Novel lanthanide coordination polymers based on bis-tridentate chelator pyrazine-2,3,5,6-tetracarboxylate with nano-channels and water clusters

Abstract

Three novel lanthanide coordination polymers with large channels and water clusters, [Yb₂(pztc)_1.5(H₂O)₆]·7H₂O (1), [Lu₂(pztc)_1.5(H₂O)₆]·7.5H₂O (2) and [Er₂(pztc)_1.5(H₂O)₆]·7H₂O (3), have been synthesized by the reactions of pyrazine-2,3,5,6-tetracarboxylic acid (H₄pztc) and Ln(III) salts in aqueous solution at room temperature or under hydrothermal conditions, and characterized by X-ray crystallography, elemental analysis, IR, UV-vis and thermal gravimetric analysis (TGA). Single crystal X-ray diffraction determination indicates that the Ln(III) ions were coordinated by three tridentate cheated pztc⁴⁻ ligands and bis-tridentate cheated pztc⁴⁻ ligands bridged Ln(III) ions to form hexanuclear metal ring structures with nano-channels which were filled with (H₂O)₁₄clusters.