Conductometric measurements of complexation study between 4-Isopropylcalix[4]arene and Cr3+ cation in THF–DMSO binary solvents

In the present work, the conductometric measurements for complexation process between Cr3+ cation and the macrocyclic ionophore, 4-Isopropylcalix[4]arene (IPC4) were studied in tetrahydrofuran–dimethylsulfoxide (THF–DMSO) binary non-aqueous medium at different temperatures. The results reveal that the stoichiometry of the IPC4–Cr3+ complex in all binary mixed solvents is 1:1. A non-linear behavior was observed for changes of log Kf of this complex versus the composition of the binary mixed solvents, which was explained on the basis of changes occurring in the structure of the mixed solvents and also the preferential solvation of the cation, ionophore and the resulting complex in the solution. The thermodynamic parameters (ΔH°c and ΔS°c) for the formation of IPC4–Cr3+ complexes were obtained from the temperature dependence of the stability constant using the van’t Hoff plots. The results obtained in this study, show that the formed complex is enthalpy destabilized, but entropy stabilized and the values of the mentioned parameters are affected strongly by the nature and composition of the binary mixed solvents. The experimental data was tested by using artificial neural network (ANN) program and was in a good agreement with the estimated data.