Thermodynamic study of the binding of dibenzo-18-crown-6 with Ag⁺, Pb²⁺and Cd²⁺in acetonitrile–water solvents

Abstract

Thermodynamic data for the binding of Ag', Pb2+ and Cd2+ nitrates with dibenzo-18-crown-6 in acetonitrile-, water solvents have been obtained in the temperature range 288-308 K using a conductometric technique. The observed molar conductivities, A, were found to decrease significantly for mole ratios less than unity. The conductivity data have been analysed using a model involving 1 : 1 stoichiometry. The stability constant, K , and the limiting molar conductivity, A , , for each 1 : 1 complex have been obtained from the measured conductivities by using a non-linear least-squares curve-fitting procedure. The complexation sequence, based on the value of log K at 298 K, was found to be Pb2+ > Cd2+ > Ag+. The significance of the reported values of AHo and ASo in the present work has been discussed.

A Newly Synthesized Tris(crown ether) Ionophore for Assisted Ion Transfer at NanoITIES Electrodes

“…For Li + ‐DB18C6, we calculated m to be ∼1 from the slope of 0.0262 mV −1 in Figure D. These measured stoichiometric coefficients are consistent with that reported in literatures, validating our method of determining the stoichiometric coefficients …”

“…Indeed, two‐step oxidation has been reported for the oxidation reaction of molecules with two oxidation centers . For Cd 2+ ‐ TriBCE , the calculated m is ∼2 based on the slope of 0.0263 mV −1 (Figure A), which is different from 1 : 1 ratio between DB18C6 and Cd 2+ . The difference in these stoichiometric ratios is likely due to the divalent property and the larger cation size of Cd 2+ .…”

“…These measured stoichiometric coefficients are consistent with that reported in literatures, validating our method of determining the stoichiometric coefficients. [66][67][68][69] For Li + -TriBCE, we calculated m to be~1 based on the slope of 0.0266 mV À 1 ( Figure 4B). This stoichiometric coefficient was similar to that of Li + -DB18C6.…”

“…[70] For Cd 2 + -TriBCE, the calculated m is~2 based on the slope of 0.0263 mV À 1 (Figure 4A), which is different from 1 : 1 ratio between DB18C6 and Cd 2 + . [68,69] The difference in these stoichiometric ratios is likely due to the divalent property and the larger cation size of Cd 2 + . Note that, a similar pattern in the stoichiometric coefficient was observed for the ionophore calcimycin, where the ratio was 1 : 1 between calcimycin and Li + , [71] and it was 2 : 1 between calcimycin and Cd 2 + .…”

Thermodynamic Study of Complexation Phenomena of Some Alkaline Earth Metal (II) Complexes in Propanol‐1‐Water Mixtures at Various Temperatures

“…Here, [A] which represents the molar concentration of free DADCT ligand shouldn't be replaced by [A]o which refers to the molarity of the total DADCT ligand because [A] can be experimentally deduced.Eqn. (10) can be rearranged as a quadratic equation in L where all these details of calculations and the physical significance of their parameters are included elsewhere 13. …”