Computational simulation with experimental result correlation of organophosphate pesticides: Fenthion, Fenamiphos, and Azamethiphos

Abstract

Amidst growing food production demands caused by demographic expansion, the use of chemical pesticides became pivotal, being most notable for the increase in consumption of insecticide DDT. However, awareness of their environmental and health impacts led to the ban of DDT; the transition to alternatives such as carbamate and organophosphates needs to be investigated to understand the environmental and health impacts that may be associated. Nowadays, electroanalytical techniques have been used with a way to quantify pesticides, a practice and cost-effective form to investigate these substances. The present study investigates organic pesticide organophosphates (OPs), particularly Fenthion, Fenamiphos, and Azamethiphos—through density functional theory (DFT) using the functional B3LYP and the 6-31G(d) basis set. Optimization process reveals variations in atomic charges linked to phosphorus, indicating differing electronegativity levels, while electrostatic potential maps (EPMs) highlight regions susceptible to interaction, aiding in understanding molecular interactions. UV–Vis spectra analysis demonstrated similarity between theoretical and experimental spectra, with observed hyperchromic effects. Frontier molecular orbital (HOMO) analysis indicated Fenamiphos (− 0.2196 eV) as an electron donor and Azamethiphos (− 0.2455 eV) as an electron acceptor of the group, with cyclic voltammetry analysis revealing oxidation processes, with Fenamiphos (1.2 V) exhibiting the lowest oxidation potential followed by Fenthion (1.3 V) and Azamethiphos (1.7 V), consistent with theoretical predictions and demonstrating the good consistency of the results obtained experimentally. This concise study combines computational and experimental approaches to offer insights into the properties, behavior, and potential of these pesticides, crucial for understanding their environmental impact and toxicity.