Chelate and intramolecular ion-pair formation. A guiding concept for structure/selectivity relationships in the liquid-liquid extraction of alkali and alkaline earth metal ions by anionic crown ether derivatives

Yoshiki Katayama, Ryuji Fukuda, Makoto Takagi

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

Crown ether dyes with pendent anionic side-arms were synthesized for extractionspectrophotometry of alkali and alkaline earth metal ions. Dramatic changes in metal selectivity were obtained simply by changing the nature of the anionic side-arm on the same crown ether skeleton. A structure/metal selectivity relationship is discussed in detail in terms of "chelate" and "intramolecular ion-pair" formation. Small metal cations (high charge density) are preferred in the extraction by a crown ether reagent with a charge-localized anionic side-arm through the formation of a "chelate". Large metal cations (low charge density) are preferred in the extraction by reagents with a charge-delocalized anionic side-arm through the formation of an "intramolecular ion-pair". Steric restrictions imposed by the side-arm on the metal ion approaching the crown ether are also important factor in controlling the selectivity of these reagents.

Original languageEnglish
Pages (from-to)295-306
Number of pages12
JournalAnalytica Chimica Acta
Volume185
Issue numberC
DOIs
Publication statusPublished - Jan 1 1986

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Biochemistry
  • Environmental Chemistry
  • Spectroscopy

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