Resolution of carboxylate protonation microequilibria of NTA, EDTA and related complexones

Zoltán Szakács, Szabolcs Béni, Béla Noszál

Research output: Contribution to journalArticle

11 Citations (Scopus)


Potentiometric and NMR-pH titrations were carried out on four classical complexones to elucidate their overall and site-specific basicities. NMR-pH profiles and Bjerrum's functions were adjusted to compound-specific symmetries and appropriate evaluation methods were developed. Symmetry-modulated relationships between the macro- and microconstants were deduced and self-consistent sets of microconstants were determined. The inherent basicity of carboxylates surrounded by adjacent, intramolecular ammonium and carboxylate sites have been found to be in the range of 1.83-2.02 log k units, which are reduced by 0.05-0.12 log k units upon a nearby carboxylate protonation.

Original languageEnglish
Pages (from-to)666-674
Number of pages9
Issue number4
Publication statusPublished - Jan 15 2008


  • H NMR titration
  • In situ pH monitoring
  • Protonation
  • Strong acidic solution
  • pK determination

ASJC Scopus subject areas

  • Analytical Chemistry

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