Lanthanide coordination polymers constructed by a new semirigid bridging salicylamide ligand: Synthesis, supramolecular structure and luminescence properties

A new semirigid exo -bidentate ligand was designed, synthesized, and used as building blocks for constructing lanthanide polymers both with interesting supramolecular structures and luminescent properties. Among a series of lanthanide nitrate complexes which have been characterized by elemental analysis, X-ray powder diffraction, IR spectroscopy and molar conductance analysis, five new coordination polymers have been determined using X-ray diffraction analysis. All the coordination polymers exhibit the same metal-to-ligand molar ratio of 1:1 and the semirigid exo -bidentate ligand as a bridging ligand, reacts with lanthanide nitrates forming a zigzag chain which further interconnected to three dimensional supramolecular structure in aid of cooperative C–H⋯O hydrogen bond and π–π stacking interactions. The europium and terbium containing compounds exhibit luminescence of the referring trivalent lanthanide ions, giving a red luminescence for EuIII and a green luminescence for TbIII triggered by an efficient antenna effect of the picolylsalicylamide group.