Structure and luminescent properties of 2D Salen-type lanthanide coordination polymers from the flexible N,N′-bis(salicylidene)-1,4-butanediamine ligand

Three new Salen-type lanthanide coordination polymers, [Ln2(H2L)2(NO3)4(CH3O)2]n (Ln = Sm (1), Eu (2) and Lu (3); H2L = N,N′-bis(salicylidene)-1,4-butanediamine), have been synthesized by a solvothermal method and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectra and thermogravimetric analysis. Single-crystal X-ray diffraction studies reveal that complexes 1–3 are isostructural 2D coordination polymers based on dinuclear units, where the μ2-(methoxy-O)2-bridged Ln2O2 cores are linked by four Salen-type ligands in a bidentate mode. Each lanthanide ion is eight-coordinated by eight oxygen atoms, forming a distorted dodecahedral geometry. Luminescence analysis in the solid state at room temperature indicates that complex 1 exhibits the co-luminescence of the ligand and SmIII ions and complex 2 shows the characteristic red luminescence of EuIII ions. Furthermore, the energy transfer mechanisms are described and discussed.

Graphical abstractNovel 2D Salen-type lanthanide coordination polymers based on rare dinuclear units from a flexible ligand with luminescent properties are constructed. Luminescence analysis in the solid state proposes that 1 exhibits co-luminescence of the ligand and the SmIII ion, whilst 2 shows the characteristic red luminescence of the EuIII ion.Figure optionsDownload full-size imageDownload as PowerPoint slide