Synthesis, structure and luminescent properties of 3D lanthanide (La(III), Ce(III)) coordination polymers possessing 1D nanosized cavities based on pyridine-2,6-dicarboxylic acid

Two novel coordination polymers, namely, {[Ln2(PDA)(HPDA) (H2O)4ClSO4]·2H2O}n (Ln = La(III) and Ce(III) for complexes I and II, respectively) were synthesized through the reaction between pyridine-2,6-dicarboxylic acid (H2PDA) and La(NO3)3·6H2O and Ce2(SO4)3·8H2O under hydrothermal conditions. Both of these polymers possess 1D infinite nanosized cavities embedding guest water molecules. The complexes were characterized by elemental analyses, IR spectroscopy, thermal analyses and single crystal X-ray diffraction. Two compounds crystallize in orthorhombic system, space group Pna2(1). Both of the complexes exhibit 3D metal–organic framework structure, where SO42− anions play as the bridge between 1D wavelike chains and the adjacent parallel pyridine rings were arranged through π–π interactions. The bi-bidentate coordination mode of SO42− anion was observed. Luminescent emissions of complex I were measured in the solution of DMF at room temperature. In addition, the luminescent emissions of complex I showed certain selectivity among some metal ions.