Syntheses,Crystal Structures,and Magnetic Properties of Mn(Ⅱ) and Co(Ⅱ) Coordination Polymers Constructed from Pyridine-tricarboxylate Ligand

Two coordination polymers, namely {[Mn(HL_1)(phen)]·4H_2O}_n(1) and [Co_2(HL_2)_2(H_2O)_2]_n(2) have been constructed hydrothermally using H_3L_1 and H_3L_2(H_3L_1 = 2-(5-carboxypyridin-2-yl)terephthalic acid, H_3L_2 = 2-(4-carboxypyridin-3-yl)terephthalic acid), phen, MnCl_2×4H_2O and CoCl_2×6H_2O. The products were isolated as stable crystalline solids and were characterized by IR spectroscopy, elemental, thermogravimetric(TGA), powder(PXRD) and single-crystal X-ray diffraction analyses. Compound 1 features a 3D framework structure, which was topologically classified as a trinodal 4,6,6-connected net with the unique topology defined by the point symbol of(3~(10).5.6~4)4(3~(10).6.7~4)2(5.6~2.8~2.9). Compound 2 possesses a 2D metal-organic layer, which was topologically classified as a binodal 4,4-connected layer defined by the point symbol of(4~3.6~2.8). The layers are further extended into a 3D supramolecular framework via hydrogen bonds. The magnetic properties for both compounds were also investigated, indicating antiferromagnetic interactions between the adjacent metal ions.