The reaction between p-R-[3.1.3.1]- or [3.3.3]homooxacalixarenes and uranyl salts in the presence of 30-crown-10 and the alkali or alkaline-earth metal cations K+ or Ba2+ gives various supramolecular assemblages characterized by “complex-within-complex” architectures. These can be of the simple nesting or sandwich types, as in [{Ba(30-crown-10)}{UO2(L1)}]·2H2O·3CHCl3
(L1H4
=
p-tert-butyl[3.1.3.1]homooxacalixarene) and [{Ba(30-crown-10)}{UO2(L4)}2]·2CHCl3
(L4H3
=
p-bromo[3.3.3]homooxacalixarene), respectively, with the cation held in the cavity of the homooxacalixarene complexes in cone conformation by weak interactions, but more original structures arise when uranyl-cation bonds are present. In [{Ba(30-crown-10)}{UO2(L2)}]
(L2H4
=
p-phenyl[3.1.3.1]homooxacalixarene), the barium ion included in the crown ether is bound to the uranyl oxo group located out of the calixarene cavity, resulting in the formation of a neutral species which self-organizes to form a columnar assembly by auto-inclusion. In [{K(30-crown-10)}{UO2K(L1)(H2O)3}]2·6H2O, the nesting-type subunit dimerizes around two oxo-bound potassium ions. Finally, the use of the coordinating solvent dimethylsulfoxide leads to the neutral complex [UO2Ba(L3)(dmso)2(MeOH)]2
(L3H4
=
p-methyl[3.1.3.1]homooxacalixarene), in which the crown ether is absent and two oxo-, phenoxo- and ether-bound barium atoms ensure the dimerization of the uranyl complex.
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