Selective optical sensing of iron(III) ions in an aqueous medium by benzochromone-based Schiff base and its application on test strips.

In this work, we designed and synthesized a novel, simple, low-cost, and effective chromone-based Schiff base ligand () and its application as a chemosensor for Fe detection. The structure of the synthesized sensor bears carboxylic, azomethine, and carbonyl groups which act as chelating sites for the detection of Fe ions. The chemosensor HL exhibited highly selective detection of Fe a significant colour change from yellow to brown. The colour change is due to the ligand-to-metal charge-transfer (LMCT) mechanism. The sensor () was characterized using UV-Vis, FTIR, NMR (H- and C), and mass spectroscopy. The ligand solubility, detection condition, and sensitivity assessment suggested optimal use of DMF-water (9:1 v/v) as a working solvent at pH 7.0. Among a list of 15 metal ions screened, was highly selective, with instant response, towards Fe ions without significant interferences with the other metal ions. The complexation ratio and association constants of to Fe was determined by Job's plot and Benesi-Hildebrand methods, and were 2:1 and 2.24 × 10 M, respectively, with a detection limit of 2.86 μM. The probe was also applied to detect Fe in real samples with acceptable performance. The simple test strips have been successfully developed and applied to the visual monitoring of Fe ions with a detection limit of 68 µM. The DFT was used to examine the best interaction mode of with Fe metal to be Fe(III)-L or Fe(III)-2L. The chemical-reactivity and molecular electrostatic optional were figured to predict the interaction behaviour of the tested compounds.