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Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
Published on: August 22, 2018
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A 13C-NMR study of azacryptand complexes
Aljoscha A C Wild1, Kevin Fennell, Grace G Morgan
1SFI Strategic Research Cluster in Solar Energy Conversion, School of Biomolecular and Biomedical Science, Centre for Synthesis and Chemical Biology, Conway Institute, University College Dublin, Dublin 4, Ireland. J.Paul.G.Malthouse@ucd.ie.
Dalton Transactions (Cambridge, England : 2003)
|August 6, 2014
Summary
This study shows an azacryptand can solubilize zinc and cadmium. The azacryptand binds two zinc ions and one carbonate, forming carbamate derivatives, with structural insights from NMR spectroscopy.
Area of Science:
- Coordination Chemistry
- Supramolecular Chemistry
- Analytical Chemistry
Background:
- Azacryptands are macrocyclic ligands capable of complexing metal ions.
- Solubilizing metal ions in aqueous media is crucial for various applications.
- Understanding metal-ligand interactions, particularly with carbonate, is key in coordination chemistry.
Purpose of the Study:
- To investigate the complexation of zinc and cadmium by an azacryptand in aqueous media.
- To characterize the structure and dynamics of the azacryptand-metal-carbonate complexes.
- To compare solution and crystal structures of zinc-carbonate-azacryptand complexes.
Main Methods:
- 13C Nuclear Magnetic Resonance (NMR) spectroscopy, including 13C-enriched bicarbonate.
- Variable temperature NMR studies to assess exchange dynamics.
- Heteronuclear Overhauser Effect SpectroscopY (HOESY) to determine positional information.
- Comparison of solution structures with existing crystal structures.
Main Results:
- The azacryptand solubilizes zinc and cadmium at alkaline pH.
- Four different carbamate derivatives of the azacryptand were observed.
- The azacryptand-zinc complex binds two zinc ions and one carbonate ion.
- Cadmium-113 NMR revealed two distinct cadmium-carbonate complexes in slow exchange, with carbonate bridging two metal ions.
- Zinc complexes exhibited fast exchange between complexes and slow exchange with free bicarbonate.
Conclusions:
- Azacryptands are effective agents for solubilizing zinc and cadmium in aqueous solutions.
- The binding of carbonate to the metal-azacryptand complex involves bridging metal ions.
- NMR spectroscopy provides detailed insights into the structure and dynamics of these supramolecular complexes.
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