially detect H₂PO₄^- by fluorescence quenching. The limits of detection for Al³⁺ and H₂PO₄^- were determined to be 0.83 and 1.7 μM, respectively. The binding ratios of <b>NATB</b> to Al³⁺ and <b>NATB</b>-Al³⁺ to H₂PO₄^- were found to be 1:1. The sequential recognition of Al³⁺ and H₂PO₄^- by <b>NATB</b> could be repeated consecutively. In addition, the practicality of <b>NATB</b> was confirmed with the application of test strips. The sensing mechanisms of Al³⁺ and H₂PO₄^- by <b>NATB</b> were investigated through fluorescence and UV-Visible spectroscopy, Job plot, ESI-MS, ¹H NMR titration, and DFT calculations.