Search

This paper presents first investigations on a novel An(III), Ln(III), Cs(I) and Sr(II) co-extraction conceptual process using a CHONsolvent composed of the calixarene crown-ether MAXCalix and the diglycolamide TODGA in a 1-octanol/kerosene diluent. The co-extraction is followed by a sequential stripping of (1) Cs(I) and Sr(II), (2) An(III) and (3) Ln(III).

(2R,2′S)-2,2′-oxybis-(N,N-didecylpropanamide) (cis-mTDDGA) and (2R,2′R)-2,2′-oxybis-(N,N-didecylpropanamide) (trans-mTDDGA) were studied using time-resolved laser fluorescence spectroscopy (TRLFS), vibronic side-band spectroscopy (VSBS) and density functional theory calculations (DFT) to find reasons for their different extraction properties. Stability constants of the respective Cm(III) and Eu(III) complexes show cis-mTDDGA to be the superior ligand which is in agreement with results from extraction experiments. cis-mTDDGA extracts Cm(III) and Eu(III) as 1:3 complexes. In case of trans-mTDDGA, 1:2 complexes of the form [M(trans-mTDDGA)2(η1-NO3)(H2O)2]2+(M = Cm, Eu) are extracted additionally to the 1:3 complexes. VSBS and DFT confirm the presence of inner-sphere nitrate in the 1:2 complex.

To develop a selective ligand for the separation of lanthanides(III) and actinides(III) the coordination chemistry of the chelating N-donor ligand 2,6-bis(1-(p-tolyl)-1H-1,2,3-triazol-4-yl)pyridine (BTTP) was investigated. The two isostructural lanthanide compounds [Ln(BTTP)3(OTf)3] (Ln = Eu (1), Sm (2); OTf = trifluoromethanesulfonate) were synthesized and fully characterized. The solid-state structures of both compounds were established by single-crystal X-ray diffraction. The complexation of Cm(III) and Eu(III) with BTTP in acetonitrile was studied using time-resolved laser fluorescence spectroscopy. With increasing BTTP concentration Cm(III) 1:2 and 1:3 complexes and Eu(III) 1:1 and 1:3 complexes are identified. The conditional stability constants of the 1:3 complex species with BTTP are log β3= 14.0 for Cm(III) and log β3= 10.3 for Eu(III). Both M(III) 1:3 complexes are prone to decomplexation with increasing acidity.