Photophysical properties and energy transfer mechanism of a praseodymium compound with a two-dimensional layer

A hydrothermal reaction results in the formation of a novel [Pr-2(2,5-PA)(2)(2,5-HPA)(2)(H2O)(4)](n)center dot 2nH(2)O complex (2,5-H(2)PA = 2,5-pyridinedicarboxylic acid). The complex is structurally characterized by single-crystal X-ray diffraction and crystallizes in the space group P2(1) of the monoclinic system with two formula units in one cell. This praseodymium complex is characterized by a two-dimensional layered structure. A solid-state photoluminescence experiment reveals that the praseodymium complex shows an emission in the red region. The complex has Commission Internationale de I'eclairage chromaticity coordinates of 0.5495 and 0.4492. The photoluminescence emission bands could be assigned to the characteristic emission of the 4f electron intrashell transition of the P-3(0) -> H-3(5), D-1(2) -> H-3(4), P-3(0) -> H-3(6), P-3(0) -> F-3(2), and P-3(1) -> F-3(3) of the Pr3+ ions. The energy transfer mechanism is explained by the energy level diagrams of the praseodymium ions and the 2,5-H(2)PA ligand. A solid-state diffuse reflectance measurement shows that the complex possesses a wide optical band gap of 3.48 eV.