A Highly Selective Chemosensor for Naked-Eye Detection of Fluoride and Aluminium(iii) Ions Based on a New Schiff Base Derivative

A new chromogenic receptor, 4-((2,4-dichlorophenyl)diazenyl)-2-(3-hydroxypropylimino)methyl)phenol, has been designed and synthesized for quantitative and low-cost detection of various biological anions and cations. The dye was characterized by elemental analyses, infrared, UV-visible spectroscopy, and NMR spectroscopy. The chemosensor showed visual changes towards anions, such as F- and H2PO4-, in DMSO and towards cations, such as Al3+, Cu2+, Fe3+, and Cr3+, in DMSO/water (9:1). The anion recognition property of the receptor via proton transfer was monitored by UV-visible titration and H-1 NMR spectroscopy. The binding constant (K-a) and stoichiometry of the host-guest complexes formed were determined by the Benesi-Hildebrand (B-H) plot and Job's method, respectively.