1H and 7Li NMR study on the complex formation of lithium cations with pyridinium derivatives of calix[4]arenes

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Abstract

Complexation of lithium ions by three chromoionophoric calix[4]arenes has been studied by 1H and 7Li NMR spectroscopy. The signalling unit of the chromoionophores is the N- methylpyridinium(methyleneimino) group in conjugation with a phenolic group of the calixarene ring while the coordination spheres contain esteric (ethoxycarbonylmethoxy) or etheric (ethoxy, propoxy) units. 1H NMR and NOESY measurements suggest the dominance of cone conformations of the calixarene rings with slight, solvent-dependent distortions. Complexation occurs only in the presence of a weak base. The interaction with lithium ions causes a broadening of both the 1H and 7Li NMR signals. Analysis of the chemical shifts in the three complexes indicates a different coordination environment for the lithium with the calixarene containing esteric groups from those having etheric groups. This explains the differences in the stabilities of the lithium complexes of the two types of calixarenes.

Original languageEnglish
Pages (from-to)415-421
Number of pages7
JournalSupramolecular Chemistry
Volume16
Issue number6
DOIs
Publication statusPublished - szept. 1 2004

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ASJC Scopus subject areas

  • Chemistry(all)

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