基于“马鞍型”环八四噻吩低聚物激发态过程的理论研究

In recent years, organic materials with aggregation-induced emission (AIE) phenomenon have attracted great attentions due to their promising applications in solid-state lighting, bio-sensing and imaging. AIE luminogens and mechanisms studies based on the restriction of intramolecular rotation have been reported extensively. However, the mechanism research and material design concept based on the restriction of intramolecular vibration is still insufficient. The saddle-shaped cyclooctatetrathiophene (COTh) has been found to demonstrate AIE phenomena in our research group, which is quite different from most other reported AIE luminogens and the AIE mechanism is still uncertain. In this proposal, we plan to investigate the aggregation effects on the optical emission property of the COTh system on the basis of quantum mechanics/molecular mechanics (QM/MM) calculations coupled with excited-state decay rate formalism. Meanwhile, we will focus on the impact of isomeric COThs, polymerization modes and the degree of polymerization of COThs on their AIE behaviors, and investigate the effect of temperature and pressure on the emission property. The relationship between AIE behaviors and molecular structures may provide a theoretical clue for designing new and high-performance luminescent materials.

聚集诱导发光（AIE）体系因其在固态照明和生物检测成像等方面潜在的应用价值而受到广泛的关注。基于分子内转动受限的AIE体系和机理研究已有大量报道，但基于分子内振动受限的机理研究和材料设计理念还十分欠缺。我们前期实验研究发现分子内核骨架为环辛四烯的“马鞍型”环八四噻吩（COTh）具有明显的AIE现象，不同于目前已报道的AIE分子体系，且缺乏相关的聚集发光机理的研究。因此，本项目拟以环八四噻吩为研究对象，利用QM/MM方法并结合激发态衰减的速率理论为研究手段，系统研究“马鞍型”环八四噻吩体系的发光机理；考察COTh的同分异构体、COTh聚合方式和聚合度以及外界因素（如温度、压力）对聚集发光机理和发光效率的影响，揭示发光效率与COTh种类（同分异构体）及其低聚物的分子内在的性质参数之间的相关性，为设计和开发新结构与高效的发光材料提供理论依据。

聚集诱导发光（AIE）体系因其在固态照明和生物检测成像等方面潜在的应用价值而受到广泛的关注。基于分子内转动受限的AIE体系和机理研究已有大量报道，但基于分子内振动受限（RIV）的机理研究和材料设计理念还十分欠缺。通过项目实施，我们实现了：1）预测了两种具有较高发光效率的RIV型AIE体系；2）通过研究内核双键个数对环八四噻吩AIE效率的影响，揭示了能量转移是导致RIV型AIE材料发光效率受限的关键因素；3）通过研究压力对环八四噻吩体系发光性能的影响，揭示了能量转移是RIV型AIE体系压致荧光淬灭的根本原因。本项目的实施为设计RIV型AIE材料体系提供了重要的理论指导。.另外，我们对研究内容进行了拓展：1）研究了环八四噻吩-三嗪体系的AIE行为，拓展了环八四噻吩的应用领域；2）设计了六种RIV型高效发光的苯并环八四噻吩体系。