Synthesis, characterization and photoluminescence properties of two new europium(III) coordination polymers with 3D open framework

The 3D open framework coordination polymers, [Eu2(fum)3(H2O)4]n·3nH2O (1, fum=fumaric acid) and [Eu(pdc)(Hpdc)]n (2, pdc=pyridine-2,5-dicarboxylic acid) have been synthesized via hydrothermal procedure. Their molecular structures were determined by single-crystal X-ray diffraction analysis. Polymer 1 adopts a 3D microporous structure filled with disordered free water molecules which interact by hydrogen bonds with terminal water bound to the metal centers. IR spectroscopy, TGA and powder X-ray diffraction analysis revealed that the remarkable dehydration–rehydration process of open-framework 1 is completely reversible. Polymer 2 forms a 3D framework composed of 2D grid-like inorganic subnetworks and pdc ligands as linkers. This solid is highly stable up to 405 °C. The solid-state photoluminescence measurements exhibited red light-emitting characteristic of two europium(III) coordination polymers. Moreover, the anhydrous products were found to be more strongly fluorescent and be of longer lifetime.