Stability constants for metal complexation by isomers of mimosine and related compounds

1980 ◽  
Vol 33 (10) ◽  
pp. 2207 ◽  
Author(s):  
H Stunzi ◽  
LN Harris ◽  
DD Perrin ◽  
T Teitei
Keyword(s):  
Aqueous Solution ◽  
Complex Formation ◽  
Blood Plasma ◽  
Stability Constants ◽  
Complexing Agent ◽  
Propanoic Acid ◽  
Metal Chelation ◽  
Plasma Model ◽  
Physiological Conditions ◽  
Related Compounds

Stability constants for the Mg2+, Ca2+, Cu2+ and Zn2+ complexes of two isomers (2) and (3) of the defleecing agent mimosine (1) have been sought from potentiometric titrations in aqueous solution, 0.15 M KNO3, at 37°. For the interpretation of the results, complex formation of the simpler ligands 3-hydroxypyridin-4(1H)-one (4), its 2-oxo isomer (5) and DL-α-amino-β-(6-oxo-1,6-dihydropyridin-2-yl)propanoic acid (6) was studied. The results with ligand (2) are very similar to those with mimosine, for which a computer blood-plasma model indicates metal chelation under physiological conditions. Ligand (3) is a much weaker complexing agent.

Study of the properties of pyridine-2-azo-p-phenyltetramethylguanidine as a metal ion complexing agent

1991 ◽  
Vol 69 (8) ◽  
pp. 1238-1244 ◽  
Author(s):  
Kenneth T. Leffek ◽  
Arnold Jarczewski
Keyword(s):  
Complex Formation ◽  
Stability Constants ◽  
Metal Ion ◽  
Nmr Spectra ◽  
Dissociation Constants ◽  
Activation Parameters ◽  
Complexing Agent ◽  
The Stability ◽  
Metal Ligand ◽  
C Nmr

Pyridine-2-azo-p-phenyltetramethylguanidine (PAPT) was synthesized and the properties of this compound examined. The dissociation constants of the conjugate acids in H2O are [Formula: see text] and [Formula: see text] at 25 °C at I = 0.1, and in acetonitrile are [Formula: see text] and [Formula: see text]. The properties of metal–ligand chelates in acetonitrile have been examined and the stability constants for Ni2+, Co2+, and Zn2+ complexes measured. The rates of reaction of PAPT with Ni2+, Co2+, and Zn2+ in acetonitrile have been determined and the activation parameters measured for the complex formation of LNi2+. The stability constants for both complexing centres of PAPT have been calculated. The 13C NMR spectra for PAPT and LNi2+ are quoted. The expected enhancement of the metal ion complexing ability of PAPT due to the strongly electron-releasing nature of the tetramethylguanidinyl group was not found. Key words: metal ion complexes, pyridine-2-azo-p-phenyltetramethylguanidine, stability constants, pKa.

Uranium(VI) complexes with sugar phosphates in aqueous solution

2004 ◽  
Vol 92 (12) ◽  
Author(s):  
A. Koban ◽  
Gerhard Geipel ◽  
A. Roßberg ◽  
G. Bernhard
Keyword(s):  
Aqueous Solution ◽  
Complex Formation ◽  
Potentiometric Titration ◽  
Stability Constants ◽  
Complex Stability ◽  
Aqueous Systems ◽  
Ligand Ratio ◽  
Sugar Phosphates ◽  
Complex Stability Constants

SummaryThe complex formation in the aqueous systems of uranium(VI) with glucose 6-phosphate (G6P) and fructose 6-phosphate (F6P) were studied using potentiometric titration, TRLFS, and EXAFS. Two complexes with a uranyl-to-ligand ratio of 1:1 and 1:2 for both sugars were observed. Complex stability constants were determined by potentiometric titration for both complexes to be log βThe TRLFS measurements results show the UOUranium

Complex formation of nickel(II) ions with citric acid in aqueous solution: a potentiometric and spectroscopic study

1980 ◽  
Vol 33 (8) ◽  
pp. 1685 ◽  
Author(s):  
GR Hedwig ◽  
JR Liddle ◽  
RD Reeves
Keyword(s):  
Aqueous Solution ◽  
Citric Acid ◽  
Complex Formation ◽  
Spectroscopic Study ◽  
Hydroxy Group ◽  
Stability Constants ◽  
Spectrophotometric Study ◽  
Ph Range

From a potentiometric and visible spectrophotometric study of the nickel(II)-citric acid (H3L) system in the pH range 3-6, four complexes, NiL-, NiHL, NiH2L+ and NiL24-, have been characterized. Stability constants for the formation of these complexes have been determined at 25°C in 0.1 mol dm-3 KCl. The results suggest that the hydroxy group of citric acid is coordinated in the nickel-citrate complexes.

Schiff base equilibria. II. Beryllium complexes of N-n-butylsalicylideneimine and the hydrolysis of the Be2+ ion

1965 ◽  
Vol 18 (5) ◽  
pp. 651 ◽  
Author(s):  
RW Green ◽  
PW Alexander
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Complex Formation ◽  
Distribution Coefficient ◽  
Dilute Aqueous Solution ◽  
The Stability ◽  
Ph Range ◽  
Hydrolysis Of ◽  
Beryllium Complexes ◽  
Equilibria In Aqueous Solution

The Schiff base, N-n-butylsalicylideneimine, extracts more than 99.8% beryllium into toluene from dilute aqueous solution. The distribution of beryllium has been studied in the pH range 5-13 and is discussed in terms of the several complex equilibria in aqueous solution. The stability constants of the complexes formed between beryllium and the Schiff base are log β1 11.1 and log β2 20.4, and the distribution coefficient of the bis complex is 550. Over most of the pH range, hydrolysis of the Be2+ ion competes with complex formation and provides a means of measuring the hydrolysis constants. They are for the reactions: Be(H2O)42+ ↔ 2H+ + Be(H2O)2(OH)2, log*β2 - 13.65; Be(H2O)42+ ↔ 3H+ + Be(H2O)(OH)3-, log*β3 -24.11.

Complexation of Iron with the Orally Active Decorporation Drug L1 (3-Hydroxy-1,2-Dimethyl-4-Pyridinone)

1992 ◽  
Vol 38 (4) ◽  
pp. 562-565 ◽  
Author(s):  
M A Kline ◽  
C Orvig
Keyword(s):  
Blood Plasma ◽  
Potentiometric Titration ◽  
Stability Constants ◽  
Computer Model ◽  
Chelating Agent ◽  
Glass Electrode ◽  
Simple Computer ◽  
Active Iron ◽  
The Stability ◽  
Orally Active

Abstract The stability constants for the Fe(III) complexes of the orally active iron decorporation drug L1 (3-hydroxy-1,2-dimethyl-4-pyridinone) have been determined by potentiometric titration [glass electrode, 25.0 degrees C, mu = 0.15 mol/L (isotonic) NaCl]. A simple computer model of blood plasma (citrate 100 mumol/L, transferrin 37 mumol/L) has been used to compare the Fe(III) binding efficacies in blood of L1 and the clinically used intravenously administered chelating agent deferoxamine.

Complex Formation in the Ternary System Tl(III)−CN-−Cl-in Aqueous Solution. A205Tl NMR Study

1996 ◽  
Vol 35 (24) ◽  
pp. 7074-7081 ◽  
Author(s):  
Katja E. Berg ◽  
Johan Blixt ◽  
Julius Glaser
Keyword(s):  
Aqueous Solution ◽  
Complex Formation ◽  
Ternary System ◽  
Nmr Study
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