Ternary Complexes Of Zn Research Articles

Relative stability and species formation of Zn(II) ternary complexes involving L-Tryptophan, L- Citrulline, L-Glutamine with biologically active nulceobases Uracil and Thymine in solution

Binary and ternary complexes of Zn(II) metal ions were prepared with the two nucleobases viz. Thymine and Uracil in a stoichiometric ratio of 1:1 and 1: 1:1 (Mn+: L), where Mn+ =Zn2 + and L = ligand (A) Amino acids (aa) L-Tryptophan, L- Citrulline, L-Glutamine and B = nulceobases : Uracil and Thymine in aqueous solution at 37 ± 1 °C. All the experiments performed kept the ionic strength I = 0.1 mol dm-3 (NaNO3) and done by potentiometric titration technique. The stoichiometric ratios of the formed complexes were done by using molar ratio method. The protonation constants of the ligands and the stability constants of the binary and ternary complexes of Zn(II) with the ligands were calculated from the method suggested by Irving and Rossetti method. Computed data were obtained using the ‘‘SCOGS’’ computer program are more refined. Origin 6.0 program software program used to the get the species distribution diagrams of the species formed at different pH range. The mixed ligand ternary complexes showed simultaneous formation in most cases observed at high pH range. The gradual drop of the binary concentration showed the ternary specie formation in that pH range. Here, we have described the general equilibria of complexes, amount of species (%) formed and their relative stability of Zn(II) mixed ligand ternary complexes and order of stability of the ternary complexes with respect to ligands used.

Ternary complexes of Zn(II) and Cu(II) with 1-((2-hydroxynaphthalen-1-yl)methylene)-4-phenylthiosemicarbazide in the presence of heterocyclic bases as auxiliary ligands: Synthesis, spectroscopic and structural characterization and antibacterial activity

The new ternary complexes, ZnLL′ [L = 1-((2-hydroxynaphthalen-1-yl)methylene)-4-phenylthiosemicarbazide and L′ = imidazole (1), 2, 2′-bipyridine (2) and 2-methyimidazole (3)], Zn2L2L′ [L′ = 4, 4′-bipy (4)] and CuLL′ [L′ = 2, 2′-bipy (5)] have been synthesized by the reaction of a metal(II) acetate salt with the thiosemicarbazone and in presence of heterocyclic bases as auxiliary ligands. The synthesized compounds were investigated by elemental analysis and IR, 1H NMR, and 13C NMR spectroscopy and complex 5 was structurally characterized by X-ray crystallography. The results indicate the thiosemicarbazone doubly deprotonated and coordinates to metal through the thiolate sulfur, imine nitrogen and phenolic oxygen atoms. The nitrogen atom(s) of the auxiliary ligand complete the coordination sphere. Complex 4 is binuclear with 4, 4′-bipy acting as a bridging ligand. The structure of 5 is a distorted square pyramid with one of the bipyridine nitrogen atoms in the apical position. This compound creates an inversion dimer in solid state by intermolecular hydrogen bonds of NH⋯S type. The in vitro antibacterial activity of the synthesized compounds were evaluated against Gram-positive (B. subtilis and S. aureus) and Gram-negative (P. aeruginosa) bacteria and is compared to that of standard antibacterial drugs. All complexes exhibit good inhibitory effects and are significantly more effective than the parent ligand.

PH-Metric Studies of Mixed Ligand Complexes of Zn(II) with Famotidine and Peptides

Solution equilibria of the ternary complexes of Zn(II) with famotidine (FAM) as primary ligand and peptides (L) as secondary ligands have been studied pH-metrically under the experimental conditions (25°C and ionic strength I=0.10 mol/L NaNO3). Ternary complexes are formed by a simultaneous mechanism. The concentration distribution of the complexes in solution was evaluated as a function of pH. The values of Δ log K values for the ternary complexes have been evaluated and discussed.

Studies of Ternary Complexes of Zn (Il) Involving Aminocarboxylic Acids and NTA (Nitrilotriacetic Acid) by Paper Electrophoresis

Paper Electrophoresis study of mixed complexes of metal ions with 2-aminobenzoic acid, 3-aminobenzoic acid and 4-aminobenzoic acid as primary ligand and NTA as secondary ligand. Experimental procedure adopted for simple complexation studies is modified. The background electrolyte contains primary ligand in addition to perchloric acid and the pH is maintained at 8.5, the concentration of secondary ligand NTA is progressively increased and the electrophoretic observation of the metal ion spot on paper strip is taken at every addition of the secondary ligand, all the observations have been recorded under the Potential, 200 volts; Time, 30 min; Temperature, 25°C; Ionic strength, 0.1; Potential gradient; 6.66 volt/cm. Using the principle of average mobility, stability constant can be calculated with the help of mobilities. The higher values or stability constant of ternary complexes of 3-aminobenzoic acid than those of 4-aminobenzoic acid and 2-aminobenzoic acid and that of 4aminobenzoic acid than 2-aminobenzoic acid are attributed to the stronger acidic character of 3-aminobenzoic acid than 4-amino, and 2-aminobenzoic acid and that of 4-aminobenzoic acid than 2-aminobenzoic acid. It must be noted that higher values of stability constants in case of ternary complexes than binary complexes indicate their increased stability.

Solution Equilibria of Binary and Ternary Complexes Involving Zinc(II) with 2,6-Diaminopyridine and Various Biologically Relevant Ligands

The complexing properties of 2,6-diaminopyridine (DAP) with zinc(II) were investigated pH-metrically at 25 °C and at ionic strength of 0.1 mol·dm−3 (NaNO3). Binary and ternary complexes of Zn(II) involving DAP and various biologically relevant ligands containing different functional groups are investigated. The ligands used (L) are amino acids, dicarboxylic acids, amides and DNA unit constituents. The ternary complexes are formed by simultaneous reactions. The results showed the formation of Zn(DAP)(L) complexes with amino acids and dicarboxylic acids. Amides form both Zn(DAP)(L) complexes and the corresponding deprotonated amide species Zn(DAP)(LH−1). The concentration distributions of the various complex species formed in solution were also evaluated as a function of pH. The effect of dioxane as a solvent on the protonation constant of DAP and the formation constants of Zn(II)–DAP complexes were discussed. The effect of ionic strength on the protonation constants of DAP is also evaluated.

Potentiometric studies of binary and ternary complexes of Zn(II) with triethylenetetramine as primary ligand and selected amino acids and DNA units as secondary ligands

The acid-base equilibria of triethylenetetramine. (Trien) and the formation equilibria of binary and ternary complexes of Zn(II) with Trien as primary ligand and some selected arnino acids and DNA units as secondary ligands have been investigated. The results showed the formation of a 1∶1 Zn (Trien)2+ complex. At higher pH, the Zn (Trien)2+ complex is hydrolysed to give Zn (Trien) (OH)+ and Zn(Trien)(OH)2 complexes. The fraction of the monohydroxo species attains a maximum of 81.3% at pH 10. The stability constantsKZn(Trien)AZn(Trien) for the ternary complexes were determined. Histidine coordinates in a histamine-like way. Lysine and ornithine ligate by the two amino groups. Serine and methionine are bound in a glycine-like mode. However, penicillamine, cysteine and glutathione ligate partly like mercaptoethylamine and partly like mercaptopropionic acid. In the case of DNA complexes, inosine is bound through the n1 atom. However, uracil, undine, thymine and thymidine ligate through the N3 atom. The relative stabilities of ternary complexes are compared with those of the corresponding binary complexes in terms of Δ logK values. The concentration distribution diagrams of the complexes are evaluated.

Interligand interaction in ternary complexes of Zn(II) and Cd(II) with dipeptides and aminoacids

The stability constants of binary and ternary complexes [MA], [Ma2], and [MAL] (where M = Zn(II) or Cd(II); A = glycylglycine, glycyl L-alanine, glycyl L-leucine; L = α-alanine phenylalanine, tyrosine, tryptophan, or L-histidine) in aqueous medium have been determined potentometrically at 25 °C and an ionic strength of 0.2 M NaClO4 (0.2 mol dm−3) using a computer system. It is observed that Δ log K of MAL complexes has low negative or positive values. Probable reasons have been discussed.

Mixed ligand complexes involving sulphur containing ligands—Part II. Ternary complexes of Zn(II) involving L-cysteine/ D-penicillamine/ L-cysteic acid and imidazoles

The chemical equilibria involved in nine mixed ligand systems Zn(II)— L-cysteine (Cys)/ D-penicillamine(Pen)/ L-cysteic acid(Cya)(A)—imidazole(Him), histamine(Hist) and L-histidine(His)(B) have been investigated in aqueous perchlorate medium by pH titrimetry at 37° and ionic strength, I = 0.15 M (NaClO 4). The mixed ligand complex species of the types ZnABH 2, ZnABH, ZnAB or ZnAB 2 have been detected in addition to various binary species due to ligands A and B. The results obtained for the ZnABH type of species indicate that the site of protonation is the amino group of Cys/Pen ligands in the Zn(II)—Cys/Pen(A)—Him, Hist and His(B) systems, and the amino group of Hist/His secondary ligands in the Zn(II)—Cya(A)—Hist and His(B) systems. In the ZnABH 2 type of species, one proton is attached with the primary ligand (A) and the other with the secondary ligand(B). In both ZnAB and ZnAB 2 type ternary species in all the systems, the primary ligand binds the metal in a bidentate manner and the secondary ligands Him, Hist and His bind the metal, respectively in a uni, bi and terdentate manner.

Synthesis and biocidal activity of Zn(II) complexes of some 2,2'-substituted diphenylamines

Binary as well as ternary complexes of Zn(II) with diphenylamine-2,2'-dicarboxylic acid (dpdc), diphenylamine-2-amino-2'-carboxylic acid (dpac), diphenylamine-2-hydroxy-2' -carboxylic acid (dphc), diphenylamine-2-mercapto-2'-carboxylic acid (dpmc), and N-(2-pyridino) anthranilic acid (npa) have been synthesized and characterized by their elemental analysis, IR spectral data, and molar conductance measurements. Antimicrobial activity of these ligands and their respective Zn(II) complexes have been determined on gram positive ( Staphylococcus aureus) and gram negative ( Escherichia coli) bacteria and on Aspergillus niger and Aspergillus nidulense, two common fungi by the serial dilution method. A considerable increase in the biocidal activity of these ligands on being coordinated with the metal ion has been reported in terms of their minimum inhibitory concentration (MIC) values.

Potentiometric Studies on Ternary Complexes of Zn(II) and Cd(II)

Potentiometric Studies on Ternary Complexes of Zn(II) and Cd(II)