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.

Studies on the Coordination Reaction of VO2+ and Tannic Acid in the Tannin Extract Desulfurization

2012 ◽  
Vol 239-240 ◽  
pp. 1573-1576
Author(s):  
Zhu Qing Gao ◽  
Xiao Dong Cai ◽  
Kai Cheng Ling
Keyword(s):  
Stability Constants ◽  
Tannic Acid ◽  
Ph Value ◽  
Protonation Constants ◽  
Conditional Stability ◽  
Tannin Extract ◽  
Acid Effect ◽  
Different Temperatures ◽  
The Stability ◽  
Apparent Stability

At different temperatures, the protonation constants of tannic acid and the complex apparent stability constants between tannic acid and VO2+ were determined by using pH potentimetric method. The results showed that the protonation constants and the complex apparent stability constants slightly decreased with the raising temperature. In accordance with the pH value in the tannin extract technology, the conditional stability constants of the complex were calculated on the basis of the acid effect of tannic acid and the hydrolysis effect of VO2+. It was found that pH greatly affected the stability constants of the complex , so pH must be strictly controlled in the tannin extract technology.

Physicochemical investigation on thiomalate complexes of nickel

1968 ◽  
Vol 21 (3) ◽  
pp. 641 ◽  
Author(s):  
RS Saxena ◽  
KC Gupta ◽  
ML Mittal
Keyword(s):  
Aqueous Medium ◽  
Stability Constants ◽  
Alternative Methods ◽  
Acid System ◽  
Kcal Mole ◽  
Physicochemical Investigation ◽  
Different Temperatures ◽  
The Stability ◽  
Ph Range ◽  
Deep Violet

Potentiometric and conductometric studies of the nickel-thiomalic acid system, in aqueous medium of 0. lM KNO3, reveal the formation of two complexes; one light violet 1 : 1 predominating at pH 6.5-7.5 and another deep violet 1 : 2 in the pH range 8.5-10.0. The stability constants of the complexes formed have been determined by applying Calvin and Melchior's extension of Bjerrum's method at three different temperatures and were further refined by using alternative methods. The logK values (final) for 1 : 1 and 1 : 2 complexes at 20, 25, and 30� have been found to be 7.86, 7.87, 7.96, and 6.24, 6.31, 6.39 respectively. The values of the overall changes in ΔG, ΔH, and ΔS accompanying the reaction have also been evaluated at 25� and found to be -19.31 kcal/mole, -8.77 kcal/mole, and +35.36 cal/deg respectively.

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.

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.

Stability constants and spectral studies of complexes of 2-hydroxy-5-methylazobenzene-2′-carboxylic acid with some divalent metal ions

1984 ◽  
Vol 62 (11) ◽  
pp. 2299-2301
Author(s):  
C. Mahalingam ◽  
J. K. Sthapak ◽  
D. D. Sharma ◽  
R. L. Tiwari ◽  
Smita Sthapak
Keyword(s):  
Carboxylic Acid ◽  
Metal Ions ◽  
Metal Complexes ◽  
Stability Constants ◽  
Divalent Metal ◽  
Reflectance Spectra ◽  
Spectral Studies ◽  
Divalent Metal Ions ◽  
The Stability

The stability constants of metal complexes of 2-hydroxy-5-methylazobenzene-2′-carboxylic acid have been determined spectrophotometrically. These follow the Irving–Williams sequence: log KOH(H) = 10.67, log K1(Co) = 9.02, log K1(Ni) = 9.68, log K1(Cu) = 13.37, log K1(Zn) = 7.58, and [Formula: see text]The chelates of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and [Formula: see text] with the dye have been prepared and characterized on the basis of their ir and reflectance spectra.

Metal Complexes of 6-Hydroxymethylpyridine-2-carboxylic Acid

1962 ◽  
Vol 15 (4) ◽  
pp. 786 ◽  
Author(s):  
RW Green ◽  
GKS Ooi
Keyword(s):  
Carboxylic Acid ◽  
Transition Metal ◽  
Metal Ions ◽  
Metal Complexes ◽  
Stability Constants ◽  
Steric Hindrance ◽  
Transition Metal Ions ◽  
Complexing Agent ◽  
Ph Titration ◽  
The Stability

Spectrophotometric and pH-titration methods have been used to determine the stability constants at 25 �C of complexes between transition metal ions and the anion of 6-hydroxymethylpyridine-2-carboxylic acid. This anion is found to be a weaker base and a weaker complexing agent than the pyridine-2-carboxylate ion. There is some evidence for steric hindrance of tris complexes.

Interactions du Cu(II), du Hg(II) et du Pt(II) avec les formes monomères et dimères de la thymine, de la thymidine et de l'acide orotique

1987 ◽  
Vol 65 (7) ◽  
pp. 1479-1484 ◽  
Author(s):  
Raoul M'Boungou ◽  
Michelle Petit-Ramel ◽  
Germaine Thomas-David ◽  
Gérard Perichet ◽  
Bernard Pouyet
Keyword(s):  
Ionic Strength ◽  
Stability Constants ◽  
Binding Sites ◽  
Orotic Acid ◽  
Protonation Constants ◽  
Carboxylate Anion ◽  
Ring Nitrogen ◽  
The Stability

The protonation constants of monomeric (TM) and dimeric (TD) forms of thymine and monomeric (OM) and dimeric (OD) forms of orotic acid and thymidine (TY) have been calculated at 25 and 37 °C and at ionic strength μ = 0.1 (NaNO3). Under the same conditions the stability constants of their Cu(II), Hg(II), and Pt(II) complexes have been determined by protometric methods. The results have been discussed and a comparison has been established in terms of binding sites: nitrogen N3 for monomeric and dimeric forms of thymine and thymidine; carboxylate anion at C6 and adjacent ring nitrogen N1 for monomeric and dimeric forms of orotic acid.

Complexation binaire et ternaire des ions Cu(II), Hg(II) et Pt(II) par la D-valine et une série d'homologues de l'uracile

1989 ◽  
Vol 67 (6) ◽  
pp. 973-982 ◽  
Author(s):  
Raoul M'boungou ◽  
Michelle Petit-Ramel ◽  
Germaine Thomas-David ◽  
Gérard Perichet ◽  
Bernard Pouyet
Keyword(s):  
Ionic Strength ◽  
Stability Constants ◽  
Orotic Acid ◽  
Protonation Constants ◽  
Second Step ◽  
Simple Method ◽  
Mixed Complexes ◽  
The Stability

The protonation constants of uracil (UR), cytosine (CY), and D-valine (VA) have been calculated at 25 °C and at ionic strength μ = 0.1 (NaNO3). In a first step the stability constants of their Cu(II), Hg(II) and Pt(II) simple complexes were determined. In a second step the mixed complexation of several uracil homologues as thymine, thymidine, orotic acid and cytosine was also investigated under the same conditions by protometric methods. Concerning the mixed complexes, a new simple method of estimating their stability constants has been developed and verified. Keywords: Cu(II), Hg(II), Pt(II) coordination, ternary coordination, uracil homologues, D-valine, protometric methods.

Mercury(II) and Lead(II) Complexes of 1-Oxa-7-thia-4,10-diazacyclododecane ([12]aneN2OS)

1999 ◽  
Vol 52 (1) ◽  
pp. 1 ◽  
Author(s):  
Trevor W. Hambley ◽  
Shahara Afshar ◽  
Sebastian T. Marcus ◽  
Lawrence R. Gahan
Keyword(s):  
Stability Constants ◽  
Macrocyclic Ligand ◽  
Protonation Constants ◽  
Secondary Amines ◽  
Monoclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Stability ◽  
Lead Complex

The mixed donor 12-membered macrocyclic ligand 1-oxa-7-thia-4,10-diazacyclododecane ([12]aneN2OS) has been synthesized and the mercury(II) and lead(II) complexes, [Hg([12]aneN2OS)(NO3)2] and [Pb([12]aneN2OS)(NO3)2], have been isolated and characterized by X-ray crystallography. Crystals of the mercury complex are monoclinic, space group P 21/c, a 9·576(2), b 10·757(2), c 14·789(4) Å, β 93·58(2)°, whilst crystals of the lead complex are monoclinic, space group P 21/n, a 19·490(7), b 8·010(2), c 19·576(6) Å, β 109·90(2)°. The protonation constants and stability constants have been determined potentiometrically in aqueous solution. The protonation constants for [12]aneN2OS (log KHL 9·13; log K H2L 6·85) appear typical for secondary amines in similar trans-substituted 12-membered macrocycles. The magnitudes of the stability constants (HgII, log KHgL 10·5; PbII, log KPbL 6·6) are consistent with trends observed previously for macrocyclic ligands as secondary amine donors are replaced with oxygen and thioether donors.

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