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 SO₄^2? 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 SO₄^2? 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.