Controllable Preparation Of Nanoscale Metal-Organic Framework Materials For Fluorescence Sensing

Metal-organic frameworks (MOFs) compound is a new class of multifunctional porous materials. Owing to this material shows various pore channels, high surface and the size, shape, dimensions and surface functionality of the nanochannels can be systematically tuned by changing the combination of organic ligands and metal ions, these materials have been widely regarded as a promising materials in gas storage, catalysis, medicine, photonics, magnetic and selective guest adsorption. Recently, Miniaturization to the nanometer scale regime is a very prolific strategy for the development of new materials with novel and often enhanced properties compared to traditional materials, opening up avenues for technological and biomedical applications. Developing nanoscale metal-organic materials with astonishing properties and applications have attracted considerable interest. Synthesis of nanocrystals MOFs materials built up by metal ions and various polyfunctional organic ligands components at the molecular level has recently afforded a new class of highly tailorable hybrid nanomaterials. Some of these can help to develop novel drug delivery systems, encapsulating matrices, contrast agents, porous catalytic materials, gas storage materials, magnetic and optical nanomaterials, etc. Recent great advances have been made towards these directions.In this paper, we use a facile and environmentally friendly synthesis of nanocrystals MOFs under a novel ultrasonic and vapor diffusion combined technique. The main contents of this thesis are as follows:1. A novel MOF structures,[Zn2(bdc)2(dabco)], with charming topologies were prepared by ultrasonic and vapor diffusion combined strategy. To provide an insight on the formation of [Zn2(bdc)2(dabco)] NMOFs by this novel method, a series of contrast experiment were carried out. The results reveal that hexagonal [Zn2(bdc)2(dabco)] can be synthesized by direct mixing of TEA method, slow diffusion of TEA and ultrasonic and vapor diffusion combined strategy. In addition, transmission electron microscopy (TEM) and scanning electron microscope (SEM) images of all samples reveal that size and shape of hexagonal [Zn2(bdc)2(dabco)] can be tuned by different methods. Microcrystals can be obtained by slow diffusion of TEA method, while nanocrystals can be obtained by ultrasonic and vapor diffusion combined strategy. All these reveal that ultrasonic and the vapor diffusion combined technique is an efficient, low cost, simple strategy to construct porous NMOFs for applications in a wide range of areas including fluorescence sensing, magnetic resonance imaging and drug delivery.2. Highly luminescent nanocrystals of [Cd4(BTC)3(DMF)2(H2O)2] a three-dimensional (3D) MOF with a one-dimensional (1D) channel system,44were prepared by a novel ultrasonic and vapor diffusion combined technique. And the structures of these samples were confirmed by powder X-ray diffraction (PXRD). A simple test-paper-like platform for visual trace-level detection of nitroaromatic explosives was fabricated by an in-situ assembly of luminescent nanocrystals of [Cd4(BTC)3(DMF)2(H2O)2] on the surface of cotton fibers. The results obtained from both the spectrometry titration experiment and visual explosive detection have clearly demonstrated that such a test-paper-like platform incorporating luminescent MOF nanocrystals exhibits high sensitivity and selectivity, as well as ultrafast response, for sensing of nitroaromatic explosives.3. A rational self-sacrificing template strategy to fabricate highly fluorescent MOF nanotubes of [Cd2(btc)2(H2O)2], a cadmium-based3D MOF, were reported, the growth mechanism for MOFNTs was discussed to understand the crystal growth and self-assembly process of nanostructured MOF materials. We also demonstrated its applications in trace detection of nitroaromatic explosives. The results obtained from fluorescent sensing of DNT in the vapor phase have clearly demonstrated that such fluorescent MOFNTs exhibits high sensitivity and selectivity, as well as fast response for sensing of nitroaromatic compounds, making it an ideal candidate for nitro explosive detection with low cost, high sensitivity and selectivity, high response rate, as well as better reversibility.