Synthesis And Characterization Of Fluorescent Polymers Containing Tetraphenylethene Units

Organic luminophores with aggregation-induced emission(AIE)property are practically non-luminescent in solution state but emit brightly in solid sate,which is opposite to conventional dyes suffering from heavy aggregation-caused quenching(ACQ)effect.In recent years,the kind of organic luminescence with AIE characteristics has caused wide attention.Among these AIE molecules,tetraphenylethylene(TPE)and its derivatives have numerous advantages,such as facile synthesis,high efficient emission,and high thermal stability.In this work,six compounds containing TPE unit,two oil-soluble polymers and one water-soluble polymer containing TPE unit were synthesized and characterized by NMR,FTIR,UV-Vis and PL,and then the water-soluble polymer containing TPE unit was characterized and measured by MTT and living cell imaging.1,2-di(4'-(2'',3''-epoxypropoxy)phenyl)-1,2-diphenylethylene(M2)was synthesized using 4-hydroxybenzophenone as a kind of starting material.The oil-soluble hyperbranched polymer(P1)containing TPE unit was synthesized by anionic ring-opening polymerization using M2 as monomer and potassium tert-butoxide as initiator.The chemical structure and optical properties of M2 and P1 were characterized and tested by NMR,MALDI-TOF-MS,FTIR,GPC,UV-Vis and PL,respectively.The results showed P1 maintained the oil-soluble aggregation-induced emission(AIE)characteristics that TPE enjoys;P1 emitted blue-green fluorescence in solution and aggregation state;the fluorescence intensity of P1 in the mixture of THF/H2O(1/99,V/V)increased 6.6-fold than that of P1 in THF.The structure of P1 restricts the free-rotation of phenyl groups so that P1 can solve the limitation that the quantum yields of AIE molecules are extremely low in solution.The electrochemical behavior of P1 was investigated by cyclic voltammetry and its energy levels of the HOMO,LUMO and the band gap were estimated.The cyctotoxicity study of P1 against HeLa cells was measured by MTT assay,and the result shows P1 has shown few cytotoxicity(concentration below 100 ?g·mL-1).The TG data of P1 reveals that P1 has a high thermal decomposition temperature and excellent thermal stability.The compound M2 containing TPE unite was synthesized using 4-hydroxybenzophenone and 4-bromobenzophenone as starting materials by Suzuki-couping reaction and McMurry-couping reaction.The ATRP initiator M6 containing tetraphenylethylene-perylene bisimides(TPE-PBI)conjugated unites was synthesized using Suzuki-couping reaction.Besides,the oil-soluble polymer P2 was prepared by the ATRP reaction using M6 as initiator and 2-(2',3',4',6'-tetra-O-acetyl-?-D-mannopyranosyloxy)ethyl methacrylate as a monomer.After removing the acetyl group,we obtained a water-soluble fluorescent polymer P3 with a TPE-PBI conjugated unit.The chemical structure and optical properties of M3,M4,M5,M6 and P2,P3 were characterized and tested by NMR,MALDI-TOF-MS,GPC,UV-Vis and PL,respectively.