Hydrothermal syntheses, structures and magnetic properties of two transition metal coordination polymers with a square grid framework

Abstract

Two coordination polymers, [M(NDA)(4,4 ′-bpy)(H 2O) 2] · nH 2O (M=Co, n=1 ( 1); M=Ni, n=0.5 ( 2), NDA=1,4-naphthalenedicarboxylate, 4,4 ′-bpy=4,4 ′-bipyridine) have been synthesized by the hydrothermal reaction of MCl 2 · 6H 2O, NDA and 4,4 ′-bpy. Single-crystal X-ray diffraction analysis shows that they are isostructural and represent the first examples of a square grid metal-organic framework constructed by a transition metal, dicarboxylate and 4,4 ′-bpy with each edge formed by one ligand. The layers are assembled together through hydrogen bonding, resulting in a 3-D supramolecular architecture. Magnetic susceptibility studies reveal that there is a weak antiferromagnetic exchange interaction between the Co(II) ions in the 2-D square grid network of 1, and a weak ferromagnetic exchange interaction between the Ni(II) ions in 2.