Rapid Preparation, Adsorption And Fluorescence Sensing Of Several Porous Frameworks

Metal-Organic Frameworks (MOFs) and Covalent Organic Frameworks (COFs), a fantastic type of porous materials, have attracted considerable attention because of the high surface area, the controlled pore size, pore distribution and pore agriculture, and have their potential applications in hydrogen storage, gas adsorption and separations, catalysis, sensing, as well as photonics and magnetics. However, traditional methods for synthesis of this type of porous frameworks often should undertake drawbacks such as long reaction time, high boiling-point solvents and high pressure, which not only makes the synthetic process boring, dangerous and cumbersome, but also causes a great waste of energy. Herein in this thsis, we are designed to rapidly synthesize porous framework materials by using microwave (MW) and ultrasonic methods, and explore routes for synthsis of other porous materials based on MOF or COF templated materials. The main contents of this thesis are as follows:1. A terbium-based MOF,[Tb(1,3,5-BTC)]n, with a three-dimensional structure, was prepared by using a combined ultrasound-vapour phase diffusion technique. The results reveal that MOF nanocrystals can be facilely prepared by such method in a shorter reaction time with higher yields and smaller crystal sizes in comparison with the ultrasound or conventional heating method.[Tb(1,3,5-BTC)]n nanocrystals show excellent luminescence properties for the highly selective and sensitive detection of PA, and no obvious interference from other nitro-aromatic compounds or common organic solvents, was observed. We believe that the results presented in this work not only provide a new way for the rapid preparation of MOF nanocrystals under mild synthesis conditions, but also are very helpful for designing novel luminescence sensors for the highly sensitive and selective sensing of PA in solutions containing other nitroaromatic compounds.2. Highly luminescent crystalline polyimide (PI) nanosheets in high yields (up to95%) were facilely prepared via a MW-enhanced high temper-ature ionothermal method. Structures of the as-prepared PI nanosheets were confirmed by powder X-ray diffraction (PXRD), and the most appropriate MW reaction time and raw material configuration was determined to be3minutes and ZnCl2/1mass ratio of0.6:1. Such multilayer structures also be assured from scanning electron microscope (SEM) and transmission electron micros-copy (TEM) images of the sample. The studies conducted show that the PI nanosheets are excellent chemical sensor for highly selective sensing of metal ion Cr3+. The highly sensitive and selective sensing of metal ions in aqueous solution will certainly extend the applications of such luminescent COFs in biology and biomedicine.3. A series of magnetic porous covalent organic frameworks SNW-1(MPSNW-1) with various BET surface areas from344to600m2g-1were synthesized through a MW-assisted method. SEM images give evidence for the porous structures of the MPSNW-1composite, and it can be seen from TEM images that Fe3O4nanoparticles were well dispersed in the composite. Such a novel type of magnetic porous organic framework SNW-1was convinced to have potential in adsorption of heavy metal ions due to the fact that SNW-1is constructed from polycondensation reaction of melamine and terephthalaldehyde, which results in an N-rich polymer material. Therefore, the adsorption properties were preliminarily tested by the adsorptive removal of heavy metal ions from waste water. The results suggest that the composites show highly selective adsorption of Hg2+with adsorption capacity of97.65mg g-1, without interference from other metal ions such as Na+, Cd2+, Zn2+, Ni2+, Pb2+,Mg2+and Cr3+.4. Magnetic porous carbons with high surface areas were easily synthesized from a Fe-based metal-organic framework (MOF) by a novel microwave-enhanced high temperature iono-thermal method. By choosing a Fe-based MOF called MIL-100(Fe) as both a Fe and C precur-sor and a porous template, and furfuryl alcohol as a second precursor, a series of γ-Fe2O3/C composites with strong magnetism were prepared in3min by a MW-enhanced high temperature ionothermal method. The products exhibit high surface areas (up to800m2g-1) with different magnetic separation performance (Ms=4.12-19.54emu g-1), and possess high adsorption capacity toward methylene blue (303.95mg g-1). Magnetic porous carbon materials are potential to be recoverable and recycla-ble super-adsorbents for removal and recovery of pollutants from wastewater. We believe the results presented here open a new opportunity for the rapid and large-scale industrial preparation of MOFs derived magnetic porous carbons with high surface areas and high adsorption capacities for removal of various organic contaminants from wastewater.