An Acylhydrazone-Based Fluorescent Sensor for Sequential Recognition of Al(3+) and H(2)PO(4)(−)

A novel acylhydrazone-based fluorescent sensor NATB was designed and synthesized for consecutive sensing of Al(3+) and H(2)PO(4)(−). NATB displayed fluorometric sensing to Al(3+) and could sequentially detect H(2)PO(4)(−) by fluorescence quenching. The limits of detection for Al(3+) and H(2)PO(4)(−) were determined to be 0.83 and 1.7 μM, respectively. The binding ratios of NATB to Al(3+) and NATB-Al(3+) to H(2)PO(4)(−) were found to be 1:1. The sequential recognition of Al(3+) and H(2)PO(4)(−) by NATB could be repeated consecutively. In addition, the practicality of NATB was confirmed with the application of test strips. The sensing mechanisms of Al(3+) and H(2)PO(4)(−) by NATB were investigated through fluorescence and UV–Visible spectroscopy, Job plot, ESI-MS, (1)H NMR titration, and DFT calculations.