A new colorimetric chemosensor based on 1,3,4-oxadiazole derivative for the high selectivity and sensitivity of Fe3+ ion detection

This paper reports the development of new iron chemosensor, 2-(5-sulfanyl-1,3,4-oxadiazol-2-yl) phenol (HL). The structural properties of HL were confirmed by FTIR, H-1 NMR, C-13 NMR and ESI-MS techniques. The sensor was applied for detection of various metal ions in DMF/H2O (1:9 v/v) medium. The results revealed an instant color change of Fe3+ solution from yellow to black. However, white and light brown precipitates were observed in the case of Pb2+, Hg2+ and Cu2+, respectively, whereas no optical response for the other cations were detected. Beside its high selectivity for Fe3+, no interference from other coexisted ions was seen. Moreover, the detection limit (LOD) of 3 mu M, which is less than the acceptable value of the Fe3+ from WHO in environment, was observed. The interaction between Fe3+ ions and HL sensor using Job's plot analysis was found to be a 1:1 binding stoichiometry with a binding constant of 1.8 x 10(3) M-1 as calculated using Benesi-Hilderbrand equation. The advantage of HL in propping of Fe(3+)in real environmental samples were also tested which revealed its practical applicability as an effective chemosensor. (C) 2021 Elsevier B.V. All rights reserved.