Synthesis, structure and fluorescence studies of the lanthanide complexes with 4-fluorobenzoic acid

•The infinite 1D chain of 1–2 is formed by bidentate bridging carboxyl groups.•There are 4 coordinated and one free H2O molecules in the complexes.•The complexes present intense emission even though 5 H2O in the first coordination sphere.

Tb (1) and Eu (2) complexes with 4-fluorobenzoic acid have been synthesized by hydrothermal method. The structures of them were established by X-ray crystallography, which revealed that complexes 1 and 2 are isostructural and crystallized into one infinite 1D chains by bidentate bridging carboxyl groups. There are four coordinated and one free H2O molecules around each Tb3+ or Eu3+ centers. But the complexes present excellent luminescence under ultraviolet excitation. The photoluminescent properties of the two complexes were investigated by the solid state excitation, the emission spectra and the luminescent decay. The complexes exhibited strong green and red luminescence in visible spectral region on the broad excitation of the ultraviolet ligand absorption, which indicates the antenna effect might have taken place effectively. The overall quantum yields of complexes 1 and 2 are 41% and 14%, respectively, and the sensitization efficiency of the ligand in complex 2 is estimated to be 82%.

Graphical abstractInfinite 1D chain is formed by bidentate bridging carboxyl groups in Tb-4-fluorobenzoic acid complex. Intense green emission was observed even though lots of high-frequency vibrational centers exist in the first coordination sphere.Figure optionsDownload full-size imageDownload as PowerPoint slide