Complex formation equilibria of zinc (II) ion with schiff bases as primary ligands and amino acids as secondary ligand

摘要

The formation constant of mixed ligand complexes of zinc (II) with Schiff bases (1-(2-hydroxy benzamido)-2-(fur-2- yl)-azomethine) L1, (1-2-hydroxyhexamido)-2-(thien-2-yl)-azomethine) L2 as primary ligands and Glycine (R1) , DLValine (R2) as secondary ligands have been determined potentiometrically in 40% (v/v) THF-water mixture at 300 C and ionic strength of 0.1 M NaClO4 . The proton ligand stability constants of free ligands and stability constant for ternary systems involving Schiff bases and amino acids were also determined under identical conditions .The PH titration data were analysed using the computer SCOGS programme. The relative stability of ternary complexes as compared to that of corresponding binary complexes has been quantitatively explained in terms of ΔlogK, KR, and KL values. The concentration distribution of various complex species as a function of PH was evaluated.