Fluorescence Sensing Analysis Based On Organic Framework Materials

Organic frame materials include metal organic frame materials and covalent organic frame materials.Metal organic frame material is a kind of porous material formed by metal ions and organic ligands.Due to the diversity of metal ions and ligands,a variety of metal organic framework materials can be formed.Metal-organic frame materials have some excellent properties which make them useful in gas adsorption and separation,catalysis,electrochemistry and fluorescence sensing.Covalent organic frame material is a new type of porous material proposed after metal organic frame material.It is a kind of frame material formed by non-metal through covalent bond.Due to its advantages of adjustable structure,porosity and larger than the surface,it has a wide range of applications in catalysis,photoelectricity and gas storage and adsorption.In this thesis,we synthesized fluorescent sensors based on metal-organic frame materials and covalent organic frame materials.The specific work is as follows:1.Zeolitic imidazolate framework-8?ZIF-8?loading rhodamine-B?ZIF-8@rhodamine-B?nanocomposites was proposed and used as ratiometric fluorescent sensor to detect Cu²⁺.Scanning electron microscopy,Fourier transform infrared spectroscopy,X-ray powder diffraction,N₂ adsorption/desorption isotherms and fluorescence emission spectroscopy were employed to characterize the ZIF-8@rhodamine-B nanocomposites.The results showed the rhodamine-B was successfully assembled on ZIF-8 based on the?-?interaction and the hydrogen bond between the nitrogen atom of ZIF-8 and–COOH of rhodamine-B.The as-obtained ZIF-8@rhodamine-B nanocomposites were octahedron with size about 150-200 nm,owned good water dispersion,and exhibited the characteristic fluorescence emission of ZIF-8 at 335 nm and rhodamine-B at 575 nm.The Cu²⁺could quench fluorescence of ZIF-8 rather than rhodamine-B.The ZIF-8 not only was acted as the template to assemble rhodamine-B,but also was employed as the signal fluorescence together with the fluorescence of rhodamine-B as the reference to construct a novel ratiometric fluorescent sensor to detect Cu²⁺.The resulted ZIF-8@rhodamine-B nanocomposite fluorescence probe showed good linear range?68.4 nM-125?M?with a low detection limit?22.8 nM?for Cu²⁺combined with good sensitivity and selectivity.The work also provides a better way to design ratiometric fluorescent sensors from ZIF-8 and other fluorescent molecules.2.1,3,5-tris?4-aminophenyl?benzene and 1,4-dihydroxyterephthalaldehyde containing-OH to synthesize a fluorescent covalent organic framework?COF?material and used as a fluorescence sensor to detect trace amounts in organic solvent N,N-dimethylformamide?DMF?water.Scanning electron microscopy,Atomic force microscopeFourier transform infrared spectroscopy,ultraviolet absorption spectrum and fluorescence emission spectroscopy were used to characterize the COF material.The two monomers were condensed to form a COF material by schiff base reaction.The material had a hollow network structure,and exhibited characteristic fluorescence emission of COF at 420 nm.The obtained fluorescent probe showed a good linear range of 0.1-1%,a low detection limit of 0.03%,good sensitivity and selectivity.This work also provides a better way to design fluorescent sensors.3.Benzaldehyde and benzidine and 1,3-propanedithiol containing mercapto groups synthesized a thiol-functionalization fluorescent COF material and acted as a fluorescence sensor to detect mercury ions.Scanning electron microscopy,Fourier transform infrared spectroscopy,ultraviolet absorption spectrum and fluorescence emission spectroscopy were used to characterize the COF material.The two monomers were condensed to form a COF material by Schiff base reaction.The material had a spherical shape and a size of about 500-600 nm,and exhibited characteristic fluorescence emission of COF at nm.The obtained fluorescent probe showed a good linear range 18.8 nM,low detection limit 56 nM-12?M,good sensitivity and selectivity.This work also provides a better way to design fluorescent sensors.