金属-羧酸骨架材料中主客体相互作用的研究及其对有毒分子的检测

Host–guest interactions in metal organic frameworks (MOFs) are intensely important to elucidate the interaction mechanism between them at the molecular level, and the exploit of their potential applications. Currently, the vastly reported studies of the interactions of guest molecules with the MOFs are focused on energy molecules such as H2, CH4, and CO2. There are a limited number of studies reported on the interaction of toxic molecules (e.g. CO, NOx, and volatile organic compounds) with MOFs. Furthermore, the limited understanding on the interaction of toxic molecules in a specific MOF and a selected molecule in random MOFs, makes it difficult to compare their results and draw a comprehensive conclusion. In this project, two iso-structural types of MOFs are synthesized systematically in the following two strategies: changing the metal ions with the same organic ligands; and selecting various organic ligands functionalized with different functional groups while keeping the metal ion constant in order to retain the same crystalline MOF structure. For detailed investigation, direct characterization tools of gas adsorptions and vibrational spectroscopy (infrared spectroscopy and Raman spectroscopy) will be employed. Adsorption measurements will give us useful information on host MOF materials, such as porosity, pore size, etc. IR and Raman studies will provide direct evidences on the interactions of gases and MOFs by monitoring the changes of vibration modes when the gases contact with MOFs. The underling rules of host–guest interactions between toxic molecules and MOFs will be clarify and summarized, which will provide us guidance on the exploit of the detection of guide poisonous pollutants using MOFs-based sensors as well as the elucidation of their sensing mechanism. The results based on these future studies will provide theoretical and practical basis for realizing targeted design and adjustment of MOFs materials between their structure and function.

金属-有机骨架材料（MOFs）的主客体相互作用的研究对于从分子水平阐述两者的作用机理及开发其应用是非常重要的。目前，MOFs的主客体相互作用研究多选用能源分子（如H2、CO2）为客体分子，仅有数量有限的工作报道有毒分子（如CO、VOCs）与MOFs间的作用，且这些工作多集中于多种有毒分子与一种选定MOF或一种有毒分子与不同MOFs相互作用，这些MOFs具有不同的金属离子和有机配体，难以总结出一个一般性的规律。基于以上问题，本项目拟合成具有相同配体不同金属中心和相同金属中心不同功能化的配体的两类同构MOFs，利用吸附和振动光谱（红外和拉曼光谱）首段直接研究同构MOFs中金属中心和功能化有机配体与有毒分子的相互作用，探索有毒分子与MOFs主客体间相互作用关系的规律，并将此规律用于指导MOF气敏元件的有毒污染物检测和传感机理研究，为实现MOFs材料结构与功能的定向设计和调控提供理论和实验依据。

有毒分子对环境、人体及国土安全均有重要影响，本课题着眼于目前的社会需求及科研发展前沿，以金属有机骨架材料（MOFs）为研究对象，探索基于MOFs薄膜器件对有毒分子的检测。首先，从杂原子羧酸类有机配体的设计与合成入手，并利用已合成配体构筑多功能MOFs结构；从单晶结构等表征入手，充分分析了其晶体结构、稳定性以及吸附性能等一系列性质。与此同时，利用电化学法制备基于金属有机骨架薄膜器件材料；通过调节施加的电压和电镀的时间来调控晶体的尺寸和薄膜的厚度，并分析薄膜电镀形成的过程和机理；以电化学刻蚀法制备的多孔金属镍为载体，采用原位生长法制备多孔镍载体支撑的金属有机骨架复合膜；通过各种手段表征复合膜的结构和形貌等信息，并获得沉积时间在复合膜形成过程中的影响。作为应用扩展，我们利用金属有机骨架材料的催化作用和氧化还原活性分子（杂多酸和多孔镍）的电子媒介体/催化放大作用，重点研究了基于金属有机骨架膜材料对有毒分子（溴酸盐和水合肼）的放大检测；发现这些传感器具有线性范围宽，检测限低的优势，均可用于实际样品中该物质的分析检测。此外，作为项目的扩展，利用表征手段从多个角度系统地分析和评价金属有机骨架的体相和表面结构的化学稳定性，并基于水分子与主体骨架间的相互作用，将获得的晶体材料用于质子传输方面的应用，研究不同温度和湿度下，骨架结构中的氢键链、引入的客体分子对质子传输的贡献和影响。总体来说，本课题的研究获得了大量宝贵实验数据，为后续研究工作的开展打下基础并指明方向。部分研究成果分别发表在J. Mater. Chem. A及Dalton Transactions等期刊上，授权发明专利1项。