Speciation of protonated and nonprotonated complex species in biologically important mixed-ligand systems of dopamine (DOPM)

摘要

Equilibrium studies on mixed ligand and mixed metal systems of biological relevance is the most fascinating area of research for inorganic chemists. This can be attributed to the interesting results generated from such studies. Present paper deals with the pH-metric equilibrium investigation on Ni(II)-DOPM-ala/phe/asp/glu ternary systems.The systems were investigated keeping the metal and ligands in equimolar ratio at three different ionic strengths (i.e. 0.05M, 0.10M and 0.15M (NaNO3)) at 20±1°C and 30±1°C in aqueous medium, Values of formation constants of protonated and nonprotonated complexes were calculated by algebraic method of Chaberek & Martell as modified by Dey et. al. and refined by SCOGS computer program. Various thermodynamic parameters were determined and percentage distribution of each complex species as a function of pH was obtained.