Abstract:
The aims of our research were to calculate the stability constants and thermodynamic stability of siderophore metal complexes at physiological pH, which has been using in chelation therapy of iron overload patients, efficacy of this drug against chelation therapy of other trace metal ions toxicity and its effect on the biological concentration of other ions which are present in the body. The metal ions which were used, Fe (III), Al (III), Cr (III), Co (II), Mn (II), Ca (II), Mg (II), Ni (II), Cu (II), Zn (II) and Cd(II).
In our research work the stability constants of siderophores (3, 4, 5 trihydroxy benzoic acid, N-Dihydroxy benzoxide) complexes of above mentioned trace metals were measured potentiometrically. The experimental results of ptentiometric titrations at different temperatures 30°C, 35C, 40C, 45C and 50C were treated with computer program "BEST". This program refined the results.
The stability constant values of metals-3,4,5 trihydroxy benzoic acid and N-Dihydroxy benzoxides complexes were compared and these values were found to be larger in case of trihydroxy benzoic acid complexes they were also compared with iron siderophores. It was found that iron siderophores complexes have high stability constant values and Al(lll) and Cr(lll) have comparable values with Fe(111) complexes. Among di positive ions Cu(ll) has highest value of stability constants.
Some complexes showed absorbance in the visible range such as Cr (lll), Mn (11), Fe (111), Co(ll), Ni(ll) and Cu(ll). They were studied spectrophotomeltrically. Mole ratio method and Job's method were applied and for this purpose spectra of these complexes were recorded with a UV/visible spectrophotometer and thus Amax· were selected. It was found that transition metal complexes have 1:3 metal ligand ratios while non transition metal have a ratio of 1:2.
