Estimation of the cyclic voltammetry parameters for pyridine-2,6-dicarbohydrazide and its interaction with CuCl₂ in various solutions

Abstract

The cyclic voltammetry of pyridine-2,6-dicarbohydrazide (H₂P) was performed in three different solutions with 0.1 M concentration of KCl, NaOH, and HCl. The pH value for the supporting electrolytes varies from acidic (4.30), alkaline (9.06), and neutral (6.96). Different cyclic voltammograms were obtained in the used media and discussed as follows: no cathodic or anodic peaks of ligand was observed in neutral medium whereas in acidic solution, only reduction peak detected at − 0.56 V but in case of basic solution, both reduction and oxidation peaks appeared at − 0.06 and 0.18 V, respectively. The addition CuCl₂ was also revealed to develop and explain the interaction of Cu²⁺ with the ligand in the applied media. The redox process of copper ion and ligand species appeared in using 0.1 M NaOH as a quasi-reversible wave and diffusion-controlled reaction. Upon application of 0.1 M HCl a detectable redox reaction of Cu²⁺ was observed in addition to the H₂P ligand was only reduced through an irreversible process. The high evaluated stability constants and Gibbs free energies of complexation on Cu²⁺-H₂P systems in both acidic and basic-enriched supporting electrolytes refer to the formation of stable coordinate complexes in solution measurements.

Graphical abstract