【作者】 王耀；

【导师】 何亚兵；

【作者基本信息】 浙江师范大学 ， 无机化学， 2019， 硕士

【副题名】构效关系与吸附性能优化

【摘要】 金属有机骨架材料（MOFs）,也称为多孔配位聚合物,是一种相对较新的晶态多孔材料,由金属阳离子或离子簇与有机配体通过配位键自组装形成。多孔MOFs之所以受到学术界的广泛关注,不仅源于其化学组成和分子结构的多样性,很大程度上还因其在众多领域的巨大潜力和发展空间,其应用包括但不限于气体吸附和分离、多相催化、分子传感和药物传递。其中,气体吸附仍然是主要的研究领域,因为它们与传统的多孔材料相比具有更高的比表面积、可调控的孔径和可功能化的孔表面等优点。在本论文中,主要研究了不同官能团的引入对MOFs气体吸附性能的影响,比较了MOFs异构体之间气体吸附性能的差异,以及运用了配体截断策略对MOFs的气体吸附性能进行优化。1.设计合成了三种弯曲四羧酸吡啶配体:3,5-双（3,5-二羧基苯基）-2,6-二氨基吡啶、3,5-双（3,5-二羧基苯基）-2,6-二甲基吡啶和3,5-双（3,5-二羧基苯基）-2,6-二甲氧基吡啶,采用溶剂热法制备了三种铜基MOFs:ZJNU-87,ZJNU-88和ZJNU-89。单晶X-射线衍射研究分析表明这三种MOFs是同构的,属于六方晶系,空间群为P6₃/mmc,骨架中含有三种不同类型的多面体笼。在活化过程中,由于氨基与溶剂分子之间的相互作用较强,ZJNU-87骨架坍塌。活化后甲氧基官能化的ZJNU-89吸附性能优于甲基官能化的ZJNU-88,在298 K、1.05 atm下,ZJNU-89的C₂H₂和CO₂吸附量分别为181.3和103.0 cm³·g^-1。这项工作不仅合成了两个吸附性能优异的MOFs,重要的是提供了取代基对骨架稳定性和气体吸附性能影响的基本理解,这对未来MOFs的设计和综合应用至关重要。2.设计合成了两个甲氧基官能化的异构配体:2,6-双（3,5-二羧基苯基）-1,5-二甲氧基萘和1,5-双（3,5-二羧基苯基）-2,6-二甲氧基萘,并采用溶剂热法合成了两种NbO-型的铜基MOFs:ZJNU-58和ZJNU-59。单晶X-射线衍射研究分析表明虽然ZJNU-58和ZJNU-59属于不同的空间群(ZJNU-58空间群为C2/c,ZJNU-59空间群为R3^_<sub>m),但它们具有相同的拓扑结构。气体吸附研究结果表明,虽然ZJNU-59的孔体积和比表面积比其异构体ZJNU-58低,但ZJNU-59的C₂H₂和CO₂吸附能力比ZJNU-58高,在298 K和1.05 atm下C₂H₂和CO₂吸附量分别为199.5和109.4 cm3·g-1。并且ZJNU-59的C₂H₂/CH₄和CO₂/CH₄吸附选择性也优于ZJNU-58。随后与它们不含甲氧基的母体MOFs的气体吸附性能进行比较,ZJNU-59的C₂H₂和CO₂吸附能力高于其母体化合物ZJNU-73,而ZJNU-58的C₂H₂和CO₂吸附能力略低于其母体化合物NOTT-103。然而,与它们的母体MOFs相比,这两种MOFs的C₂H₂/CH₄和CO₂/CH₄吸附选择性增强了。这项工作不仅合成了两种用于从CH₄中高选择性吸附C₂H₂和CO₂的NbO-型MOFs,而且更重要的是提供了MOF异构化以及甲氧基官能化对气体吸附性能影响的基本理解,这对设计合成性能更加优异的MOFs有指导性意义。3.合成了一个六羧酸配体:2,4,6-三（3,5-二羧基苯基）-1,3,5-三甲基苯,并构筑了一个结构新颖的铜基MOF材料:ZJNU-100。单晶X-射线衍射研究分析表明ZJNU-100属于六方晶系,空间群为P6/mmm,骨架中有七种不同类型的笼,孔径分布范围为5.36-15.91?。在298 K和1 atm下,ZJNU-100的C₂H₂和CO₂吸附量分别为149.1和83.1 cm3·g-1。为了优化其气体吸附性能,通过配体截断策略将六羧酸配体中的一个间苯二甲酸截断,设计合成了一个四羧酸配体:2,4-双（3,5-二羧基苯基）-1,3,5-三甲基苯,并构筑了一个ssa-型的铜基MOF材料:ZJNU-57。单晶X-射线衍射研究分析表明ZJNU-57属于六方晶系,空间群为P6₃/mmc,骨架中含有三种不同类型的多面体笼。ZJNU-57的吸附性能明显优于ZJNU-100,在298 K和1 atm下,ZJNU-57的C₂H₂和CO₂吸附量分别为201.5和112.2 cm3·g-1。因为ZJNU-57有不同于ZJNU-100的结构和孔环境,所以具有高于ZJNU-100的气体吸附能力。量子化学计算表明,由于具有合适的孔径和结构,ZJNU-57中的甲基增强了骨架与C₂H₂/CO₂分子之间的相互作用,因此大大地提高了C₂H₂和CO₂吸附能力。这项工作不仅合成了一个具有新颖结构的MOF材料和一个具有高C₂H₂和CO₂吸附能力的MOF材料,而且阐明了通过配体截断策略设计配体是一种合成性能优异MOFs的有效方法,也为设计合成性能优异的MOFs提供了一定的见解。</sup>更多还原

【Abstract】 Metal-organic framework materials（MOFs）,also known as porous coordination polymers,have become a relatively new class of crystalline porous materials which are self-assembled via coordination bonds between metal cations or ionic clusters and organic ligands.Porous MOFs have received extensive attention from the researchers not only because of their unprecedented diversity in chemical composition and molecular structure,but also their great potential and development space in many fields,including but not limited to gas adsorption and separation,heterogeneous catalysis,molecular sensing and drug delivery.Gas adsorption is still a major research area in a variety of applications because of their advantages of high surface area,tunable pore size,and functional pore surface compared to traditional porous materials.In this thesis,the main research is to figure out the effect of different functional groups on the adsorption properties of MOFs,compare the gas adsorption properties of MOFs isomers,and optimize the gas adsorption properties of MOFs by ligand truncation strategy.1.Three kinds of curved tetracarboxylic acid ligands,5,5’-（2,6-diaminopyridine-3,5-diyl）diisophthalic acid,5,5’-（2,6-dimethylpyridine-3,5-diyl）diisophthalic acid,and5,5’-（2,6-dimethoxypyridine-3,5-diyl）diisophthalic acid,were designed and synthesized.Three copper-based MOFs were prepared by solvothermal method:ZJNU-87,ZJNU-88 and ZJNU-89.Single-crystal X-ray diffraction analyses show that the three MOFs are isoreticular,crystallizing in the hexagonal crystal system with space group of P6₃/mmc.The framework contains three different types of polyhedral cages.During the activation process,the framework of ZJNU-87 was collapsed due to the strong interactions between the amino group and the solvent molecules.The activated methoxy-functionalized ZJNU-89 has better adsorption properties than the methyl-functionalized ZJNU-88.At 298 K and 1 atm,C₂H₂,CO₂ and CH₄ uptake capacities of ZJNU-89 are 181.3,103.0 and 22.8 cm³·g^-1,respectively.This work not only reported two MOFs with excellent adsorption properties,but also provided a basic understanding of the substituent effcet on the framework stabilities and gas adsorption properties,which is essential for the design and comprehensive application of MOFs in the future.2.Two methoxy-functionalized ligand isomers,5,5’-（1,5-dimethoxynaphthalene-2,6-diyl）diisophthalic acid,5,5’-（2,6-dimethoxynaph-thalene-1,5-diyl）diisophthalic acid,were designed and synthesized,and two NbO-type copper-based MOFs isomers were synthesized by solvothermal method:ZJNU-58 and ZJNU-59.Single-crystal X-ray diffraction analyses show that although ZJNU-58 and ZJNU-59 crystallize in different space groups(C2/c for ZJNU-58 and R3^_<sub>m for ZJNU-59),they are isoreticular.Gas adsorption analyses show that the adsorption capacity of ZJNU-59 towards C₂H₂and CO₂ is higher than that of ZJNU-58,although the pore volume and surface area of ZJNU-59 are lower than that of ZJNU-58.At 298 K and 1 atm,C₂H₂ and CO₂ uptake capacities of ZJNU-59 are 199.5 and 109.4 cm3·g-1,respectively.Also,ZJNU-59 has better adsorption selectivities of C₂H₂/CH₄ and CO₂/CH₄ than ZJNU-58.Compared with their parent MOFs without methoxy group,the C₂H₂ and CO₂ adsorption capacities of ZJNU-59 are higher than that of its parent compound ZJNU-73,while the C₂H₂ and CO₂ uptake capacities of ZJNU-58 are slightly lower than its parent compound NOTT-103.However,the adsorption selectivities of C₂H₂/CH₄ and CO₂/CH₄ of these two MOFs are enhanced compared to their corresponding parent MOFs.This work not only reported two NbO-type MOFs for highly selective adsorption of C₂H₂ and CO₂ from CH₄,but more importantly provided a basic understanding of the impact of MOF isomerization and methoxy group functionalization on gas adsorption capacities,which is instructive for designing MOFs with superior properties.3.A hexacarboxylic acid ligand,2,4,6-tri（3,5-dicarboxyphenyl）-1,3,5-trimethyl-benzene,was synthesized and a novel copper-based MOF material ZJNU-100 was constructed.Single-crystal X-ray diffraction analyses show that ZJNU-100 belongs to the hexagonal system with the space group P6/mmm.There are seven different types of cages in the overall structure of ZJNU-100,and the range of pore size is 5.36-15.91?.At 298 K and 1 atm,the adsorption capacities of C₂H₂ and CO₂ of ZJNU-100 are 149.1and 83.1 cm3·g-1,respectively.In order to optimize its gas adsorption properties,a tetracarboxylic acid ligand,2,4-bis（3,5-dicarboxyphenyl）-1,3,5-trimethyl-benzene,was designed and synthesized by a ligand truncation strategy,and an ssa-type copper-based MOF material ZJNU-57 was constructed.Single-crystal X-ray diffraction analyses show that ZJNU-57 crystallizes in the hexagonal space group P6₃/mmc.The framework of ZJNU-57 contains three different types of polyhedral cages.Due to different structure and pore environment,the adsorption properties of ZJNU-57 were enhanced than ZJNU-100.At 298 K and 1 atm,the adsorption capacities of C₂H₂ and CO₂ of ZJNU-57 are 201.5 and 112.2 cm3·g-1,respectively.The quantum chemical calculations show that the methyl group in ZJNU-57 enhances the van der Waals interactions between the framework and the C₂H₂/CO₂ molecules due to the suitable pores and structures,which greatly improves the adsorption capacities of C₂H₂ and CO₂.This work not only reported a MOF material with a novel structure and a MOF material with high C₂H₂ and CO₂ adsorption capacity,but also demonstrated that ligand truncation strategy is an effective method for synthesizing MOFs with excellent properties.The results also provide some insights for designing MOFs with excellent adsorption properties.</sup>更多还原