scholarly journals Stability Constants of Lanthanide Metal Ions Chelates with Substituted Pyrazoles in Different Solvents

2011 ◽  
Vol 8 (1) ◽  
pp. 131-136 ◽  
Author(s):  
G. H. Murhekar ◽  
A. R. Raut ◽  
R. S. Sonone
Keyword(s):  
Ionic Strength ◽  
Metal Ions ◽  
Stability Constants ◽  
Water Mixture ◽  
Solvent Medium ◽  
Acetone Water ◽  
Lanthanide Metal ◽  
Substituted Pyrazoles ◽  
Metal Ligand

The reaction of Pr (III) and Nd (III) metal ions with some substituted pyrazoles, at 0.1M ionic strength and at 30 ± 0.10C in 70% acetone-water mixture and 70% propanol-water mixture have been studied pH-metrically. The data obtained were used to estimate the values of proton-ligand (pK) and metal-ligand (logK) stability constants in different solvents. It is observed that the pK and logK values in 70% propanol-water mixture are grater than in 70% acetone -water mixture. Pr (III) and Nd (III) metal ions formed 1:1 and 1:2 complexes with all the ligands in both solvent medium.

scholarly journals Complexation equilibria of ambroxol hydrochloride in solution by potentiometric and conductometric methods

2018 ◽  
Vol 9 (1) ◽  
pp. 49-56
Author(s):  
Ahmed Hosny Naggar ◽  
Hammed Mohammed Al-Saidi ◽  
Othman Abd El-Moaty Farghaly ◽  
Taher Mohammed Hassan ◽  
Salma Zaidan Mohamed Bortata
Keyword(s):  
Ionic Strength ◽  
Metal Ions ◽  
Stability Constants ◽  
Formation Constants ◽  
Alkaline Media ◽  
Ligand Complex ◽  
Complex Species ◽  
The Stability ◽  
Ambroxol Hydrochloride ◽  
Metal Ligand

The formation constants of Li(I), Mg(II), Sr(II), Ca(II), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Ba(II), Pb(II), Al(III), Cr(III), Fe(III) and Th(IV) ions with ambroxol hydrochloride (AMB) were calculated using the half-n value. In presence of 0.1 M NaNO3, metal ions such as Zn(II), Cd(II), Ni(II), Cr(III), Li(I), Mg(II) and Al(III) forms three types of metal-ligand complexes (1:1, 1:2 and/or 1:3), while Sr(II) and Co(II) tend to form two types of metal complexes 1:1 and 1:2 (M:L). For ligand protonation constants, two logarithmic association constant values were calculated by the half-n method and are 10.7 and 7.6, respectively. The effect of ionic strength on stability constant of AMP, with different metal ions viz. Fe(III), Th(IV), Al(III), Cr(III) and Cu(II) was studied. Based on relationship between the ionic strength studied values and the 1st stability constants (Log K1H), we can conclude that the stability constants of the formed metal-ligand complex (1:1) were decreased as the ionic strength increased. The stoichiometry of the formed complexes in solution were determined by conductometric method and it is found to be of 1:1, 1:2 and/or 1:3 (M:L) complex species is formed in alkaline media. Also, study the species distribution diagrams of AMP for the calculated mole fraction αML and αML2 were discussed.

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.

Potentiometric and thermodynamic studies of 3-methyl-1-phenyl-{p-[N-(pyrimidin-2-yl)-sulfamoyl]phenylazo}-2-pyrazolin-5-one and its metal complexes

2006 ◽  
Vol 60 (1) ◽  
Author(s):  
A. Fouda ◽  
A. Al-Sarawy ◽  
E. El-Katori
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Stability Constants ◽  
Dissociation Constants ◽  
Transition Metal Ions ◽  
Effect Of Temperature ◽  
Water Mixture ◽  
Dissociation Process ◽  
The Stability ◽  
Metal Ligand

AbstractThe dissociation constants of 3-methyl-1-phenyl-{p-[N-(pyrimidin-2-yl)sulfamoyl]phenylazo}-2-pyrazolin-5-one and metal-ligand stability constants of its complexes with some transition metal ions have been determined potentiometrically in 0.1 M-KCl and ethanol—water mixture (30 vol. %). The order of the stability constants of the formed complexes increases in the sequence Mn2+, Co2+, Ni2+, Cu2+, La3+, Hf3+, UO22+, Zr4+. The effect of temperature was studied and the corresponding thermodynamic parameters (ΔG, ΔH, and ΔS) were derived and discussed. The dissociation process is nonspontaneous, endothermic, and entropically unfavourable. The formation of the metal complexes was found to be spontaneous, exothermic, and entropically favourable.

scholarly journals Formation constants of lanthanide metal ion chelates with some substituted sulfonic acids

2010 ◽  
Vol 7 (1) ◽  
pp. 235-238
Author(s):  
R. S. Sonone ◽  
G. H. Murhekar
Keyword(s):  
Ionic Strength ◽  
Sulfonic Acid ◽  
Metal Ion ◽  
Formation Constants ◽  
Trifluoromethanesulfonic Acid ◽  
Water Mixture ◽  
Benzenesulfonic Acid ◽  
Sulfonic Acids ◽  
Lanthanide Metal ◽  
The Stability

The pKa and logK values of some substituted sulfonic acid in 70% (v/v) dioxane-water mixture have been determined using pH metric measurements. The stability constant of complexes of Gd (III), Tb (III) and Ho (III) with p-aminobenzenesulfonic (L1) and p-sulfophthalic acid (L2), 2-amino-5-chloro benzenesulfonic acid (L3) and trifluoromethanesulfonic acid (L4) have been determined at 0.1M ionic strength at 28±0.1 0C pH metrically. It is observed that both the metal ions formed 1:1 & 1:2 complexes with all the ligands.

Stability Constants of Palladium, Copper, Nickel, Zinc and Manganese Chelates of N-Benzoyl-N-phenylhydroxylamine

1967 ◽  
Vol 22 (9) ◽  
pp. 922-924 ◽  
Author(s):  
J. P. C. Jaimni ◽  
N. C. Sogani
Keyword(s):  
Ionic Strength ◽  
Stability Constants ◽  
Metal Ion ◽  
Chelating Agent ◽  
Ion Concentration ◽  
Water Mixture ◽  
Ph Titration ◽  
Nickel Zinc ◽  
Copper Nickel ◽  
Titration Technique

Stabilities of palladium, copper, nickel, zinc and manganese chelates of N-benzoyl-N-phenyl-hydroxylamine have been determined in 70% v/v dioxan-water mixture by employing Bjerr um-Calvin pH titration technique. The titration medium was maintained at a constant ionic strength (0.1 M KCI) and at a temperature, 25 ± 0.5°. Titrations were carried out in duplicate using 40 : 1 ratio of chelating agent to metal ion concentration.

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