The complexation behaviour of six pyrazine-functionalized calixarenes, containing substituents such as carbamoyl dioctyl (L-1, L-2), diisopropyl phosphonate (L-3, L-4) and diphenyl phosphoryl (L-5, L-6), with Am3+ and Eu3+ ions was investigated by solvent extraction as well as by luminescence spectroscopy (only for Eu3+) in room-temperature ionic liquids (RTILs), [Cnmim][NTf2] (1-alkyl-3-methylimidazolium, n = 4, 6, and 8). The spectacular enhancement in the extraction values of the trivalent metal ions in RTILs, as compared to those reported in a molecular diluent from 3 M HNO3, was rather unusual and was further investigated by luminescence studies. Luminescence studies involving Eu3+ and performed with L-4 and L-6 confirmed the 1:1 stoichiometry of the extracted species (Eu3+ L) with log ß values of 4.42'0.51 and 5.18'0.38 for L-4 and L-6, respectively. Judd-Ofelt parameters, which give information about the nature of bonding as well as the coordinating environment, were computed from the emission spectra of the Eu3+ L-4 and Eu3+L-6 complexes.
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