Speciation of complexes of Co (II), Ni (II) and Cu (II) with L-histidine in dioxan-water mixtures
2012
Raju, S. | Bharath Kumar Naik, K. | Ananda Kumar, B. | Nageswara Rao, G.
L-Histidine complexes of Co (II), Ni (II) and Cu (II) metal ions were studied pH-metrically in 0–60% v/v dioxan–water mixtures at a temperature of 303K and at an ionic strength of 0.16mol L⁻¹. Exhaustive modeling was performed to identify the species present in the present systems. The models contain MLH, ML₂H₄, ML₂H₂, ML₂H and ML₂ for Co (II), ML₂H₄, ML₂H₂, ML₂H and ML₂ for Ni (II), and MLH, ML₂H₂, ML₂H and ML₂ for Cu (II). The appropriate experimental conditions were verified by introducing errors intentionally in the concentrations of ingredients. The trend in the variation of stability constants with the dielectric constants of dioxan is explained on the basis of electrostatic and non-electrostatic forces. The bioavailability of metals and their transportation are explained based on the distribution diagrams.
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