scholarly journals 1,5-bis[2-(dioxyphosphoryl)-4-ethylphenoxy]-3-oxapentane and its Analogs as Promising Organic Ligands for Copper(II) Binding s

2018 ◽  
Vol 1 (3) ◽  
pp. e00043
Author(s):  
V.E. Baulin ◽  
G.S. Tsebrikova ◽  
D.V. Baulin ◽  
Y.F. Al Ansary
Keyword(s):  
Dissociation Constants ◽  
Conductometric Titration ◽  
Organic Ligands ◽  
Dimethyl Formamide ◽  
Titration Curves ◽  
Carboxylic Groups ◽  
Titration Data ◽  
The Stability ◽  
Medicinal Drugs ◽  
Acidic Type

The dissociation and complexation ability toward Cu(II) of acidic type phosphoryl-containing podands – tetrabasic 1,5-bis[2-(dioxyphosphoryl)-4-ethylphenoxy]-3-oxapentane (L1), dibasic – 1,5-bis[2-(ethoxyhydroxyphosphoryl)-4-ethylphenoxy]-pentane (L2) and also of their carboxylic analogue dibasic 1,5-bis[2-(oxycarbonylphenoxy)]-3-oxapentane (L3) were investigated by spectrophotometric, conductometric and potentiometric methods in water in the presence 5% of dimethyl formamide. Spectrophotometric and conductometric titration data provided evidence for formation of 1:1 (M:L) complexes. The dissociation constants were determined and species distribution diagrams for studied acids were obtained by potentiometric method. These data are of interest for the design of binary extragents and medicinal drugs based on the studied ligands. The stability constants of Cu(II) 1:1 (M:L) complexes were estimated. Analysis of the titration curves suggests that deprotonation forms of the studied ligands react with Cu2+. Substitution of carboxylic groups in acyclic polyesters by phosphonic results in increased stability of the copper(II) complexes

scholarly journals Complex Formation of Nickel(II) and Copper(II) with Barbituric Acid

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Naciye Türkel ◽  
M. Suat Aksoy
Keyword(s):  
Complex Formation ◽  
Stability Constants ◽  
Binary Systems ◽  
Barbituric Acid ◽  
Dissociation Constants ◽  
Individual Species ◽  
Equilibrium Studies ◽  
Ph Titration ◽  
Titration Data ◽  
The Stability

Equilibrium studies have been carried out on complex formation of M2+ ions (M = Ni and Cu) with L = barbituric acid (BA) in aqueous solution at 25.0±0.1°C and with an ionic strength of I=0.10 M (KNO3) in aqueous medium. The basicity of the ligand was also assessed by the determination of the dissociation constants of the ligand. The experimental pH titration data were analyzed with the help of the BEST computer program in order to evaluate the stability constants of the various species formed. The stability constants of the binary systems decrease in the order of Cu(II) > Ni(II). Distribution diagrams for the species were drawn showing the concentrations of individual species as a function of pH by the SPE software program.

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.

The extraction of alkali metal picrates by polyurethane foam using crown ether

1981 ◽  
Vol 59 (10) ◽  
pp. 1490-1496 ◽  
Author(s):  
Anjum S. Khan ◽  
W. G. Baldwin ◽  
A. Chow
Keyword(s):  
Crown Ether ◽  
Alkali Metal ◽  
Polyurethane Foam ◽  
Dissociation Constants ◽  
Extraction Constant ◽  
Ion Pair ◽  
Constant Sequence ◽  
Extraction Constants ◽  
The Stability ◽  
Ether Complex

The distribution of alkali metal picrates between water and polyurethane foam was studied in the presence of dicyclohexyl 18-crown-6 (DCHC-6). The extraction constants and dissociation constants for the ion pair (MCrA) in polyurethane foam were determined. The extraction constant sequence of the alkali metal ions with DCHC-6 is K+ > Rb+ > Cs+ > Na+ and mainly depends on the stability of the alkali metal – crown ether complex.

554. Titration curves of whey constituents

1954 ◽  
Vol 21 (2) ◽  
pp. 229-237 ◽  
Author(s):  
M. Boulet ◽  
Dyson Rose
Keyword(s):  
Calcium Phosphate ◽  
Tricalcium Phosphate ◽  
Dissociation Constants ◽  
Calcium Content ◽  
Dicalcium Phosphate ◽  
Milk Serum ◽  
Titration Curves

Titration curves of calcium-containing and calcium-free solutions resembling milk serum indicated that precipitation of calcium from such solutions was greatly impeded by citrate. In the absence of citrate, precipitation of tricalcium phosphate was complete at pH 6·0, but, in solutions containing citrate, precipitation of tricalcium phosphate occurred gradually throughout the titration and was not complete at pH 10.In some solutions precipitation of calcium phosphate ceased at about pH 9·7, even though the base added had been insufficient to neutralize tertiary hydrogen equivalent to the known calcium content. Precipitation of dicalcium phosphate must therefore have occurred.The observed stability of calcium in these solutions was much greater than that predicted from the accepted solubility and dissociation constants. It is therefore concluded that detailed studies of these constants, and of the factors controlling precipitation of dior tricalcium phosphate, are needed.

The multiple dissociation constants of glutathione disulfide: interpreting experimental pH-titration curves with ab initio MD simulations

2019 ◽  
Vol 21 (18) ◽  
pp. 9212-9217 ◽  
Author(s):  
Vaishali Arunachalam ◽  
Anil Kumar Tummanapelli ◽  
Sukumaran Vasudevan
Keyword(s):  
Complex Systems ◽  
Ab Initio ◽  
Dissociation Constants ◽  
Md Simulations ◽  
Glutathione Disulfide ◽  
Ph Titration ◽  
Titration Curves ◽  
Ab Initio Md

Dissociation constants calculated from ab initio MD simulations can aid the interpretation of the pH-titration curves of complex systems.

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.

Stability of in 111In-ligand Complexes Studied by TDPAC

1998 ◽  
Vol 53 (6-7) ◽  
pp. 630-636 ◽  
Author(s):  
L. G. Shpinkova ◽  
V. N. Kulakov ◽  
A. A. Sorokin ◽  
G. K. Ryasny ◽  
B. A. Komissarova ◽  
...  
Keyword(s):  
Organic Ligands ◽  
Ligand Complex ◽  
Tdpac Technique ◽  
The Stability ◽  
Auger Effect

Abstract The TDPAC technique has been applied to study the stability of 111In complexes with NTA and DTPA in solutions with different concentrations of stable In at pH = 7. A sample of In-DTPA complexes attached to microspheres of albumin (MSA) has been measured at temperatures of 293 and 130 K. The results show that the products formed after 111ln → 111Cd decay and following Auger-effect are determined by the stability of In (Cd)-complexes with organic ligands. The daughter Cd behaviour depends on the In: ligand mole ratio, from 1: ∞ to 1:1. The possibility of Cd-ligand complex destruction and following Cd rechelating is discussed. The results indicate that the rechelating probability correlates with the stability of the parent and daughter complexes.

scholarly journals Investigation of the Interaction of Gadolinium with Several Organic Ligands and Humic Acid by Ligand Competition Using 4-(2-Pyridylazo)-Resorcinol (PAR)

Environments ◽  
2020 ◽  
Vol 7 (9) ◽  
pp. 69
Author(s):  
Spencer Steinberg ◽  
Vernon Hodge ◽  
Luis Becerra-Hernandez
Keyword(s):  
Humic Acid ◽  
Organic Acids ◽  
Stability Constants ◽  
Reasonable Agreement ◽  
Organic Ligands ◽  
Competitive Displacement ◽  
Colored Complex ◽  
Method Of Continuous Variation ◽  
The Stability ◽  
Displacement Approach

Gd3+ forms a strongly colored complex with 4-(2-pyridylazo)-resorcinol (PAR) in aqueous solutions. We characterized the Gd3+-PAR complex in order to use it as a probe of Gd3+ speciation in the presence of environmentally relevant ligands. The formation of the Gd3+-PAR complex was investigated from pH 5 to 8 in the presence of excess PAR. The absorbance of the Gd3+-PAR complex dramatically increased from pH 5 to 8 and application of the method of continuous variation indicates that the complex was primarily 1:2 Gd(PAR)2 at pH 8. Stability constants for Gd3+ with other ligands can be quantified by competitive displacement of the PAR ligand. To establish the viability of this approach, we measured the stability constants between Gd3+ and several organic acids and carbonate. Our measurements show reasonable agreement with the literature values. We used the competitive displacement approach to establish that humic acids can competitively displace PAR from the Gd(PAR)2 complex.

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