Syntheses,Adsorption And Sensing Of Metal-Organic Frameworks Based On A Semi-rigid Ligand

Metal-organic frameworks (MOFs) have received tremendous attention due to their powerful attributes on their intriguing network topologies and exploitable properties for potential applications such as gas adsorption and separation, sensing, catalysis, proton conduction, etc. In contrast with the prolific production of MOFs based on rigid ligands and flexible ligands, the design, syntheses and applications of MOFs based on semi-rigid ligands are somewhat overlooked. The semi-rigid ligands are not only possessed the rigid of rigid ligands but also the flexibility of flexible ligands. The characteristic of "rigid and flexibility" endows the constructed functional MOF tunable structures, which further have influence on the properties.In this thesis, we choose semi-rigid ligands H3L(3,5-(4-carboxybenzyloxy)benzoic acid) with transition metal/rare earth ions to construct a series intriguing networks by changing temperature, solvent, namely, [Cu2 (OH) (L)]·(DMF)0.8 (FJU-11), Ln-MOF{Ln (L) (H2O) (DMA)},{FJU-13-Ln, Ln= Eu, Tb, Pr}, Cd (H L) (FJU-15). Different from known long ligand and template method, a new strategy is proposed to realize a hierarchically porous (The presence of micropores are around 8.7 A, and the mesopores are ?33.3 A size range) metal-organic framework FJU-11 via using semi-rigid multi-carboxylic acids. Interestingly, FJU-11 possesses the large adsorption capacities and small isosteric heats toward CO2. The column breakthrough experiment for FJU-11 highlights its potential application in the separation of 15:85 CO2/N2. FJU-13-Eu, FJU-13-Tb, FJU-13-Pr are isostructurally with the neutral framework. We propose a new strategy to construct diamond and surfure of oxygen-rich channel via using semi-rigid multi-carboxylic acids. This strategy makes FJU-13-Eu show a highly selective and sensitive fluorescence sensor for detecting for Fe3+ ions:the semi-rigid diamond channel is beneficial cation exchange by Fe3+ partial replacement Eu3+; the surface struct of oxygen-rich is conducive to capture Fe3+ so that FJU-13-Eu and Fe3+ competition absorption light. Therefore, this work was successfully applied for the detection of Fe3+ in biological system. FJU-15 was designed by semi-rigid multi-carboxylic acids can partially deprotonate to form MOF with intramolecular hydrogen. FJU-15 shows high water, thermal and both acid and basic solutions stability by intramolecular hydrogen bonding. Noteworthy, it is one of the most stable MOFs can survive in an extensive pH range. Further, its emission band in the purple region indicates that FJU-15 may be potential candidates as purple-emitted photoactive materials.