DFT studies of complexes between ethylenediamine tetraacetate and alkali and alkaline earth cations

Density functional theory (DFT) calculations for M--([C.sub.10][H.sub.12][N.sub.2][O.sub.8.sup.4-]) and M--[([H.sub.2]O).sub.6], where M = [Na.sup.+], [K.sup.+], [Rb.sup.+], [Mg.sup.2+], [Ca.sup.2+], and [Sr.sup.2+], and ([C.sub.10][H.sub.12][N.sub.2][O.sub.8.sup.4-]) = [EDTA.sup.4-], were carried out at both all-electron and pseudopotential levels. Results from these four methods were compared, and it was found that the ions bind to [EDTA.sup.4-] with selectivity of [Mg.sup.2+] > [Ca.sup.2+] > [Sr.sup.2+] > [Na.sup.+] > [K.sup.+] > [Rb.sup.+.] Key words: ethylenediamine tetraacetic acid (EDTA), alkali metal ions, alkaline earth metal ions, binding affinity. Faisant appel a la theorie de la fonctionnelle de la densite et operant aux niveaux de tous les electrons ainsi que du pseudopotentiel, on a effectue des calculs sur les cations M--([C.sub.10][H.sub.12][N.sub.2][O.sub.8.sup.4-])] et M--[([H.sub.2]O).sub.6] dans lesquels M = [Na.sup.+], [K.sup.+], [Rb.sup.+], [Mg.sup.2+], [Ca.sup.2+], et [Sr.sup.2+] et [C.sub.10][H.sub.12][N.sub.2][O.sub.8.sup.4-] = [EDTA.sup.4-]. Les resultats obtenus avec ces methodes ont ete compares entre eux et on a trouve que les ions se lient avec [EDTA.sup.4-] avec la selectivite suivante : [Mg.sup.2+] > [Ca.sup.2+] > [Sr.sup.2+] > [Na.sup.+] > [K.sup.+] > [Rb.sup.+]. Mots-cles : acide ethylenediaminetetraacetique, ions de metaux alcalins, ions de metaux alcalinoterreux, affinite de fixation. [Traduit par la Redaction]
Introduction Ethylenediamine tetraacetic acid ([H.sub.4]EDTA) is a polyprotic acid that has been widely used, together with its associated anion ethylenediamine tetraacetate ([EDTA.sup.4-]), since the pioneering work on [H.sub.4]EDTA was done [...]