Selective Binding of Group IIIA and Lanthanide Metals by Hexahomotrioxacalix[3]arene Macrocycles

The hexahomotrioxacalix[3]arene macrocycles 1 are observed to bind trivalent metals (Sc 3+, Lu 3+,Y 3+, La 3+ ) more strongly than alkali metal ions (Li +, Na +, K + ). Complexes of macrocycle 1a with Lu(III) ( 3 ), Y(III) ( 4 ), and La(III) ( 5 ) have been structurally characterized to be μ-aryloxo-bridged dimers with the formula [M(L)(DMSO)] 2 (M = Lu, Y, La; L = trianion of macrocycle 1a ). Periodic trends in the structures and dynamic behavior of the complexes are discussed.