A series of lanthanide–organic polymers incorporating nitrogen-heterocyclic and aliphatic carboxylate mixed-ligands: structures, luminescent and magnetic properties

Abstract

Seven new lanthanide–organic coordination polymers incorporating both nitrogen heterocyclic dicarboxylate and various auxiliary ligands, {[Ln₃(Hpimda)₄(μ₂-HCOO)·5H₂O]·H₂O}_n} Ln = Sm (1), Ln = Eu (2), Ln = Gd (3), Ln = Dy (4), Ln = Ho (5), {[Ce₂(Hpimda)₂(μ₄-C₂O₄)·8H₂O]·2H₂O}_n (6), {[Yb₂(pyda)(μ₄-C₂O₄)₂·4H₂O]·3H₂O}_n (7) (H₃pimda = 1H-2-propyl-4,5-imidazoledicarboxylic acid, H₂pyda = 2,6-pyridinedicarboxylic acid) have been fabricated successfully and characterized systematically. Complexes 1–5 are isomorphous and isostructural, and are built from two-dimensional (2-D) double-decker networks based on the tetranuclear basic carboxylate as a secondary building unit (SBU). Both polymers 6 and 7 feature a (3,4)-connected 3-D framework consisting of 2-D lanthanide–organic hexagonal grids, which are further interlinked via the μ₄-oxalate ligand. The results of magnetic determination show the same end-to-end bridging fashion of formate group results in different magnetic properties occurring between lanthanide centers. The luminescence emission spectra of the complexes vary depending on the lanthanide ion present.