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

Abstract

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 (H2 L). 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 CaII 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.