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2001
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In the Laboratory
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Chemistry in Cages: Dinucleating Azacryptand Hosts and Their Cation and Anion Cryptates
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Michael Arthurs
School of Natural and Environmental Sciences, Coventry University, Coventry, CV1 5FB, UK
Vickie McKee
Chemistry Department, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK
Jane Nelson
Open University, Milton Keynes MK7 5AA, UK
Raewyn M. Town
School of Chemistry, Queen's University of Belfast, Belfast, BT9 5AG, Northern Ireland
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September 2001
Vol. 78 No. 9
p. 1269
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| Abstract |
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This experiment involves the synthesis of an iminocryptand ligand, the investigation of its fluxional NMR spectrum, and the generation of its aerobically stable dicopper(I) cryptate, whose NMR spectrum reflects the conformational change from divergent in the free cryptand to convergent in the cryptate. A m-hydroxo dicopper(II) cryptate showing strong antiferromagnetic interaction can be made if the synthesis is carried out quickly enough to avert solvolytic ring-opening. Borohydride reduction of the ligand generates the aminocryptand host, which has the capacity to stabilize the +2 in preference to the +1 redox state of copper. The pseudohalide ion cyanate can be accommodated in cascade fashion between the Cu2+ ions in the aminocryptate. This markedly affects the infrared spectrum of the pseudohalide guest, but not the magnetic susceptibility of the Cu2+ paramagnets. Finally an anion cryptate is made. The cryptands and cryptates have been structurally characterized; their structures can be accessed online to assist understanding of their spectroscopic and magnetic properties. As an optional extension, an ion-selective electrode based on the aminocryptand can be made and tested for response to Cu2+ in the presence and absence of the competing cation Zn2+.
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| Supplement |
Supplemental material comprising detailed instructions for students and notes for instructors are available. This also contains structural data in two formats, as CIF and as XYZ files, with a list of CSD refcodes. The Chime-based exercise allows three-dimensional appreciation and manipulation of the structures together with examination of the 1H NMR spectra presented.
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 Contents |
JCE2001p1269W.doc (MS Word)
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| More Information |
Citation |
Arthurs, Michael; McKee, Vickie; Nelson, Jane; Town, Raewyn M. J. Chem. Educ. 2001 78 1269.
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Keywords |
Analytical Chemistry; Coordination Chemistry; Copper; IR Spectroscopy; Laboratory Instruction; Magnetic Properties; Molecular Recognition; NMR Spectrometry; X-ray Crystallography
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History |
Created:
Last Updated: |
August 14, 2001
August 31, 2005
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| Home > JCE Print > Journal of Chemical Education > Issues >
2001
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September
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1269
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