Synthesis, structures, and photoluminescence properties of three metal(II) coordination polymers derived from a flexible tripodal ligand and 2,6-pyridinedicarboxylic acid

Abstract

Using a flexible tripodal ligand N,N′,N″-tris(3-pyridyl)-1,3,5-benzenetricarboxamide and 2,6-pyridinedicarboxylic acid, three metal(II) complexes formulated as [Co(pydc)(L)] n (1), [Zn(pydc)(L)] n (2), {[Ni(pydc)(L)]·2H2O} n (3) (L = N,N′,N″-tris(3-pyridyl)-1,3,5-benzenetricarboxamide, H2pydc = 2,6-pyridinedicarboxylic acid) have been hydrothermally synthesized and structurally characterized by physico-chemical and spectroscopic methods and single-crystal diffraction. In compounds 1 and 2, the L ligands acts as bridges to link the metal atoms into zigzag chain structures, which are further extended into three-dimensional (3D) metal–organic supramolecular frameworks by hydrogen bond interactions. In compound 3, the L ligands link three Ni(II) centers to form a two-dimensional (2D) hcb layered structure, and then, the adjacent nets interweave in parallel to generate a 3D structure by 2D → 3D interpenetration. The thermal stabilities of 1–3 and the luminescent properties of 2 in the solid state are also discussed. Three metal(II) coordination polymers, based on a flexible ligand N,N′,N″-tris(3-pyridyl)-1,3,5-benzenetricarboxamide and 2,6-pyridinedicarboxylic acid, have been successfully synthesized under hydrothermal conditions, where thermal and photoluminescent properties were also investigated.