新型偶氮苯衍生物的光控自组装结构及其光物理性质

The photocontrolled self-assembly strategy and photophysical properties of azobenzene derivatives have attracted broad attention in developing ordered molecular structures and novel functional materials. The tunable structure and photophysical property based on the universal reversible trans-cis photoisomerization of azobenzene unit is of significance in molecular device design and potential application in material science. In this project, we will design and synthesize three azobenzene derivatives consisting of azophenyl oxadiazole unit with different molecular structure, such as rodlike, tapered, twin-tapered and Y-shaped compounds. The different photoresponsive architectures of supramolecular self-assembly will be constructed by changing UV illumination condition and modulating intermolecular interaction, such as hydrogen bonding, π-π interaction, hydrophobic interaction and Van der Waals force, etc. The photophysical properties, e.g., fluorescence intensity, emission spectrum, quantum yield, lifetime and fluorescence anisotropy, corresponding to different self-assembly structures of azobenzene derivatives at different UV irradiation configurations will be systematically investigated using steady and transient spectroscopy. By combining the density function theory (DFT), we will carry out the high-performance calculation and molecular simulation to understand the mechanisms of photocontrolled luminescence and self-assembled structures of azobenzene derivatives. The performance of this project will be of significance in building up the scientific correlation between photophysical properties and self-assembled architectures, and also provide more scientific supports in designing photocontrolled functional molecule and broadening the potential application of azobenzene materials.

利用光刺激来控制偶氮苯衍生物的自组装过程，进而获得光控的有序自组装结构和优良的光物理性质，对其在材料领域的应用具有重要科学意义。而目前基于偶氮苯衍生物光控自组装聚集体的发光特性研究还很少，更缺乏发光机理的深入探讨。本项目从分子设计出发，合成不同分子形状的含有噁二唑基元的偶氮苯衍生物，包括棒状、双楔形和Y形分子。深入研究不同的光照条件和分子形状对分子间作用力、分子排列模式、微观形貌和光物理性质的影响。同时，结合密度泛函理论的模拟计算，分析光控偶氮苯自组装聚集结构的变化及光物理性质的调控机制。我们前期已经开展了楔形偶氮苯衍生物的光响应行为研究，获得了高量子产率的顺式偶氮苯聚集体，这为本项目进一步深入研究提供了可行性探索。本项目的实施，预期将获得具有光控功能的高效发光新型偶氮苯聚集体，并期望揭示其发光机理，为进一步设计与开发新型光控发光材料以及拓宽偶氮苯衍生物的应用领域提供科学依据。

利用光刺激和溶剂调控新型偶氮苯衍生物的自组装过程，进而获得具有光控特性的有序自组装结构和优良的超分子凝胶性能，对其在材料领域的应用具有重要科学意义。本研究从分子设计出发，（1）成功合成了三类新型偶氮苯衍生物：棒状（BNB-n）、楔形（BNB-tn）及Y形偶氮苯衍生物（AOB-Yn）。（2）利用紫外光调控了此类偶氮苯衍生物（BNB-t4和AOB-t8）的分子间作用力、分子排列模式、微观形貌和光物理性质。获得了具有高效发光效率的自组装聚集体。结合密度泛函理论的模拟计算，揭示了光控偶氮苯自组装聚集结构荧光增强的机理。（3）通过溶剂成功地调控了此类偶氮苯衍生物的凝胶性质，获得了具有高度热稳定性和机械性能、致密的相互交错的层状网络结构。通过建立凝胶性质与Flory-Huggins溶解度参数有关的模型，提出了一种简易的方法成功地预测了BNB-t4在水-有机混合溶剂中的自组装行为。（4）利用BNB-t4相选择凝胶的特性高效地去除水溶液中的芳香族和卤代烃污染物。并且利用BNB-t4的相选择性、良好的热稳定性和可逆性，实现了其对有机化合物的有效吸附和释放。（5）利用AOB-Y8获得了具有超疏水和高粘附力的自组装表面。通过Cassie和Wenzel模型对其粘附性的转变进行了分析。此自组装超疏水表面具有优异的耐酸碱性，有效地用于液滴的选择性无损传输、自清洁和液滴的微量检测或微反应等。（6）成功地构建了具有高透明性和瞬间自修复能力的有机小分子凝胶。此凝胶还具有去除有毒染料、粘附固体表面和自支撑等性能。