Effect of calcon carboxylic acid on association process of vanadyl sulfate in water‐N, N‐dimethyl formamide mixed solvents

The complexation reaction between calcon carboxylic acid (CCA) and vanadyl sulfate was studied in water and mixed water‐N, N‐dimethyl formamide mixed solvents (DMF-H2O) using conductometric measurements. The experimental data are already analyzed with the use of Fuoss-Shedlovsky technique in absence and presence of CCA. The ion-pair association (KA), and also the standard thermodynamic parameters for association (∆GoA, ∆HoA and ∆SoA) were estimated and compared in absence and presence of CCA. The main difference between Gibbs free energy of association in the presence and the case of absence of CCA indicate the value of free enthalpy of complexation (∆G°complexing). Walden product (Λ0 η0), hydrodynamic radii (RH) and the energy of activation (Ea.) were also calculated. This work provides the suggested structure of the complex based on elemental analyses and spectral study (IR) which provide the thermodynamic results with useful discussion. CCA act as binegative tetradentate coordination.