Hydrothermal Syntheses, Crystal Structure and Characterization of Two Alkaline Earth Metal Coordination Polymers with 1-(4-Iodophenyl)-5-methyl-1H-[1,2,3]-triazole-4-carboxylate Ligand

A two-dimensional calcium (II) coordination polymer constructed from 2,2'-[terephthaloylbis(azanediyl)]diacetate: synthesis, structure and properties

A new two-dimensional (2D) coordination polymer, namely, poly[[diaqua-[μ₄-2,2'-[terephthaloylbis(azanediyl)]diacetato]calcium(II)] monohydrate], {[Ca(C₁₂H₁₀N₂O₆)(H₂O)₂]·H₂O}_n, (I), has been synthesized by the reaction of CaCl₂ with 2,2'-[terephthaloylbis(azanediyl)]diacetic acid (H₂L). The title compound was structurally characterized by single-crystal X-ray diffraction analysis, elemental analysis and IR spectroscopy. In the crystal structure of (I), each Ca^II cation binds to six carboxylate groups from four symmetry-related L^2- dianions. The hexadentate L^2- ligand links four symmetry-related calcium cations into a 2D layer-like structure, which can be simplified as a uninodal SP 2-periodic (3,6)III net with the point symbol (4³·6³). In the lattice, all layers pack in parallel arrays through weak interlayer hydrogen bonding and π-π interactions. The thermal stability and photoluminescence properties of (I) have been investigated. Thermogravimetric analysis reveals the different thermal stabilities of the two coordinated water molecules due to their different hydrogen-bonding interactions. The title coordination polymer exhibits an excitation-wavelength-dependent fluorescence in the solid state.