两性共轭聚电解质的合成及其聚集诱导发光增强性质研究

The aggregation-caused quenching (ACQ) effect is a common problem for most conventional aromatic luminophores. In order to solve the ACQ problem, the fluorescent materials with aggregation-induced emission enhancement (AIEE) should be developed. In this proposal, a series of novel zwitterionic conjugated polyelectrolytes (ZCPEs) with AIEE characteristics are designed and synthesized. The aggregation modes between conjugated main chains could be controlled by the electrostatic interactions between the side chains, which will reduce the non-radiation energy transfer and further improve the emission efficiency in the solid state. The precursors of ZCPEs will be alternately polymerized between aryl-substituted pyrrole units and tetraphenylethylene (TPE) units, both of which are AIE molecules, and the precursors are anticipated to have AIEE properties. The aryl-substituted pyrrole units are substituted with methyl benzoate groups and TPE units are substituted with alkyl bromide, and both of them are easy to be further functionalized. The obtained precursors of ZCPEs are treated by removing the methyl group from methyl benzoate and quaternization of alkyl bromide with trimethylamine. As a result, anion and cation groups are simultaneously attached to the conjugated main chains in the target ZCPEs. The number of anions could be regulated by adjusting pH of the solution to prevent the formation of polymer salts. Moreover, the fluorene group which is an ACQ unit can be polymerized with aryl-substituted pyrrole or TPE unit to obtain the ZCPEs with AIEE. The structure-property relationship of ZCPEs will be derived. Through mechanistic study of the photophysical processes of ZCPEs in aggregated state, structural design strategies for generating new AIEE materials will be developed. In addition, the effect of stacking modes on the emitting process of ZCPEs will be investigated. Applications of the optimized ZCPEs in the sensing or optoelectronic field will also be explored.

发展聚集诱导发光增强（AIEE）材料是解决传统发光材料聚集引起荧光猝灭（ACQ）问题的最佳方案之一。本项目以前期研究为基础，以具有聚集诱导发光性质的多芳基吡咯和四苯基乙烯（TPE）为共轭主链构筑基元，侧链分别带有阴离子（羧酸根离子）和阳离子（季铵盐），拟通过共轭主链的设计及侧链的电性调控，合成两性共轭聚电解质（ZCPE）并研究其AIEE性质。利用侧链间的静电相互作用诱导主链间的可控聚集，减少非辐射能量转移，提高聚集态下的发光效率。羧酸基团的电性由pH值调节，防止高分子盐的形成影响溶解性。此外，将多芳基吡咯或TPE与芴（ACQ性质）进行聚合制备ZCPE，探索实现ACQ向AIEE转变的结构要素。新型ZCPE的开发有助于了解共轭聚电解质在聚集态下的发光行为与过程，为设计固态下高效发光材料奠定理论基础。最后，对所得ZCPE在传感或光电器件领域的应用进行尝试。

发展聚集诱导发光或聚集发光增强（AIE/AEE）材料是解决传统发光材料聚集引起荧光猝灭问题的优选方案之一。本项目设计并合成了以多芳基吡咯衍生物（MAP）和多芳基1，3-丁二烯（MAB）为核心结构的两类AIE/AEE材料，并对所得化合物的聚集发光性质以及相关的潜在应用进行了详细的探究。MAP类材料可以通过后功能化修饰，实现金属离子Al3+的定性与定量检测，尤其是可以实现血浆中或细胞中Al3+的定性检测。MAP类材料还可以实现CO2气体的检测，尤其是可以检测新陈代谢过程中产生的CO2并区分癌细胞与正常细胞。MAP材料可以实现血浆中的牛血清和人血清的定量检测。红色发光的MAP材料可以特异性染色细胞膜以及近红外发光的MAP材料可以实现细胞中线粒体的实时成像。以AIE/AEE结构单元可以制备近红外发光两性聚合物，通过后功能化修饰将其开发为荧光成像、包裹药物与可控释放于一体的聚合物纳米颗粒。MAB类材料可以实现特异性识别并检测γ-球蛋白、铈离子、有机胺、多氮唑、汞离子等。此外，利用醛基化的MAB可以实现三色可逆转换。MAB衍生物作为结构单元引入到聚合物中，得到具有AIE/AEE性质的红光聚合物，并通过后功能化修饰实现癌细胞识别、载药与释放等多功能一体化聚合物纳米颗粒。两类AIE/AEE核心结构的合成，以及结构与性能之间关系的清晰阐述，为制备多功能一体化高分子材料的设计奠定了基础。该类材料的后功能化优势为所得材料在癌症相关生理标记物的检测、识别诊疗一体化，以及有毒有害物质监测等领域都具有潜在的应用前景。