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Percentage distribution and structural elucidation of quaternary metal chelates of proline with IMDA and uracil in aqueous medium

Surabhi Sinha, V.P.Shukla, V.Krishna

A method is described for calculating equilibrium concentrations of all species in multi-metal-multi-ligand mixtures from the pH of the solution; total concentration of each metal, complexing agent, and the relevant equilibrium constants (pK(a) values and stability constants). Ternary and quaternary metal chelates of some biologically important bivalent transition metal ions viz. Co(II), Ni(II), Cu(II) and Zn(II) formed with biologically significant ligands, viz. IMDA/Uracil and Proline have been investigated. The relevant stability constants and complexation equilibria of quaternary metal chelates in solution at 37±1ºC and at constant ionic strength (I=0.1M NaNO3) have been studied potentiometrically. Species distribution curves are obtained by plotting percent (%) concentration of the species obtained through SCOGS computer technique against pH. The distribution curves are finally sketched by running the computer programORIGIN 4.0. The metal ligand formation constant of ML1, ML2, ML1L2 and M1M2L1L2 type of complexes follow IrvingWilliamorder. The order of stability constants of quaternary systems has been observed and probable solution structures of metal complexes with said ligands have been discussed.