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Abstract
Metal ion complex formations are among the prominent interactions in nature, and metal complexation is of widespread interest. It is studied not only by analytical or inorganic chemists, but by physical and organic chemists, and also, by biochemists, pharmacologists, molecular biologists and environmentalists.
The purpose of this thesis is studying in depth, the formation of binary and ternary complexes of CuII, CoII, NiII, and ZnII metal ions with some selected zwitterionic buffers and some biologically important triazoles, and evaluation of the effect of the solvent and the temperature of the medium on the stability of their binary and ternary systems. This thesis is organized as follows:-
Chapter I:
This chapter includes, aim of the work, an introduction to the role of metal ions in biological systems, binary and ternary complex formation, and the role of buffers in life (biological systems).
Chapter II:
Chapter two is a concerted attempt to outline briefly a concise and complete review of the previous relevant studies conducted on the protonation constants, and formation of binary and ternary complexes of zwitterionic buffers.
Chapter III:
This chapter describes the experimental part of this thesis, which includes materials and solutions, experimental technique, apparatus, procedure and measuring conditions.
Chapter IV:
The acid-base properties of the ligands (ADA, bicine, tricine, 1,2,4-triazole, 3-mercapto-1,2,4-triazole, and 3-amino-1,2,4-triazole) were investigated and discussed. The acidity constants of the ligands were determined and used for determining the stability constants of the binary and ternary complexes formed in aqueous medium under the experimental conditions (t =25°C and I = 0.1 mol dm-3 NaNO3). The ternary complex formation was found to occur in a stepwise manner. The order of stability of the binary and ternary complexes in terms of the nature of zwitterionic buffers, triazoles and metal ions is investigated and discussed. The values of ∆logK, % R.S and ∆log X for the ternary systems have been evaluated and discussed. In addition, evaluation of the effect of temperature of the medium on the stability of the system (MII-ADA-3-amino-1,2,4-triazole) (MII = CuII, CoII, and NiII) has been studied. The thermodynamic parameters associated with the dissociation of the ligands studied (ADA and 3-amino-1,2,4-triazole) and the interaction of metal ions with ligands at 1:1 and at 1:1:1 molar ratio were calculated and discussed. The dissociation constants of ADA and 3-amino-1,2,4-triazole, and stability constants of their 1:1 binary and 1:1:1 ternary complexes with NiII in different water + dioxane mixtures at 25.0 ± 0.1oC and I = 0.1 mol dm-3 NaNO3 were investigated.