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

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.