Syntheses, Structure And Luminescent Properties Of Series Of Zn-Ln Coordination Complexes

In this paper, using pyridine-2,3-dicarboxylic acid as the main ligands, elevencoordination complexs were synthesized by the hydrothermal method and their structureswere measured by the single-crystal X-ray diffraction. The molecular formulas are as follows:(1){[PrZn(2,3-pydc)2(ox)0.5(H2O)3].3H2O}n(7){[EuZn(2,3-pydc)2(ox)0.5(H2O)3].3H2O}n(2){[NdZn(2,3-pydc)2(ox)0.5(H2O)3].3H2O}n(8){[TbZn(2,3-pydc)2(ox)0.5(H2O)3].3H2O}n(3){[HoZn(2,3-pydc)2(ox)0.5(H2O)3].3H2O}n(9){[ErZn(2,3-pydc)(1,3-bdc)(OH)(H2O)].H2O}n(4){[ErZn(2,3-pydc)2(ox)0.5(H2O)3].3H2O}n(10){[TbZn(2,3-pydc)(1,3-bdc)(OH)(H2O)].H2O}n(5){[YbZn(2,3-pydc)2(ox)0.5(H2O)3].3H2O}n(11){[YbZn(2,3-pydc)(1,3-bdc)(OH)(H2O)].H2O}n(6){[SmZn(2,3-pydc)2(ox)0.5(H2O)3].3H2O}nComplexs (1)-(8) are isomorphous and crystallize in the triclinic system, with spacegroup P-1. In the crystals, Ln(III) and Zn(II) ions are bridged into3D network through2,3-pydc and oxalate ligands, and a large number of hydrogen bonds in the molecule make themolecular structure stability. While complexs (9)-(10) are also isomorphous and crystallizein the triclinic system, with space group P-1. They are bridged into2D layers by2,3-pydc and1,3-H2bdc ligands.At room temperature, the IR and UV-Vis-NIR absorption spectra, excitation andemission spectra in the visible and near-infrared areas of the eleven complexes werecharacterized and analyzed. All of them exhibit the characteristic emission bands ofcorresponding Ln(III) ion, which should be attributed to sensitization from the Zn-ligandsmoiety(d-block) after introducing the transition metal ion into the Ln(III) system of Ln(III)complexes. Specially for complex (1)-(6), the emission spectra in NIR region exhibit thecharacteristic emission bands of corresponding Ln(III) ion, which occur shift, broad and splitin comparison with the corresponding theoretical emission band. It may be attribution to theeffect of crystal fileld and the introduction of transition metal after the construction of Zn-Lnpolymer, i.e., the intramolecular4f-levels of Ln(III) ions may be affected. It can be confirmedby the UV-Vis-NIR spectra. Part of the absorption bands present shift, broad and split, and thetwo spectra can evidence each other.