scholarly journals Conductometric Studies of Thermodynamics of Complexation of Co2+, Ni2+, Cu2+, and Zn2+ Cations with Aza-18-crown-6 in Binary Acetonitrile-Methanol Mixtures

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Mehdi Taghdiri ◽  
Mahmood Payehghadr ◽  
Reza Behjatmanesh-Ardakani ◽  
Homa Gha'ari
Keyword(s):  
Formation Constants ◽  
Solvent Mixture ◽  
Molar Conductance ◽  
Binding Energies ◽  
Thermodynamics Of Complexation ◽  
Ratio Data ◽  
Different Temperatures ◽  
Enthalpy And Entropy Changes ◽  
The Stability ◽  
Complexation Reactions

The complexation reactions between aza-18-crown-6 (A18C6) and Co2+, Ni2+, Cu2+, and Zn2+ ions were studied conductometrically in different acetonitrile-methanol mixtures at various temperatures. The formation constants of the resulting 1 : 1 complexes were calculated from the computer fitting of the molar conductance-mole ratio data at different temperatures. Selectivity of A18C6 for Co2+, Ni2+, Cu2+, and Zn2+ cations is sensitive to the solvent composition. At 20°C and in acetonitrile solvent, the stability of the resulting complexes varied in the order but the order was reversed byadding 20% methanol. The enthalpy and entropy changes of the complexation reactions were evaluated from the temperature dependence of formation constants. It was found that the stability of the resulting complexes decreased with increasing methanol in the solvent mixture. The TΔS° versus ΔH° plot of thermodynamic data obtained shows a fairly good linear correlation indicating the existence of enthalpy-entropy compensation in the complexation reactions. In addition, binding energies of Ni2+, Cu2+, and Zn2+ complexes with A18C6 were calculated at B3LYP/6-31G level of theory.

scholarly journals Conductometric Studies of Thermodynamics of 1,10-Didecyl-1,10-diaza-18-crown-6 Complexes with , , , , , , and Ions in Acetonitrile, Methanol, and Ethanol Solutions

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Mehdi Taghdiri ◽  
Mahmood Payehghadr ◽  
Reza Behjatmanesh-Ardakani ◽  
Sirous Movahhedi ◽  
Farzaneh Nourifard
Keyword(s):  
Formation Constants ◽  
Molar Conductance ◽  
Versus Plot ◽  
Ratio Data ◽  
Different Temperatures ◽  
Enthalpy And Entropy Changes ◽  
Enthalpy And Entropy ◽  
The Stability ◽  
Complexation Reactions ◽  
Cation Size

The complexation reactions between 1,10-didecyl-1,10-diaza-18-crown-6 (DD18C6) and , , , , , and ions were studied conductometrically in acetonitrile, methanol, and ethanol at various temperatures. The formation constants of the resulting 1 : 1 complexes were calculated from the computer fitting of the molar conductance-mole ratio data at different temperatures. In the solvents studied, the stability of the resulting complexes varied in the order acetonitrile ≫ methanol > ethanol. The enthalpy and entropy changes of the complexation reactions were evaluated from the temperature dependence of formation constants. The versus plot of thermodynamic data obtained shows a linear correlation indicating the existence of enthalpy-entropy compensation in the complexation reactions. The ab initio studies calculated at B3LYP/6-31G level of theory indicate that the binding energy of complexes decreases with increasing cation size in the gas phase. The experimental data obtained in the solvents show different trends so that the stability constant of Li+and Mg2+complexes is lower than other alkali and alkaline earth ions, respectively due to the solvation of these small ions in solution.

scholarly journals Thermodynamics of the complexation between salicylaldehyde thiosemicarbazone with Cu2+ ion in methanol +1,4-dioxane binary solutions

2014 ◽  
Vol 79 (5) ◽  
pp. 565-578 ◽  
Author(s):  
Rashmidipta Biswas ◽  
Dhiraj Brahman ◽  
Biswajit Sinha
Keyword(s):  
Mixed Solvents ◽  
Formation Constants ◽  
Molar Conductance ◽  
Binary Solvent ◽  
Complexation Reaction ◽  
Solvent Mixtures ◽  
Conductance Data ◽  
Different Temperatures ◽  
Uv Visible ◽  
The Stability

The complexation reaction between salicylaldehyde thiosemicarbazone, abbreviated as STSC, with Cu2+ ion was studied in the binary mixtures of methanol + 1,4-dioxane binary by using UV-Visible spectrophotometric and conductometric methods at different temperatures. The formation constants (Kf) for the 1:1 complex, Cu2+-STSC, were calculated from computer fitting of the absorbance and molar conductance data against various mole ratios (cM:cL or cL:cM) in different binary solvent mixtures. A non-linear correlation was observed for the variation of logKf for the complex against the solvent compositions. Various thermodynamic parameters (?H, ?S and ?G) for the formation of Cu2+-STSC complex were also determined from the temperature dependence of the stability constants (Kf). The results showed that the complexation reaction is affected by the nature and composition of the mixed solvents.

scholarly journals CONDUCTOMETRIC STUDY OF COMPLEX FORMATION BETWEEN 2,3-PYRAZINEDICARBOXYLIC ACID AND SOME TRANSITION METAL IONS IN METHANOL

2012 ◽  
Vol 20 (20) ◽  
pp. 43-50
Author(s):  
A.A. El-Khouly ◽  
E. A. Gomaa ◽  
S. E. Salem
Keyword(s):  
Complex Formation ◽  
Transition Metal Ions ◽  
Formation Constants ◽  
Molar Conductance ◽  
Association Constants ◽  
Absolute Methanol ◽  
Free Energies ◽  
Titration Curves ◽  
Conductometric Study ◽  
Complexation Reactions

The complexation reactions between CuCl2 CoCL2 and NiCL2 with 2,3-Pyrazinedicarboxylic acid in methanol (MeOH) at 313.15 K were studied by conductometric methods. The association constants, formation constants and Gibbs free energies were calculated from the conduclometric titration curves. On drawing the relation between molar conductance and the ratio of metal to ligand coflCentrations, different lines were obtained indicating the formation of 1: 1 and 2: 1 (M:L) stoichiometric complexes. The formation constants and Gibbs free energies of different complexes in absolute Methanol at 313.15 Kfollow the order:

scholarly journals Spectrophotometric and conductometric study of the complexation of N-salicylidene-2-aminophenol with Cu2+ in methanol + 1,4-dioxane binary solutions

2014 ◽  
Vol 79 (10) ◽  
pp. 1263-1277
Author(s):  
Rashmidipta Biswas ◽  
Dhiraj Brahman ◽  
Biswajit Sinha
Keyword(s):  
Stability Constants ◽  
Mixed Solvents ◽  
Molar Conductance ◽  
Binary Solvent ◽  
Complexation Reaction ◽  
Solvent Mixtures ◽  
Linear Behaviour ◽  
Different Temperatures ◽  
Conductometric Study ◽  
The Stability

The complexation reaction between N-salicylidene-2-aminophenol, abbreviated as SAP, with Cu2+ ion was studied in binary mixtures of methanol and 1,4-dioxane by using conductometric and spectrophotometric method at different temperatures. The stability constants (Kf) for the 1:1 complex, Cu2+-SAP, were calculated from computer fitting of absorbance and molar conductance data against various mole ratios (cM:cL or cL:cM) in different binary solvent mixtures. A non-linear behaviour was observed for the variation of logKf for the complex against the solvent compositions. Various thermodynamic parameters (?H, ?S and ?G) for the formation of Cu2+-SAP complex were determined from the temperature dependence of stability constants (Kf). The overall results showed that the complexation reaction is entropy driven and is affected by the nature and composition of the mixed solvents.

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.

scholarly journals Solvents Influence On Thermodynamics Of Complexation Between Dibenzo 18-Crown-6 With Tl+, Cs+ And Uo22+ Cations In Pure Acetonitrile, Pure Dimethylesulfoxide And Acetonitrile-Dimethylesulfoxide Binary Mixtures By Conductometric Method

2019 ◽  
pp. 63-74
Author(s):  
Naresh Desai ◽  
Dhruvi Mehta ◽  
Raviprakash Chandra ◽  
M. M. Maisuria
Keyword(s):  
Binary Mixtures ◽  
Stability Constants ◽  
Standard Enthalpy ◽  
Macrocyclic Ligand ◽  
Standard Entropy ◽  
Free Energies ◽  
Thermodynamics Of Complexation ◽  
Enthalpy Changes ◽  
The Stability ◽  
Complexation Reactions

The stability constants of 1:1 (M-L) complexes of Dibenzo-18-crown-6 (DB18C6) with Tl+, Cs+ and UO22+ cations have been determined conductometrically. The conductance data show that the stoichiometry of the complexes formed between the macrocyclic ligand and Tl+, Cs+ and UO22+ cations is 1:1 (M:L). GENPLOT computer program used to find the stability constants of the complexes were obtained from fitting of molar conductivity curves. The selectivity order of DB18C6 for the metal cations changes with the nature and composition of the binary mixed solvent. We also determined the Gibbs standard free energies (∆G0), the standard enthalpy changes (∆H0) and standard entropy changes (∆S0) for formation of these complexes in acetonitrile – dimethylesulfoxide (AN-DMSO) binary mixtures for the complexation. The values of standard enthalpy changes (∆H0 ) for complexation reactions were obtained from the slope of the van’t Hoff plots and the changes in standard entropy (∆S0) were calculated from the relationship ∆G0298.15 = ∆H0 - 298.15 ∆S0.

Thermodynamics of Complexation of Sodium Ion with 12-Crown-4 and 18-Crown-6 in Pyridine

1995 ◽  
Vol 50 (4) ◽  
pp. 529-535 ◽  
Author(s):  
Kumiko Ohtsu ◽  
Kazuhiko Ozutsumi ◽  
Makoto Kurihara ◽  
Takuji Kawashima
Keyword(s):  
Electron Pair ◽  
Formation Constants ◽  
Sodium Ion ◽  
Titration Calorimetry ◽  
Water Molecules ◽  
Thermodynamics Of Complexation ◽  
Stability Order ◽  
Titration Data ◽  
Solvent Molecules ◽  
The Stability

The complexation of sodium ion with 1,4,7,10-tetraoxacyclododecane (12-crown-4) and 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) has been studied by titration calorimetry in pyridine (PY) containing 0.1 mol dm-3 (C2H5)4NClO4 as a constant ionic medium at 25 °C. The calorimetric titration data were well explained in terms of the formation of the [Na(12-crown-4)]+, [Na(12-crown-4)2]+, and [Na(18-crown-6)]+ complexes, and their formation constants, reaction enthalpies, and entropies were determined. The formation of [Na(18-crown-6)]+ is much pronounced in PY over N,N-dimethylformamide (DMF) and water, and the stability order is PY > DMF > water. The enthalpy values for the formation of [Na(18-crown-6)]+ are all negative in PY, DMF, and water, and increase in the order PY < DMF < water. The complexation is the least exothermic in water, though sodium ion is the most weakly solvated in water. This is because 18-crown-6 is much stabilized in water by forming hydrogen bonds with water molecules. Despite the stronger electron pair-donating ability of PY than DMF, the complexation is more exothermic in PY than in DMF. This is ascribed to the different solvation number of the sodium ion in P Y and DMF, i.e., the sodium ion is coordinated with a smaller number of solvent molecules in the former solvent than in the latter.

Physico-chemical investigation on the complexes of indium(III) with Mercapto-, Hydroxy-, and Amino-substituted propionic acid

1972 ◽  
Vol 25 (5) ◽  
pp. 929 ◽  
Author(s):  
R Sarin ◽  
KN Munshi
Keyword(s):  
Formation Constants ◽  
Alternative Methods ◽  
Potentiometric Studies ◽  
Ph Titration ◽  
Physico Chemical ◽  
Different Temperatures ◽  
Indium 111 ◽  
The Stability ◽  
Titration Technique ◽  
Stepwise Formation

Potentiometric studies have been carried out on the metal complexes of indium(111) with β-mercaptopropionic, β-hydroxypropionic, and β-aminopropionic acid. The Calvin-Bjerrum pH-titration technique, as used by Irving and Rossotti, has been applied to determine the stepwise formation constants of the complexes. The logK values have been computed by alternative methods. Thermodynamic formation constants have been obtained by extrapolation of the values at various ionic concentrations. The values of overall changes in ΔG, ΔH, and ΔS accompanying complex formation have been evaluated at three different temperatures at an ionic strength of 0.lM (NaClO4). The stability constant of the indium(111) complex decreases as the subsituted group changes from SH to OH to NH2.

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 A Superhydrophobic, Antibacterial, and Durable Surface of Poplar Wood

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1885
Author(s):  
Xinyu Wu ◽  
Feng Yang ◽  
Jian Gan ◽  
Zhangqian Kong ◽  
Yan Wu
Keyword(s):  
Stearic Acid ◽  
Antibacterial Properties ◽  
Alkali Resistance ◽  
Poplar Wood ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Acid And Alkali Resistance ◽  
The Stability

The silver particles were grown in situ on the surface of wood by the silver mirror method and modified with stearic acid to acquire a surface with superhydrophobic and antibacterial properties. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray energy spectroscopy (XPS) were used to analyze the reaction mechanism of the modification process. Scanning electron microscopy (SEM) and contact angle tests were used to characterize the wettability and surface morphology. A coating with a micro rough structure was successfully constructed by the modification of stearic acid, which imparted superhydrophobicity and antibacterial activity to poplar wood. The stability tests were performed to discuss the stability of its hydrophobic performance. The results showed that it has good mechanical properties, acid and alkali resistance, and UV stability. The durability tests demonstrated that the coating has the function of water resistance and fouling resistance and can maintain the stability of its hydrophobic properties under different temperatures of heat treatment.

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