Synthesis And Properties Of Water-stable Metal-organic Frameworks By Bithiophene Ligands Containing Hydrophobic（-CH₃） Substituents

Due to the striking physical and chemical properties such as pore size distribution, surface properties and chemical functionality, metal–organic frameworks(MOFs) have established themselves as highly promising materials for a host of applications, including molecular separations, gas storage and heterogeneous catalysis, as well as drug delivery. With the research going deeply, some relations between structures and properties have been established, which promotes the object-oriented design and synthesis of functional materials. As the critical factor for application, structural stability of MOFs is wildly studied. The stability of the framework is mainly controlled by the inorganic brick and the strength of the chemical bonding between the inorganic brick and the linker. Some inorganic building units, such as Zn4O(CO2)6, Cu2(OH)2(CO2)4, Cr3O(OH)3(CO2)6 represent high thermal stability, however, it is moisture-sensitive because the relative weak metal–oxygen coordination allows for attack by water molecules, resulting in the phase transformation and decomposition of the framework. structural stability of MOFs is still a problem needed to be solved urgently.The basic structural unit was the main factor that determining the stability of frameworks. To enhance the stability, some units which were stable to water, air and solvent were brought in the frameworks. We conceive that replace some metal ions of a kown or unkown neutral rod-chain with alkalis ions might get a nearly stabile mixed-metal rod chain. This chain could maintain well thermostability in a lower skeletal density. Some frameworks that have analogous features were reported, but there is few research in this field.In addition, it is conducive to enhance the stability of the framework with the introducing of some hydrophobic substituents such as CH3, OCH3. The steric-hinerance effect and hydrophobicity of the substituents would insulate the unsaturation coordinated metal ions from the hydrone, which would improve the stability of the building-blocks. Thereby it is good for enhancing framework’s stability.On account of the factors above, we synthesized two ionic MOFs with the mixed metal organic rod chain and carboxylate ligand which contain hydrophobic methyl. We researched the thermostability and slovent tability of the framework systematacially and preliminary about the porosity.