New Efficient Calixarene Amide Ionophores for the Selective Removal of Strontium Ion from Nuclear Waste:  Synthesis, Complexation, and Extraction Properties

Abstract

Three novel lower rim hexamide derivatives 5(6), 7(6), and 9(6) of p-hydroxycalix[6]arene and four octamides 5(8), 7(8)-9(8) derived from the corresponding p-hydroxycalix[8]arene were synthesized, and their potential as extractants in radioactive waste treatment was evaluated, in comparison with upper rim analogues 12(6) and 12(8) and other existing selective neutral ionophores currently used in radioactive waste treatment. Extraction of alkali and alkaline earth metal picrates from water to dichloromethane, and of the corresponding nitrates from acidic water solution simulating radioactive waste, to 2-nitrophenyl hexyl ether (NPHE), showed that the lower rim amides extract divalent cations much better than monovalent ones. The upper rim hexa-12(6) and octamide 12(8) are very inefficient ligands, hardly extracting any cation. In all cases, p-alkoxy octamides are more efficient and selective extractants than the corresponding hexamides. In the case of simulated waste solutions, the distribution coefficients for strontium removal by octamides (6.5 < D(Sr) < 30) are much higher than the corresponding value (D(Sr)) found for dicyclohexyl-18-crown-6 (DC18C6), and the same applies for the strontium/sodium selectivity, which is 6500 < D(Sr)/D(Na) < 30 000 for octamides and 47 for DC18C6. ESI-MS, UV-vis, and X-ray crystal structure studies give consistent results and indicate the formation of 2:1 (cation/ligand) strontium complexes for all octamides tested. Stability constants were determined in homogeneous methanol solution for alkali metal (log beta(11) < or = 2), calcium (4.3 < or = log beta(11) < or = 6.0; 9.4 < or = log beta(21) < or = 12.0), and strontium (5.6 < or = log beta(11) < or = 12.3) ions using a UV-vis competition method with 1-(2-pyridylazo)-2-naphthol (PAN). They confirm the high efficiency and high divalent/monovalent selectivity found in metal ion extraction experiments for the new octamide ligands. Evidence for a positive cooperative effect between the two metal ion binding sites was obtained in the case of the Ca(2+) complex of octamide 1(8).

C3v (Trimethyl) p‐(Benzyloxy)calix[6]arene: A Versatile Platform for the Synthesis of Functionalized C3v Calix[6]arenes

“…[7] An optimized synthetic procedure is provided (see the Experimental Section) and will be detailed in a forthcoming paper. [39] Figure 2.…”

“…Within this frame, we wish to report here on the synthesis and characterization of such a new calixarene family, starting from p-(benzyloxy)calix [6]arene (Scheme 1). [7] We show here that p-(benzyloxy)calix [6]arene may be converted into the corresponding trimethylated C 3v derivative on a preparative scale. We also describe the simple and highyield synthesis of useful derivatives from this new C 3v p-(benzyloxy)calix [6]arene (Schemes 2-4).…”

“…Second, new possibilities are opened for easy derivatization of these positions after Pd-catalyzed hydrogenolysis, as already demonstrated for other p-(benzyloxy)-functionalized calixarenes. [7,15,20,38] …”

Synthesis and Alkali Metal Picrate Extraction Capabilities of Novel Bis(benzocrown Ether)s Based on Diphenylglycoluril

“…например [25][26][27] ). Это позволяет достаточ-но просто и быстро определять количество проэкстра-гированного катиона спектрофотометрически.…”

Lanthanide Complexes with a Calix[8]arene Bearing Phosphinoyl Pendant Arms

“…[23,24] However, most of the reported complexes have 2:1 stoichiometry, [25,26] whereas 1:2 molecular ratios are less common. [27] The purpose of this paper is to investigate the influence of the narrow rim substitution of p-tert-butylcalix [8]arene by phosphinoyl groups on the coordination and photophysical properties of both the octamer toward trivalent lanthanide ions and the resulting complexes. In addition, we probe the effect of the coordination strength of the anion with regard to both the stoichiometry of the complexes and the coordination mode of the macrocycle.…”