Structures and Luminescence Lifetimes of Two Dy(III) Coordination Polymers

Rare earth ions, owing to their unique electronic structures, have important applications in luminescent materials. Among them, Dy(III) complexes have attracted considerable attention for their characteristic blue and yellow emissions. In this work, two Dy(III) coordination polymers (CPs) were synthesized by reacting Dy(ClO₄)₃ with two different aromatic dicarboxylate ligands under hydrothermal conditions at 170 °C. Single-crystal X-ray structure determination reveals that the chemical formulas of the two CPs are {[Dy₂(5-OH-1,3-bdc)(1,2-bdc)₂(H₂O)₂]·2 H₂O}ₙ (CP-1) and [Dy(1,4-bdc)₀.₅(1,2-bdc)(H₂O)₂]ₙ (CP-2) (5-OH-1,3-H₂bdc = 5-hydroxy-1,3-benzenedicarboxylic acid; 1,2-H₂bdc = 1,2-benzenedicarboxylic acid; 1,4-H₂bdc = 1,4-benzenedicarboxylic acid). In CP-1, the 5-OH-1,3-bdc and 1,2-bdc ligands coordinate with Dy(III) to form a two-dimensional (2D) layered structure, whereas in CP-2, the 1,4-bdc and 1,2-bdc ligands construct a three-dimensional (3D) framework. Both CPs exhibit the characteristic Dy(III) fluorescence upon ultraviolet (UV) excitation. The luminescence lifetimes of CP-1 and CP-2 are 5.157 µs and 3.336 µs, respectively, and a qualitative analysis of the difference between them was performed.