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

In this paper,nine coordination complexes were synthesized via hydrothermal methods and their structures were measured by the single-crystal X-ray diffraction:(1){[SmZn(2,3-pydc)(1,3-bdc)(OH)(H2O)]·H2O}n(2){[EuZn(2,3-pydc)(1,3-bdc)(OH)(H2O)]·H2O}n(3){[DyZn(2,3-pydc)(1,3-bdc)(OH)(H2O)]·H2O}n(4){[GdZn(2,3-pydc)(1,3-bdc)(OH)(H2O)]·H2O}n(5){[PrZn(2,3-pydc)(1,3-bdc)(OH)(H2O)2]·H2O}n(6){[NdZn(2,3-pydc)(1,3-bdc)(OH)(H2O)2]·H2O}n(7)[Sm3Cd2(o-C8O4H4)6(OAc)(phen)2(H2O)2]n(8)[Pr(OX)(OAc)(H2O)]n(9){[Ho(OX)1/2(C4H6O4)(H2O)2]·H2O}nComplexes(1)-(4)are isomorphous,and the number of the coordinated waters in the complexes(5)-(6)is different from that in(1)-(4).All of them crystallize in the triclinic system,with space group P-1.In the crystals,Ln(?)and Zn(?)ions are bridged into 2D layers through OH-,2,3-pyridine dicarboxylate and isophthalate ligands,and the O-H…O hydrogen bonds exist in the 2D layers stabilizing the structures.Cd-Ln complex(7)possesses the 1D chain structure,which is bridged by phthalate.Complex(8)is bridged into the 3D network by OAc-and oxalate.Complex(9)exhibits the 2D layer by using the succinate and oxalate as the bridging ligands,and the 2D layers are connected into the 3D hydrogen bonding network by hydrogen bonds.At room temperature,the IR and UV-Vis-NIR spectra,excitation and emission spectra in the visible and near-infrared regions of the nine complexes were measured and analyzed.Except the complex(4),the other complexes exhibit characteristic emission bands of corresponding Ln(?)ions.In addition,the NIR emission bands of(1),(3),(5),(6),(7)persent shift,broaden and split in comparison with the corresponding theoretical emission bands of Ln(?)ions.This may be due to the influence of the crystal field and interaction between the 3d orbital of the Zn(?)ion or 4d orbital of the Cd(?)ion and the 4f orbital of Ln(?)ions after the formation of Zn-Ln or Cd-Ln complexes,which may make the internal energy levels to be adjusted.The phenomenon presents in UV-Vis-NIR specrtra and the NIR emission spctra,the two spectra can evidence each other.