有机压致变色材料的发光机制研究和理论设计

Mechanochromic luminescent materials represent a class of intelligent responsive materials that switch their emission color in response to mechanical stimuli. Mechanochromic luminogens have become a hot topic in recent years due to their promising applications in mechanosensors, security inks, optical storage and optoelectronic devices. However, the mechanism of mechanochromic luminescence remains unclear, the species and quantity of this kind of materials are still limited. In-depth theoretical investigation on its photophysical essence and further development of their varieties are necessary and urgent. In the present project, we propose to use quantum mechanics (QM) and non-equilibrium molecular dynamics (NEMD) method respectively to simulate the aggregation structure of organic materials under hydrostatic pressure and shear stress; and then adopt quantum mechanics/molecular mechanics (QM/MM) approach to obtain the electronic structure of the organic molecule in aggregates; finally calculate the related excited-state dynamics based on the electronic information. The combined computational scheme actualizes the mechanistic study and theoretical design of organic mechanochromic luminescent materials. The results will not only strengthen understanding to the mechanism of mechanochromic luminescence, but also provide the rational design strategy to develop mechanochromic luminescent materials exhibiting multicolored luminescence with high contrast, which further shorten the creation cycle of mechanochromic luminogens and improve the utilization efficiency of energy resource.

压致变色材料是指在外力刺激下其发光颜色发生改变的一类智能响应材料，这类材料因在压力传感、商标防伪、光学记录和发光器件等领域具有重要的应用前景，成为近年来的研究热点。然而，到目前为止，压致变色材料的发光变色机理还不完全清楚，其种类和数量仍然非常有限。进一步开展深入的光物理机制研究和开发新的品种是当务之急。本项目拟分别运用量子力学（QM）和非平衡分子动力学（NEMD）方法模拟静压力和剪切力作用下有机材料的微观聚集结构；并进一步采用量子力学/分子力学（QM/MM）方法获得聚集体中有机分子的电子结构；最后基于电子结构信息计算其相应的激发态动力学性质。这种组合的计算方案可以实现对有机压致变色材料的发光机制研究和理论设计。研究结果不仅能够加深人们对压致变色机制的理解，还可以帮助人们设计出高对比度、多色的压致变色材料，从而缩短材料的创新周期和提高能源的利用效率。

有机压致变色材料是一类可以对外力刺激产生发光强度或颜色响应的智能材料，这类材料因在压力传感、商标防伪和光学存储等方面具有重要的应用前景，近年来受到人们极大的关注。然而，这类材料的发光机制还有待深入研究。本项目结合第一性原理、量子力学/分子力学方法和激发态动力学理论，研究了高压下有机分子聚集体的微观结构与发光性能之间的关系；探究了酸碱性和极性响应的荧光传感器的发光机理；还基于有机压致变色材料典型的π共轭骨架，开展了吡嗪、均二苯乙烯、四苯乙烯、芘、萘并噻二唑五类衍生物的发光机理和分子设计研究工作。研究结果有助于指导有机发光材料的设计合成和功能调控，加速有机发光器件的研发和产业化进程，为新能源材料的开发和利用提供了理论依据。