Synthesis and characterization of two novel Schiff base type macromolecular ligands and preliminary research on luminescent property of polymer-rare earth complexes

Abstract

Luminescent polymer-rare earth complexes are a class of functional materials, and bonding-type polymer-rare earth complexes is one important kind of such material. In this work, by molecular design and through polymer reactions, two types of bidentate Schiff base groups, benzaldehyde/ortho-aminophenol (BAOA) type and benzaldehyde/glutamic acid (BAGL) type groups, were synchronously synthesized and bonded on the side chain of polysulfone (PSF), respectively, and two new Schiff base type macromolecular ligands, PSF-BAOA and PSF-BAGL, were obtained. Then through coordination reactions, the luminescent polymer-rare earth complexes with different chemical structures were prepared. The synthesis and characterization of PSF-BAOA and PSF-BAGL were taken as the emphases of this study. The effects of main factors on the synthesis of the macromolecular ligands of PSF-BAOA and PSF-BAGL were fully researched, and their structures were fully characterized by FTIR and 1H-NMR. The luminescent properties of the prepared polymer-rare earth complexes were preliminarily discussed. The experimental results show that the Friedel-Crafts alkylation reaction of PSF with 4-(chloromethyl)benzaldehyde (CMBA) as the first step of the polymer reaction process can be smoothly carried out so that benzaldehyde (BA) as a group can be effectively bonded on the side chain of PSF, resulting in the modified polysulfone, PSF-BA. The appropriate solvent is N,N-dimethylacetamide (DMAC) with stronger polarity and suitable temperature is 70 °C. The subsequent Schiff reaction of PSF-BA with ortho-aminophenol (OAP) or glutamic acid (GLA) as the second step of the polymer reaction process can be easily carried out, successfully getting two macromolecular ligands, PSF-BAOA and PSF-BAGL. The complex of PSF-BAOA and Eu(III) ion produces strong red luminescence, whereas the complex of PSF-BAGL and Tb(III) ion exhibits strong green emission.