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The stereochemistry of crown ethers. II —1H and 13C NMR structural study in solution

✍ Scribed by E. Kleinpeter; M. Gäbler; W. Schroth; J. Mattinen; K. Pihlaja

Publisher
John Wiley and Sons
Year
1988
Tongue
English
Weight
335 KB
Volume
26
Category
Article
ISSN
0749-1581

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✦ Synopsis

The 'H and I3C NMR spectra of a series of structurally related crown ethers have been recorded, and the signals assigned by means of 'H/I3C heteronuclear correlated and 'H/'H homonuclear NOE difference spectroscopy. The NMR parameters so extracted have been used to discuss the preferred, rapidly interconverting solution conformations of the studied species The high-field shifts in the I3C NMR spectra, within the so-called y-fragments, and also the 'H/'H homonuclear NOES, are particularly informative in this respect. The T, relaxation times of the I3C atoms show segmental motions within the ether segments and suggest different intramolecular flexibilities for the studied compounds.

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