含五苯基吡咯侧基聚丙烯酸酯的制备及其聚集诱导发光增强性能

设计合成了具有聚集诱导发光增强活性(AEE)的含五苯基吡咯的甲基丙烯酸酯单体M-PPP,并通过自由基聚合制备了系列均聚物及不同五苯基吡咯侧基含量的聚甲基丙烯酸酯共聚物.所制备的均聚物P与共聚物CP在THF/H_2O体系中均具有AEE特性,在水含量大于20%时荧光开始增加,大于80%时荧光快速增加,95%时相对荧光强度达到最大;单体M-PPP则在水含量低于70%时荧光强度略有降低,随后迅速增加,95%后荧光强度下降.五苯基吡咯侧基含量较高的共聚物表现出更好的AEE特性.进一步的研究发现,共聚物CP在THF/H_2O混合溶液中能够对赖氨酸产生荧光点亮型响应.

Synthesis and Aggregation-enhanced Emission of Polymethacrylate with Pentaphenylpyrrole Side Group

Methacrylate monomer M-PPP,which is aggregation-enhanced emission (AEE) active and with a conjugated pentaphenylpyrrole side group,was designed and synthesized through palladium-catalyzed cyclization of arylamine and diaryl acetylene,Suzuki cross-coupling and esterification with EDCI as dehydrant.A series of homopolymers P1,P2,P3 and copolymers CP41,CP21,CP11,CP12,CP14 were prepared by free radical polymerization of M-PPP and copolymerization of M-PPP with BMA.The molar ratio of M-PPP unit and BMA unit in copolymers CPs was calculated based on the chemical shift and integrations of their CH2 groups.The content of M-PPP units in the copolymers was lower than those in raw materials,mainly due to the low polymerization activity attributed to the bulky conjugated pentaphenylpyrrole side group.The monomer M-PPP,the polymers P1,P2,P3 and the copolymers CP41,CP21,CP11 were of high thermal stability with their decomposition temperature above 300 ℃,while the decomposition temperatures of CP12,CP14 decreased slightly because of the lower content of the conjugated pentaphenylpyrrole side group.Both the monomer M-PPP and the polymers exhibited obvious AEE feature in THF/H2O mixture.The fluorescence intensity of the polymers increased slowly when the water fraction (fw) was above 20％,and it increased faster whenfw is above 80％.The relative fluorescence intensity (I/I0) reached to a maximum atfw of 95％,mainly attributed to the aggregation of the conjugated luminogen pentaphenylpyrrole segment in the side-chain and the entanglement of the flexible polymer main chains in THF/H2O mixture,which could restrict the motion of pentaphenylpyrrole and intramolecular rotation of the benzene rings,leading to enhanced fluorescence emission.The fluorescence intensity of M-PPP decreased a little whenfw was lower than 70％,then increased sharply,and the maximal I/I0 was 3.9 at fw of 95％,which was higher than those of the polymers due to the lower content of conjugated pentaphenylpyrrole side group in the polymers.The copolymers CPs exhibited similar AEE behavior as the polymers P1,P2,P3 in THF/H2O mixture,and they showed better AEE feature when increasing the content of the conjugated pentaphenylpyrrole side group.Furthermore,the copolymers CPs could "tum-on" to detect lysine selectively in THF/H2O mixture due to the interaction of BMA unit and lysine,and more sensitive fluorescence response was observed for CP14 due to the higher BMA side-chain content,which is known to have stronger interaction with lysine.