ISSN:
0749-1581
Keywords:
Dibenzo crown ethers
;
Conformations
;
NMR
;
Molecular mechanics
;
Alkali complexes
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The preferred conformations and the complexing behaviour of 16- and 17-membered dibenzo crown ethers were studied by means of both NMR spectroscopy and molecular mechanical calculations. Conclusions could be drawn about the stoichiometry and stability of the alkali metal ion corand complexes. The spin-lattice relaxation times of the crown ether carbon atoms and the relevant complexes are discussed with respect to the intramolecular flexibility of these species. The intramolecular reorientations detected are reduced considerably in the alkali metal ion complexes. In the preferred conformers of corands 2, 3 and 6, the molecular mechanical calculations prove that the phenyl rings are positioned in a chair conformation at a twist to each other. The same phenyl rings in the crown ethers 1, 4 and 5 are in a boat conformation. These conformations seem to be important for the optimum complexation of the alkali cations.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1260300514
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