Structure and luminescent property of complexes of aryl carboxylic acid-functionalized polystyrene with Eu(III) and Tb(III) ions

Abstract

Via polymer reactions, naphthoic acid (NA) and benzoic acid (BA) were bonded onto the side chains of polystyrene (PS), respectively, and two aryl carboxylic acid-functionalized polystyrenes, PSNA and PSBA, were obtained. Using PSNA and PSBA as macromolecule ligands and Eu3+ and Tb3+ ions as central ions, various luminescent binary polymer-rare earth complexes were prepared. At the same time, with 1,10-phenanthroline (Phen) and 4,4′-bipyridine (Bipy) as small-molecule co-ligands, various ternary polymer-rare earth complexes were also prepared. On the basis of characterizing PSNA, PSBA and complexes, the relationship between structure and luminescent property for these prepared complexes were mainly investigated. The study results show that the macromolecule ligands PSNA and PSBA, or the bonded NA and BA ligands, can strongly sensitize the fluorescence emissions of Eu3+ ion or Tb3+ ion, but the sensitization effect is strongly dependent on the structure of the ligands and the property of the central ions, namely it is strongly dependent on the matching degree of energy levels. The fluorescence emission of the binary complex PS-(NA)3-Eu(III) is stronger than that PS-(BA)3-Eu(III), indicating ligand NA has stronger sensitization action for Eu3+ ion than ligand BA; the binary complex PS-(BA)3-Tb(III) emit strong characteristic fluorescence of Tb3+ ion, displaying that ligand BA can strongly sensitize Tb3+ ion, whereas the binary complex PS-(NA)3-Tb(III) nearly does not emit the characteristic fluorescence of Tb3+ ion, showing that ligand NA does not sensitize Tb3+ ion. The fluorescence intensity of the ternary complexes is much stronger than that of the binary complexes in the same series.