Relative stability and species formation of Zn(II) ternary complexes involving L-Tryptophan, L- Citrulline, L-Glutamine with biologically active nulceobases Uracil and Thymine in solution

Abstract

Binary and ternary complexes of Zn(II) metal ions were prepared with the two nucleobases viz. Thymine and Uracil in a stoichiometric ratio of 1:1 and 1: 1:1 (Mn+: L), where Mn+ =Zn2 + and L = ligand (A) Amino acids (aa) L-Tryptophan, L- Citrulline, L-Glutamine and B = nulceobases : Uracil and Thymine in aqueous solution at 37 ± 1 °C. All the experiments performed kept the ionic strength I = 0.1 mol dm-3 (NaNO3) and done by potentiometric titration technique. The stoichiometric ratios of the formed complexes were done by using molar ratio method. The protonation constants of the ligands and the stability constants of the binary and ternary complexes of Zn(II) with the ligands were calculated from the method suggested by Irving and Rossetti method. Computed data were obtained using the ‘‘SCOGS’’ computer program are more refined. Origin 6.0 program software program used to the get the species distribution diagrams of the species formed at different pH range. The mixed ligand ternary complexes showed simultaneous formation in most cases observed at high pH range. The gradual drop of the binary concentration showed the ternary specie formation in that pH range. Here, we have described the general equilibria of complexes, amount of species (%) formed and their relative stability of Zn(II) mixed ligand ternary complexes and order of stability of the ternary complexes with respect to ligands used.