A series of three-dimensional rare-earth coordination polymers, [M 2 (bpdc) were synthesized by solvothermal reactions of 2,2Ј-bipyridine-5,5Ј-dicarboxylate (bpdc) with corresponding metal salts. Single-crystal and powder X-ray diffraction analyses demonstrated that these coordination polymers are isostructural. The carboxyl groups of the bpdc ligand are coordinated to metal ions and the 2,2Ј-bipyridine moieties are left free due to the preferable affinity of rare-earth metals for oxygen-donor atoms. The adjacent eight-coordinate MO 8 cores show dicapped trigonal prismatic environments; they are interconnected by carboxyl