Stability Constants Of Mixed Ligand Complexes Research Articles

Solution and Solid State Study of Nickel(II) Ternary Complexes Containing 5-Aminolevulinic Acid Drug and Amino Acids

Solution equilibria of the systems Ni(II)-5-aminolevulinic acid as ligand (A) and the amino acids [alanine (Ala), valine (Val), methylamine (Met), imidazole (Imi), Histidine (His), serine (Ser), cysteine (Cys) and penicillamine (Pen)] as ligands (L) have been studied pH-metrically. The stability constants of mixed ligand complexes were calculated with I = 0.10 mol L-1 KNO3 using HYPERQUAD program at 25 ± 0.1 ºC. The log10 X values showed a higher stabilities for the mixed ligand complexes compared to the binary analogues. The synthesis and characterization of the new amino acid mononuclear Ni(II) binary complex [NiA] (1) and ternary complex [NiAL] (2) were achieved via molar conductance, elemental analysis UV-vis, IR, 1H NMR, thermal analysis and magnetic moment. The thermogravimetric analysis of complexes were investigated by TG-DTA suggests that the complexes possess high thermal stability formation and their respective nickel oxide for 1 and nickel sulfide for 2 as final chemical entities, which are thermally stable. The nickel(II) chelates were found to be non-electrolytes, diamagnetic moments and the geometry around Ni(II) ion in complexes 1 and 2 is square planar

Stability Constants of Mixed-Ligand Complexes of Cu(II) with Oxprenolol HCl as Pharmaceutical Ligand and Some Biologically Active Ligands

Stability Constants of Mixed-Ligand Complexes of Cu(II) with Oxprenolol HCl as Pharmaceutical Ligand and Some Biologically Active Ligands

Electrophoretic studies on the mixed nitrilotriacetate-penicillamine complexes of Pb2+ and UO2+2

A technique involving the use of paper electrophoresis is described for the study of binary and mixed-complex systems in solution. This technique is based on the movement of a spot of metal ion in an electric field with the complexants added in the background electrolyte at pH 8.5. The concentration of primary ligand (nitrilotriacetate) was kept constant, while that secondary ligand (penicillamine) was varied. A graph of log[penicillamine] versus mobility was used to obtain information on the mixed complexes and to calculate stability constants. The stability constants of mixed-ligand complexes lead(II)-nitrilotriacetate-penicillamine and uranyl(II)-nitrilotriacetate-penicillamine have been found to be 5.68 ± 0.09 and 6.56 ± 0.05 (logarithm stability constant values), respectively, at ionic strength 0.1 M and a temperature of 35°C.

Mixed-ligand complexes of copper(II) ions with AMP and CMP in the systems with polyamines and non-covalent interaction between bioligands

The occurrence of non-covalent interactions and formation of molecular complexes between adenosine 5′-monophosphate (AMP) or cytidine 5′-monophosphate (CMP) and the polyamines, putrescine, 1,7-diamino-4-azaheptane (3,3-tri), spermidine and 1,11-diamino-4,8-diazaundecane (3,3,3-tet), were detected in metal-free systems. The stoichiometric composition of the adducts and their stability constants were determined on the basis of computer analysis of the titration data, taking into account the fact that the acid–base properties of the system change as a result of these interactions. Spectral analysis allowed an identification of the interaction centers in the adducts as protonated amine groups of polyamines, phosphate groups as well as nitrogen atoms of high electron density from nucleotides. Unexpectedly, no participation of the phosphate group from AMP in the formation of molecular complexes with tetramine-3,3,3-tet was detected. The stoichiometric composition and stability constants of mixed-ligand complexes in the systems of Cu(II) with AMP or CMP and polyamines were obtained. Analysis of the results of equilibrium studies and 13C, 31P NMR, UV–Vis, IR and EPR data permitted determination of the mode of coordination. In the systems with metal ions, the formation of molecular complexes Cu(CMP)H 4(3,3-tri) was found, apart from heteroligand complexes of the MLL′ and MLL′H x type. In protonated complexes the occurrence of non-covalent interactions leading to stabilization of the coordination compounds was observed. The differences in the character of coordination biogenic amines and their biologically inactive analogs were identified.

Stability Constants of Mixed-ligand Complexes of lron(III), Cobalt(II), Zinc(II) and Cadmium(II) with Oxalic Acid as Primary Ligand and Glutathione(reduced) as Secondary Ligand

Stability Constants of Mixed-ligand Complexes of lron(III), Cobalt(II), Zinc(II) and Cadmium(II) with Oxalic Acid as Primary Ligand and Glutathione(reduced) as Secondary Ligand

Stability Constants of Mixed-ligand Complexes of lron(III), Cobalt(II), Zinc(II) and Cadmium(II) with Oxalic Acid as Primary Ligand and Glutathione(reduced) as Secondary Ligand

Stability Constants of Mixed-ligand Complexes of lron(III), Cobalt(II), Zinc(II) and Cadmium(II) with Oxalic Acid as Primary Ligand and Glutathione(reduced) as Secondary Ligand

Studies on Mixed-Ligand Complexes of Cadmium with 2,2′-Bipyridyl and Some Dicarboxylic Acids in Dioxane Medium

Abstract The mixed-ligand complexes of cadmium with 2,2′-bipyridyl and dicarboxylic acids (tartaric, succinic, maleic, malonic, and malic) were studied polarographically in the 50% dioxane medium. The stability constants of simple systems were calculated by Deford and Hume method, and the values of stability constants of mixed-ligand complexes have been determined by the method of Schaap and McMasters. The overall stability constants have been evaluated with the help of Leden’s graphical extrapolation method and the values of β11, β12 and β21 are (5.24, 5.80, and 8.19) for Cd-bpy-tartarate system (5.62, 6.15, and 8.34) for Cd-bpy-succinate system (5.48, 6.10, and 8.32) for Cd-bpy-maleate system (5.57, 6.15, and 8.37) for Cd-bpy-malonate system, and (5.57, 6.15, and 8.34) for Cd-bpy-malate system.

Polarographic Studies on Mixed Ligand Complexes of Cadmium with Dl-3-(3,4-Dihydroxyphenyl)alanine and Some Dicarboxylic Acids

Abstract The reductiou of Cd(II) has been carried out polarographically in the aqueous solution of Dl-3-(3,4-dihydroxyphenyl)alanine(DOPA). The stability constants were determined for the simple Cd–DOPA system first, and then mixed-ligand complexes of cadmium with DOPA and dicarboxylic acids (oxalic and malic) have been studied. The stability constants of mixed-ligand complexes have been evaluated by the method of Schaap and McMasters. With these data the statistical and electrostatic effects have also been considered.