Ternary Coordination Complexes Between Copper(II) and Amino Acids, and an Appraisal of the Enhancement of Ternary Complex Stability

1973 ◽  
Vol 51 (21) ◽  
pp. 3555-3562 ◽  
Author(s):  
Theo P. A. Kruck ◽  
Bibudhendra Sarkar
Keyword(s):  
Stability Constants ◽  
Ternary Complex ◽  
Ternary Systems ◽  
Formation Constants ◽  
Coordination Complexes ◽  
Binary Complex ◽  
Complex Species ◽  
Successive Formation ◽  
The Stability ◽  
The Individual

The equilibria involved in the ternary systems Cu(II)–A–B′ and Cu(II)–A–B″ (A = L-histidine, B′ = L-serine, B″ = L-glutamine) have been investigated by potentiometry in aqueous solution (0.15 M NaCl, 25°). In the ternary system Cu(II)–A–B′, three mixed complexes (MHAB′, MAB′, and MH−1AB′) were detected in addition to the binary complex species (MHA, MA, MH2A2, MHA2, MA2, MH−1A2, MB′, MB′2). The results observed in the Cu(II)–A–B″ system were quite similar to the system Cu(II)–A–B′ except that it did not show the presence of the species MH−1AB″. The stability constants were refined with a general least squares treatment. In the case of an equimolecular mixture of the constituents, a maximum of about 75% of Cu(II) is present as MAB′ at pH 5.5–9 and about 60% of Cu(II) as MAB″ at pH 5–10 when the concentration of each constituent is set equal to 10−2 M. A theoretical analysis and derivations of the expected stability constants of the complexes are presented on the basis of successive formation constants of the individual complexes carrying identical ligands. In each case an enhancement of the stability was observed with the ternary coordination complexes. Attempts have been made to explain the enhanced stability of the ternary coordination complexes.

Equilibria of the Simultaneously Existing Multiple Species in the Copper(II)–L-Histidine System

1973 ◽  
Vol 51 (21) ◽  
pp. 3549-3554 ◽  
Author(s):  
Theo P. A. Kruck ◽  
Bibudhendra Sarkar
Keyword(s):  
Statistical Analysis ◽  
Standard Deviation ◽  
Stability Constants ◽  
Individual Values ◽  
Complex Species ◽  
Molar Ratios ◽  
Multiple Species ◽  
The Stability ◽  
Ph Range ◽  
The Individual

The complete species distribution and the stability constants of the complex species in the Cu(II)–L-histidine system have been worked out for the pH range 2–11. The method of "analytical potentiometry" has been applied successfully to this system having excess ligand with respect to Cu(II) ion. The equilibria of three systems of Cu(II) (M) and L-histidine (H3A) in molar ratios of 1:2, 1:4, and 1:8 were investigated by this technique in 0.15 M NaCl at 25°. The following species were detected in this system: MHA, MA, MH2A2, MHA2, MA2, MH−1A2, MH−1A, and M2H−2A2. Statistical analysis on the numerical results has been performed and is given as standard deviation together with the individual values for the stability constants.

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.

The affinity of aldehydic compounds to complex formation. Nickel(II) and cobalt(II) complexes with 2-pyridinecarboxaldehyde

1977 ◽  
Vol 55 (14) ◽  
pp. 2613-2619 ◽  
Author(s):  
M. S. El-Ezaby ◽  
M. A. El-Dessouky ◽  
N. M. Shuaib
Keyword(s):  
Complex Formation ◽  
Aqueous Solutions ◽  
Stability Constants ◽  
Metal Ion ◽  
Experimental Conditions ◽  
Complex Species ◽  
Spectrophotometric Methods ◽  
Complex Equilibria ◽  
The Stability ◽  
Hydroxy Groups

The interactions of Ni(II) and Co(II) with 2-pyridinecarboxaldehyde have been investigated in aqueous solutions at μ = 0.10 M (KNO3) at 30 °C. The stability constants of different complex equilibria have been determined using potentiometric methods. Spectrophotometric methods were also used in the case of the nickel(II) – 2-pyridinecarboxaldehyde system. It was concluded that nickel(II) and cobalt(II), analogous to copper(II), enhance hyrdation of 2-pyridinecarboxaldehyde prior to deprotonation of one of the geminal hydroxy groups. Complex species of 1:1 as well as 1:2 metal ion to ligand composition exist under the experimental conditions used.

scholarly journals Interaction of Ampicillin and Amoxicillin with Mn2+: A Speciation Study in Aqueous Solution

Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3110
Author(s):  
Claudia Foti ◽  
Ottavia Giuffrè
Keyword(s):  
Aqueous Solution ◽  
Stability Constants ◽  
Metal Ion ◽  
Formation Constants ◽  
Enthalpy Change ◽  
Ligand Concentration ◽  
Empirical Parameter ◽  
Speciation Study ◽  
Potentiometric Measurements ◽  
The Stability

A potentiometric and UV spectrophotometric investigation on Mn2+-ampicillin and Mn2+-amoxicillin systems in NaCl aqueous solution is reported. The potentiometric measurements were carried out under different conditions of temperature (15 ≤ t/°C ≤ 37). The obtained speciation pattern includes two species for both the investigated systems. More in detail, for system containing ampicillin MLH and ML species, for that containing amoxicillin, MLH2 and MLH ones. The spectrophotometric findings have fully confirmed the results obtained by potentiometry for both the systems, in terms of speciation models as well as the stability constants of the formed species. Enthalpy change values were calculated via the dependence of formation constants of the species on temperature. The sequestering ability of ampicillin and amoxicillin towards Mn2+ was also evaluated under different conditions of pH and temperature via pL0.5 empirical parameter (i.e., cologarithm of the ligand concentration required to sequester 50% of the metal ion present in traces).

scholarly journals NEW SPECTROPHOTOMETRIC METHOD FOR DETERMINING TITANIUM(IV) IN NATURAL OBJECTS

2021 ◽  
Vol 2021 (1) ◽  
pp. 44-51
Author(s):  
Adilya Jeyhun Ragimova ◽  
Vusala Ismayil Mardanova ◽  
Abel Maharram Maharramov ◽  
Khalil Jamal Nagiyev ◽  
Famil Musa Chyragov
Keyword(s):  
Stability Constants ◽  
Spectrophotometric Method ◽  
Alkaline Earth ◽  
Mixed Ligand ◽  
Binary Complex ◽  
Transition Elements ◽  
Foreign Ions ◽  
Mixed Ligands ◽  
The Stability ◽  
Twofold Excess

The article considers the interaction of Ti(IV) with 2, 3, 4-trihydroxy-3'-fluoroazobenzene (H3R) in the presence and absence of phenontroline (Phen), α, α'-dipyridine (α, α'-dip), and batophenontroline (B-phen) studied by using a spectrophotometric method. It has been found that the yield of the binary complex is maximum at pHopt = 5 (λmax = 428 nm), and for mixed-ligand complexes, pHopt = 3.0; 4.0; 3.5; λmax = 477 nm, 443 nm, 440 nm Ti(OH)2(H2R)-Phen, Ti (OH)2(H2R)-α, α'-dip and Ti(OH)2(H2R)-B-phen, respectively. It has been investigated that a twofold excess of the reagent is required for complete binding of titanium(IV) into the complex. The influence of time and temperature on the complexation is investigated. The stability constants of binary and mixed-ligand titanium(IV) complexes were calculated: logβ = 8.61 ± 0.05 for Ti(OH)2(H2R)2, logβ = 10.98 ± 0.06 for Ti(OH)2(H2R)-Phen, logβ = 10.85 ± 0.04 for Ti (OH)2(H2R)-α, α'-dip, logβ = 11.26 ± 0.03 for Ti(OH)2(H2R)-B-phen. The ratio of the reacting components in the binary complex is 1 : 2, and in the mixed ligands 1 : 2 : 2. The influence of foreign ions and masking substances on the titanium(IV) complexation with reagents has been studied. The determination is practically not interfered by alkaline, alkaline-earth and some transition elements. Due to these characteristics, the complexes can be used for defining titanium(IV) in different objects.

Equilibrium studies of triphenyltin(IV) complexes with glycine, glycyl-glycine, and glycyl-glycyl-glycine in different aqueous solutions of ethanol

2010 ◽  
Vol 88 (9) ◽  
pp. 877-885 ◽  
Author(s):  
Morteza Jabbari ◽  
Farrokh Gharib
Keyword(s):  
Hydrogen Bond ◽  
Stability Constant ◽  
Formation Constants ◽  
Least Squares Regression ◽  
Hydrogen Bond Donor ◽  
Equilibrium Studies ◽  
Hydrogen Bond Acceptor ◽  
Complex Species ◽  
The Stability ◽  
Glycyl Glycine

The protonation equilibria of glycine (gly), glycyl-glycine (gly-gly), and glycyl-glycyl-glycine (gly-gly-gly) and their formation constants with triphenyltin(IV) chloride were studied over a wide pH range (pH 1–11), using a combination of spectrophotometric and potentiometric methods at constant temperature (25 °C), different ethanol–water mixtures (50%–80%, v/v), and constant ionic strength (0.1 mol dm–3 NaClO4). Least-squares regression calculations are consistent with the formation of ph3SnHL+, ph3SnL, and ph3SnH–1L– complex species, where L– represents the fully dissociated form of each ligand. The stability constant of the formed complexes in different media were analyzed in terms of Kamlet, Abboud, and Taft (KAT) parameters. Single-parameter correlations of the stability constants versus α (hydrogen-bond donor acidity), β (hydrogen-bond acceptor basicity), and for π* (dipolarity/polarizability) are relatively poor in all solutions, but multi-parameter correlations represent significant improvements with regard to the single- and dual-parameter models. Linear correlation is observed when the experimental logβxyz values are plotted versus the calculated ones, while all the KAT parameters are considered. Also, the stability constant values of the formed complexes are determined in zero percent of organic solvent using the Yasuda–Shedlovsky extrapolation approach. Finally, the results are discussed in terms of the effect of solvent on complexation.

Contribution to the thermodynamics of complexes of alkali metal cations with dibenzo-18-crown-6 in water-nitrobenzene extraction system

1984 ◽  
Vol 49 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Emanuel Makrlík ◽  
Jaroslava Hálová ◽  
Miroslav Kyrš
Keyword(s):  
Alkali Metal ◽  
Alkali Metal Cation ◽  
Alkali Metal Cations ◽  
Complex Species ◽  
Cation Order ◽  
Extraction Constants ◽  
Equilibrium Data ◽  
Individual Extraction Constants ◽  
The Stability ◽  
The Individual

The stability constants for the ML+ complex species, where M+ is an alkali metal cation and L is dibenzo-18-crown-6, in nitrobenzene saturated with water were calculated by employing published equilibrium data. The stability is found to increase in the cation order Li+ < Cs+ < Rb+ < K+ < Na+. For the NaL+, KL+, RbL+, and CsL+ complex cations the individual extraction constants in the water-nitrobenzene system were determined; their values increase in the series Na+ < K+ < Rb+ < Cs+.

scholarly journals Studies on biologically important copper(II) / manganese(II) / uranyl(II) – norvaline binary complexes

2008 ◽  
Vol 27 (2) ◽  
pp. 157 ◽  
Author(s):  
Brij Bhushan Tewari
Keyword(s):  
Stability Constants ◽  
Coordination Compounds ◽  
Metal Ion ◽  
Background Electrolyte ◽  
Binary Complex ◽  
Paper Strip ◽  
Ph Values ◽  
Binary Complexes ◽  
Stability Constants Of Complexes ◽  
The Stability

In coordination compounds studies, a knowledge of the magnitude of the stability constants of complexes is necessary for preliminary quantitative treatment. Described herein is a method that involves the use of advanced ionophoretic technique for the study of the equilibria in binary complex systems in solution. This method is based upon the migration of a spot of the metal ion on a paper strip at different pH values of background electrolyte containing 0.1 M perchloric acid and 0.01 M norvaline. A graph of pH against mobility provides information about the nature of the complexation and helps in calculating stability constants. Using this method, the stability constants of binary complexes metal(II) – norvaline have been determined to be (8.11 ± 0.02, 7.03 ± 0.09); (3.77 ± 0.11, 2.39 ± 0.07) and (7.59 ± 0.05, 6.17 ± 0.04) (log K values) for Cu(II), Mn(II) and UO2(II) complexes, respectively, at 35 ºC.

Paper ionophoretic technique in the study of biologically important beryllium(II) / cobalt(II)-homoserine binary complexes in solution

2010 ◽  
Vol 29 (2) ◽  
pp. 139
Author(s):  
Brij Bhushan Tewari
Keyword(s):  
Complex System ◽  
Stability Constants ◽  
Present Method ◽  
Background Electrolyte ◽  
Binary Complex ◽  
Paper Strip ◽  
Successive Addition ◽  
Binary Complexes ◽  
Quantitative Indication ◽  
The Stability

Quantitative indication of the process of forming a complex comes from the evaluation of the stability constants, which characterize the equilibria corresponding to the successive addition of ligands. A method, involving the use of paper electrophoretic technique is described for the study of binary complex system in solution. Present method is based upon the migration of a spot of metal ions on a paper strip at different pH’s of background electrolyte. A graph of pH against mobility gives information about the binary complexes and permits calculation of their stability constants. The first and second stability constants of [Be(II)-homoserine] and [Co(II)-homoserine] complexes were found to be (7.13 ± 0.02; 6.11 ± 0.09) and (4.27 ± 0.07; 3.47 ± 0.11) (logarithm stability constant values) for Be(II) and Co(II) complexes, respectively, at ionic strength of 0.1 mol/L and a temperature of 35 °C.

scholarly journals Study of Complex Formation Between Iodoquinol (IQ) and Co2+, Mn2+, Cd2+, Pb2+and Zn2+Cations in Binary Aqueous / Non-aqueous Solvent Using Spectrophotometry

2007 ◽  
Vol 4 (4) ◽  
pp. 581-586 ◽  
Author(s):  
A. Nezhadali ◽  
H. A. Hosseini ◽  
P. Langara
Keyword(s):  
Ionic Strength ◽  
Complex Formation ◽  
Stability Constants ◽  
Spectrophotometric Method ◽  
Formation Constants ◽  
The Other ◽  
Aqueous Solvent ◽  
The Stability ◽  
Complexation Reactions

The complexation reactions between iodoquinol and Co2+, Mn2+, Cd2+, Pb2+and Zn2+cations were studied in different DMF/H2O binary mixtures at the ionic strength of 0.1(using NaNO3).The spectrophotometric method was used for the determination of formation constants and the stoichiometries. The stoichiometry of the complexes is established 1:1 by Job's and mole ratio methods. It was found that the stability constants of the complex formed between the ligand (IQ) and the cations in the all cases increase with increasing of the non-aqueous solvent. In the most cases the maximum formation constants between Zn2+ion and IQ were obtained respect to the other cations.

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