The extraction of 135Cs from high-activity liquid waste, arising from reprocessing of spent nuclear fuel, can be achieved by using calix[4]arene crown-6 compounds. The radiolytic degradation of di(n-octyloxy)calix[4]arene crown-6 (octMC6), in aliphatic or aromatic solvent in contact with 3 M nitric acid, was studied by high-performance liquid chromatography directly coupled to electrospray ionisation mass spectrometry (LC/ESI-MS). More than 50 distinct degradation products were observed, and about 30 of these were identified. These compounds can be assigned to three categories, namely, products of reactions involving radical cleavage or addition, of oxidation reactions, or of aromatic substitution reactions. The major product, corresponding to substitution by an NO2 group, was quantified by external standard calibration using a purified synthetic sample. Despite the observation of all these degradation compounds, octMC6 appears to be remarkably stable under these drastic conditions, combining hydrolysis (HNO(3) 3 M) and an extreme exposure to radiolysis (10(6) Gy). Less than 35% degradation of octMC6 was observed in aromatic solvent under these conditions.

The selective HNO3 nitration of di-n-octylcrown-6 calix[4]arene using different conditions, studied with LC–MS and NMR (1H and 13C) spectroscopic techniques, lead to the identification of most of the expected nitro derivative isomeric compounds. The formation of these isomers under acidic and radiolytic conditions is discussed with the help of molecular modelling.Key words: calix crown compounds, nitration of calixarenes, NMR of isomeric nitrocalixarenes, LC-ESI-MS.

Novel molecules, composed of a β-cyclodextrin coupled via a succinic diamide linker to di-n-octyl-calix[4]arene monocrown-6 or to biscrown-6-calix[4]arene, were synthesized by two independent routes: from mono-6′-deoxy-6′-amino-β-cyclodextrin, and from tetraaminocalix[4]arene derivatives. Key words: β-cyclodextrin–calix[4]arene coupling, aminosuccinate-β-CD, aminosuccinate-calix[4]arene, octyloxy-calix[4]arene–monocrown-6, calix[4]arene–biscrown-6.

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