From helicates to borromean links: chain length effect in uranyl ion complexes of aliphatic α,ω-dicarboxylates
Résumé
When reacted with undecane-1,11-dicarboxylic acid under solvo-hydrothermal conditions in the presence of Mn(II) cations and 1,10-phenanthroline, uranyl ions give two-dimensional honeycomb networks which assemble to form a 3-fold Borromean entanglement. This structure is closely related to that of the helicates previously obtained with the shorter dodecanedioic acid. Replacement of 1,10-phenanthroline by 2,2′-bipyridine leads to the formation of a neutral one-dimensional heterometallic polymer. A mong the poly(carboxylic acid)s which have been considered in the design of uranyl−organic coordination polymers or frameworks, 1−6 the aliphatic α,ω-dicarboxylic acids HOOC−(CH 2) n−2 −COOH (denoted as H 2 Cn) provide a family of divergent ligands with a regularly increasing separation between the two functional groups. Those with long chains (n up to 12) have been much investigated, 7−13