First examples of ternary lanthanide 2,2′-bipyridine-3,3′-dicarboxylate coordination polymers with zigzag chains structures assembled from lanthanide ions, 2,2′-bipyridine-3,3′-dicarboxylate and 1,10-phenanthroline

Abstract

Four lanthanide coordination polymers, [{Ln 2(bpdc) 3(phen) 2(H 2O) 2} · (H 2O) 6] n (Ln = Sm ( 1); Eu ( 2); Gd ( 3), Tb ( 4)), were self-assembled from 2,2′-bipyridine-3,3′-dicarboxylic acid (H 2bpdc),1,10-phenanthroline(phen) and corresponding lanthanide oxides by hydrothermal synthesis. Compounds 1– 4 are found to be isomorphous and isostructural. Single-crystal X-ray diffraction studies show that compounds 1– 4 are all of one-dimensional zigzag chain structures and extend to two-dimensional networks through π–π interactions and hydrogen bonds. The pyridyl nitrogen atoms of the 2,2′-bipyridyl unit in the bpdc ligand are uncoordinated in an anti-conformation along the central C–C bond of the ligand. Thermogravimetric analysis of 1– 4 showed an obvious thermal stability indicating that the coordination habit of the metal ions with bpdc and phen has an effect on the overall framework. Photoluminescence measurement indicates that compound 2 and compound 4 are strong red and green emitters, respectively.