Simultaneous Hydrolysis and Detection of Organophosphate by Benzimidazole Containing Ligand-Based Zinc(II) Complexes

Gaber Mersal (1) , Hamdy El-Sheshtawy (2) , Mohammed Amin (1) , Nasser Mostafa (3) , Amine Mezni (4, 1) , Sarah Alharthi (1) , Rabah Boukherroub (5) , Mohamed Ibrahim (1)

1 TU - Taif University
2 Kafrelsheikh University
3 Suez Canal University
4 Faculté des Sciences de Bizerte [Université de Carthage]
5 NBI - IEMN - NanoBioInterfaces - IEMN

The agricultural use of organophosphorus pesticides is a widespread practice with significant advantages in crop health and product yield. An undesirable consequence is the contamination of soil and groundwater by these neurotoxins resulting from over application and run-off. Here, we design and synthesize the mononuclear zinc(II) complexes, namely, [Zn(AMB)2Cl](ClO4) 1 and [Zn(AMB)2(OH)](ClO4) 2 (AMB = 2-aminomethylbenzimidazole), as artificial catalysts inspired by phosphotriesterase (PTE) for the hydrolysis of organophosphorus compounds (OPs) and simultaneously detect the organophosphate pesticides such as fenitrothion and parathion. Spectral and DFT (B3LYP/Lanl2DZ) calculations revealed that complexes 1 and 2 have a square-pyramidal environment around zinc(II) centers with coordination chromophores of ZnN4Cl and ZnN4O, respectively. Both 1 and 2 were used as a modifier in the construction of a biomimetic sensor for the determination of toxic OPs, fenitrothion and parathion, in phosphate buffer by square wave voltammetry. The hydrolysis of OPs using 1 or 2 generates p-nitrophenol, which is subsequently oxidized at the surface of the modified carbon past electrode. The catalytic activity of 2 was higher than 1, which is attributed to the higher electronegativity of the former. The oxidation peak potentials of p-nitrophenol were obtained at +0.97 V (vs. Ag/AgCl) using cyclic voltammetry (CV) and +0.88 V (vs. Ag/AgCl) using square wave voltammetry. Several parameters were investigated to evaluate the performance of the biomimetic sensor obtained after the incorporation of zinc(II) complex 1 and 2 on a carbon paste electrode (CPE). The calibration curve showed a linear response ranging between 1.0 μM (0.29 ppm) and 5.5 μM (1.6 ppm) for fenitrothion and 1.0 μM (0.28 ppm) and 0.1 μM (0.028 ppm) for parathion with a limit of detection (LOD) of 0.08 μM (0.022 ppm) and 0.51 μM (0.149 ppm) for fenitrothion and parathion, respectively. The obtained results clearly demonstrated that the CPE modified by 1 and 2 has a remarkable electrocatalytic activity towards the hydrolysis of OPs under optimal conditions.

Mots clés: benzimidazole containing Zn(II) ligand; biomimetic; organophosphate hydrolysis; carbon paste electrode; electrochemical detection; fenitrothion; parathion

Domaines: Chimie de coordination; Chimie analytique; Ingénierie de l'environnement

Gaber Mersal, Hamdy El-Sheshtawy, Mohammed Amin, Nasser Mostafa, Amine Mezni, et al.. Simultaneous Hydrolysis and Detection of Organophosphate by Benzimidazole Containing Ligand-Based Zinc(II) Complexes. Crystals, 2021, 11 (6), pp.714. ⟨10.3390/cryst11060714⟩. ⟨hal-03442205⟩