Synthesis of a new Cd (II) complex as ionophores and its application in construction of a highly selective and sensitive cadmium (II) sensor in petroleum water samples

Abstract

The measurement of Cd (II) ions in various matrices requires the development of sensors that are selective, sensitive, and simple to produce. The cadmium complex of a ligand prepared by the reaction of 2‐pyridinecarbohydrazide with sodium 3‐formyl‐4‐hydroxybenzenesulfonate, [Cd (NaPH)(H2O)].H2O, was synthesized, analyzed by elemental analysis, and structurally elucidated using various spectroscopic techniques. The infrared spectrum of Cd (II) complex suggests a bi‐negative tri‐dentate ONO behavior for the ligand via deprotonated form of both the enolic oxygen atom (C‐O−) and the hydroxyl group of phenolic ring in addition to the azomethine group. The thermal behavior of this complex was revealed using TGA analysis. Applying Coast–Redfern and Horowitz–Metzger equations, we were able to calculate the kinetic and thermodynamic parameters to support the proposed fragmentation experiment for the Cd (II) complex. Cyclic voltammetry measurement was measured to estimate the electrochemical behavior of the Cd (II) ions as well as the impact of adding various NaH2PH ligand concentrations. The biological applications of [Cd (NaPH)(H2O)].H2O complex were assessed as antioxidant, anticancer, and antimicrobial. Based on the Cd (II) complex, we were able to modify Cd (II) ions carbon paste electrode (modified carbon paste electrode, MCPE) as a Cd (II) selective modifier. The created electrode displays a Nernstian slope in the linear range of 0.0001 to 10 mmol/L of 29.16 ± 0.03 mV decade−1, a quick reaction time of 6 s, and pH independence from 3–7. The suggested MCPE demonstrated strong selectivity to Cd (II) ions relative to many other cations and displayed negligible change in the slope or operating range if the experiment was achieved in a partially non‐aqueous solution. This fabricated MCPE was used to determine Cd (II) ions in diverse water samples.