Interaction of diphenyltin(IV) dichloride with some selected bioligands.

The interaction of diphenyltin(IV) with selected bioligands having a variety of model functional groups were investigated using the potentiometric technique. The hydrolysis constants of diphenyltin(IV) cation and the step-wise formation constants of the complexes formed in solution were calculated using the non linear least-squares program MINIQUAD-75. The participation of different ligand functional groups in binding to organotin is discussed. The concentration distribution of the various complex species was evaluated as a function of pH.

Equilibrium studies of the binary and ternary complexes involving tetracycline and amino acid or DNA constituents.

The acid-base equilibria of tetracycline and its copper(II) complex formation equilibria are investigated in dioxane-water mixtures. The ternary complexes of copper(II) with tetracycline as primary ligand and amino acid or DNA constituent as secondary ligand are studied in 50% dioxane-water solution. The formation constants of the ternary and binary complexes with amino acids or DNA constituents are determined. The concentration distribution of the various complex species are evaluated. Probable mode of chelation with tetracycline and DNA constituents is discussed.

Equilibrium studies of organotin(IV) complexes with vitamin B(6).

The complex-formation equilibria of dimethyltin(IV), trimethyltin(IV) and tributyltin(IV) with pyridoxamine were investigated in dioxane-water mixtures and at different temperatures using a potentiometric technique. The stepwise formation constants of the complexes formed in solution were calculated using the non-linear least-square program MINIQUAD-75. The effect of dioxane as a solvent on the protonation constants of pyridoxamine and the formation constants of organotin(IV) complexes was discussed. The thermodynamic parameters DeltaH degrees and DeltaS degrees calculated from the temperature dependence of the equilibrium constants were investigated. The concentration distribution of the various complex species was evaluated as a function of pH.

Coordination properties of cefadroxil antibiotic: synthesis and equilibrium studies of the binary and ternary complexes involving amino acids and DNA units.

The formation equilibria for the binary complexes of Cu(II), Ni(II), Co(II), Zn(II), Mn(II), Hg(II), Cd(II), Ca(II), and Mg(II) with cefadroxil (Cef) and for the ternary complexes Cu(Cef)(L), where L refers to amino acid or DNA, were investigated. The protonation constants of cefadroxil and formation constants of the formed complexes were determined at 25 degrees C and mu = 0.1 M NaNo(3). Cooper(II) and cobalt(II) complexes of cefadroxil were isolated in solid state and characterized by elemental analysis, infrared and electronic spectral, conductivity and magnetic measurement.

Equilibrium studies of the diorganotin(IV) complexes with some amino acids and related compounds.

The interaction of dimethyltin(IV) and diethyltin(IV) cations with water and some amino acids and related compounds was investigated at 25 degrees C and ionic strength 0.1 M NaNO(3) using a potentiometric technique. The results showed the formation of 11 and 12 (organotin:ligand) complexes and the corresponding stability constants were determined. The participation of different ligand functional groups in binding to organotin is discussed. The effect of the pK(a) value of the respective ligand on the stability constant of its complex species was elucidated. The concentration distribution of the complexes in solution was evaluated.

Potentiometric studies of binary and ternary complexes of amoxycillin.

The formation equilibria for the binary complexes of copper(II), nickel(II), cobalt(II) and zinc(II) with amoxycillin (Amx) and for the ternary complexes M(Arm)(Amx), where Arm refers to aromatic amines, namely 2,2'-dipyridyl or 1,10-phenanthroline, were investigated by a potentiometric technique. The protonation constants of amoxycillin and conditional stability constants of the formed complexes were determined at 25 degrees (=0.1M NaNO(3)). Probable mode of chelation with amoxycillin is discussed.

Ternary complexes of zinc(II) with nitrilotriacetic acid and some selected thiol amino-acids and related molecules.

Solution equilibria of the system zinc(II)-nitrilotriacetic acid (NTA)-secondary ligand (L) have been studied. The secondary ligands investigated are thiol amino-acids and related molecules. Potentiometric titrations of reaction mixtures containing equimolar Zn(2+), NTA and secondary ligand have shown the formation of 1 : 1 : 1 ternary complexes. The formation constants of these complexes have been determined at 25 degrees (mu = 0.1M, KNO(3)). The mode of chelation is discussed.