A BIOMIMETIC SPECIATION STUDY OF BINARY COMPLEXES OF L-PHENYLALANINE AND MALEIC ACID WITH SOME METAL IONS IN UREA-WATER MIXTURES

Abstract

Speciation of binary complexes of Co(II), Ni(II), and Cu(II) with L-phenylalanine and maleic acid in the presence of Urea water mixtures in the concentration range of 0–50% v/v has been studied potentiometrically at a temperature of 298K and at an ionic strength of 0.16 mol L−1. The selection of best fit chemical models is based on statistical parameters and residual analysis. The species detected were ML, ML2, and ML2H2 for Co(II), Ni(II), and Cu(II). The appropriateness of the experimental conditions was verified by introducing errors deliberately. The models containing different numbers of species were refined by using the computer program MINIQuAD75. The chemical speciation was explained based on the distribution diagrams drawn using HYSS HYPERQUAD. The trend in variation of stability constants of the complexes with dielectric constant of the medium was attributed for the formation and possible structures of the complex species presented.