Synthesis, Crystal Structures, and Magnetic Properties of Three Cobalt(II) Coordination Polymers Constructed from 3,5-Pyridinedicarboxylic Acid or 3,4-Pyridinedicarboxylic Acid Ligands

Three 2D new coordination polymers Co-2(L-1)(2)(1,10-Phenanthroline)(2)(DMF)(0.5)(H2O) (1), (H2L1 = Pyridine-3,5-dicarboxylic acid) Co(L-1)(2,2-bipyridine) (2), and Co(L-2)(2,2-bipyridine) (DMF) (3) (H2L2 = Pyridine-3,4-dicarboxylic acid) were synthesized through a solvothermal reaction of cobalt nitrate and pyridine carboxylic acid ligand with the auxiliary ligand (1,10-Phenanthroline or 2,2-bipyridine). They were characterized by X-ray diffraction and elemental analysis, infrared spectroscopy, thermogravimetry analysis, and magnetism. Compounds 1-3 featured 2D hexagonal (6,3) networks which linked into 3D supramolecular architectures through pi-pi interaction. In addition, compounds 1 and 2 showed the antiferromagnetic exchange interactions, and the magnetic property of compound 3 exhibited ferromagnetic exchange interactions.