高稳定疏水金属有机框架的构筑与吸附分离性质研究

Metal-organic frameworks (MOFs) are a class of promising porous materials with application potential in many fields due to many advantages, such as structural variety and designability. During the past many years, one research hotspot for MOFs is to improve their structural stability against water. In the last few years, much studies have also been carried out to investigate the effects of water on application performance of MOFs. Water may react with MOFs, resulting in degradation of their crystalline and porous structures, and loss of their functions. On the other hand, competitive sorption between water and other adsorbates may significantly limit practical applicability of MOFs in some applications. For example, when MOFs are utilized as adsorbents to remove indoor harmful substances like formaldehyde, benzene, ammonia etc., the indoor air must be more or less humid, and the concentration of water vapor in the air is always much higher than those of the harmful substances. If water is preferentially adsorbed by MOFs, their pores are occupied, and the capability of the MOFs to adsorb these harmful substances may reduce, even lose. In this proposal, we are planning to construct highly water stable and hydrophobic MOFs with some robust second building units, such as Zr6(µ3-O)4(µ3-OH)4(-CO2)12 and [Fe2M(μ3-O)(-CO2)6] (M = Fe2+, Co2+, Ni2+, Mn2+ or Zn2+), by two synthetic strategies, namely, ligand design and postsynthetic modification, quest the factors for hydrophobicity of MOFs and methods to tune the hydrophobicity, investigate the effects of hydrophobicity on the application performances of the MOFs, and generalize scientific laws as a guide for future research on the design, synthesis and application of water stable and hydrophobic MOFs.

MOF材料被认为是一类具有广阔应用前景的新兴多孔材料。实际应用中MOF材料的水稳定性和水的竞争吸附问题近年来受到越来越多的关注。众多吸附分离体系中都含有不同程度的水，MOF水稳定性差势必限制其应用，水的竞争吸附也可能影响其实用性。例如，当MOF材料应用于吸附去除甲醛、苯、氨等室内空气有害物时，室内空气中不可避免地含有水蒸汽，且浓度明显高于这些有害物。如果水被优先吸附到MOF孔道中，MOF材料对有害物的吸附去除能力可能减弱甚至丧失。本项目拟采用配体设计和后合成修饰两种思路构筑基于Zr6(µ3-O)4(µ3-OH)4(-CO2)12，[Fe2M(μ3-O)(-CO2)6]（M代表系列金属离子）等稳固型结构基元的疏水性MOF，探索MOF疏水性的影响因素和调节方法，研究MOF的疏水性对其实际吸附分离的影响，并归纳总结规律，为疏水性和水稳定性兼具型MOF材料的设计合成与应用提供实验基础和理论指导。

MOF材料被认为是一类具有广阔应用前景的新兴多孔材料。实际应用中MOF材料的水稳定性和水的竞争吸附问题近年来受到越来越多的关注。构筑疏水性MOF是提升其稳定性的有效策略之一。本项目通过有机配体的设计和无机金属建筑单元的合理选择制备了系列MOF材料，部分表现出高稳定性和高疏水性。对这些MOF的性质研究表明，MOF材料的疏水性对其稳定性和选择性吸附性能具有重要影响。一些MOF还表现出响应性的荧光性质，在水中污染物快速检测上具有应用潜力。我们也发现MOF材料的亲疏水性可以通过一些简单易行的后合成方法进行调节。这些方法为MOF材料的孔性微调提供了一种可选路径。此外，我们对研究内容进行了适当拓展，设计制备了几种结构相似但孔表面功能基团不同的MOF材料，研究了其质子导电性，探索了几种MOF材料的成膜制备方法及所得膜对水中染料分子的纳滤去除效果，结果显示功效良好。在本项目资助下，研究结果共发表SCI收录论文16篇（影响因子大于10的论文4篇，JCR一区论文12篇），部分论文发表在Chem、 Chem. Rev.、Adv. Sci.等期刊上；参编中文专著两部三章节，申请中国发明专利7项，1项已授权。项目执行期间，联合培养博士生和硕士生各3名。