Synthesis and equilibrium studies of the Organotin (IV) species in relation to their toxic and the antitumor activity

The project aimed to study the behavior of organotin(IV) compounds as tripropyltin(IV) chloride and dipropyltin(IV) chloride in biological systems. The interaction of these organotin(IV) with some ligands of biological significance containing various binding sites as amino acid, peptides and DNA constituents was studied using potentiometric technique. The hydrolysis of tripropyltin(IV) and dipropyltin(iv) was investigated to calculate the hydrolysis constants. The formation constants of the complex of general formula MlLpHq were determined where M, L and H represent organotin, ligand and proton respectively. The result of tripropyltin(IV) hydrolysis proved the formation of the following hydrolysis species: [TPT(OH)], [TPT(OH)2]-, and [(TPT)2OH]-. The hydrolysis of dipropyltin(IV) leads to the formation of the following species: [(DPT) (OH)]+, [(DPT) (OH)2], [(DPT) (OH)3]- , [(DPT)(OH)4]2- and [(DPT)2(OH)3]3+.
The thermodynamic parameters for the hydrolysis were calculated. The result showed that amino acids and DNA constituents from 1:1 and 1:2 (organotin: ligand) complex with tripropyltin(IV) and dipropyltin(IV). However, peptides form 1:1 complex and the corresponding deprotonated form. The binding sites of the ligands were assigned and the concentration distributions of the various complexes were evaluated as a function of pH.