1,1ʹ-Dimethyl-4,4ʹ-bipyridinium as a multivalent structure-directing counterion to anionic uranyl ion polycarboxylate complexes

4-(Ammoniomethyl)benzoate, a protic zwitterionic bifunctional linker in uranyl ion carboxylate complexes

“…1–3, the shape of the polymer is slightly different in the three compounds, with the Hamb ligands located on both edges of serpentine chains in 1 and 3 , or on only one side of a linear chain in 2 . The tdc 2− ligand found in 1 has frequently been employed in uranyl chemistry, 5,7,53–61 and complexes involving also aprotic dizwitterions are known but an unusual feature is the formation of crystals in which there is separation of the ligands into anionic and cationic polymer units, 5,7 which is not observed here. The polymer chains in 1 can be considered to lie side-by-side in sheets parallel to (101̄), with the Hamb ligands alternating in orientation relative to the mean polymer axis and projecting, along with water molecules, into dips in the adjacent strands.…”

“…Generally speaking, when only anionic dicarboxylates are used in uranyl ion complex synthesis, a frequent outcome of uranyl tris-chelation is the formation of honeycomb networks, as is for example very often found with tdc 2− . 55–59,61 The fact that complex 1 is formed preferentially to a honeycomb network involving only tdc 2− ligands may be seen as further indication of the particular ease with which true mixed-ligand species can be obtained through mixing anionic and zwitterionic carboxylates. 3 Chains with double bridges between uranyl centres are found in complexes 4 and 6 , with either both ligands or only the dicarboxylate, respectively, being bridging, and complex 5 illustrates the effect of a coordinating solvent (deleterious in regard to polymer formation in the present case, but not necessarily so in general 82 ).…”