CONDUCTOMETRIC STUDY OF LIGAND STRUCTURE INFLUENCE ON THE Pb(II) COMPLEXATION WITH CROWN ETHERS

The conductometric study of ligand structure influence on the Pb(II) complexation with crown ethers in different solvents has been investigated. In this paper, the complexation reaction of macrocyclic ligand, 18-crown-6 (18C6), dibenzo-18-crown-6 (DB18C6), and Pb(II) cation was studied in different solvents: dichloromethane (DCM) and 1,2- dichloroethane (1,2-DCE). The effects of surfactant structure (Triton X-100 and Triton X-45) on the conductivity of the Pb(II) complex with 18-crown-6 and dibenzo-18-crown-6 ether have been investigated. The conductance data showed that the stoichiometry of the complexes in most cases is 1:1(ML). It is also demonstrated that the influence of crown ethers is deeply affected by the organic solvent used. In the solvents studied, the stability of the resulting complexes showed higher stability in dichloromethane comparing with 1,2- dichloroethane. Macrocyclic ligand 18-crown-6 showed more suitable for complexation of Pb(II) ions compared to dibenzo-18-crown-6. Adding a surfactant affected the higher absolute values of the conductivity of systems, but not the change in the stoichiometric ratio between a metal ion and macrocyclic ligand.

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

Journal of the Serbian Chemical Society ◽

10.2298/jsc140129034s ◽

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.

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Thermodynamic investigations of complexation between dibenzo 18-crown-6 with Ni2+, Zn2+ and Cd2+ cations in pure acetonitrile, pure dimethylesulfoxide and acetonitrile-dimethylesulfoxide binary mixtures using conductometric method

Towards Excellence ◽

10.37867/te110105 ◽

2019 ◽

pp. 43-53

Author(s):

Naresh Desai ◽

Dhruvi Mehta ◽

Raviprakash Chandrab ◽

M.M. Maisuria

Keyword(s):

Binary Mixtures ◽

Stability Constants ◽

Standard Enthalpy ◽

Macrocyclic Ligand ◽

Standard Entropy ◽

Free Energies ◽

Enthalpy Changes ◽

Conductance Data ◽

The Stability ◽

Complexation Reactions

The stability constants of 1:1 (M-L) complexes of Dibenzo-18-crown-6 (DB18C6) with Ni2+, Zn2+ and Cd2+ cations have been determined conductometrically. The conductance data show that the stoichiometry of the complexes formed between the macrocyclic ligand and Ni2+, Zn2+ and Cd2+ 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.

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

Journal of the Serbian Chemical Society ◽

10.2298/jsc130730137b ◽

2014 ◽

Vol 79 (5) ◽

pp. 565-578 ◽

Cited By ~ 1

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.

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ChemInform Abstract: LIGAND STRUCTURE AND COMPLEXATION, V. NEW CROWN ETHERS AND THEIR ALKALI METAL ION COMPLEXES

Chemischer Informationsdienst ◽

10.1002/chin.197627287 ◽

1976 ◽

Vol 7 (27) ◽

pp. no-no

Author(s):

EDWIN WEBER ◽

FRITZ VOEGTLE

Keyword(s):

Alkali Metal ◽

Crown Ethers ◽

Metal Ion ◽

Metal Ion Complexes ◽

Alkali Metal Ion ◽

Ligand Structure

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Extraction of strontium and barium salts by the nitrobenzene solution of dicarbolide in the presence of glymes

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19850581 ◽

1985 ◽

Vol 50 (3) ◽

pp. 581-599 ◽

Cited By ~ 41

Author(s):

Petr Vaňura ◽

Emanuel Makrlík

Keyword(s):

Stability Constants ◽

Organic Phase ◽

Equilibrium Constants ◽

Minor Role ◽

Nitrobenzene Solution ◽

Ligand Structure ◽

Stability Constants Of Complexes ◽

Separation Factors ◽

The Stability ◽

A Minor

Extraction of microamounts of Sr2+ and Ba2+ (henceforth M2+) from the aqueous solutions of perchloric acid (0.0125-1.02 mol/l) by means of the nitrobenzene solutions of dicarbolide (0.004-0.05 mol/l of H+{Co(C2B9H11)2}-) was studied in the presence of monoglyme (only Ba2+), diglyme, triglyme, and tetraglyme (CH3O-(CH2-CH2O)nCH3, where n = 1, 2, 3, 4). The distribution of glyme betweeen the aqueous and organic phases, the extraction of the protonized glyme molecule HL+ together with the extraction of M2+ ion and of the glyme complex with the M2+ ion, i.e., ML2+ (where L is the molecule of glyme), were found to be the dominating reactions in the systems under study. In the systems with tri- and tetraglymes the extraction of H+ and M2+ ions solvated with two glyme molecules, i.e., the formation of HL2+ and ML22+ species, can probably play a minor role. The values of the respective equilibrium constants, of the stability constants of complexes formed in the organic phase, and the theoretical separation factors αBa/Sr were determined. The effect of the ligand structure on the values of extraction and stability constants in the organic phase is discussed.

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Structure of the complexes of ethylenediphosphinetetraacetic acid in solution

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19850445 ◽

1985 ◽

Vol 50 (2) ◽

pp. 445-453 ◽

Cited By ~ 2

Author(s):

Jana Podlahová ◽

Josef Šilha ◽

Jaroslav Podlaha

Keyword(s):

Metal Ion ◽

Carboxyl Groups ◽

Complex Solution ◽

Square Planar ◽

Weak Complexes ◽

Carboxylic Groups ◽

Uv Visible ◽

The Stability ◽

Tetrahedral Complexes ◽

Free Carboxyl

Ethylenediphosphinetetraacetic acid is bonded to metal ions in aqueous solutions in four ways, depending on the type of metal ion: 1) through an ionic bond of the carboxylic groups to form weak complexes with a metal:ligand ratio of 1 : 1 (Ca(II), Mn(II), Zn(II), Pb(II), La(III)); 2) through type 1) bond with contributions from weak interaction with the phosphorus (Cd(II)); 3) through coordination of the ligand as a monodentate P-donor with the free carboxyl groups with formation of 2 : 1 and 1 : 1 complexes (Cu(I), Ag(I)); 4) through formation of square planar or, for Hg(II), tetrahedral complexes with a ratio of 1 : 2 with the ligand as a bidentate PP-donor with the free carboxyl groups (Fe(II), Co(II), Ni(II), Pd(II), Pt(II)). On acidification of the complex solution, the first two protons are bonded to the carboxyl groups. The behaviour during further protonation depends on the type of complex: in complexes of types 1) and 2) phosphorus is protonated and the complex dissociates; in complexes of types 3) and 4) the free carboxyl groups are protonated and the phosphorus-metal bond remains intact. The results are based on correlation of the stability constants, UV-visible, infrared, 1H and 31P NMR spectra and magnetic susceptibilities of the complexes in aqueous solution.

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