Use of Electrospray Mass Spectrometry (ESI-MS) for the Study of Europium(III) Complexation with Bis(dialkyltriazinyl)pyridines and Its Implications in the Design of New Extracting Agents

Abstract

ESI mass spectrometry was used to investigate the europium complexation by tridentate ligands L identical with 2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl)-pyridines (DATP) that have shown unique separation properties of actinides(III) from lanthanides(III) in nitric acid solutions. Complexes of three ligands, namely methyl (DMTP), n-propyl (DnPTP), and iso-propyl (DiPTP), have been investigated in acidic solutions to check the aqueous-phase stability of Eu(L)(3)(3+) ions identified previously in the solid state. The data obtained show, first, the presence of stable Eu(L)(3)(3+) ions with DnPTP (log beta(3)(app) = 12.0 +/- 0.5) and DiPTP (log beta(3)(app) = 14.0 +/- 0.6) in methanol/water (1:1 v/v) solutions under pH range 2.8-4.6 and, second, a mechanism whereby alkyl moieties contribute to a self-assembling process leading to the formation of Eu(L)(3)(3+) ions. Other complexes such as Eu(L)(2)(3+) ions are only observed for DnPTP (log beta(2)(app) = 6.7 +/- 0.5) and DMTP (log beta(2)(app) = 6.3 +/- 0.1) and Eu(L)(3+) only for DMTP (log beta(1)(app) = 2.9 +/- 0.2). The log beta(n)(app) values for the Eu(L)(n)(3+) (n = 1-3) complexes were determined at pH 2.8. Better insight was given in this study concerning the role of the hydrophobic exterior of the ligands for the design of a new range of extracting agents.

Electrospray mass spectrometry (ESI‐MS) in the study of metal–ligand solution equilibria

“…Several authors considered the ion response factors to be roughly equivalent for all the species in solution (Wang & Gokel, 1996;Goolsby et al, 1999;Reany et al, 2000;Ross, Ikonomou, & Orians, 2000a;Moulin et al, 2001;Colette et al, 2002;Jacopin et al, 2003) or for part of them (Cheng et al, 1992). (g) Finally, high concentrations of supporting electrolyte cannot be used in ESI-MS, because the signal of the analyte ions would be suppressed in the presence of high concentrations of other electrolytes (Smith et al, 1993;.…”

A TRLFS Study on the Complexation of CmIII and EuIII with 2,6‐Bis(5,6‐dipropyl‐1,2,4‐triazin‐3‐yl)pyridine in Water/Methanol Mixture

“…It was shown that BTPs act as tridentate ligands, [10] forming 1:3 complexes with An III and Ln III in the solid state [10][11][12] and in organic solution. [6,[13][14][15][16][17][18][19]36,37] Titrations in organic phase [16,17] [16,17,19] We perform a comparative study on the complexation of Cm III and Eu III with nPr-BTP [2,6-bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine] ( Figure 1) in water/methanol, 1:1. The formation of the respective BTP complexes is followed by time resolved laser-induced fluorescence spectroscopy (TRLFS).…”

Electrospray mass spectrometry for actinides and lanthanide speciation

“…Fig. 3a [11,12]. In this particular case (DiPTP) and surprisingly enough only 1-3 complex are observed.…”