Photoluminescence Properties Of 2,3-pyrazinedicarboxylic Acid Zn-Ln Heteronuclear Complexes

Under hydrothermal conditions,a series of three-dimensional Zn–Ln heteronuclear complexes,namely,{[Ln₂Zn（Pzdc）₄（H₂O）₆]·2H₂O}_n（Ln=La（1）,Pr（2）,Nd（3）,Sm（4）,Eu（5）,Gd（6）,Tb（7）,Dy（8））,were synthesized by the one-pot reactions of2,3-pyrazine dicarboxylic acid（H₂Pzdc）with LnCl₃·nH₂O and Zn（NO₃）₂·6H₂O in this paper.The corresponding complexes were tested by IR,TG,elemental analysis,single crystal X-ray diffraction,and powder X-ray diffraction.The results showed that the eight target complexes were synthesized.The single crystal data of the complexes 1,2,4,5,and 7 were obtained.Single crystal X-ray diffraction and powder X-ray diffraction analyses indicate complexes 1–8are isostructural,and exhibit a three-dimensional framework structure with the parallel quadrilateral channels and{4.6^2}₂{4^2.6^2.8^2}{6^3}2{6^5.8}₂ topology,in which the central Ln（III）ion is nine-coordinated by four oxygen atoms and two nitrogen atoms from four ligands and three oxygen atoms from three coordinated H₂O molecules and the central Zn（II）ion is six-coordinated by four oxygen atoms and two nitrogen atoms from four ligands.The photophysical properties related to the electronic transition for complexes 4,5,7,and 8 were studied by using excitation spectrum,emission spectrum,and emission lifetime.Under the specific excitation wavelengths,complexes 4,5,7,and 8 show the characteristic emission peaks of Sm³⁺,Eu³⁺,Tb³⁺,and Dy³⁺,respectively,indicating that the 2,3-pyrazine dicarboxylic acid ligand can effectively sensitize the luminescence of rare earth ions in the visible area.