research
Conductometric measurements of complexation study between
4-Isopropylcalix[4]arene and Cr3+ cation in THF–DMSO binary
solvents
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Abstract
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 logKf 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 (DH�c and DS�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