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, [Ln(2)(H2L)(2)(NO3)(4)(CH3O)(2)] (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 thermo-gravimetric analysis. Single-crystal X-ray diffraction studies reveal that complexes 1-3 are isostructural 2D coordination polymers based on dinuclear units, where the mu(2)-(methoxy-O)(2)-bridged Ln(2)O(2) 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 Sm-III ions and complex 2 shows the characteristic red luminescence of Eu-III ions. Furthermore, the energy transfer mechanisms are described and discussed. (C) 2015 Elsevier Ltd. All rights reserved.