Complexation of americium with humic, fulvic and citric acids at high ionic strength

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.

Download Full-text

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

Journal of the Serbian Chemical Society ◽

10.2298/jsc0310729s ◽

2003 ◽

Vol 68 (10) ◽

pp. 729-749 ◽

Cited By ~ 13

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.

Download Full-text

Determination of Co(II) and Ni(II)-humate stability constants at high ionic strength NaCl solutions

Radiochimica Acta ◽

10.1524/ract.2000.88.9-11.583 ◽

2000 ◽

Vol 88 (9-11) ◽

Cited By ~ 9

Author(s):

D.N. Kurk ◽

Gregory R. Choppin

Keyword(s):

Humic Acid ◽

Ionic Strength ◽

Solvent Extraction ◽

Potentiometric Titration ◽

Stability Constants ◽

Dissociation Constants ◽

High Ionic Strength ◽

Extraction Technique ◽

Solvent Extraction Technique

Complexation of Ni(II) and Co(II) by unfractionated humic acid (HA) was measured in 0.3 to 5.0 m NaCl solutions at pH 6 and 20 °C, using a solvent extraction technique. The dissociation constants and capacities of the humic acid were investigated in 0.1 to 5.0 m NaCl solutions at 25 °C using potentiometric titration methods.

Download Full-text

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

Canadian Journal of Chemistry ◽

10.1139/v94-140 ◽

1994 ◽

Vol 72 (4) ◽

pp. 1107-1110 ◽

Cited By ~ 7

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.

Download Full-text

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

Canadian Journal of Biochemistry ◽

10.1139/o77-139 ◽

1977 ◽

Vol 55 (9) ◽

pp. 928-934 ◽

Cited By ~ 6

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.

Download Full-text

Europium tartronate and mandelate ion association in water

Canadian Journal of Chemistry ◽

10.1139/v67-267 ◽

1967 ◽

Vol 45 (14) ◽

pp. 1643-1647 ◽

Cited By ~ 3

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.

Download Full-text

On the stability of extremely diluted aqueous solutions at high ionic strength

Journal of Thermal Analysis and Calorimetry ◽

10.1007/s10973-007-8840-y ◽

2008 ◽

Vol 92 (2) ◽

pp. 643-648 ◽

Cited By ~ 12

Author(s):

V. Elia ◽

E. Napoli ◽

M. Niccoli

Keyword(s):

Ionic Strength ◽

Aqueous Solutions ◽

High Ionic Strength ◽

Extremely Diluted Aqueous Solutions ◽

The Stability

Download Full-text

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

Canadian Journal of Chemistry ◽

10.1139/v72-420 ◽

1972 ◽

Vol 50 (16) ◽

pp. 2622-2625 ◽

Cited By ~ 1

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.

Download Full-text