电场响应晶态多孔固体的结构变化及其性质研究

Crystalline porous materials have received continuous interest in application of adsorption, separation, sensors, electricity and so on, due to their modulated and modified structures. In the recent years, researches show that their structures are always changed under external stimuli, i.e. light, temperature, solvent, etc., which revealed an unique advantage of regulating and controlling the properties of crystalline materials. Curiously, how electric field stimulus (a quick response and eco-friendly physical stimuli) affects the structures of porous materials? In the previous experiments, we found that the structures and morphologies of a serious of Ag complexes based on azolate ligands and Co complexes base on hydroxyl-carboxylate ligands have changed and their performance improved under electric field. Therefore, here we present an relationship of electric field, structures and performances, in order to regulate and control the structures and properties of porous materials under electric field. In this project, we plan to use the methods of crystal engineering, and monitor the structural transformation and property change on the materials before, under, and after applying an electric field, to confirm the structural change process combined computer simulation and structural characterizations, and elaborate the influencing mechanism and regulating behaviors on the structures and properties of porous materials by electric field, giving a scientific basis for exploring porous materials with excellent performances.

晶态多孔材料具有可调节、可修饰等特点，在吸附分离、荧光传感、电学等领域具有广泛应用。近几年的研究表明，外部刺激（光、热、溶剂等）可以诱发结构变化，还展现出调控材料性能的独特优势。那么，电场，做为一个快速响应且环境友好的外部刺激，会对多孔材料有什么影响？作用机制是什么？我们在预实验中发现，电场可以改变一系列银多孔配位聚合物以及由活泼酚羟基羧酸配体与钴盐构筑的新型三维配位聚合物的外貌与结构，它们的性能也大幅度提升。据此，我们提出建立电场-结构-性能三者的对应关系，希望通过电场调控多孔材料结构及其性能。本项目拟采用晶体工程学方法，对目标晶态多孔固体在施加电场前、中、后三个不同的阶段，进行原位结构动态变化监测以及性能变化研究，结合计算机理论模拟等技术确定结构变化机理，阐述电场对多孔材料结构与性能的影响机制以及调控作用，为进一步探索优良性能的多孔材料提供更充分的科学依据。

晶态多孔材料具有结构可修饰、可调节的特点，且结构受外部刺激后容易发生动态转变。本项目原计划研究这些材料在电场刺激下结构的动态变化，但是实际研究发现，纯物理电场对大多数结构的影响并不大，还需要考虑周围环境因素的影响，比如空气中的氧气或水汽等。为此，本项目利用单晶/粉末衍射、多种原位表征以及理论计算与模拟技术对材料在应用（电）环境中的结构动态进行了深入研究，并据此对结构进行改性修饰，实现了系列高性能的电催化、吸附、分离功能。例如：1)首次通过电催化/化学剥离手段，将泡在（碱）水中的多例柱层式结构剥离成二维层状超薄纳米片，并获得高性能的水氧化电催化剂；2)吸附空气中的水后的氢键多孔固体转变成含有特殊三维水网的水合物，利用原位同步辐射单晶衍射、原位中子衍射、原位介电等多种原位表征技术，首次观察到三维水网表现出罕见的偶极玻璃动态行为，为解释自然界的水/冰动态行为提供新的思路；3)通过热刺激客体脱出改变结构与孔道尺寸，首次提出“中间尺寸分子筛”分离新理念，并用于分离提纯混合物中的苯乙烯。4)通过原位退火，首次实现二维氢键网络转变为同构的配位网络，实现对富勒烯和二茂铁的选择性吸附与识别调控。本项目成果在Nat. Mater.、JACS、Angew. Chem. Int. Ed.、Chem. Sci.、Sci. Bull.、Chem. Commun.、Inorg. Chem. Front.、Inorg. Chem.等专业学术期刊发表了11篇标注论文，并应邀在多次国际国内学术会议上宣讲相关成果。