Influence of solvent, anion and presence of nitrogen in the ring structure on the mechanism of complexation of alkali metal cations with crown ethers.
Biophys Chem
; 26(2-3): 225-33, 1987 May 09.
Article
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| MEDLINE
| ID: mdl-17010281
ABSTRACT
The mechanism of complexation of alkali metal cations with macrocyclic ligands such as the simple crown ethers and the role of desolvation vs. ligand rearrangement are discussed. The unique role of water solvent in the rate-determining step of complexations in aqueous solutions is brought into focus. The competitive role of the anion, which becomes of paramount importance in solvents of low permittivity, is reiterated. Monoazo crown ethers are shown to possess isomeric equilibria in methanol solvent. The rate-determining process for the first step of complexation of these macrocycles with Na+ in methanol appears to be the rearrangement of the ligand through inversion to an exo position of the nitrogen lone electron pair. The rate-determining step of the overall complexation is the entrance of the Na+ into the ring with (possibly) concomitant rotation of the lone electron of the nitrogen to an endo configuration.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Idioma:
En
Revista:
Biophys Chem
Año:
1987
Tipo del documento:
Article
País de afiliación:
Estados Unidos