scholarly journals Study of Metal-1,10-Phenanthroline Complex Equilibria by Potentiometric Measurements

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Naciye Türkel
Keyword(s):  
Stability Constants ◽  
Metal Cations ◽  
Potentiometric Method ◽  
Ionic Radii ◽  
Binary Complexes ◽  
Potentiometric Measurements ◽  
Software Program ◽  
Phenanthroline Complex ◽  
The Stability ◽  
Potentiometric Data

The interaction of Sc(III), Y(III), and La(III) ions with 1,10-phenanthroline (Phen) has been investigated, using the potentiometric method at 25   and  M KNO3. Collected potentiometric data were processed by the “BEST” software program to establish the complexation model for each system. SPE software program was used to evaluate the concentration distributions of the species formed in solution. The stability constants for the binary complexes increased as the ionic radii of the metal cations decreased.

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).

scholarly journals Thermodynamic and Spectroscopic Studies of the Complexes Formed in Tartaric Acid and Lanthanide(III) Ions Binary Systems

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1121 ◽  
Author(s):  
Michal Zabiszak ◽  
Martyna Nowak ◽  
Zbigniew Hnatejko ◽  
Jakub Grajewski ◽  
Kazuma Ogawa ◽  
...  
Keyword(s):  
Tartaric Acid ◽  
Stability Constants ◽  
Binary Systems ◽  
Equilibrium Constants ◽  
Spectroscopic Studies ◽  
Luminescence Spectroscopy ◽  
Binary Complexes ◽  
Overall Stability ◽  
The Stability

Binary complexes of tartaric acid with lanthanide(III) ions were investigated. The studies have been performed in aqueous solution using the potentiometric method with computer analysis of the data for detection of the complexes set, determination of the stability constants of these compounds. The mode of the coordination of complexes found was determined using spectroscopy, which shows: Infrared, circular dichroism, ultraviolet, visible as well as luminescence spectroscopy. The overall stability constants of the complexes as well as the equilibrium constants of the reaction were determined. Analysis of the equilibrium constants of the reactions and spectroscopic data allowed the effectiveness of the carboxyl groups in the process of complex formation.

Fletcher–Powell minimization of analytical potentiometric data by microcomputer: application to the Cu(II) complexes of biological polyamines

1985 ◽  
Vol 63 (11) ◽  
pp. 3122-3128 ◽  
Author(s):  
Douglas M. Templeton ◽  
Bibudhendra Sarkar
Keyword(s):  
Biological Activity ◽  
Metal Complex ◽  
Stability Constants ◽  
Speciation Analysis ◽  
Complex Stability ◽  
Minimization Algorithm ◽  
The Stability ◽  
Best Fit ◽  
Complex Stability Constants ◽  
Potentiometric Data

The Fletcher–Powell minimization algorithm has been successfully implemented for the extraction of metal complex stability constants from analytical potentiometric data. The procedure has been adapted to run on a microcomputer with acceptable execution times, and several strategies are employed to speed convergence and avoid false minima. This allows economical minimization for a large number of models of speciation, and improves the reliability of the proposed best fit by encouraging the checking of more models than previously possible. The Ni(II)–glycine system has been analyzed and excellent agreement with the stability constants of an earlier multi-laboratory study has been attained. The system proves useful in the evaluation of both analytical and computational methods. The procedure has also been used for speciation analysis of the Cu(II) complexes of the growth regulating polyamines, spermine, and spermidine. Both systems form fully deprotonated complexes at physiological pH, which are relevant to their biological activity.

scholarly journals Studies of Binary Complexes of Tripodal Ligandcis,cis-1,3,5-tris(methylamino)cyclohexane with Cr(III) and Fe(III)

2005 ◽  
Vol 2 (1) ◽  
pp. 52-57
Author(s):  
S. Esakki Muthu ◽  
Suban K. Sahoo ◽  
Minati Baral ◽  
B. K. Kanungo
Keyword(s):  
Ionic Strength ◽  
Aqueous Medium ◽  
Molecular Mechanics ◽  
Stability Constants ◽  
Potentiometric Method ◽  
Molecular Mechanics Calculations ◽  
Tripodal Ligand ◽  
Binary Complexes ◽  
Overall Stability ◽  
Mode Of Coordination

The formation of binary complexes of Cr(III) and Fe(III) with a tripodal ligandcis,cis-1,3,5-tris(methylamino)cyclohexane (tmach) (L) has been investigated in solution. The overall stability constants oftmachwith Cr(III) and Fe(III) were determined by potentiometric method at an ionic strength of 0.1 M NaClO4at 25±1°C in aqueous medium. The formation of species like MLH25+, MLH4+, ML3+, ML(OH)2+and ML(OH)3were observed. Fe(III) was found to form more stable complexes than Cr(III). Molecular mechanics calculations were performed to explain the mode of coordination in solution.

Electrochemical Studies of the Stability of Copper β-Diketone Chelates

1998 ◽  
Vol 63 (12) ◽  
pp. 1963-1968 ◽  
Author(s):  
Wulfhard Mickler ◽  
Anke Mönner ◽  
Erhard Uhlemann
Keyword(s):  
Experimental Data ◽  
Stability Constants ◽  
Relative Stability ◽  
Complex Stability ◽  
Electrochemical Studies ◽  
Overall Stability ◽  
Potentiometric Measurements ◽  
The Stability

The voltammetric reduction of copper β-diketone chelates was used to get information on their complex stability. 1,1,1-Trifluoropentane-2,4-dione, pentane-2,4-dione, 1-phenylbutane-1,3-dione, 1,3-diphenylpropane-1,3-dione and 2,2,6,6-tetramethylheptane-3,5-dione were chosen as model ligands. The complexes were reduced in two separate steps the first of which proved to be reversible. The experimental data are suitable for calculation of the relative stability constants of corresponding Cu(I) and Cu(II) complexes. The data well correlate with the overall stability constants determined potentiometrically. The results were applied to some new hydrophobic β-diketones which are not accessible to potentiometric measurements.

Interaction en milieu eau–dioxane des ions Cu2+, Ni2+ et Ag+ avec les acides furannecarboxylique-2 et tetrahydrofurannecarboxylique-2

1982 ◽  
Vol 60 (9) ◽  
pp. 1063-1066 ◽  
Author(s):  
Emmanuelle Michaud ◽  
Gilles Pivert ◽  
Gérard Duc ◽  
Michelle Petit-Ramel ◽  
Germaine Thomas-David
Keyword(s):  
Carboxylic Acid ◽  
Stability Constants ◽  
Protonation Constants ◽  
Acid System ◽  
Copper Nickel ◽  
Uv Visible ◽  
The Stability ◽  
Potentiometric Data

The protonation constants of furan-2 carboxylic (HFC) and tetrahydrofuran-2 carboxylic (THFC) acids and the stability constants of their copper, nickel and silver 1:1 complexes have been measured in water containing 50% dioxane (I = 0.1 (NaNO3); t = 25 °C). Treatment of the potentiometric data has been completed by uv–visible spectrophotometric measurements. The results are discussed and a chelate structure is displayed for the Cu – tetrahydrofuran-2 carboxylic acid system.

scholarly journals Electrometric Investigation of the Nature and Stability of Mixed Ligand Complexes of L-Ornithine and 1,10-Phenanthroline with Some Essential Metal Ions in Aqua-TBAB or PEG-400 Surfactant

2021 ◽  
Author(s):  
Atnafu Guadie Assefa ◽  
Molla Tefera Negash ◽  
Mulugeta Legesse Akele ◽  
Bewketu Mehari Workneh ◽  
Ayal Adugna Mesfin ◽  
...  
Keyword(s):  
Metal Ions ◽  
Stability Constants ◽  
Tetrabutylammonium Bromide ◽  
Mixed Ligand ◽  
Mixed Ligand Complexes ◽  
Essential Metal ◽  
Peg 400 ◽  
Chemical Models ◽  
Binary Complexes ◽  
The Stability

Abstract Background Despite the availability of information about the effect of aqua-surfactants media on the stability of binary complexes, data related to mixed ligand complexes of Phen and Orn with essential metals in aqua-surfactant medium is scarce. The aim of this study was, to determine the stabilities of the mixed ligand complexes of essential metal ions (Co2+, Ni2+, Cu2+) with Phen and Orn in aqua-TBAB and PEG-400 surfactants with an eye on the prediction of the bioavailability of the metal complexes. Results Complexes of some essential metal (M) ions (Co2+, Ni2+, Cu2+) of L-ornithine (L) and 1,10-phenanthroline (X) ligands in various concentrations (0.0–2.5% v/v) of aqueous tetrabutylammonium bromide (TBAB) or polyethylene glycol-400 (PEG-400) surfactant were synthesized pH-metrically at 298 K and 0.16 mol L− 1 ionic strength. The relative amounts of L:M:X were 2.5:1.0:2.5; 5.0:1.0:2.5; 2.5:1.0:5.0. The data acquisition of acid-base equilibria and determination of stability constants were performed using MINIQUAD75 algorithm. The distribution patterns of the complexes with varying pH and compositions of surfactants were presented from the plots of SIM run data. Conclusions The best fit chemical models were found to be MLXH, MLX2H in the lower pH, and MLX, ML2X in the higher pH ranges for all the metals. The logged values of stability constants decreased linearly with increasing concentrations of surfactants, indicating the dominance of electrostatic factors. The log of the disproportionation constant and the change in log values of the mixed ligand constant indicated additional stability of the mixed ligand complexes, compared to the parent binary complexes due to interactions outside the coordination sphere. This makes the mixed ligand complexes more amenable to metal ion storage and transport and threw light to have information on the less stable binary complexes easily bioavailability while the mixed ligand complexes could be stored and transported in the bio-fluids. Significant change on the magnitudes of the stability constants, high values of standard deviation and rejection of some of the proposed chemical models were observed due to pessimistic error, indicating the sufficiency of the models to represent the data and accuracy of the method employed.

scholarly journals Studies on biologically important copper(II) / manganese(II) / uranyl(II) – norvaline binary complexes

2008 ◽  
Vol 27 (2) ◽  
pp. 157 ◽  
Author(s):  
Brij Bhushan Tewari
Keyword(s):  
Stability Constants ◽  
Coordination Compounds ◽  
Metal Ion ◽  
Background Electrolyte ◽  
Binary Complex ◽  
Paper Strip ◽  
Ph Values ◽  
Binary Complexes ◽  
Stability Constants Of Complexes ◽  
The Stability

In coordination compounds studies, a knowledge of the magnitude of the stability constants of complexes is necessary for preliminary quantitative treatment. Described herein is a method that involves the use of advanced ionophoretic technique for the study of the equilibria in binary complex systems in solution. This method is based upon the migration of a spot of the metal ion on a paper strip at different pH values of background electrolyte containing 0.1 M perchloric acid and 0.01 M norvaline. A graph of pH against mobility provides information about the nature of the complexation and helps in calculating stability constants. Using this method, the stability constants of binary complexes metal(II) – norvaline have been determined to be (8.11 ± 0.02, 7.03 ± 0.09); (3.77 ± 0.11, 2.39 ± 0.07) and (7.59 ± 0.05, 6.17 ± 0.04) (log K values) for Cu(II), Mn(II) and UO2(II) complexes, respectively, at 35 ºC.

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