Novel Cobalt(II) Coordination Polymers Constructed from 3,3′,4,4′-Oxydiphthalic Acid and N-Donor Ligands: Syntheses, Crystal Structures, and Magnetic Properties

Abstract

Four novel cobalt(II) coordination polymers [Co2(OA)(dib)2(H2O)] (1), [Co2(OA)(bbi)2]·3H2O (2), [Co3(HOA)2(bpe)2(H2O)6]·2H2O (3), and [Co2(OA)(dpe)(H2O)2] (4) were obtained by hydrothermal reactions of Co(NO3)2·6H2O with 3,3′,4,4′-oxidiphthalic acid (H4OA) and corresponding N-donor ligands, namely, 1,4-di(1-imidazolyl)benzene (dib), 1,1′-(1,4-butanediyl)bis(imidazole) (bbi), 1,2-bis(4-pyridyl)ethane (bpe), and 1,2-di(4-pyridyl)ethylene (dpe), respectively. Single crystal X-ray diffraction analysis revealed that 1 is a two-dimensional (2D) network containing infinite -(Co–O–C–O)n- chains, while 2 features a 2D double-layered structure with two types of homochiral helical chains filled in the cavities. Complex 3 is a three-dimensional (3D) framework with (64.82)(66) topology containing infinite 2D networks pillared by bpe bridging ligands. 4 is a (44.66) topological 3D framework with coordinated dpe molecules occupied in the channels. The results revealed that the flexible multi-carboxylate and N-donor auxiliary ligands are effective building blocks in constructing coordination polymers with diverse architectures. In addition, the magnetic properties of 1, 3, and 4 were investigated, and the results showed that weak ferromagnetic interactions occurred between Co(II) ions in 1 and 3, while 4 displays a weak antiferromagnetic behavior.