A novel diimine two-tetradentate ionic macrocycle Schiff base ligand as a Colorimetric Chemosensor for the Detection of Fe 2+ andFe 3+ ions

In this paper, a novel diimine two-tetradentate ionic macrocycle Schiff base ligand (L) was synthesized by reacting 1,2-bis((1H-imidazol-1-yl)methyl)benzene (OB) with 5- chloromethyl salicylaldehyde in methanol and followed by the addition of ethylenediamine under refluxing conditions, and characterized by elemental analysis, FT-IR, UV–Visible, fluorescence, proton nuclear magnetic resonance ( ¹ H NMR), carbon-13 nuclear magnetic resonance ( ¹³ C NMR), liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The sensing ability toward the metal ions of Mo ⁵ +, V ⁴⁺ , Cr ³⁺ , Al ³⁺ , Zn ²⁺ , Cd ²⁺ , Hg ²⁺ , Cu ²⁺ , Ni ²⁺ , Co ²⁺ , Mn ²⁺ , Sn ²⁺ , Pb ²⁺ , Fe ³⁺ , Fe ²⁺ , K ⁺ , Ag ⁺ , Mg ²⁺ , Ca ²⁺ , Ba ²⁺ and Na ⁺ was investigated in mixture of dimethyl sulfoxide (DMSO) and water (H ₂ O) (2/8, v/v) solvent. The L is used as a colorimetric chemosensor for the detection of Fe ²⁺ and Fe ³⁺ ions, by a rapid and significant color change from yellow to brown and brownish red Respectively, by the naked eye and at room temperature. Also, the limit of detection (LOD) was obtained 0.45 µM for Fe ²⁺ and 0.68 µM for Fe ³⁺ . Job’s plots indicated a 1:2 complexation stoichiometry between the sensor (L) and Fe ions. Moreover, the sensor (L) demonstrated reversible behavior upon the addition of EDTA. This probe (L) could be prepared into test paper strips for visual detection of Fe ²⁺ and Fe ³⁺ ions at room temperature.