基于主客体作用的固态门控型光致变色化合物的构建及性能研究

Compounds with gated photochromic property in the solid state can avoid the expression of wrong information led by external interrupt light source, so they can be used as promising candidates for application in many fields such as information storage, anti-fake materials and defense materials. Now, the construction of such kinds of compounds is still faced with the challenges of difficult to synthesis and lacking efficient strategy. As a representative photochromic compound, the photochromic property of dithienylethene can be gated by taking advantage of its conformation change induced by external stimuli. However in the solid state, the tight molecular packing and minor molecular gap will prevent external stimuli from changing the molecular conformation. Concerning this issue, this project intends to design and synthesize a series of host-guest complex based on dithienylethene and cucurbit[n]urils, and reaches the goal of regulating and controlling the molecular gap by utilizing the steric effect of cucurbit[n]urils and the specific assembly between host and guest. Also we will try to study the regulatory effect of external stimuli to the molecular conformation and photochromic property of the host-guest complex in the solid state. The structure-activity relationship of stimuli responsive behavior and structural characteristics will also be deeply investigated. Accomplishment of our proposal will promote the construction of stimuli-responsive host-guest complex and photochromic compounds with gated property in the solid state.

固态门控型光致变色化合物能够有效避免外界干扰光源刺激所导致的信息错误表达，因此在信息存储、防伪及国防材料等领域中具有广泛的应用前景。目前，该类化合物的构建依然面临着合成困难、缺乏有效指导策略的挑战。二噻吩乙烯是一种典型的光致变色化合物，利用外界刺激下其分子构象的变化，可实现对其光响应性能的门控调节。然而在固态下，其紧密的分子堆积的方式和较小的分子间隙，导致外界刺激难以改变其分子构象。针对这一问题，本项目拟基于二噻吩乙烯单元和葫芦[n]脲构建一系列主客体复合物，利用葫芦[n]脲刚性空腔的空间位阻效应以及主客体间的特异性组装，达到调控分子间隙的目的；并探究外界刺激对主客体复合物固态下分子构象和光致变色性能的调控作用，深入揭示其刺激响应行为与结构特性间的构效关系。研究成果对于刺激响应型主客体复合物和固态下的门控型光致变色化合物的构建具有指导意义。

基于二芳基乙烯的固态门控型光致变色材料的构建依然面临着较大的挑战，这主要归咎于难以对该类化合物固相下的分子构象和堆积模式进行有效调控。本项目旨在基于主客体作用，通过机械力刺激实现对二芳基乙烯衍生物固态下的光致变色性能的门控调节。项目执行期间，研究了葫芦脲主体对一系列客体分子的发光、光致变色、力致变色性能的影响，探究了分子构象、分子堆积与其光物理性质间的构效关系，实现了固态门控型光致变色化合物的构建，以及主客体作用对材料力致变色性能的调控。例如，1）基于葫芦[10]脲与四苯乙烯客体分子的识别，发现客体分子的构象可通过改变主客体结合位点来进行调节，继而影响分子的发光性能。2）研究了葫芦[10]脲与平面型金属配合物的识别，探究了主客体作用对分子堆积模式和发光性能的影响。3）合成了含有不同主客体识别位点的二芳基乙烯客体分子，研究了不同空腔大小的葫芦脲对二芳基乙烯衍生物溶液状态下的光致变色性能的影响。结果表明主客体的结合模式、主体空腔尺寸均能影响二芳基乙烯的光反应。4）构建了新型机械变色主客体复合物，其可表现出与客体分子截然不同的力刺激响应行为。研究了机械力刺激对主客体复合物中的客体分子的构象、堆积模式的影响，证明了机械力刺激是调控主客体复合物中客体分子构象的一种可行的手段。5）首次报道了固态门控型光致变色主客体复合物。以季铵盐为识别位点，可将二芳基乙烯单元“锁于”葫芦[10]脲空腔内部，实现了对客体分子光致性能的抑制。经机械研磨后，其光致变色性能可被激活。6）除此之外，开展了主客体作用在改善化合物机械变色性能中的研究。项目研究结果对于优化智能变色材料性能和构建新型功能化主客体复合物具有一定指导意义。