scholarly journals Spectrophotometric study on the stability constants and thermodynamic parameters of Zn2+, Cd2+ and Hg2+ complexes with Imino Thiazolidinone

2015 ◽  
Vol 9 (8) ◽  
pp. 175-183 ◽  
Author(s):  
B Gemechu Zewdu ◽  
Kebede Tesfahun ◽  
G Demissie Ephrem ◽  
W Woyessa Girma ◽  
B Kassa Solomon
Keyword(s):  
Thermodynamic Parameters ◽  
Stability Constants ◽  
Spectrophotometric Study ◽  
The Stability

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.

scholarly journals 1H NMR and spectrophotometric study of alkaline metal ion complexes with N-dansyl aza-18-crown-6

2006 ◽  
Vol 4 (1) ◽  
pp. 13-28 ◽  
Author(s):  
Tadeusz Ossowski ◽  
Hanna Sulowska ◽  
Tomasz Karbowiak ◽  
Dorota Zarzeczanska ◽  
Błażej Gierczyk ◽  
...  
Keyword(s):  
Fluorescence Spectroscopy ◽  
Stability Constants ◽  
Metal Ion ◽  
Spectrophotometric Study ◽  
Alkaline Metal ◽  
Empirical Methods ◽  
Absorption And Fluorescence Spectroscopy ◽  
The Stability ◽  
Semi Empirical ◽  
Formation Of Complexes

AbstractFormation of complexes of A18C6-Dns and metal cations (Ca2+, Sr2+, Ba2+ and Mg2+) in acetonitrile has been studied by NMR, absorption and fluorescence spectroscopy and PM5 semi-empirical methods. A18C6-Dns forms stable complexes with Ca2+, Sr2+ and Ba2+ cations. The stability constants of various complexes are determined by different methods and their structures are visualised by the PM5 semi-empirical calculations.

A spectrophotometric study of the complex formation between cobalt(III) and trans-1,2-cyclohexanedinitrilotetraacetic acid (CyDTA)

1979 ◽  
Vol 57 (17) ◽  
pp. 2292-2296 ◽  
Author(s):  
Rita K. Hessley ◽  
Shoba Waykole ◽  
Robert L. Sublett
Keyword(s):  
Complex Formation ◽  
Stability Constants ◽  
Spectrophotometric Study ◽  
Higher Order ◽  
Order Complex ◽  
Spectrophotometric Methods ◽  
Investigation Result ◽  
Unique System ◽  
The Stability

An intriguing and unique system has been observed during the otherwise routine study of the cobalt(III) complex of trans-1,2-cyclohexanedinitrilotetraacetic acid (CyDTA). Using classical spectrophotometric methods to determine the stoichiometry and the stability of a complex, significant deviations from the predicted 1:1 complex were observed in a system buffered at pH = 4.6. It is postulated that in addition to the usual 1:1 complex, the propensity of the reactants to form complexes and the strong oxidizing conditions used in this investigation result in the formation of a second, higher order complex between Co(III) and CyDTA. When the concentration of CyDTA exceeds that of Co(III), the metal:ligand ratio for this complex is 1:2. A structure is proposed, and approximate stability constants of both complexes are discussed.

Chalcones as Analytical Reagents of Aluminum: Stability, Thermodynamic and Kinetic Study

2015 ◽  
Vol 229 (3) ◽  
Author(s):  
Vanesa A. Muñoz ◽  
Carolina G. Kretek ◽  
M. Paulina Montaña ◽  
Nora  B. Pappano ◽  
Nora  B. Debattista ◽  
...  
Keyword(s):  
Kinetic Study ◽  
Thermodynamic Parameters ◽  
Stability Constants ◽  
Driving Force ◽  
Biological Properties ◽  
Polyphenolic Compounds ◽  
Formation Reaction ◽  
Long Time ◽  
Analytical Reagents ◽  
The Stability

AbstractChalcones, a group of polyphenolic compounds, has been studied for a long time due to their biological properties and their ability as analytical reagents. In this work the stability and thermodynamic parameters concerning the fotmation in ethanolic medium of two chalcone–aluminium complexes (2′,3-dihydroxychalcone-Al(III) and 2′,4′,3-trihydroxychalcone-Al(III)) were studied and a kinetic study of the formation reaction was aslo performed. Both systems showed 1:1 L : M stoichiometry and stability constants at four temperatures were determined. Thermodynamic parameters indicate that both formation reactions are endothermic and driving force is entropic. Kinetic study revealed that 2′,4′,3-trihydroxychalcone-Al(III) formation is faster than 2′,3-dihydroxyclacone-Al(III), a factor which can be interesting when proposing new analytical reagents.

scholarly journals Thermodynamic parameters for the complexation of technetium(IV) with EDTA

2018 ◽  
Vol 106 (12) ◽  
pp. 963-970 ◽  
Author(s):  
Mitchell T. Friend ◽  
Cecilia Eiroa Lledo ◽  
Lindsey M. Lecrivain ◽  
Donald E. Wall ◽  
Nathalie A. Wall
Keyword(s):  
Thermodynamic Parameters ◽  
Stability Constants ◽  
High Yield ◽  
Edta Complex ◽  
Liquid Liquid Extraction ◽  
Geological Repository ◽  
The Stability ◽  
Apparent Stability ◽  
Accurate Quantification ◽  
Acid Dependence

Abstract Technetium-99 is a high yield (~6% fission yield) fission product and long-lived (2.13×105 year half-life) component of nuclear waste that will be disposed of in a geological repository. Some 99Tc has been released into the environment due to nuclear fuel and weapon production activities at sites such as Hanford, WA. Strongly complexing ligands such as ethylenediamine-N,N,N′,N′-tetraacetic acid (EDTA) are known to increase Tc(IV) solubility and mobility in environmental systems and an accurate quantification of the complexation of Tc(IV) with EDTA is important for predicting its behavior in a geological repository. A liquid–liquid extraction system utilizing 0.2 M TOPO in dodecane was used to measure the stability constants of Tc(IV)-EDTA in 0.50 m NaNO3 at variable temperatures (14.0±0.1, 25.0±0.1, and 32.0±0.1°C). The acid dependence of the apparent stability constants in the pCH range of 2.00–2.70 indicated the formation of TcO(EDTA)2− (logβ101=17.9±0.3, 25.0±0.1°C) and a protonated complex TcO(H)(EDTA)− (logβ111=20.5±0.1, 25.0±0.1°C). The associated thermodynamic parameters ΔrG101=−101.7±0.4 kJ·mol−1, ΔrH101=−47±9 kJ·mol−1, ΔrS101=179±36 J·mol−1·K−1, ΔrG111=−117.2±0.3 kJ·mol−1, ΔrH111=−23±5 kJ·mol−1, and ΔrS111=315±63 J·mol−1·K−1 (0.50 m NaNO3, 25.0±0.1°C) were determined by van’t Hoff analysis. The formation of each Tc(IV)–EDTA complex is exothermic and present favorable entropy terms.

Synthesis, characterization, and thermodynamics of tertiary phosphine cobalt(III) Schiff-base complexes

2001 ◽  
Vol 79 (9) ◽  
pp. 1360-1365 ◽  
Author(s):  
Mozaffar Asadi ◽  
Ali Hossein Sarvestani
Keyword(s):  
Schiff Base ◽  
Ionic Strength ◽  
Thermodynamic Parameters ◽  
Stability Constants ◽  
Schiff Base Complex ◽  
Axial Ligand ◽  
Adduct Formation ◽  
Schiff Base Complexes ◽  
Tertiary Phosphine ◽  
The Stability

[Co(5-nitroSalen)(PBu3)]ClO4·H2O and [Co(Salpd)(PBu3)]ClO4·H2O were synthesized and characterized. The stability constants and the thermodynamic parameters were measured spectrophotometrically for 1:1 adduct formation of [CoL(PBu3)]ClO4·H2O, (L = Salen, 5-nitroSalen, Salpd), and [Co(Salen)(PMe2Ph)]ClO4·H2O as acceptors with P(OR)3, (R = Me, Et, i-Pr) as donors, in acetonitrile solvent and in constant ionic strength (I = 0.01 M) and at various temperatures. The trend of the reactivity of cobalt(III) Schiff-base complexes with PBu3 axial ligand toward a given donor is as follows: 5-nitroSalen > Salen > Salpd.Also, the following reactivity trend of the donors toward a given cobalt(III) Schiff-base complex is in the operation: P(O-i-Pr)3 > P(OEt)3 > P(OMe)3.Key words: cobalt(III) Schiff-base complexes, thermodynamic parameters, trialkylphosphite, adduct complexes, stability constants.

Thermodynamics of substituted pyrazolone. V: Potentiometric and conductometric studies of complexes of some transition metals with 4-(4-acetophenyl)hydrazono-3-methyl-2-pyrazolin-5-one

1999 ◽  
Vol 77 (7) ◽  
pp. 1305-1309 ◽  
Author(s):  
Ashraf A El-Bindary ◽  
Adel Z El-Sonbati ◽  
Hanan M Kera
Keyword(s):  
Thermodynamic Parameters ◽  
Stability Constants ◽  
Dissociation Constants ◽  
Transition Metal Ions ◽  
Water Mixture ◽  
Dissociation Process ◽  
Different Temperatures ◽  
The Stability ◽  
Dissociation And Stability Constants ◽  
Key Words 4

Proton-ligand dissociation constants of 4-(4-acetophenyl)hydrazono-3-methyl-2-pyrazolin-5-one (AHMP) and metal-ligand stability constants of its complexes with some transition metal ions were calculated potentiometrically in 0.1 M KCl and 50% (v/v) ethanol-water mixture. The order of stability constants was found to be Th4+ > UO22+ > Ce3+ > La3+ > Mn2+ < Co2+ < Ni2+ < Cu2+ > Zn2+. The dissociation constant, pK1H, of AHMP and the stability constants, log K, of their complexes were determined at different temperatures (298, 308, and 318 K). 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 has been found to be spontaneous, exothermic, or endothermic (depending the metal), and entropically favourable. The stoichiometries of these complexes were determined conductometrically and indicated the formation of 1:1 and 1:2 (metal:ligand) complexes. Key words: 4-(4-acetophenyl)hydrazono-3-methyl-2-pyrazolin-5-one, dissociation and stability constants, thermodynamic parameters, stoichiometries.

Spectrophotometric Study of the Formation of Iron(III) Complexes with Some Salicylic Acid Derivatives

1995 ◽  
Vol 60 (3) ◽  
pp. 464-472 ◽  
Author(s):  
Terézia M. Surányi ◽  
Evgenija A. Djurendić ◽  
Gyöngyi Gy. Vastag
Keyword(s):  
Salicylic Acid ◽  
Stability Constants ◽  
Aqueous Ethanol ◽  
Side Reaction ◽  
Spectrophotometric Study ◽  
Stoichiometric Ratio ◽  
Ligand Ratio ◽  
Salicylic Acid Derivatives ◽  
The Stability

The stoichiometric ratio and stability constants of iron(III) complexes with 1,n-di-O-salicyloylalkane-1,n-diols (n = 2 - 8) and N,N'-disalicyloyl-1,n-alkanediamines (n= 2 - 4) were determined spectrophotometrically. In 61.10% aqueous ethanol, the iron-to-ligand ratio is 1 : 1 (FeL+). The stability constants of the complexes were measured at 298 K and μ = 0.5 mol dm-3 (LiCl). Since the determination was performed in a glycinate buffer, the constants were corrected for the side reaction of iron(III) with glycine.

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 Stability constants and thermodynamic parameters of cadmium complexes with sulfonamides and cephapirin

2018 ◽  
Vol 33 (1) ◽  
pp. 29
Author(s):  
M. S. Parihar ◽  
Farid Khan
Keyword(s):  
Stability Constant ◽  
Metal Complexes ◽  
Thermodynamic Parameters ◽  
Stability Constants ◽  
Cadmium Complexes ◽  
Electrode Processes ◽  
Diffusion Controlled ◽  
Higher Temperature ◽  
The Stability ◽  
And Diffusion

Stability constant (log 􀁠) and thermodynamic parameters of Cd2+ complexes with sulfonamide and cephapirin were determined by Polarographic technique at pH = 7.30 ± 0.01 and μ = 1.0 MKNO3 at 250°C. The sulfonamides were sulfadiazine, sulfisoxazole, sulfamethaxazole, sulfamethazine, sulfathiazole, sulfacetamide and sulfanilamide used as primary ligands and cephapirin as secondaryligand. Cd2+ formed 1:1:1, 1:2:1 and 1:1:2 complexes. The nature of electrode processes were reversible and diffusion controlled. The stability constants and thermodynamic parameters (􀂨G, 􀂨Hand 􀂨S) were determined. The formation of the metal complexes has been found to be spontaneous, exothermic in nature, and entropically unfavourable at higher temperature.

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