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 Cd-II compound, {[Cd-2(C13H7NO4)(2)(H2O)(4)]center dot 5H(2)O}(n), was synthesized by the hydrothermal reaction of Cd(NO3)(2)center dot 4H(2)O and 5-(pyridin-4-yl)isophthalic acid (H2L). The asymmetric unit contains two crystallographically independent Cd-II cations, two deprotonated L2- ligands, four coordinated water molecules and five isolated water molecules. One of the Cd-II cations adopts a six-coordinate octahedral coordination geometry involving three O atoms from one bidentate chelating and one monodentate carboxylate group of two different L2- ligands, one N atom of another L2- ligand and two coordinated water molecules. The second Cd-II cation adopts a seven-coordinate pentagonal-bipyramidal coordination geometry involving four O atoms from two bidentate chelating carboxylate groups of two different L2- ligands, one N atom of another L2- ligand and two coordinated water molecules. Each L2- ligand bridges three Cd-II cations and, likewise, each Cd-II cation connects to three L2- ligands, giving rise to a two-dimensional graphite-like 6(3) layer structure. These two-dimensional layers are further linked by O-H center dot center dot center dot O hydrogen-bonding interactions to form a three-dimensional supramolecular architecture. The photoluminescence properties of the title compound were also investigated.