Fast Preparation And Properties Of Nanoscale Metal-Organic Framework Materials

Metal-organic frameworks (MOFs) are a new class of crystalline materials built from metal ions (or metallic clusters) with well-defined coordination geometry and various polyfunctional organic ligands. They have attracted extensive attention in recent years owing to their intriguing variety of architectures and topologies and their tremendous potential applications in catalysis, adsorption, magnetism, photonics, and molecular sensing.Although some traditional techniques, such as slow vapour or solution diffusion techniques, hydrothermal and solvothermal methods, are applied to prepare MOFs and nanoscale MOFs, the reaction and crystallization processes using these traditional methods usually take long time. The syntheses of MOF-type materials have been studied widely not only for finding new structures but also for searching simple and facile methods such as microwave (MW) and ultrasound (US) synthesis. The main contents of this thesis are as follows:1. The objective of this content is to describe a very rapid method for Expanded graphite (EG)-assisted synthesis of MIL-101(Cr) that allows the synthesis to be completed in2hours. The structures were confirmed by powder X-ray diffraction (XRD) patterns, scanning electron microscopy and Nitrogen sorption-desorption isotherms. Compared with the traditional synthesis method, this synthesis method can increase nuclei growth, show a much high speed of reaction, and the size of MIL-101(Cr) crystals from micro-scale to nano-scale, where the EG acts as the nucleation template. The reaction time was shortened greatly by adopting this synthesis method.2. Nanocomposites containing EG and MIL-53(Cr) have been prepared with various ratios of the two components. The material obtained has a unique layered texture with a preserved structure of MIL-53(Cr) and EG. With various ratios of EG, the unusual MOF/EG nanorods, nanospheres and nanosheets were synthesized based on the template-directed nucleation effect of EG. The composites exhibit good performance as aniline adsorbents, this indicates the presence of a synergetic effect between the two components. According to their preserved porosity and synergy, these materials might be tested for more amines-adsorption applications.3. We successfully fabricated highly luminescent nanowires of a1-D lanthanide MOF,[Tb(1,3,5-btc)(H2O)6]n, in a relatively high yield by using an ultrasonic method, and demonstrated their application for highly selective sensing of aromatic amines. Such an ultrasonic method was demonstrated again to be highly efficient for the fabrication of nanostructures on the basis of MOF-type materials. Particularly, luminescence property of the as-synthesized [Tb(1,3,5-btc)(H2O)6]n nanowires was found to be selectively sensitive to aromatic amines. The results presented in this work may be helpful for developing MOFs in nanoscale with various physicochemical properties and designing novel luminescence sensor for selective sensing of aromatic amines in waste water containing various organoamines.