Electrochemical study of gallium(III) with <Emphasis Type="SmallCaps">l</Emphasis>-glutamine at the dropping mercury electrode

Abstract  

Gallium complexes of l-glutamine have been studied polarographically in aqueous media. The reduction was found to be irreversible and diffusion controlled in the presence of 0.1 M KNO₃ and 0.002% Triton-x-100. The values of kinetic parameters, transfer coefficient (α _n), and formal rate constant ( k_{\textf,\texth}⁰ k_{{{\text{f}},{\text{h}}}}^{0} ) of the electrode reactions were calculated by Koutecky's method. The stability constants and composition of the gallium(III)-l-glutamine complexes were evaluated with the help of the Deford-Hume method. The values of stability constants of 1:1, 1:2, and 1:3 gallium(III)-l-glutamine complexes are 1.35, 6.5, and 1,350 at 30 °C, respectively. The values of thermodynamic parameters, the free energy of activation, the enthalpy of activation, and the entropy of activation have been determined at 30 °C. The formation of the metal complexes has been found to be non-spontaneous, endothermic in nature, and entropically favorable at higher temperature.