Synthesis, Structural Characterization, and Luminescence Studies on an Unreported Series of Oxalate Linked Heterometallic Coordination Polymers

Abstract: A previously unreported series of heterometallic, rare earth-niobate coordination polymers of the formula [LnNbO(C₂O₄)₃(DMSO)₃ Ln = (Y, La, Ce, Nd, Sm, Eu, Gd) ] have been synthesized via a feasible treatment of Ln(NO₃)₃•5H₂O, NH₄NbO(C₂O₄)₂ •X H₂O, and oxalic acid in DMSO solvent. A single crystal of the La analogue was obtained, and the structure was solved via single crystal x-ray diffraction. Rietveld refinement techniques were performed on the remaining lanthanide analogues to understand structural variation as a function of ionic radius. The structure consists of LnO₉ and NbO₇ polyhedra bridged by oxalate ligands to form an anhydrous coordination polymer. Luminescence studies evinced characteristic rare earth emission, and high Eu³⁺ quantum yield of 66% was observed due to an anhydrous crystal lattice.