| In this study, by molecular design, select linear polystyrene as the substrate, after threesteps of macromolecular reactions, two kinds of bidentate Schiff base ligands which havechelating-coordinating and energy transfer sensitization action, were bonded on the side chainof polystyrene, and two kinds of the bidentate Schiff base ligand-functionalized polystyrenewere prepared. Then each of them was coordinated with Eu (Ⅲ) and Tb (Ⅲ) ions respectively.Luminous Schiff bases type polymer-rare earth complexes were prepared successfully, andtheir luminescence performance and luminescence mechanism were researched andexploreded. The two complex products in this paper designed and prepared are new kinds ofbonding type photoluminescence polymer-rare earth complexes. Obviously, the results in thisarticle have important scientific significance and application value in the preparation anddevelopment of high-performance photoluminescence polymer-rare earth complexes.Firstly, based on1,4-dichloro methoxy butane as chloromethylation reagent,chloromethylation polystyrene (CMPS) was got through Friedel-Crafts alkylation reaction.Then, the nucleophilic substitution between CMPS and p-hydroxy benzaldehyde (HBA) wasconducted with p-Hydroxybenzaldehyde(HBA) as nucleophilic reagent, resulting in themodified Polystyrene PS-BA, on whose side chain, benzaldehyde (BA) was bonded. Finally, aSchiff base reaction between the primary amino group of3-aminopyridine (AP) and thealdehyde group of PS-BA was allowed to be carried out, and Schiff base ligands were bond onthe side chain of PS, forming functionalized polystyrene PS-SB, on whose side chain,bidentate Schiff base ligand was bonded. The chemical structure of PS-SB was characterizedby FTIR and1H-NMR spectra. The effects of the main factors on nucleophilic substitution reaction were investigated emphatically and the reaction conditions were optimized. Theexperimental results show that during the nucleophilic substitution reaction,N,N-dimethylacetamide with stronger polarity is a suitable solvent, and the appropriatereaction temperature is80℃. Under the optimal reaction condition, the SB bonding quantityof functional polymer PS-SB is2.55mmol/g.PS-SB was used as macromolecular ligand, and the coordination reaction between it andEu(Ⅲ) ion was allowed to be carried out, resulting in the binary polymer-rare earth complexPS-(SB)3-Eu(Ⅲ). At the same time, with phenanthroline as second ligand, the ternarypolymer-rare earth complex PS-(SB)3-Eu(Ⅲ)-(Phen)1was also prepared. On this basis ofcharacterizing the two complexes by infrared spectroscopy and ultraviolet absorptionspectrum, their fluorescence emission characteristics and luminescent mechanism wereexamined in depth. The experimental results show that the bond bidentate Schiff base ligandSB possesses the dual functions of coordination chelating and energy transfer-sensitizationtowards rare earth ion. The prepared complexes are stable, and can emit strong characteristicfluorescence of Eu(Ⅲ) ion——red light. The macromolecular ligand PS-SB itself has strongfluorescence emission. However, after coordinating with Eu(Ⅲ) ion, the fluorescenceemission of its own weakens remarkably, and the energy is transferred to Eu(Ⅲ) ion viaintramolecular energy transfer. As a result, Eu(Ⅲ) ion fluorescence is strongly sensitized. Thefluorescence emission intensity of the ternary polymer-rare earth complexPS-(SB)3-Eu(Ⅲ)-(Phen)1is much higher than that of the binary polymer-rare earth complexPS-(SB)3-Eu(Ⅲ) owing to the two effects of the second ligand Phen, synergistic coordinationand replacement of coordinated water molecules. The macromolecular ligands PS-SB has nosensibilization for the fluorescence emission of Tb(Ⅲ) ion.The research has prepared another bidentate schiff base ligand-functionalized polystyrene.On the basis of the preparation of linear chloromethylation polystyrene (CMPS), theesterification reaction between CMPS and glyoxalic acid (GA) was conducted with glyoxalic acid as nucleophilic reagent, resulting in the modified Polystyrene PS-GA, on whose sidechain, glyoxalic acid was bonded. Then a Schiff base reaction between the primary aminogroup of3-aminopyridine (AP) and the aldehyde group of PS-GA was allowed to be carriedout, and Schiff base ligands were bond on the side chain of PS, forming anotherfunctionalized polystyrene PS-GSB, on whose side chain, bidentate Schiff base ligand wasbonded. The experimental results show that during the nucleophilic substitution reaction,N,N-dimethylacetamide with stronger polarity is a suitable solvent, and the appropriatereaction temperature is75℃. Under the optimal reaction condition, the GSB bonding quantityof functional polymer PS-GSB is2.25mmol/g. Finally, PS-GSB was used as macromolecularligand, and the coordination reaction between it and Tb(III) ion was allowed to be carried out,resulting in the binary polymer-rare earth complex PS-(GSB)3-Tb(III). At the same time, withphenanthroline as second ligand, the ternary polymer-rare earth complexPS-(GSB)3-Tb(III)-(Phen)1was also prepared. On this basis of characterizing the twocomplexes by infrared spectroscopy and ultraviolet absorption spectrum, their fluorescenceemission characteristics and luminescent mechanism were examined in depth. Theexperimental results show that the bond bidentate Schiff base ligand GSB possesses the dualfunctions of coordination chelating and energy transfer-sensitization towards rare earth ion.The prepared complexes are stable, and can emit strong characteristic fluorescence of Tb(III)ion——green light. It is showed that the macromolecular ligand PS-GSB can stronglysensitize the fluorescence-emission of Tb(III) ion, but have no sensibilization for thefluorescence emission of Eu(Ⅲ) ion. The fluorescence emission intensity of the ternarypolymer-rare earth complex is much higher than that of the binary polymer-rare earthcomplex owing to the two effects of the second ligand Phen, synergistic coordination andreplacement of coordinated water molecules. The fluorescence properties of solid membraneof binary and ternary complexes have similar laws. |
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