A 13C-NMR study of azacryptand complexes

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Title: A 13C-NMR study of azacryptand complexes
Authors: Wild, Aljoscha A. C.
Fennell, Kevin
Morgan, Grace G.
Hewage, Chandralal
Malthouse, J.Paul G.
Permanent link: http://hdl.handle.net/10197/5894
Date: 29-Jul-2014
Online since: 2015-07-29T03:00:11Z
Abstract: An azacryptand has been solubilised in aqueous media containing 50% (v/v) dimethyl sulphoxide. 13C-NMR has been used to determine how the azacryptand is affected by zinc binding at pH 10. Using 13C-NMR and 13C-enriched bicarbonate we have been able to observe the formation of 4 different carbamate derivatives of the azacryptand at pH 10. The azacryptand was shown to solubilise zinc or cadmium at alkaline pHs. Two moles of zinc are bound per mole of azacryptand and this complex binds 1 mole of carbonate. By replacing the zinc with cadmium-113 we have shown that the 13C-NMR signal of the 13C-enriched carbon of the bound carbonate is split into two triplets at 2.2 °C. This shows that two cadmium complexes are formed and in each of these complexes the carbonate group is bound by two magnetically equivalent metal ions. It also demonstrates that these cadmium complexes are not in fast exchange. From temperature studies we show that in the zinc complexes both complexes are in fast exchange with each other but are in slow exchange with free bicarbonate. HOESY is used to determine the position of the carbonate carbon in the complex. The solution and crystal structures of the zinc–carbonate–azacryptand complexes are compared.
Funding Details: Science Foundation Ireland
Type of material: Journal Article
Publisher: Royal Society of Chemistry
Journal: Dalton Transactions
Volume: 43
Issue: 36
Start page: 13557
End page: 13562
Copyright (published version): The Royal Society of Chemistry 2014
Keywords: Carbon fixationNuclear magnetic resonance spectroscopy
DOI: 10.1039/c4dt01594k
Language: en
Status of Item: Peer reviewed
Appears in Collections:Biomolecular and Biomedical Science Research Collection

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