Syntheses, Crystal Structures, Thermal Stabilities and Luminescent Properties of Two Pillared Layered Alkaline–Earth Coordination Polymers

Two new three-dimensional pillared layered coordination polymers, [M(2,5-PDC)H2O]n [M(II) = Sr(1), Ba (2)] were synthesized under hydrothermal conditions using alkaline–earth metal centers strontium and barium with 2,5-pyridinedicarboxylic acid as the organic ligand. The structures of two compounds have been determined by single-crystal X-ray diffraction analyses and further characterized by IR spectrum, elemental analyses, powder X-ray diffraction, and thermogravimetric analyses. The compounds are isostructural, confirmed by their powder XRD measurements. They feature a pillared layered framework structures. Within the layer, the dinuclear [M2O2] units through the bridge of the coordination water molecule are found, which are connected by carboxylate groups along the a- and b-axis, respectively. The layers are further pillared by the pyridyl groups of the 2,5-PDC2− ligands. Furthermore, the luminescent properties of two compounds have also been investigated in the solid state.