多孔功能MOFs材料的设计合成与氢气、二氧化碳气体吸附性能研究

Emerging as a new class of crystalline porous materials, metal–organic frameworks (MOFs, also known as porous coordination polymers, PCPs) have great potential applications in economical, safe and efficient storage of energy-environment related gas (such as hydrogen, carbon dioxide and so on) due to their large surface area, adjustable pore size and chemically-tunable functionalities. Therefore, how to understand the structure-property relationship between the structures and gas storage performance of MOFs is of great scientific and practical significance for future design and construction of novel MOFs with high-performance. This project intends to design and synthesize series of highly porous MOFs decorated by different groups (such as –CH3, –Br, -NO2, –OH, -NH2, -SO3H and so on) through crystal engineering by utilizing highly symmetrical isophthalic acids and two-dentate bipyridine mixed-ligand systems, aiming at significant enhancement of the materials’ water-stability and gas storage performance: The incorporated polar groups (-NO2,–OH, -NH2, -SO3H, etc) may act as the strong gas (hydrogen, carbon dioxide, etc) molecule binding sites to optimize the framework-gas interactions. Meanwhile, both the introduced hydrophobic groups (–CH3,–Br, -NO2, etc) and bipyridine auxiliary ligands (which can effectively increase the connectivity numbers of the second building units (SBUs) through coordination, which in turn will improve the water-stability of the MOF materials) may have positive effect upon the water-stability of the MOFs. Most importantly, the relationship between the specially porous structures and gas sorption performance of the MOF materials, including the effect of different factors such as different pore sizes and polar groups on energy-environment related gas storage performance, the gas (hydrogen and carbon dioxide) sorption mechanism at the molecular level and so on, will be systematically investigated and disclosed by both experimental and theoretical methods including GCMC (Grand Canonical Monte Carlo) molecular simulations and DFT (Density Functional Theory) calculations. The results of this project may have significant implications for future design and construction of new novel high-performance MOF materials for energy-environment related gas capture and storage.

金属-有机框架材料（MOFs）在经济、安全、高效地吸附存储氢气、二氧化碳等能源环境相关气体方面具有广泛的应用前景。系统理解MOFs储气性能的构效关系是定向设计合成新型高性能储气材料的一个重要基础。本项目拟基于高对称性间苯二酸类——二齿吡啶类混合配体，依据晶体工程原理设计合成系列高孔隙率MOFs材料，并对材料进行甲基、溴基、硝基、羟基、氨基、磺酸基等功能基修饰，探索通过吡啶类辅助配体参与配位以增加无机次级构筑单元的连接数以及在框架结构中引入甲基、溴基、硝基等不同疏水基对提高材料水稳定性的影响。同时采用实验和理论计算相结合的手段，系统考察不同孔径、不同极性功能基（硝基、羟基、氨基等）对材料储气性能的影响，探讨MOFs吸附气体的微观机理，揭示该类材料的特殊孔洞结构与其气体吸附存储性能间的构效关系，为今后定向设计合成新型高性能氢气、二氧化碳等能源环境相关气体存储MOFs材料提供科学依据和研究基础。

金属-有机框架材料（MOFs）在气体吸附存储与分离、催化等方面具有广泛的应用前景。系统理解MOFs储气、催化等性能的构效关系是定向设计合成新型高性能MOFs材料的一个重要基础。本项目设计合成了系列极性酰胺基桥连的、不同功能基（甲基、甲氧基、羟基、吡啶氮配位点等）修饰的含间苯二间酸单元高对称性多齿羧酸配体，依据晶体工程原理，在溶剂热条件下与铜离子等配位，制备了若干结构新颖、框架结构稳定性好、具有优异二氧化碳等气体吸附存储分离性能和催化活性的MOFs材料。通过系统的结构表征、单组分气体吸附、混合气体动态突破、催化等实验与相关理论研究，结果表明，在MOFs的框架结构中引入极性桥连酰胺功能基不但能极大地提升材料的多孔性，而且与金属Cu(II)不饱和配位点类似，酰胺功能基也能与CO2等气体分子间产生较强的分子间相互作用，进一步提高材料对CO2等气体的吸附存储与分离能力；此外，在酰胺基修饰MOFs材料的设计合成中，采用穿插策略、在框架结构中引入甲基等疏水基、或引入吡啶氮配位点参与配位提高无机节点的连接数等方法，能有效地提高材料的框架结构稳定性；另外，酰胺基修饰MOFs框架结构中的路易斯酸性铜（II）不饱和配位点和路易斯碱性酰胺基能分别有效催化deacetalization-Knoevenage连续反应的第一步和第二步反应，使该类MOFs材料具有优异的非均相催化效果等。经过三年的努力，在本项目的资助下，项目组成员在Chem. Commun.、CrystEngComm等国际高影响力刊物上发表了2 篇与项目相关的高质量SCI学术论文，此外还有多篇论文正在整理、投稿和评审中。培养硕士研究生4人，其中已获硕士学位2人。本项目较圆满地完成了相关研究任务，达到了预期目标。相关结论对今后设计合成新型高性能MOFs材料以期实际应用于二氧化碳等能源环境相关气体吸附存储与分离、非均相催化等领域提供了新思路与研究基础。