Hydrothermal Synthesis, Structural Diversity and Magnetic Properties of a New Ni(II) Coordination Polymer Based on a Multifunctional Pyridyl-Tricarboxylate Ligand

A coordination polymer of nickel(II), namely, {[Ni_1.5(dppa)(bpa)_1.5(H₂O)]·5H₂O}_n [H₃dppa = 5-(3,4-dicarboxyphenyl)picolinic acid, bpa = 1,2-bis(4-pyridyl)ethane] was designed and synthesized under hydrothermal condition. Its structure was characterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction data. The structural analysis shows that the H₃dppa is completely deprotonated to connect adjacent Ni(II) ions into a 1D chain, and again bridged by bpa ligands to a 2D coordination polymer. The 3D supramolecular network is formed through O–H···O hydrogen bonds. Thermal analysis (TGA) feature and solid-state variable temperature magnetic susceptibility data of the title compound are reported as well. The magnetic susceptibility data indicate that dominant ferromagnetic interactions are mediated between Ni(II) centers.