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.

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.

scholarly journals Stability Studies of Transition Metal Chelates of 5-Bromosalicylidene-4-methoxyaniline andSalicylidene-2,3-dimethylaniline as Ligands

2011 ◽  
Vol 8 (4) ◽  
pp. 1911-1915
Author(s):  
N. G. Nadkarni ◽  
K. V. Mangaonkar
Keyword(s):  
Ionic Strength ◽  
Transition Metal ◽  
Stability Constants ◽  
Metal Chelates ◽  
Ternary Complexes ◽  
Water Medium ◽  
Stability Studies ◽  
Binary And Ternary Complexes ◽  
Transition Metal Chelates ◽  
The Stability

Binary and ternary complexes of the type M-Y and M-X-Y [M = Mn(II), Ni(II), Cu(II) and Zn(II); X = 5-bromosalicylidene-4-methoxyaniline and Y = salicylidene-2,3-dimethylaniline] have been examined pH-metrically at 27±0.5°C and at constant ionic strength, μ = 0.1 M (KCl) in 75 : 25(v/v) 1,4-dioxne-water medium. The stability constants for binary (M-Y) and ternary (M-X-Y) systems were calculated.

scholarly journals Potentiometric and spectrophotometric studies of the complexation of Schiff-base hydrazones containing the pyrimidine moiety

2003 ◽  
Vol 68 (10) ◽  
pp. 729-749 ◽  
Author(s):  
H.S. Seleem ◽  
B.A. El-Shetary ◽  
S.M.E. Khalil ◽  
M. Shebl
Keyword(s):  
Schiff Base ◽  
Ionic Strength ◽  
Thermodynamic Parameters ◽  
Stability Constants ◽  
Elemental Analysis ◽  
Mass Spectra ◽  
Dissociation Constants ◽  
The Stability ◽  
Pyrimidine Moiety ◽  
Metal Ligand

Three Schiff-base hydrazones (ONN ? donors) were prepared by condensation of 2-amino-4-hydrazino-6-methylpyrimidine with 2-hydroxyacetophenone 2-methoxybenzaldehyde and diacetyl to yield 2-OHAHP, 2-OMeBHPand DHP respectively. The structures of these ligands were elucidated by elemental analysis, UV, IR, 1H-NMR and mass spectra. The metal?ligand stability constants of Mn2+, Fe3+,Co2+,Ni2+,Cu2+, Zn2+,Cd2+,UO22+ and Th4+ chelates were determined potentiometrically in two different media (75%(v/v) dioxane?water and ethanol?water) at 283, 293, 303 and 313 K at an ionic strength of 0.05 M (KNO3). The thermodynamic parameters of the 1:1 and 1:2 complexes were evaluated and are discussed. The dissociation constants of 2-OHAHP, 2-OMeBHP and DHPligands and the stability constants of Co2+, Ni2 and Cu2+ with 2-OHAHP were determined spectrophotometrically in 75 % (v/v) dioxane?water.

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

1994 ◽  
Vol 72 (4) ◽  
pp. 1107-1110 ◽  
Author(s):  
Alexander Varghese Vaidyan ◽  
Pabitra K. Bhattacharya
Keyword(s):  
Ionic Strength ◽  
Aqueous Medium ◽  
Computer System ◽  
Stability Constants ◽  
Ternary Complexes ◽  
Binary And Ternary Complexes ◽  
The Stability ◽  
Interligand Interaction

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.

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.

The role of divalent cations in the activation of the NADP+-specific isocitrate dehydrogenase from Pisum sativum L.

1977 ◽  
Vol 55 (9) ◽  
pp. 928-934 ◽  
Author(s):  
Robert J. Maloney ◽  
David T. Dennis
Keyword(s):  
Ionic Strength ◽  
Stability Constants ◽  
Isocitrate Dehydrogenase ◽  
Divalent Cations ◽  
Free Form ◽  
Saturation Kinetics ◽  
The Difference ◽  
The Stability ◽  
Kinetics Of

A divalent cation electrode was used to measure the stability constants (association constants) for the magnesium and manganese complexes of the substrates for the NADP+-specific isocitrate dehydrogenase (EC 1.1.1.42) from pea stems. At an ionic strength of 26.5 mM and at pH 7.4 the stability constants for the Mg2+–isocitrate and Mg2+–NADP+ complexes were 0.85 ± 0.2 and 0.43 ± 0.04 mM−1 respectively and for the Mn2+–isocitrate and Mn2+–NADP+ complexes they were 1.25 ± 0.07 and 0.75 ± 0.09 mM−1 respectively. At the same ionic strength but at pH 6.0 the Mg2+–NADPH and Mn2+–NADPH complexes had stability constants of 0.95 ± 0.23 and 1.79 ± 0.34 mM−1 respectively. Oxalosuccinate and α-ketoglutarate do not form measureable complexes under these conditions. Saturation kinetics of the enzyme with respect to isocitrate and metal ions are consistent with the metal–isocitrate complex being the substrate for the enzyme. NADP+ binds to the enzyme in the free form. Saturation kinetics of NADPH and Mn2+ indicate that the metal–NADPH complex is the substrate in the reverse reaction. In contrast the pig heart enzyme appears to bind free NADPH and Mn2+. A scheme for the reaction mechanism is presented and the difference between the reversibility of the NAD+ and NADP+ enzyme is discussed in relation to the stability of the NADH and NADPH metal complexes.

Europium tartronate and mandelate ion association in water

1967 ◽  
Vol 45 (14) ◽  
pp. 1643-1647 ◽  
Author(s):  
P. G. Manning
Keyword(s):  
Ionic Strength ◽  
Solvent Extraction ◽  
Stability Constant ◽  
Stability Constants ◽  
Ion Association ◽  
Tridentate Ligand ◽  
Radiotracer Method ◽  
The Stability ◽  
Two Stages ◽  
Low Ionic Strength

Stepwise stability constants have been determined for the 1:1 and 1:2 Eu3+:mandelate− and Eu3+:tartronate2− complexes in water. Measurements were made at low ionic strength and the temperature was 25 °C. The solvent-extraction–radiotracer method was used.For the mandelate system at an ionic strength of 0.104, K1 = 5.0 × 102, K2 = 1.58 × 102, and K1:K2 = 3.1. The K1:K2 ratios suggest monodentate ligandcy.The stepwise stability constants for the two stages of tartronate ion association are: K1 = 7.1 ( ± 15%) × 104 and K1K2 = 4.2 ( ± 5%) × 108. The magnitudes of the stability constants suggest that tartronate is a tridentate ligand. The stability constant ratios are discussed with reference to the ratios for piperidinedicarboxylate and iminodiacetate complexes.

Coordination Compounds of Indium. Part XV. The Stability Constants of some Trifluoromethyl-β-diketonate Complexes of Indium (III)

1972 ◽  
Vol 50 (16) ◽  
pp. 2622-2625 ◽  
Author(s):  
Keith Bowden ◽  
(Mrs.) G. M. Tanner ◽  
D. G. Tuck
Keyword(s):  
Ionic Strength ◽  
Stability Constants ◽  
Coordination Compounds ◽  
Divalent Cations ◽  
Aqueous Acetone ◽  
Solvent Systems ◽  
The Stability

The stability constants K1 and K2 have been measured for the interaction of indium(III) with the ligands R•CO•CH2•CO•CF3 (R = 2-furyl, 2-thienyl, phenyl, 2-naphthyl, i-butyl, and (t-butyl). The pKa values for these compounds, and for R = 3-pyridyl and methyl, are also reported. A conventional potentiometric technique was used; the results refer to 46% aqueous acetone, at an ionic strength of approximately 0.1 M. The results are compared with published values for complexes of these ligands with divalent cations in other solvent systems.

Effects of ionic strength and pH on the stability constants of the complex of Co(II) with soil fulvic acid

1999 ◽  
Vol 241 (2) ◽  
pp. 351-353 ◽  
Author(s):  
W. M. Dong ◽  
W. J. Li ◽  
H. Q. Zhang ◽  
X. D. Wang ◽  
Z. J. You ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Fulvic Acid ◽  
Stability Constants ◽  
The Stability
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