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

A new semirigid exo-bidentate ligand incorporating thenylsalicylamide terminal groups, namely 1,4-bis{[(2′-thenylaminoformyl)phenoxyl]methyl}-2,5-bismethylbenzene was synthesized and used as building blocks for constructing lanthanide coordination polymers with luminescent properties. The series of lanthanide nitrate complexes have been characterized by elemental analysis, IR spectroscopy, and X-ray diffraction analysis. All the lanthanide coordination polymers exhibit the same metal-to-ligand molar ratio of 2:3 and the semirigid exo-bidentate ligand as a bridging ligand, reacts with lanthanide nitrates forming 1D annular chains {[Ln2(NO3)6L3]∞ (Ln = Nd (1), Sm (2), Eu (3), Tb (4)}. The samarium, europium and terbium containing compounds exhibit luminescence of the referring trivalent lanthanide ions, giving an orange luminescence for SmIII, a red luminescence for EuIII and a green luminescence for TbIII triggered by an efficient antenna effect of the thenylsalicylamide group.