Fluorescence Properties Of Rare Earth Coordination Polymers Based On AIE Ligands

As a widely used aggregation-induced emission(AIE)fluorophore,tetrastyrene(TPE)and its derivatives have become research hotspots in the fields of materials science and biotechnology due to their unique luminescence mechanisms.They hardly emit light in dilute solutions,but emit bright fluorescence in the aggregated state due to the restriction of the internal movement of the molecules.In the past few years,people have successfully covered some metal-organic coordination polymers with AIE activity through coordination-driven self-assembly,and their special properties and applications were also studied.In this paper,4-(1,2,2-triphenylethylene)benzoic acid(tpemc)was replaced as a ligand,and four rare earth coordination polymers[Ln(tpemc)₂(AcO)(DMA)]_n(1-4,Ln=Tb,Eu,Gd,Dy)with one-dimensional structure were synthesized by hydrothermal method with Tb³⁺,Eu³⁺,Gd³⁺and Dy³⁺ions,respectively.All of complex 1-4 have AIE properties because of their one-dimensional chain structures which have less restriction on ligands.After screening the cell inhibition rate test,Hela's cell imaging test was performed on the low toxicity complex 1.Through the temperature-changing fluorescence test of the complex 1-4,it was found that the complex 2 showed characteristic fluorescence peaks in the low temperature range,and their intensity linearly attenuated with the increase of temperature.1,2-diphenyl-1,2-bis(4-phenylbenzene)ethylene(tpedc)was replaced as a ligand,and four rare earth coordination polymers{[Ln₂(tpedc)₃(DMA)(H₂O)₂]·3DMA·2H₂O}_n(5-8,Ln=Tb,Eu,Gd,Dy)with two-dimensional structure were synthesized by hydrothermal method with four kinds of above ions,respectively.The AIE properties were not detected in the complex 5-8,which may be due to the obvious limitation of the benzene ring rotation in the two-dimensional structure.The results of the AIE test of 1-4 with one-dimensional structures were compared with the AIE test results of 5-8 with two-dimensional structures,explaining the apparent effect of the spatial structure on the AIE properties of complexes based on AIE ligands.By performing fluorescent ion detection tests on complexes 1-8,it was found that they have great detection ability for Fe³⁺,CrO₄^2-and Cr₂O₇^2-ions,and their fluorescence recognition mechanism was explained.Here the optical properties of these compounds were also characterized by IR spectrum,UV-vis absorption spectrum and solid fluorescence spectrum.Finally,two novel AIE ligands 4-methyl-N-[3-(1,2,2-triphenylethenyl)-phenyl]b-enzenesulfonamide(MTBF)and tert-butyl(3-(1,2,2-triphenylvinyl)phenyl)carbamate(BTPC)were also synthesized determinated by ¹HNMR spectrum,mass spectrum and single crystal X-ray diffraction.The solid fluorescence spectrum and AIE properties of these two ligands were also tested.