A two-dimensional cadmium(II) coordination polymer based on 5-(pyridin-4-yl)isophthalic acid: poly[[tetraaquabis[μ3-5-(pyridin-4-yl)isophthalato]dicadmium(II)] pentahydrate]

The title CdIIcompound, {[Cd2(C13H7NO4)2(H2O)4]·5H2O}n, was synthesized by the hydrothermal reaction of Cd(NO3)2·4H2O and 5-(pyridin-4-yl)isophthalic acid (H2L). The asymmetric unit contains two crystallographically independent CdIIcations, two deprotonatedL2−ligands, four coordinated water molecules and five isolated water molecules. One of the CdIIcations adopts a six-coordinate octahedral coordination geometry involving three O atoms from one bidentate chelating and one monodentate carboxylate group of two differentL2−ligands, one N atom of anotherL2−ligand and two coordinated water molecules. The second CdIIcation adopts a seven-coordinate pentagonal–bipyramidal coordination geometry involving four O atoms from two bidentate chelating carboxylate groups of two differentL2−ligands, one N atom of anotherL2−ligand and two coordinated water molecules. EachL2−ligand bridges three CdIIcations and, likewise, each CdIIcation connects to threeL2−ligands, giving rise to a two-dimensional graphite-like 63layer structure. These two-dimensional layers are further linked by O—H...O hydrogen-bonding interactions to form a three-dimensional supramolecular architecture. The photoluminescence properties of the title compound were also investigated.