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.

Chélates du fer (III) avec des anions dicarboxylates

1968 ◽  
Vol 46 (8) ◽  
pp. 1383-1388 ◽  
Author(s):  
M. Deneux ◽  
R. Meilleur ◽  
R. L. Benoit
Keyword(s):  
Ionic Strength ◽  
Complex Formation ◽  
Dicarboxylic Acids ◽  
Formation Constants ◽  
Acidity Constants ◽  
Spectrophotometric Methods ◽  
Stability Order ◽  
The Stability

Complex formation between iron(III) and oxalate, malonate, succinate, glutarate, and acetate ions has been studied by potentiométric and spectrophotométric methods at 25 °C, ionic strength 0.52 ± 0.02, and [Formula: see text] and 0.1 M H+ concentrations. The acidity constants of the dicarboxylic acids and the formation constants of the monochelates of iron(III) have been determined. The stability order is as follows: [Formula: see text].

scholarly journals Interaction of Dioxovanadium (V) ion with L-alanine at Different Ionic Strengths

2009 ◽  
Vol 5 (1) ◽  
pp. 570-574
Author(s):  
Mohammad Hossein Fekri ◽  
F. Gharib ◽  
M. Darvishpour
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Stability Constants ◽  
Least Squares Method ◽  
Type Equation ◽  
Formation Constants ◽  
Amino Group ◽  
Fitting Method ◽  
The Stability ◽  
Curve Fitting Method

The formation constants of species formed in the system H+ + alanine and VO2+ +alanine have been determined in aqueous solution for 1.0<pH<7.0 and at different ionic strengths ranging from 0.1 to 1.0 mol dm-3 NaClO4, using a combination of potentiometric and spectrophotometric techniques.The compositions of the formd complexes and their stability constants were determined by curve fitting method and it was shown that dioxivanadium(V) forms two mononuclear 1:1 and 1:2 species with alanineof type VO2L and VO2L2-.The porotonation constant of the amino group of alanine has been determined using potentiometric techniques and calculated using a computer program wich employ a least-squares method. The dependence of the porotonation of alanine and the stability constants of the species on ionic strength are described by a deby-huckel type equation.

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 The Stability Constants and Thermodynamic Parameters of Borate - Carbohydrate Complexes by pH Measurements

2012 ◽  
Vol 25 (1) ◽  
pp. 15-20 ◽  
Author(s):  
Farida Akhtar ◽  
Md Anisur Rahman ◽  
DM Shafiqul Islam ◽  
Md Anamul Hoque
Keyword(s):  
Ionic Strength ◽  
Complex Formation ◽  
Thermodynamic Parameters ◽  
Stability Constants ◽  
Chemical Society ◽  
Ph Measurements ◽  
Negative Contribution ◽  
Exothermic Process ◽  
Different Temperatures ◽  
The Stability

The complexation of borate with carbohydrates was studied potentiometrically at  temperatures 298.15-328.15K in aqueous medium at constant ionic strength, I = 0.1M  KCl. The stability constants (?) and thermodynamic parameters of borate-carbohydrate  complexes were determined using the technique proposed by Verchere and Hlaibi.  Carbohydrates such as D-fructose, D-Sorbitol, D-Mannitol, D-Galactose, D-Glucose and  D-Raffinose were used as ligands in this study. The ?1 values for the complexes at  different temperatures were found to follow the order: D-fructose > D-Sorbitol > DMannitol > D-Galactose > D-Glucose > D-Raffinose. The ?G0 values were found to be  negative and the negative values increased according to the above order. The values of  ?H0 and ?S0 were both negative which indicated that the complex formation was an  exothermic process and the spontaneity of its formation is driven by enthalpic  contribution overcoming the negative contribution of ?S0. DOI: http://dx.doi.org/10.3329/jbcs.v25i1.11766 Journal of Bangladesh Chemical Society, Vol. 25(1), 15-20, 2012

scholarly journals Synthesis ,spectroscopic study of Antipyryl azo 2-Naphthol and use it as new reagent for determination of Co(II) and Cu(II)

2013 ◽  
Vol 10 (3) ◽  
pp. 977-985
Author(s):  
Baghdad Science Journal
Keyword(s):  
Optimum Condition ◽  
Spectroscopic Study ◽  
Aqueous Medium ◽  
Stability Constants ◽  
Spectrophotometric Method ◽  
Full Color ◽  
Color Development ◽  
The Stability ◽  
Sensitive Spectrophotometric Method

A simple ,accurate and sensitive spectrophotometric method has been developed the determination of Cobalt(II) and Cupper (II) .The method is based on the chelation of Co(II) and Cu(II) ions with 4-(4´-pyrazolon azo) -2-Naphthol(APAN) in aqueous medium . The complexes have a maximum absorption at (513) and (506) nm and ? max 0.531×10 4 and 0.12×10 5 L.mol -1.cm -1 for Co(II) and Cu(II) respectively .The reagent and two complexes have been prepared in ethanolic solution.The stoichiometry of both complexes were found to be 1:2 (metal :legend) .The effects of various cations and anions on Co(II) and Cu(II) determination have been investigated .The stability constants and standard deviations for Co(II) and Cu(II) 0.291 x107 ,0.909X108 L.mol -1 ,(0.291) and (0.332) respectively .The optimum condition for full color development for described methods were applied satisfactorily to synthetic samples.

Ionic Strength Dependence of Formation Constants, Protonation and Complexation of Phenylalanine with Dioxovanadium(V) at different temperatures

2000 ◽  
Vol 2000 (4) ◽  
pp. 186-187 ◽  
Author(s):  
Farrokh Gharib ◽  
Karim Zare ◽  
Kavosh Majlesi
Keyword(s):  
Ionic Strength ◽  
Stability Constants ◽  
Sodium Perchlorate ◽  
Type Equation ◽  
Formation Constants ◽  
Ionic Strength Dependence ◽  
Different Temperatures ◽  
Strength Dependence ◽  
The Stability ◽  
Ph Range

The protonation constants of phenylalanine and the stability constants of the complexes between dioxovanadium(V) ion and phenylalanine have been determined spectrophotometrically, in the temperature range 15–35°C and ionic strength ranging from 0.1 to 1.5 mol dm−3 sodium perchlorate as a background salt, in the pH range 1.5–10.5, with high ligand to metal ratios. The values of enthalpy and entropy changes based on these formation constants were calculated. The dependence of protonation and the stability constants on ionic strength are described by a Debye-Huckel type equation.

scholarly journals Stability Constants of Some Biologically Important Pyrazoles and Their Ni2+Complexes in Different Dielectric Constant of Medium

2012 ◽  
Vol 9 (2) ◽  
pp. 637-641 ◽  
Author(s):  
S. D. Deosarkar ◽  
A. L. Puyad ◽  
S. A. Chavan
Keyword(s):  
Dielectric Constant ◽  
Ionic Strength ◽  
Stability Constants ◽  
Metal Ion ◽  
Formation Constants ◽  
Water Mixture ◽  
Electrostatic Forces ◽  
Ph Titration ◽  
Titration Technique

The proton-ligand stability constants of some biologically important new pyrazoles and formation constants of their complexes with Ni(II) were determined at 0.1 mol dm-3ionic strength and at 303.15 K in different dielectric constant of dioxane-water mixture by potentiometric method. The Calvin-Bjerrum's pH-titration technique as used by Irving and Rossotti was used for determination of stability constants. The results enabled to study the electrostatic forces of attraction between metal ion and ligand with changes in dielectric constant of the medium.

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