scholarly journals Stability Constants of Some Biologically Important Pyrazoles and Their Ni2+Complexes in Different Dielectric Constant of Medium

2012 ◽  
Vol 9 (2) ◽  
pp. 637-641 ◽  
Author(s):  
S. D. Deosarkar ◽  
A. L. Puyad ◽  
S. A. Chavan
Keyword(s):  
Dielectric Constant ◽  
Ionic Strength ◽  
Stability Constants ◽  
Metal Ion ◽  
Formation Constants ◽  
Water Mixture ◽  
Electrostatic Forces ◽  
Ph Titration ◽  
Titration Technique

The proton-ligand stability constants of some biologically important new pyrazoles and formation constants of their complexes with Ni(II) were determined at 0.1 mol dm-3ionic strength and at 303.15 K in different dielectric constant of dioxane-water mixture by potentiometric method. The Calvin-Bjerrum's pH-titration technique as used by Irving and Rossotti was used for determination of stability constants. The results enabled to study the electrostatic forces of attraction between metal ion and ligand with changes in dielectric constant of the medium.

Stability Constants of Palladium, Copper, Nickel, Zinc and Manganese Chelates of N-Benzoyl-N-phenylhydroxylamine

1967 ◽  
Vol 22 (9) ◽  
pp. 922-924 ◽  
Author(s):  
J. P. C. Jaimni ◽  
N. C. Sogani
Keyword(s):  
Ionic Strength ◽  
Stability Constants ◽  
Metal Ion ◽  
Chelating Agent ◽  
Ion Concentration ◽  
Water Mixture ◽  
Ph Titration ◽  
Nickel Zinc ◽  
Copper Nickel ◽  
Titration Technique

Stabilities of palladium, copper, nickel, zinc and manganese chelates of N-benzoyl-N-phenyl-hydroxylamine have been determined in 70% v/v dioxan-water mixture by employing Bjerr um-Calvin pH titration technique. The titration medium was maintained at a constant ionic strength (0.1 M KCI) and at a temperature, 25 ± 0.5°. Titrations were carried out in duplicate using 40 : 1 ratio of chelating agent to metal ion concentration.

Potentiometric Determination of Stability Constants of Trivalent Metal Ion Complexes with Di-p-tolyl-thiovioluric Acid

1976 ◽  
Vol 31 (8) ◽  
pp. 1096-1098 ◽  
Author(s):  
Pavan Mathur ◽  
D. P. Goel ◽  
R. P. Singh
Keyword(s):  
Stability Constants ◽  
Atomic Number ◽  
Metal Ion ◽  
Formation Constants ◽  
Potentiometric Determination ◽  
Trivalent Metal ◽  
Ionic Radii ◽  
Metal Ion Complexes

The consecutive formation constants of 1:1, 2:1, 3:1 chelate species formed by the interaction of di-p-tolyl-thiovioluric acid (D-p-TOTVA) with the tripositive lanthanons and yttrium cations were determined potentiometrically at 0.1 µ (NaClO4) at 30± 1°C, in 75% aqueous dioxan.The 1:1 formation constants (log K1) for the complexes increase with the increase in the atomic number of the lanthanon (3), with a break at gadolinium.The results indicate that the ligand bonds bidentately to heavier lanthanons (smaller ionic radii). However, definite dentate character of bonding to lighter (larger ionic radii) lanthanons could not be established.

scholarly journals Formation constants of lanthanide metal ion chelates with some substituted sulfonic acids

2010 ◽  
Vol 7 (1) ◽  
pp. 235-238
Author(s):  
R. S. Sonone ◽  
G. H. Murhekar
Keyword(s):  
Ionic Strength ◽  
Sulfonic Acid ◽  
Metal Ion ◽  
Formation Constants ◽  
Trifluoromethanesulfonic Acid ◽  
Water Mixture ◽  
Benzenesulfonic Acid ◽  
Sulfonic Acids ◽  
Lanthanide Metal ◽  
The Stability

The pKa and logK values of some substituted sulfonic acid in 70% (v/v) dioxane-water mixture have been determined using pH metric measurements. The stability constant of complexes of Gd (III), Tb (III) and Ho (III) with p-aminobenzenesulfonic (L1) and p-sulfophthalic acid (L2), 2-amino-5-chloro benzenesulfonic acid (L3) and trifluoromethanesulfonic acid (L4) have been determined at 0.1M ionic strength at 28±0.1 0C pH metrically. It is observed that both the metal ions formed 1:1 & 1:2 complexes with all the ligands.

scholarly journals Study of Complex Formation Between Iodoquinol (IQ) and Co2+, Mn2+, Cd2+, Pb2+and Zn2+Cations in Binary Aqueous / Non-aqueous Solvent Using Spectrophotometry

2007 ◽  
Vol 4 (4) ◽  
pp. 581-586 ◽  
Author(s):  
A. Nezhadali ◽  
H. A. Hosseini ◽  
P. Langara
Keyword(s):  
Ionic Strength ◽  
Complex Formation ◽  
Stability Constants ◽  
Spectrophotometric Method ◽  
Formation Constants ◽  
The Other ◽  
Aqueous Solvent ◽  
The Stability ◽  
Complexation Reactions

The complexation reactions between iodoquinol and Co2+, Mn2+, Cd2+, Pb2+and Zn2+cations were studied in different DMF/H2O binary mixtures at the ionic strength of 0.1(using NaNO3).The spectrophotometric method was used for the determination of formation constants and the stoichiometries. The stoichiometry of the complexes is established 1:1 by Job's and mole ratio methods. It was found that the stability constants of the complex formed between the ligand (IQ) and the cations in the all cases increase with increasing of the non-aqueous solvent. In the most cases the maximum formation constants between Zn2+ion and IQ were obtained respect to the other cations.

Chelate Formation of Riboflavine with Yttrium (III), Lanthanum (III), and Cerium (III)

1974 ◽  
Vol 29 (7-8) ◽  
pp. 339-342
Author(s):  
B.S. Sekhon ◽  
S.L Chopra
Keyword(s):  
Free Energy ◽  
Ionic Strength ◽  
Stability Constants ◽  
Ph Titration ◽  
Entropy Changes ◽  
Chelate Formation ◽  
Titration Technique

Abstract Stepwise stability constants of the interactions of 7,8-dimethyl (ribo-2,3,4,5-tetrahydroxypentyl) isoalloxazine (riboflavine) with Y (III) , La (III) and Ce (III) have been determined at 35 and 45 °C and ionic strength of 0.05 ᴍ using Bjerrum-Calvin pH titration technique. The values of free energy (⊿G), enthalpy (⊿H) and entropy changes (⊿S) have been reported.

The polarography of glycine metal complexes and the determination of stepwise formation constants

1961 ◽  
Vol 14 (4) ◽  
pp. 562 ◽  
Author(s):  
DP Mellor ◽  
HA McKenzie
Keyword(s):  
Metal Complexes ◽  
Formation Constants ◽  
Substantial Agreement ◽  
Titration Method ◽  
Ph Titration ◽  
Polarographic Behaviour ◽  
The Stability ◽  
Titration Technique ◽  
Stepwise Formation

The polarography of metal-glycine complexes has been studied with a view to assessing its usefulness in measuring the stability of metal complexes, especially the stepwise formation constants. It is shown that the equation derived by De Ford and Hume (1951) may be transformed in a way that makes possible the calculation of both overall and stepwise stoichiometric constants from experimental data obtained with solutions of constant ionic strength. Problems in the use of maximum suppressors and buffer ions are considered. Stoichiometric stepwise stability constants for the glycine complexes of copper(II) and cadmium(II) have been determined : (i) polarographically and (ii) by the pH- titration method of Irving and Rossotti (1954a, 1954b). The values obtained by the two methods agree reasonably well. Problems of hydrolysis and precipitation arise with t8he lead(II) complexes. The zinc(II) complexes exhibit anomalous polarographic behaviour. The reasons for this behaviour are briefly discussed. Although the polarographic technique is capable of yielding values for step constants in substantial agreement with those obtained by the pH-titration technique, there is evidence that it in not so generally applicable as the latter.

Chelation Reactions of Adenine

1972 ◽  
Vol 27 (6) ◽  
pp. 688-690 ◽  
Author(s):  
Ram Nayan ◽  
Arun K. Dey
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Metal Ions ◽  
Formation Constants ◽  
Ph Titration ◽  
Ionic Concentrations ◽  
Antimitotic Drug ◽  
Titration Technique

Chelation reactions of the antimitotic drug, 6-amino-purine (adenine; abbr. ADN) with the metal ions: Be(II), Al(III), Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Pb(II), and UO2(II) have been investigated in aqueous solution at 30° using Bjerrum-Calvin pH titration technique. The formation constants have been determined at various ionic concentrations, and have been extrapolated to zero ionic strength to get the thermodynamic values of the constants.

scholarly journals Potentiometric studies on complexes of Cr (Ⅲ) and Zr (IV)with some carboxylic acids

2015 ◽  
Vol 3 (1) ◽  
pp. 25 ◽  
Author(s):  
Abdalazeem Omar ◽  
Elmugdad Ali
Keyword(s):  
Stability Constants ◽  
Transition Elements ◽  
Ph Titration ◽  
Oxalacetic Acid ◽  
The Stability ◽  
Titration Technique ◽  
Metal Ligand ◽  
Sensitive Method ◽  
Good Agreement

<p>The present work, deals with the study of proton-ligand (pK) and metal-ligand (logK) of acetic acid, oxalic acid, and oxalacetic acid with Cr (Ⅲ) and Zr (IV) by potentiometric titration technique. The stoichiometries and stability constants of these complexes were evaluated, usingCalvin-Bjerrum pH-titration technique as adopted by Irriving and Rossotti.</p><p>Graphic and algebraic methods have been employed, for determination of the stability constants, in purpose to select the most accurate and sensitive method. Furthermore, aiming to determine, the factor that effectingthe precision of those methods under investigation, and to compare the complexes of these ligands with first and second series transition elements of D-block Cr and Zr taken as an example. The obtained results were in a good agreement with each other.</p>

scholarly journals Interaction of Ampicillin and Amoxicillin with Mn2+: A Speciation Study in Aqueous Solution

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3110
Author(s):  
Claudia Foti ◽  
Ottavia Giuffrè
Keyword(s):  
Aqueous Solution ◽  
Stability Constants ◽  
Metal Ion ◽  
Formation Constants ◽  
Enthalpy Change ◽  
Ligand Concentration ◽  
Empirical Parameter ◽  
Speciation Study ◽  
Potentiometric Measurements ◽  
The Stability

A potentiometric and UV spectrophotometric investigation on Mn2+-ampicillin and Mn2+-amoxicillin systems in NaCl aqueous solution is reported. The potentiometric measurements were carried out under different conditions of temperature (15 ≤ t/°C ≤ 37). The obtained speciation pattern includes two species for both the investigated systems. More in detail, for system containing ampicillin MLH and ML species, for that containing amoxicillin, MLH2 and MLH ones. The spectrophotometric findings have fully confirmed the results obtained by potentiometry for both the systems, in terms of speciation models as well as the stability constants of the formed species. Enthalpy change values were calculated via the dependence of formation constants of the species on temperature. The sequestering ability of ampicillin and amoxicillin towards Mn2+ was also evaluated under different conditions of pH and temperature via pL0.5 empirical parameter (i.e., cologarithm of the ligand concentration required to sequester 50% of the metal ion present in traces).

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