Poly[[[(2,2′-bipyridine-κ2N,N′)cobalt(II)]-μ3-5-hydroxyisophthalato-κ4O,O′:O":O"′] dihydrate]

In the title compound, {[Co(C8H4O5)(C10H8N2)](.)2H(2)O]}(n) or {[Co(OH-BDC)(2,20-bipy)](.)2H(2)O]}(n) (where OH-H2BDC is 5-hydroxyisophthalic acid and 2,2'-bipy is 2,2'-bipyridine), the Co atoms are chelated by two N atoms from the 2,2'-bipy ligand and by four O atoms from OH-BDC ligands in a highly distorted octahedral geometry. OH-BDC acts as a tetradentate ligand, with one carboxylate group chelating one Co atom and the other binding in a monodentate fashion to two other Co atoms to form a one-dimensional zigzag chain. In the crystal structure, one of the solvent water molecules lies on a crystallographic twofold axis. The one-dimensional molecular chains are assembled into a two-dimensional network via (OHO)-O-... hydrogen-bonding interactions, while pi-pi stacking interactions generate a three-dimensional open framework between the two-dimensional networks.