Calixcrowns, the combination of calixarene and crown ether, are a novel class fo host compounds which have attracted increasing attention because of their increased ability for selective complexation of cations and neutral molecules compared with crown ethers or calixarenes.~(1-3) During the past decade various calixcrowns have been synthesized~4-9 and applied as ionophores in extractive processes~8-9 or as selective ligands in ion selective electrodes.~10-12 Apart from the cavity geometry, the nature of donor sites plays an important role in determining complexation selectivity, i.e. azacrown ether in which nitrogen atoms are incorporated, was found to be the best liganding agent for transition metal ions.~13
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