水溶性荧光增强共轭聚合物的合成及性能研究

通过Suzuki反应将1,2-二[4-(6-溴己氧基)苯基]-1,2-二(4-溴苯基)乙烯与1,4-对苯二硼酸丙二醇酯共聚得到含有四苯乙烯基团的共轭聚合物P-0,通过后功能化得到了具有良好水溶性的聚合物P-1.通过1H-NMR、MALDI-TOF、MS和凝胶渗透色谱(GPC)对其结构进行表征.测定了P-1在水溶液中的紫外吸收光谱、荧光发射光谱以及荧光量子产率.通过P-1与小分子化合物MC-1的对比,P-1的荧光增强灵敏度优于MC-1.在P-1的溶液中分别加入沉淀剂或带有负电荷的生物大分子,两者的紫外吸收光谱与荧光发射光谱有很大的差异,通过结果对比,初步探讨了聚集诱导荧光增强的机理,经过静电作用限制苯环内旋转可以实现荧光强度的线型增长.

SYNTHESIS AND PROPERTIES OF A WATER-SOLUBLE AGGREGATION-INDUCED EMISSION ENHANCEMENT CONJUGATED POLYMER

A conjugated polymer(P-0) containing tetraphenylethene(TPE) groups has been designed and synthesized by Suzuki coupling reaction between 1,2-di[4-(6-bromohexyloxy)phenyl]-1,2-di(4-bromophenyl)ethene(monomer 2) and benzen-1,4-bis(boronic acid)propane-1,3-diol diester(monomer 3).A water-soluble cationic conjugated polyelectrolyte(P-1) was obtained by quaternization of P-0 with trimethylamine at the end of side-chains as a novel method for investigation into the aggregation-induced emission enhancement(AIEE) phenomena and mechanism.The structures of P-0 and P-1 were characterized by 1H-NMR,MALDI-TOF-MS and GPC.P-1 is completely soluble in water and insoluble in common organic solvents such as THF and acetone.When a poor solvent such as THF was added into P-1 aqueous solutions,a slight decrease of the fluorescent intensity of P-1 is observed before the volume rate of THF∶ H2O arrived at 60%.However,a dramatic enhancement of luminescence is observed and concomitant with an obvious blue-shift of PL maxima when volume rate of THF∶ H2O arrived at 70%.Addition of heparin into P-1 aqueous solution showed a gradual increase in fluorescence intensity at 519 nm without PL maxima shift.Compared with its unit analogue,1,2-di[4-(6-(N,N,N-trimethyl ammonium)hexyloxy) phenyl]-1,2-diphenylethene dibromide(MC-1),the emission enhancement of P-1 showed higher sensitivity and better linearity than that of MC-1.Since heparin has four negative charges per repeat unit,and each polymer repeat unit has two positive charges,the concentrations for the positive and negative charges are the same(2.0 μmol/L or 20.0 μmol/L) at the saturation point.This indicates that the aggregation-induced emission enhancement stems from the restriction of their intramolecular rotations due to electrostatic attraction as the main driving force between the oppositely charged polymer and heparin,which can eliminate some disturbance factors such as aggregation-caused quenching of light emission.In summary,the present results indicate that cationic conjugated polyelectrolyte with AIEE property is expected to be generalized for studying AIE(E) mechanism and the detection of biological analytes of interest.