Rapid Preparation Of Metal-Organic Framework Materials For Fluorescence Sensing

Traditional inorganic and organic luminescent materials have been extensively explored and realized for their diverse functionalities and applications in lighting, display, sensing, and optical devices. Porous metal-organic frameworks (MOFs) consisting of multiple metal ions and polyfunctional organic ligands have received tremendous attention in recent years after proposed as a kind of new material in1990s. Currently, reports of research of MOF emerge in endlessly.Metal organic frameworks (MOFs) are a class of crystalline organic-inorganic hybrid compounds formed by coordination of metal clusters or ions with organic linkers, in which bivalent or trivalent aromatic carboxylic acids or N-containing aromatics are commonly used to form frameworks with zinc, copper, chromium, aluminum, zirconium, and other elements. They have been extensively researched during the past decade for their intriguing structural diversity and many attractive applications in catalysis, selective adsorption and separation, gas storage, drug delivery and in fluorescent sensing.In this paper, we use an environmentally friendly synthesis of MOFs in a novel ultrasonic and vapor diffusion combined technique. In the meantime, we also study the fluorescent property of the as-synthesized MOFs. The main contents of this thesis are as follows:1. In this work, different MOFs have been synthesized in a novel ultrasonic and vapor diffusion combined technique with changing the metal ions and organic ligands. In the same time, a series of contrast experiment were carried out by using this novel method to provide an insight on the formation of MOFs. The results demonstrate that they can be successfully synthesized by ultrasonic and vapor diffusion combined strategy. In addition, scanning electron microscope (SEM) images of all samples show that the shape and size of MOFs can be affected with changing the ultrasonic power. All these results show that ultrasonic and the vapor diffusion combined technique is a low-cost, effective, efficient, and environmentally strategy to synthetize MOFs for different applications, such as fluorescence sensing, photocatalysis and drug delivery.2. In this work, Mg-BTC and Tb3+-doped Mg-BTC were synthesized using the ultrasonic method under the same conditions. The structures of Mg-BTC and Tb3+-doped Mg-BTC were confirmed by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) patterns. Moreover, scanning electron microscopy (SEM) images show that Mg-BTC of nanoscale can be synthesized by using this ultrasonic method, and these Mg-BTC nano-crystals show different shape and morphology with the change of the ultrasonic power. Fluorescence emission spectra reveal that emission spectroscopy can be tuned by varying ratio of Tb to Mg-BTC. The sensing of picric acid in an aqueous solution was quantitatively analyzed by a fluorescence spectrometric titration experiment. This kind of coordination co-polymers may be useful for displayer devices, fluorescence imaging, and fluorescence label.3. In this work, we present novel kinds of Fe3O4@Tb-BTC magnetic metal-organic framework (MOF) nanospheres which possess both magnetic characteristics and fluorescent properties using a layer by layer assembly technique. The structure and morphology of the as-prepared Fe3O4@Tb-BTC were systematically characterized and it was applied in detection of nitroaromatic explosives, such as2,4-dinitrotoluene (2,4-DNT),2,6-dinitrotoluene (2,6-DNT),2-nitrotoluene (2-NT),4-nitrotoluene (4-NT), nitrobenzene (NB) and picric acid (PA). The results indicate that the fluorescence intensity of Fe3O4@Tb-BTC can be quenched by all analytes studied in the present work. Remarkably, the as-synthesized nanospheres exhibit high sensitivity for2,4,6-trinitrotoluene (TNT) detection with Ksv value of (94800M-1). Besides, the magnetic nanospheres can be easily recycled, which makes it more convenient for reutilization and friendly to the environment. The results show that it has broad application prospects in the detection of nitroaromatic explosives.