A novel tetradentate ligand combining hard O-donor and soft N-donors in the same molecule, N,N′-diethyl-N,N′-ditolyl-2,9-diamide-1,10-phenanthroline (Et-Tol-DAPhen), was developed in our laboratory aiming at the group separation of actinides from lanthanides. Herein, the solvent extraction of UO 2 2+ by Et-Tol-DAPhen in 1-(trifluoromethyl)-3-nitrobenzene diluent was investigated in detail. The effects of contact time, Et-Tol-DAPhen concentration, acidity, and competing ions on the extraction were discussed, the extracted UO 2 2+ speciation was analysed, and the stripping of UO 2 2+ from organic phase was performed. The results clearly show that Et-Tol-DAPhen/1-(trifluoromethyl)-3-nitrobenzene provides a highly efficient extraction of UO 2 2+ from HNO 3 media with a fast extraction kinetics of less than 5 min and a large distribution ratio of more than 300. Moreover, the system shows excellent selectivity toward UO 2 2+ over Ln 3+ in a wide acidity range. Stripping experiments indicate that almost a complete back extraction of UO 2 2+ could be achieved via only one stage operation using 5% Na 2 CO 3 solution. Findings of the present work provide new data for assessing the feasibility of Et-Tol-DAPhen, as well as other new ligand with hard–soft donors combined in the same molecule, applied in the group separation of actinides over lanthanides.
Four new 3D uranyl complexes, [(UO2)2(H2O)(ipa)2]·9H2O (1), [(UO2)2(H2O)(nip)2]·H2O·Et3NH (2), [(UO2)2(H2O)(aip)2]·Et3NH (3) and [(UO2)(hip)]2·17H2O (4) (H2ipa = isophthalic acid, H2nip = 5-nitroisophthalic acid, H2aip = 5-aminoisophthalic acid, H2hip = 5-hydroxyisophthalic acid, Et3N = triethylamine), were hydrothermally synthesized. Structural analyses reveal that compounds 1–4 consist of pentagonal bipyramidal uranyl monomers bridged via acid inkers to form a structural motif, [(UO2)2L2], serving as the foundation of the 3D framework. Two structural motifs adopt different arrangement modes to connect to two types of chains. For 1–3, uranium atoms and carboxyl groups being from two types of chains respectively are coordinated to build similar 3D frameworks, while for 4, one type of chain links to the 3D architecture by the bond of the uranium atoms and –OH of the 5-hydroxyisophthalic acid ligand. The different guest molecules and structure assemblies displayed by the four compounds are a function of the variation of substituent groups of 5-X-1,3-benzenedicarboxylic acid (X = –H, –NO2, –NH2, –OH). Furthermore, the photocatalytic properties of 2 and 4 for degradation of rhodamine-B (RhB) upon xenon lamp irradiation have been examined. Elemental analysis, infrared spectroscopy, DRS and luminescence properties were also discussed.
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