Metal ion recognition: the interaction of cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), silver(I) and lead(II) with N-benzylated macrocycles incorporating O2N2-, O3N2- and O2N3-donor sets
Kim, Jeong, Ahn, Tae-Ho, Lee, Myungro, Leong, Anthony J., Lindoy, Leonard F., Rumbel, Brendan R., Skelton, Brian W., Strixner, Tania, Wei, Gang, and White, Allan H. (2002) Metal ion recognition: the interaction of cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), silver(I) and lead(II) with N-benzylated macrocycles incorporating O2N2-, O3N2- and O2N3-donor sets. Dalton Transactions, 2002 . pp. 3993-3998.
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View at Publisher Website: http://dx.doi.org/10.1039/b206106f
The interaction of cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), silver(I) and lead(II) with a series of mixed-donor, N-benzylated macrocyclic ligands incorporating O2N2-, O3N2- and O2N3-donor sets has been investigated. The log K values for the respective 1 1 complexes in 95% methanol (I= 0.1 mol dm–3; Et4NClO4, 25 °C) have been determined potentiometrically and the results compared with the values obtained previously for the parent (non-benzylated) macrocyclic systems. Examples of N-benzylation of individual parent macrocycles leading to enhanced discrimination for silver(I) are presented. In the case of a dibenzylated O3N2-ring and a tribenzylated O2N3-ring, both 17-membered, high selectivity for this ion was observed relative to the other metal ions investigated. Competitive mixed-metal transport experiments across a bulk chloroform membrane have been performed using the benzylated derivatives as ionophores. For each experiment the source contained equimolar concentrations of the above metal ions and transport was performed against a pH gradient; the aqueous source and receiving phases were buffered at pH 4.9 and 3.0, respectively. In parallel to the log K results, transport selectivity for silver(I) was exhibited by the di- and tri-benzylated ligands mentioned above. The remaining ligands proved to be poor ionophores, showing no significant metal ion transport under the conditions employed. In a further study, high silver ion (transport) selectivity was maintained when the above tribenzylated ligand was incorporated as the ionophore in a polymer inclusion membrane system. Single metal and mixed (seven-metal) solvent extraction experiments employing similar aqueous source and chloroform phases to those used in the bulk membrane transport runs have also been performed for the tribenzylated ligand derivative; significant selectivity for silver was again maintained in these solvent extraction experiments. An X-ray study of [AgL]ClO4(where L is the above-mentioned dibenzylated derivative) confirms that all donor atoms of the macrocycle coordinate to the silver ion; the latter is five-coordinate with the complex cation exhibiting a highly distorted trigonal bipyramidal geometry.
|Item Type:||Article (Refereed Research - C1)|
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|FoR Codes:||03 CHEMICAL SCIENCES > 0302 Inorganic Chemistry > 030207 Transition Metal Chemistry @ 33%|
03 CHEMICAL SCIENCES > 0305 Organic Chemistry > 030503 Organic Chemical Synthesis @ 34%
03 CHEMICAL SCIENCES > 0303 Macromolecular and Materials Chemistry > 030302 Nanochemistry and Supramolecular Chemistry @ 33%
|SEO Codes:||97 EXPANDING KNOWLEDGE > 970103 Expanding Knowledge in the Chemical Sciences @ 100%|
|Deposited On:||25 Jun 2009 09:10|
|Last Modified:||13 Feb 2011 18:21|
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