以聚集诱导发光小分子为单元构筑的多孔结晶聚合物的结构与功能研究

Recently, porous opto-electronic functional materials have attracted great attention in the fields of chemo-/bio-sensors and photo-electronic devices owing to their excellent properties derived from their unique open framework structure. However, most of these materials are built from organic molecules that tolerate low fluorescence or phosphorescence quantum yields and limited sensor sensitivities. Hereby, in this proposal, we will utilize small organic molecules with aggregation induced emission (AIE) features as building blocks to design and construct a series of porous crystalline polymers, including covalent organic frameworks (COFs) and metal-organic frameworks (MOFs). This approach will integrate the extraordinary properties from both AIE materials and porous structures. It is envisioned that the fluorescence quantum yields of the designed porous materials will enhance due to the restriction of intramolecular rotations of AIE-active building blocks. We will study the effect of reaction conditions on the structure and crystalline degree of the obtained polymers, investigate the role of aromaticity, push-pull substituent and ligand-metal ion interactions in wavelength, efficiency, and lifetime of emission, and clarify the influence of organic building blocks, metal ions, coordination modes, and topological structures of the designed materials on the performance. Ultimately, the applications of these porous frameworks in chemo-/bio-sensors and bioimaging will be explored.

近年来，多孔光电材料因其特殊的孔道结构而在化学、生物传感和光电器件等领域呈现独特的性质，从而引起了人们的广泛关注。然而大部分多孔光电材料仍然是以荧光或磷光量子效率不高、传感灵敏度有限的有机化合物为构筑单元。为了克服这些缺点，本项目拟结合聚集诱导发光与多孔特殊结构所具备的各自优异特性，合成一系列以聚集诱导发光有机小分子为构筑单元的多孔结晶聚合物，包括共价有机骨架结构(COFs)以及金属有机骨架结构(MOFs)等。利用分子内旋转受限状态下独特的荧光增强特性，来提高这类材料的荧光量子效率。探索反应条件对所得聚合物结构以及结晶程度的影响，研究芳香性、推－拉电子取代基以及配体-金属离子相互作用对荧光发射波长、发射效率和发射寿命的影响，阐明有机构筑单元、过渡金属离子类型、配位方式、聚合物拓扑学空间结构等因素对性能影响规律，并拟研究这类多孔材料在化学、生物传感以及医用成像等领域中的应用。

多孔结晶骨架材料因其有序排列的结构、高孔隙率、结构的可设计性等特点在气体吸附、存储、分离、传感和催化等方面都有广泛的应用。本课题以具有聚集诱导发光性能（AIE）的功能有机分子为构筑单元制备了多种新型多孔结晶骨架材料，包括6种金属有机骨架材料（MOFs）和2种共价有机骨架材料（COFs），并对它们的发光性能及应用进行了研究。通过改变金属离子的种类实现了MOFs荧光特性的调节，并由此制备出低荧光量子产率的Ni-MOF和不发光的Co-MOF。研究发现，Co-MOF能够通过荧光点亮实现五元杂环高能量密度爆炸物的高选择性、高灵敏度、快速地检测。该研究成果实现了新型高能钝感爆炸物的检测，对于国防和人民安全具有一定的意义。另外，我们深入研究了COFs材料中发光基元排列方式、旋转程度对发光效率和发光寿命的影响，初步结果表明，苯环的自由旋转程度越高，其发光效率越低。此研究对于设计、制备寿命更长、发光效率更高的磷光材料具有一定的价值。