Syntheses, Structures And Properties Of Metal-organic Frameworks Based On Low Symmetrical Tridentate Carboxylic Acids

In the21st century, it is critically important to use clean energies (hydrogen, solar,nuclear, biomass, ect.) for the development of global economy and the improvementof environment problems. The usage and storage of clean energies are greatlydependent on the material science. The research of new materials that can safely storeand use the clean energies is of great meaningful. Porous materials have been widelyused in petroleum chemical industries, fine chemical industries and sewagepurifications by taking advantages of their high surfaces, regular and well-definedchannels, as well as the functional active centers. Great efforts have been made toimprove the performances of conventional porous materials, such as zeolites,molecular sieves, porous oxide and mesoporous materials, by modification andmodulation. Meanwhile, the exploration of new type of porous materials is interesting.Metal-organic frameworks (MOFs) are constructed by the assembly of metalions/metal clusters and organic ligands to generate a class of crystalline materials withperiodic network structures. Compared to traditional porous materials, metal-organicframeworks (MOFs), as a new class of porous material, have a variety of intriguingstructures, and much higher surface area and pore volume. Most importantly, MOFscan be rationally designed and functionalized. The applications of MOFs in catalysis,gas storage and separation, chemical sensors and photoelectric materials have beenexplored.Currently, the researches on MOFs mainly focus on the function-oriented designand synthesis. Metal centers, especially organic ligands, can greatly dominate thestructures and properties of the final products of MOFs. In the thesis, we aim tosynthesize MOFs with novel structures and properties by the utilization of thepre-designed novel organic ligands.The main results in the thesis are summarized as follows:1. The Suzuki coupling reaction has been used to synthesize the novel lowsymmetrical tridentate carboxylic acid, p-terphenyl-3,4″,5-tricarboxylic acid (H3TPT). H3TPT ligand is designed and synthesized based on the following reasons. Firstly,compared with the reported low symmetrical tridentate carboxylic acids, the H3TPTligand with extended backbone may facilitate the construction of three-dimensional(3D) frameworks with pore structures. Secondly, H3TPT ligands with aromatic π ringsmay impart luminescent property to its resulting MOFs by properly selectinginorganic metal centers.2. Three-dimensional (3D) metal-organic frameworksCd3(TPT)2(DMF)2·(H2O)0.5(1) Zn3(TPT)2(DMF)2·0.5HNMe2(2) andNH2Me2·[Zn(TPT)]·DMF (3) have been solvothermally synthesized by using H3TPTligands and transition metal ions. Compounds1and2possess the infinitemetal–carboxylate chains constructed from transition metel ions and carboxylategroups of TPT3-ligands, which are further linked into3D frameworks by TPT3-ligands. In compound3, two adjacent Zn2+ions are bridged by six carboxylate groupsfrom six TPT3-linkers to form a binuclear [Zn2(COO)6] building unit. These binuclearunits are linked by the TPT3-ligands to generate an anionic3D framework. Moreover,all of these three compounds (1-3) show excellent luminescent properties, and theirmicrometer-sized compounds1’-3’ can be used in the detection of aromatic nitroexplosives.3. A luminescent microporous lanthanum-based metal-organic frameworkLa(TPT)(DMSO)2·H2O (4) has been solvothermally synthesized by using H3TPTligands and La3+ions. Its neutral framework with interconnected3D channels is basedon bi-nuclear lanthanum clusters linked by TPT3-ligands. Compound4presents amoderate adsorption capacity of CO2at ambient temperature, as well as excellentselectivity detection properties of both PA and Fe3+ions.4. A new agw-type metal-organic framework [Cu3(TPT)2(H2O)3]·xGuest (5) hasbeen solvothermally synthesized by using H3TPT ligands and Cu2+ions. The unusualtrinuclear Cu(II) clusters and the common binuclear Cu(II) paddlewheel clusters arepresented in5. These two kinds of clusters are bridged by TPT3-ligands to form ahighly porous framework. Compared to other agw-type MOFs, compound5shows the expanded pore dimension due to the existence of low symmetrical tridentatecarboxylic acid ligands. In addition, a3D metal-organic framework[Cu4(5-AIPA)3(OH)2]·2DMF (6) with the tetranuclear [Cu4(μ3-OH)2] clusters hasbeen solvothermally synthesized by using5-aminoisophthalic acids (5-AIPA) andCu2+ions. In compound6, the tetranuclear [Cu4(μ3-OH)2] clusters are connected byamino and carboxylic groups of AIPA ligands to form2D layers, which are furtherlinked into a3D framework by bridging the other type of AIPA ligands withuncoordinated amino groups. It is noteworthy that there are abundent uncoordinatedamino groups, guest DMF molecules and H2O molecules in the channels, compound6shows a high proton conductivity under high humidity and high temperaturecondition.