Photoluminescence property of polymer–rare earth complexes containing acetaldehyde/aminophenol type bidentate Schiff base ligand

Acetaldehyde was introduced onto the side chains of polysulfone, and then Schiff base reactions were carried out between the introduced acetaldehyde and ortho-aminophenol (OAP) or meta-aminophenol (MAP). Two bidentate Schiff base (B) ligands of acetaldehyde/aminophenol type, OAPB and MAPB, were bonded on the side chains of polysulfone, and two new bidentate Schiff base ligand functionalized-polysulfones, PSF-OAPB and PSF-MAPB, were obtained. The triplet state energies of OAPB and MAPB are well matched with the resonant level energy of Tb(III), and the Tb(III) complexes emit the strong characteristic fluorescence of Tb(III) (green luminescence). Complexes of Eu(III) have no fluorescence emission because of the mismatching of the energy levels. In comparison, the fluorescence intensity of the binary complex PSF-(MAPB)₃-Tb(III) is stronger than that of the binary complex PSF-(OAPB)₃-Tb(III) because of the structured difference of the chelating ring. The ternary complexes PSF-(MAPB)₃-Tb(III)-(Phen)₁ (Phen represents 1,10-phenanthroline) and PSF-(OAPB)₃-Tb(III)-(Phen)₁ have stronger fluorescence emissions than the corresponding binary complexes. The fluorescence emission intensities of solid films of the complexes are stronger than that of their solutions. The prepared luminescent polymer-Tb(III) complexes containing acetaldehyde/aminophenol type bidentate Schiff base ligands have very high quantum yields (80–86%), reflecting the high intramolecular energy transfer efficiencies from the ligands to Tb(III).