Title of article
A Thermodynamic Study of Complex Formation between 15-Crown-5 with Mg2+, Ca2+, Sr2+ and Ba2+ in Acetonitrile Methanol Binary Mixtures Using Conductometric Method
Author/Authors
Rounaghi, Gholam Hossein Department of Chemistry - Faculty of Science Ferdowsi University of Mashhad , Sanavi Khoshnood, Raziyeh Department of Chemistry - Faculty of Science Ferdowsi University of Mashhad
Pages
8
From page
82
To page
89
Abstract
The complexation reactions between Mg2+, Ca2+, Sr2+ and Ba2+ metal cations with 15-crown-5 (15C5) were studied in acetonitrile (AN)-methanol (MeOH) binary mixtures at different temperatures using conductometric method. 15C54 forms 1:1 complexes with Mg2+, Ca2+ and Sr2+ cations in solutions. The Ma2+ cation forms a 2:1 complex (ratio of lighand to cation) in solutions. A linear relation was observed for variation of logKf of 15C5-Ca2+ and 15C5-Sr2+ complexes vs the composition of An-MeOH binary systems, but a non-linear behavior was observed in the case of 15C5-Mg2+ complex in these binary mixtures. Selectivity of 15C5 for Mg2+, Ca2+ and Sr2+ cations is sensitive to solvent composition. In some cases and in certain compositions of the mixed solvent systems, the selectivity order is changed. The values of thermodynamic parameters (DH0c , DS0c ) for formation of 15C5-Mg2+ , 15C5-Ca2+ and 15C5-Sr2+ complexes were obtained from temperature dependence of stability constants and the results show that the thermodynamics of complexation reactions is affected by the nature and composition of the mixed solvents.
Keywords
Conductometry , An-MeOH binary mixtures , Mg2+; Ca2+; Sr2+ and Ba2+ cations , 15-Crown-5 , Ba2+ cations , Sr2+ , Ca2+ , Mg2+
Journal title
Astroparticle Physics
Serial Year
2001
Record number
2429033
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