聚集诱导发光的基本科学问题年度报告(2013)

摘要：建立和完善AIE模型和理论可以为分子设计、材料制备、聚集体结构调控及器件实际应用等方面提供了理论指导。 2013年度本研究重要进展如下： （1）. 基于第一性原理计算，定量考察了位阻、温度、聚集等因素对分子体系发光性质的影响。从微观角度给出了分子聚集诱导发光机理：分子激发态的无辐射能量衰减通道主要是对应于低频模式的芳香环扭转和高频模式的碳碳伸缩振动。当位阻增加、温度降低或者分子聚集时，芳香环的转动受限，无辐射能量衰减通道被抑制，从而提高分子的荧光量子产率，荧光增强；为了更深层次地理解蓝色磷光分子结构与发光效率之间的关系，结合密度泛函理论，运用我们最近发展的系间窜越速率的振动关联函数计算方法，定量研究了新型蓝光发射分子fac-tris（2-（4，6-difluorophenyl）pyridyl iridium （fac-Ir（F2ppy）3）的磷光光谱、辐射跃迁和无辐射跃迁速率及其与温度的依赖关系，计算结果很好地解释了实验测量结果。理论研究表明可以通过分子设计来抑制这些振动来进一步提高这类材料的发光效率。 （2）. 研究了AIE分子作为生物探针和生物体系的相互作用。BSPOTPE分子和蛋白质可以通过BSPOTPE的芳香环和蛋白质疏水性氨基酸之间的疏水相互作用结合，研究表明，BSPOTPE可以同时作为胰岛素分子错误折叠纤维化的过程的探针和抑制剂。运用Markov态模型对导致II型糖尿病的hIAPP蛋白质误折叠聚集进行了理论研究，找到了一些可能导致其聚集的重要的构象态，初步实验中也证实了AIE分子有可能作为hIAPP蛋白质聚集的分子探针和抑制剂。 （3）. 发展了一种利用不水溶的荧光探针和水凝胶体系定量检测纯水中F？的新方法。合成了一个新的荧光探针N-（3-（benzo[d]thiazol-2-yl）-4- （tertbutyldiphenylsilyloxy） phenyl） acetamide （BTBPA），其与F？作用后荧光颜色由蓝色变为绿色。这种方法可以在15 s内定量检测浓度低至饮用水标准级别的F？，具有检测速度快，灵敏度高，选择性好等特点。而且该方法可使用非水溶性荧光探针，大大扩展了可用于离子检测的荧光分子应用范围。

关键词：聚集诱导发光；热振动关联函数；系间窜越速率理论；磷光量子效率；氟离子检测；蛋白质错误折叠；聚集体

Scientific problems of aggregation-induced emission--establishment and improvement of the AIE models and the theories

Abstract：The establishment and improvement of the AIE models and the theories has shown importance in molecular design， material preparation， structure control of aggregates， and device application. The project is in proper progress and some achievements have been made， which meets the annual objectives. Eleven SCI papers have been published this year （the impact factor is higher than 10 for two papers， and higher than 5 for another two papers）. One patent is authorized and four patents have been notified for the acceptance of application. Three and two students have obtained their PhD degree and Master degree， respectively. The fund in place of this year is 1.13 million yuan， and the outlay on the scientific research has been 0.498 million yuan. The important achievements of the project are as follows. （1）. Based on the first principles， we quantitatively investigated the effect of steric hindrance， temperature and aggregation for the molecular luminescence properties. It is found that （i） the low frequency normal modes associated with the phenyl ring rotational motions and the high frequency normal modes belonging to CCC stretching vibration are the main channels to dissipate excited-state energy nonradiatively； （ii） the aggregate restricted rotation of the phenyl rings is the main factor for blocking the nonradiative decay process and thus enhancing the fluorescence quantum efficiency. （2）. We found that BSPOTPE can indeed affect the insulin fibrillogenesis under low pH at high temperature. Theoretical modeling using molecular dynamics simulations and docking reveals that BSPOTPE is prone to binding to partially unfolded insulin through hydrophobic interaction of the phenyl rings of BSPOTPE with the exposed hydrophobic residues of insulin. Our model reveals a number of metastable states with populations of only a few percent or less rather than a single dominant free energy minimum. （3）. We invented a new method for F？ detection by adopting the hydrogel as the supporter of reaction between a water insoluble fluorescent probe and F？ in the water environment. This method is highly rapid， selective， and sensitive， which can determine F？ levels in 15 s at the drinking water standard. Additionally， this method does not require the probe substances to be water-soluble， which greatly expands the range of the specific fluorescent molecules used in ion detection.

Keywords：aggregation induced emission （AIE）； thermal vibration correlation formalisms； theory of intersystem crossing； phosphorescence quantum efficiency； F- detection； protein misfolding； aggregation

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