Russian Journal of General Chemistry, ( ISI ), Volume (78), No (10), Year (2008-10) , Pages (1866-1871)

Title : ( Discussion on complexation reactions between dicyclohexyl-18-crown-6 (DCH18C6) with Na+, K+, Cs+, Rb+, and Tl+ metal cations in acetonitrile-water binary mixtures )

Authors: Mohammad Hassan Soorgy , Glamhossein Ronagi , ,

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Abstract

The complex formation between Na+, K+, Cs +, Rb+ and Tl+ metal cations with macrocyclic ligand, dicyclohexyl-18-crown-6 (DCH18C6) was studied in acetonitrile-water (AN-H2O) binary systems at different temperatures using conductometric method. DCH18C6 forms 1:1 complexes with these metal cations. The stability constants of the complexes were obtained from fitting of molar conductivity curves using a computer program Genplot. The results show that the selectivity order of DCH18C6 for the metal cations in acetonitrile-water mixtures (AN = 25.3 and 50.4 mol %) is: Tl+ > K+ > Rb+ > Cs+ > Na+. A non-linear behaviour was observed between the log K f of the complexes versus the composition of the mixed solvent which it related to changes of acidity, basicity, polarity and also polarizability of AN-H2O mixtures with the composition of this binary solution. The values of standard enthalpy changes (ΔH s0 ) for complexation reactions were obtained from the slope of the van\\\\\\\'t Hoff plots and the changes in the standard entropy (ΔS s0 ) were calculated from the relationship: ΔG s,298.150 = ΔH s0 - 298.15ΔS s0 . The obtained results show that in most cases, the complexes are enthalpy stabilized but entropy destabilized.

Keywords

, macrocyclic ligand; dicyclohexyl, 18, crown, 6 (DCH18C6); acetonitrile, water (AN, H2O) binary systems.
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@article{paperid:1009151,
author = {Soorgy, Mohammad Hassan and Ronagi, Glamhossein and , },
title = {Discussion on complexation reactions between dicyclohexyl-18-crown-6 (DCH18C6) with Na+, K+, Cs+, Rb+, and Tl+ metal cations in acetonitrile-water binary mixtures},
journal = {Russian Journal of General Chemistry},
year = {2008},
volume = {78},
number = {10},
month = {October},
issn = {1070-3632},
pages = {1866--1871},
numpages = {5},
keywords = {macrocyclic ligand; dicyclohexyl-18-crown-6 (DCH18C6); acetonitrile-water (AN-H2O) binary systems.},
}

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%0 Journal Article
%T Discussion on complexation reactions between dicyclohexyl-18-crown-6 (DCH18C6) with Na+, K+, Cs+, Rb+, and Tl+ metal cations in acetonitrile-water binary mixtures
%A Soorgy, Mohammad Hassan
%A Ronagi, Glamhossein
%A ,
%J Russian Journal of General Chemistry
%@ 1070-3632
%D 2008

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