The Synthesis Of New Water-soluble Conjugated Polymers For Fluorescence Sensing

As novel fluorescent probes, water soluble conjugated polymers have a number of advantages such as high absorption coefficients, high fluorescence quantum yield signal, amplification and water solubility. In this thesis, three cationic polyfluorene-acetylene conjugated polymers were synthesized and their properties had been studied. Based on water-soluble conjugated polymers, new sensors had been establishedThe main contents were demonstrated as follows:(1)Synthesis of cationic polyfluorene-acetylene conjugated polymer and its propertiesThree cationic polyfluorene-acetylene conjugated polymers were synthesized via Sonogashira-hagihara coupling reaction. The corresponding structures of monomers and cationic conjugated polymers were confirmed via HNMR spectra, physical properties and their thermal stability were studied by viscosity method and thermal gravimetric analysis respectively. The effect of polarity of the solvent on the optical properties and fluorescence quantum yield of polymers were investigated by ultraviolet absorption and fluorescence spectroscopy. The influence of pH on fluorescence properties of the conjugated polymer P3 containing pyridine functional groups was examined.(2) Detection of Pd2+based on cationic water soluble conjugated polymerA new analytical method for the detection of divalent palladium ion was developed with high sensitivity and selectivity in the aqueous system based on a cationic water soluble conjugated polymer P1,which contains pyridine and fluorene groups in the mainchain. The advantages of the method were because of the unique interaction between the palladium ion and pyridyl. The aggregation state of polymer in aqueous solution can effectively amplify quenching efficiency. The linear range of palladium ion detection was 4.0×10-8 mol/L～1.5×10-6 mol/L with the detection limit of 1.7×10-9 mol/L for excellent selectivity relative to other metal ions.(3) Berberine detection based on an anion water soluble conjugated polymerA fluorescence probe for the detection of berberine was developed based on an anionic water soluble conjugated polymer PPESO3, including a poly(phenylene ethynylene) backbone and anionic 3-sulfonatopropyloxy side groups. The fluorescence of PPESO3 was efficiently quenched by berberine based on the formation of nonfluorescence complex due to the electrostatic interactions between sulfonate anions of PPESO3 and quaternary ammonium cations of berberine. Under the optimum conditions, the detection method for berberine exhibits a good linear relationship in a range of 7.5×10 mol/L to 4.0×10-6 mol/L with the detection limit of 8.7×10-9 mol/L (S/N=3). The results show that PPESO3 is a fast, selective and highly sensitive probe for the detection of berberine.