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

Sonia Colette (1) , Badia Amekraz (1) , Charles Madic (1) , Laurence Berthon (1) , Gérard Cote (1) , Christophe Moulin (1)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)

ESI mass spectrometry was used to investigate the europium complexation by tridentate ligands L ≡ 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 β$_3$$^{app}$ = 12.0 ± 0.5) and DiPTP (log β$_3$$^{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$$^{app}$ ions. Other complexes such as Eu(L)$_2$$^{3+}$ ions are only observed for DnPTP (log β$_2$$^{app}$ = 6.7 ± 0.5) and DMTP (log β$_2$$^{app}$ = 6.3 ± 0.1) and Eu(L)$^{3+}$ only for DMTP (log β$_1$$^{app}$ = 2.9 ± 0.2). The log β$_n$$^{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.

Domaines: Analyse numérique [cs.NA]; Physique Nucléaire Expérimentale [nucl-ex]

Sonia Colette, Badia Amekraz, Charles Madic, Laurence Berthon, Gérard Cote, et al.. 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. Inorganic Chemistry Communications, 2002, 41 (26), pp.7031-7041. ⟨10.1021/ic025637t⟩. ⟨cea-02360138⟩