Uranyl(VI) complexes with a diaminobisphenol from eugenol and N-(2-aminoethyl)morpholine: Syntheses, structures and extraction studies

The syntheses and structural studies of an [O,N,O,N′]-type phenolic ligand [(N’,N’-bis(2-hydroxy-3-methoxy-5-(propen-2-yl)benzyl)-N-(2-aminoethyl)morpholine), (H2L) and two new uranyl complexes of this ligand are described. The reaction between uranyl nitrate hexahydrate and H2L in a 1:2 M ratio (M to H2L) results in a uranyl complex of the formula [UO2(HL)(NO3)(H2O)] (1). In the presence of a base (triethylamine), with the same molar ratio, the uranyl complex [UO2(HL)2]·2CH3CN (2) is formed. The molecular structures H2L, 1 and 2 were verified by X-ray crystallography. Both uranyl complexes are zwitterions with a neutral net charge. A comprehensive NMR-structural analyses of all compounds were performed in CDCl3, DMSO-d6 and pyridine-d5. Complex 2 dissociates in all the studied NMR-solvents, forming a 1:1 complex and free ligand, but according to the spectra the formed complexes are not alike. The results of the ability of the ligand to extract the uranyl ion from water into dichloromethane are also presented.

The syntheses and characterization (spectroscopically and structurally) of a phenolic [O,N,O,N′]-type phenolic ligand, [(N’,N’-bis(2-hydroxy-3-methoxy-5-(propen-2-yl)benzyl)-N-(2-aminoethyl)morpholine) (H2L), and its two uranyl complexes [UO2(HL)(NO3)(H2O)] (1) (in the picture) and [UO2(HL)2]·2CH3CN (2) are presented. Also an extraction study of the uranyl ion by H2L is reported.Figure optionsDownload as PowerPoint slideResearch highlights
► Synthesis and crystal structure determination of a new aminobisphenol ligand from eugenol and N-(2-aminoethyl)morpholine.
► Two new uranyl complexes of the ligand have been prepared and their crystal structures determined.
► Stabilities of these new complexes have been studied by multinuclear NMR in several solvents.
► Extraction studies of the uranyl ion with the new ligand are reported.