title: Metal ion recognition via 'selective detuning'. The interaction of selected transition and post-transition metal ions with a mono-N-benzylated O2N3-donor macrocycle and its xylyl-bridged ring analogue.
abstract: The interaction of cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), silver(I) and lead(II) with symmetrical mono-N-benzylated and xylyl-linked macrocyclic ligands derived from the O2N3-macrocycle, 1,12,15-triaza-3,4:9,10-dibenzo-5,8-dioxacycloheptadecane, has been investigated. The log K values for the respective 1 : 1 complexes in 95% methanol (I= 0.1; Et4NClO4, 25 degrees C) of the mono-benzylated derivative have been determined potentiometrically and the results compared with the values obtained previously for the parent (non-benzylated) ring system as well as for related di- and tri-benzylated macrocyclic species. Mono-benzylation results in slightly enhanced stability for the 1 : 1 silver(I) complex while the values for the corresponding complexes of the other six ions are in each case decreased even though the highest stability is still maintained for the 1 : 1 copper(II) complex. The log K results are in accord with a previous proposal that N-benzylation of amine-containing macrocyclic rings of the present type will normally have only a minor (positive or negative) influence on the affinity towards silver(I) while the corresponding binding strengths towards the remaining six metal ions are significantly reduced-behaviour we term 'selective detuning'. Competitive seven-metal transport experiments across a bulk chloroform membrane have been performed using both ligand systems as ionophores. In parallel to the log K results, transport selectivity for copper(II) was exhibited by both systems, with similar transport efficiencies being evident when compared on a 'per macrocyclic cavity' basis.
authors.affiliation: Centre for Heavy Metals Research, School of Chemistry, University of Sydney, NSW, Australia.
authors.forename: Marina
authors.initials: M
authors.lastname: Fainerman-Melnikova
authors.forename: Azizollah
authors.initials: A
authors.lastname: Nezhadali
authors.forename: Gholamhossin
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authors.lastname: Rounaghi
authors.forename: John C
authors.initials: JC
authors.lastname: McMurtrie
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authors.lastname: Kim
authors.forename: Karsten
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authors.lastname: Gloe
authors.forename: Matthias
authors.initials: M
authors.lastname: Langer
authors.forename: Shim Sung
authors.initials: SS
authors.lastname: Lee
authors.forename: Leonard F
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authors.lastname: Lindoy
authors.forename: Tomoko
authors.initials: T
authors.lastname: Nishimura
authors.forename: Ki-Min
authors.initials: KM
authors.lastname: Park
authors.forename: Joobeom
authors.initials: J
authors.lastname: Seo