Chain, Network and Framework Formation in Uranyl Ion Complexes with 1,1′-Biphenyl-3,3′,4,4′-Tetracarboxylate

1,1 '-Biphenyl-3,3 ',4,4 '-tetracarboxylic acid dianhydride has been reacted with uranyl nitrate under solvo-hydrothermal conditions and in the presence of different counterions to give three complexes of varying periodicity. [Co(en)(3)]- [UO2(bptc)(HCOO)] . 2.5H(2)O (1) crystallizes as a monoperiodic coordination polymer in which the bptc(4-) ligand is exclusively bound through formation of two 7-membered chelate rings. The [Co(en)(3)](3+) counterion is essentially a hydrogen bond donor, forming 15 hydrogen bonds with carboxylate and water oxygen atoms. In [H2NMe2](2)[UO2(bptc)] . 0.5H(2)O (2), half the ligand forms a 7-membered chelate ring, and the other half bridges two uranium atoms, resulting in the formation of a diperiodic network with hcb topology, the H2NMe2+ counterions being located between the undulating sheets. [PPh4](4)[(UO2)(4)(bptc)(3)] . 6H(2)O (3) contains a mixture of ligands forming either four 4-membered or two 7-membered chelate rings, the latter with further bridging, which gives a triperiodic framework displaying large channels, each of which contains two rows of PPh4+ counterions. These results are compared to those of previous studies with this ligand, and of similar studies of phthalate complexes of uranyl ion, in particular in relation to 7-membered chelate ring formation.

Automated summary

In this study, three complexes of varying periodicity of 1,1 '-Biphenyl-3,3 ',4,4 '-tetracarboxylic acid dianhydride were synthesized under solvo-hydrothermal conditions with different counterions. The complex structures varied due to the different forms of ligands used, leading to different periodicity frameworks.