Two unique cobalt-organic frameworks based on substituted imidazole-dicarboxylate and dipyridyl-type ancillary ligands: Crystal structures and magnetic properties

• Two 3-D Co(II) coordination polymers incorporating similar substituted imidazole- dicarboxylate have been afforded.
• They are nearly isostructural, possessing similar units based on trinuclear clusters.
• The dipyridyl-type ancillary ligand does not result in obvious diversity structures.
• Magnetic measurements revealed spin-canting-like antiferromagnetism behaviors for compounds at lower temperature.

Two three dimensional (3D) Co(II) coordination polymers incorporating similar substituted imidazole-dicarboxylate and dipyridyl-type ancillary ligands pillared layer, namely, {Co3(mimda3 −)2 (bpe)3·3H2O}n (1) and {Co3 (eimda3 −)2(bipy)3·8H2O}n (2) (H3mimda = 1H-2-methyl-4,5-imidazole-dicarboxylic acid, while H3eimda = 1H-2-ethyl-4,5-imidazole-dicarboxylic acid, bpe = 1,2-di(4-pyridyl) ethylene and bipy = 4, 4′-bipyridine) have been successfully synthesized. Both polymers 1 and 2 have been characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction, and thermogravimetric analysis (TGA). X-ray structural analysis reveals that they are nearly isostructural, possessing similar symmetry units based on trinuclear clusters, and further is propagated into a Kagomé-like lattice. The lattice consists of corner-sharing triangles of spins with magnetic coupling between the nearest neighboring Co(II) ions. Magnetic measurements revealed spin-canting-like antiferromagnetism behaviors for compounds 1 and 2 at lower temperature. The interaction in 1 is slightly stronger than that of 2, which can be explained by the discrepancy of organic linker between the adjacent Co(II) centers.

Two three dimensional (3D) Co(II) coordination polymers incorporating similar substituted imidazole-dicarboxylate and dipyridyl-type ancillary ligands pillared layer have been successfully afforded. X-ray structural analysis reveals that they are nearly isostructural and magnetic measurements revealed spin-canting-like antiferromagnetism behaviors at lower temperature.We show a mixed ligands approach used in a promising way to construct new molecular magnetic materials.Figure optionsDownload as PowerPoint slide