THE FLUORESCENCE AND VISIBLE ABSORBANCE OF Cu(II) AND Mn(II) COMPLEXES OF FULVIC ACID: THE EFFECT OF METAL ION LOADING

1981 ◽  
Vol 61 (2) ◽  
pp. 469-474 ◽  
Author(s):  
ALAN W. UNDERDOWN ◽  
COOPER. H. LANGFORD ◽  
DONALD S. GAMBLE
Keyword(s):  
Fulvic Acid ◽  
Metal Ion ◽  
Carboxyl Groups ◽  
Collisional Quenching

The fluorescence of a well-characterized fulvic acid is found to be quenched by the binding of Cu(II), Mn(II) or H+. Below 40% protonation of the 5.0 mmole/g most strongly acidic carboxyl groups, the results indicate weak collisional quenching by OH−. Metal ion complexing becomes weaker with increasing amounts bound.

Structure of the complexes of ethylenediphosphinetetraacetic acid in solution

1985 ◽  
Vol 50 (2) ◽  
pp. 445-453 ◽  
Author(s):  
Jana Podlahová ◽  
Josef Šilha ◽  
Jaroslav Podlaha
Keyword(s):  
Metal Ion ◽  
Carboxyl Groups ◽  
Complex Solution ◽  
Square Planar ◽  
Weak Complexes ◽  
Carboxylic Groups ◽  
Uv Visible ◽  
The Stability ◽  
Tetrahedral Complexes ◽  
Free Carboxyl

Ethylenediphosphinetetraacetic acid is bonded to metal ions in aqueous solutions in four ways, depending on the type of metal ion: 1) through an ionic bond of the carboxylic groups to form weak complexes with a metal:ligand ratio of 1 : 1 (Ca(II), Mn(II), Zn(II), Pb(II), La(III)); 2) through type 1) bond with contributions from weak interaction with the phosphorus (Cd(II)); 3) through coordination of the ligand as a monodentate P-donor with the free carboxyl groups with formation of 2 : 1 and 1 : 1 complexes (Cu(I), Ag(I)); 4) through formation of square planar or, for Hg(II), tetrahedral complexes with a ratio of 1 : 2 with the ligand as a bidentate PP-donor with the free carboxyl groups (Fe(II), Co(II), Ni(II), Pd(II), Pt(II)). On acidification of the complex solution, the first two protons are bonded to the carboxyl groups. The behaviour during further protonation depends on the type of complex: in complexes of types 1) and 2) phosphorus is protonated and the complex dissociates; in complexes of types 3) and 4) the free carboxyl groups are protonated and the phosphorus-metal bond remains intact. The results are based on correlation of the stability constants, UV-visible, infrared, 1H and 31P NMR spectra and magnetic susceptibilities of the complexes in aqueous solution.

scholarly journals Chelation and Metal-Ion Complex Formation of Chitosan Treated Cotton

2019 ◽  
Vol 8 (3) ◽  
pp. 93-100 ◽  
Author(s):  
Sudirman Habibie
Keyword(s):  
Cotton Fabric ◽  
Metal Ion ◽  
Chelating Agents ◽  
Transition Metal Ions ◽  
Cotton Fabrics ◽  
Carboxyl Groups ◽  
Polycarboxylic Acid ◽  
Salt Solutions ◽  
Polycarboxylic Acids ◽  
Zinc Salts

Chitin dan chitosan adalah bahan “chelate” yang sangat kuat untuk ion transisi logam terutama tembaga, nikel dan merkuri, dan sifat-sifat ini yang akan intensif di bahas. Pada studi ini kain kapas (cotton) dikerjakan dengan larutan chitosan-asam polikarboksilat untuk memperoleh kain kapas-chitosan yang mengandung gugus group karboksilat (-COOH) dan gugus amina (-NH2) fungsional. Penggunaan asam polykarboksilat (asam sitrat dan maleik) pada pelarutan chitosan menghasilkan group karboksil 0,5 meqs/g pada kain yang dicelup dengan larutan chitosan asam karboksilat. Kemudian kain kapas yang telah mengandung gugus karboksilat dan gugus amina ini dicelupkan pada larutan garam logam (garam tembaga dan seng). Terbukti bahwa larutan garam tembaga (copper) memberikan warna biru pada kain, hal ini mengindikasikan telah terjadi reaksi kompleks atau “Chelate”. Implikasi dari hasil ini maka diperkirakan kandungan group karboksil dan amina ini akan mempengaruhi pada pencelupan kain, namun hal ini tidak diuji.Kata kunci : Chitosan, Kain Kapas, Chelate, Asam asetat, Asam citrate, Asam maleik, Tembaga sulphate, Tembaga acetate.AbstractChitin and chitosan are powerfull chelating agents for transition metal ions, particularly copper, nickel and mercury, and these properties have been extensively reviewed. In this study, cotton fabric has been treated with chitosan- polycarboxylic acid solution to form chitosan treated cotton fabric containing carboxyl (-COOH) and amine (-NH2) functional groups. The use of polycarboxylic acids (citric and maleic acids) to dissolve chitosan has given carboxyl groups 0.5 meqs/g into chitosan treated cotton fabrics. Instead, the complexing of the treated cotton samples with copper and zinc salts was examined. The copper salt solutions gave blue fabrics confirming easily that complexing or chelation had occurred. There are implications for dyeing cotton making use of these groups but this was not investigated.Keyword : Chitosan, Cotton fabric, Chelation, Acetic acid, Citric acid, Maleic acid, Copper (II) sulphate, Copper (II) acetate.

Kinetics and Equilibrium of Binding of Fe3+ by a Fulvic Acid: A Study by Stopped Flow Methods

1975 ◽  
Vol 53 (20) ◽  
pp. 2979-2984 ◽  
Author(s):  
Cooper H. Langford ◽  
Tahir R. Khan
Keyword(s):  
Ionic Strength ◽  
Complex Formation ◽  
Fulvic Acid ◽  
Metal Ion ◽  
Equilibrium Constants ◽  
Acid Dissociation ◽  
Stopped Flow ◽  
Solution Ph ◽  
Sulfosalicylic Acid ◽  
Flow Measurements

The first report of a rate of binding of a metal ion (Fe3+) by a soluble fulvic acid is derived from stopped flow measurements. The rate of complex formation is normal in Wilkins' sense and similar to that for sulfosalicylic acid. Dissociation is slow (t1/2 > 10 s). The binding of Fe3+ by the fulvic acid in acid solution, pH = 1–2.5, was investigated by kinetic analysis in which the reaction of free Fe3+ with sulfosalicylic acid was followed by stopped flow spectrophotometry on a time scale short compared to release of Fe3+ by fulvic acid. Conditional equilibrium constants found were 1.5 ± 0.3 × 104 at pH = 1.5 and 2.5, and 2.8 ± 0.3 × 103 at pH = 1.0 at 25 °C (ionic strength 0.1).

scholarly journals Complexes of Cu(II) Ions and Noncovalent Interactions in Systems with L-Aspartic Acid and Cytidine-5'-Monophosphate

2008 ◽  
Vol 2008 ◽  
pp. 1-10 ◽  
Author(s):  
Romualda Bregier-Jarzebowska ◽  
Anna Gasowska ◽  
Lechosław Lomozik
Keyword(s):  
Aspartic Acid ◽  
Metal Ion ◽  
Molecular Complexes ◽  
Main Reaction ◽  
Carboxyl Groups ◽  
Reaction Centre ◽  
Solution Ph ◽  
Metal Free ◽  
Reaction Centres ◽  
Oxygen Atoms

Interactions between aspartic acid (Asp) and cytidine-5-monophosphate (CMP) in metal-free systems as well as the coordination of Cu(II) ions with the above ligands were studied. The composition and overall stability constants of the species formed in those systems were determined by the potentiometric method, and the interaction centres in the ligands were identified by the spectral methods UV-Vis, EPR, NMR, and IR. In metal-free systems, the formation of adducts, in which each ligand has both positive and negative reaction centres, was established. The main reaction centres in Asp are the oxygen atoms of carboxyl groups and the nitrogen atom of the amine group, while the main reaction centre in CMP at low pH is the N(3) atom. With increasing pH, the efficiency of the phosphate group of the nucleotide in the interactions significantly increases, and the efficiency of carboxyl groups in Asp decreases. The noncovalent reaction centres in the ligands are simultaneously the potential sites of metal-ion coordination. The mode of coordination in the complexes formed in the ternary systems was established. The sites of coordination depend clearly on the solution pH. In the molecular complexesML⋯L, metallation involves the oxygen atoms of the carboxyl groups of the amino acid, while the protonated nucleotide is in the outer coordination sphere and interacts noncovalently with the anchoringCuHx(Asp) species. The influence of the metal ions on the weak interactions between the biomolecules was established.

Yeast enolase carboxyl modification using Woodward's reagent K

1986 ◽  
Vol 64 (10) ◽  
pp. 970-975 ◽  
Author(s):  
Uma Sinha ◽  
John M. Brewer
Keyword(s):  
Metal Ion ◽  
Carboxyl Groups ◽  
Tryptic Peptides ◽  
Woodward’S Reagent K ◽  
Carboxyl Modification ◽  
Yeast Enolase

Yeast enolase is inactivated by Woodward's reagent K. Substantial protection is afforded by binding of 1 mol of "conformational" metal ion/subunit. Inactivation is correlated with modification of 13 carboxyl groups/subunit in the absence of conformational metal ion and 17 in its presence. Ten tryptic peptides labeled by Woodward's reagent K can be isolated, mostly from the C-terminal half of the protein. The changes in reactivity of these peptides produced by conformational metal ion suggest direct coordination to Glu-181 together with a contraction of the protein.

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