New lanthanide coordination polymers of 1,2,4,5-benzenetetracarboxylic acid and 4,4′-bipyridine with 1D channels

Three new lanthanide coordination polymers with 1,2,4,5-benzenetetracarboxylic acid, Pr2(betc)2(4,4′-bpyH2)·0.25H2O (1), Ln2(betc)2(4,4′-bpyH2) (Ln=Eu (2), Gd (3)) were hydrothermally prepared. The crystallographic data of 1-3 show that they are isostructural, and possess 3D framework with 1D rhomboid channels, where the 4,4′-bipyridine molecules exist steadily via hydrogen bonds. Meanwhile, a supramolecular structure of (4,4′-bpyH2)2(betc) (4) was also obtained by hydrothermal reaction. The results of 1-4 indicate that 4,4′-bipyridine molecule acting as a template plays an important role in the formation of complexes 1-3, and thus has a synergistic action in the construction of 3D framework with large channels.