Design, Synthesis, And Properties Of Fluorescent Chemsensor For Chromium Ions

Recently, the fluorescent chemosensors have gained wide attentions due to their quick response, high sensitivity and good selectivity in the detection of heavy metal ions. In this paper, we described the design and synthesis of two fluorescent probe molecules on the basis of the strong oxidizing effect of hexavalent chromium for the detection of hexavalent chromium in the environmental and in vivo. Firstly,2,4-dimethylpyrrole was further mixture with anisaldehyde in "one-pot" to prepare borondipyrromethene (BODIPY). The BODIPY was appled to react with Vilsmeier-Haack reagent to get β-formyl-BODIPY. Finally, compounds A and B were obtained through the nucleophilic addition of aldehyde and aine for the protection of aldehyde group.The reaction conditions of preparation of β-formyl-BODIPY were also optimized by orthogonal experiments. The results revealed that the optimal experimental condition was to add Vilsmeier-Haack reagent dropwise into the solution of BODIPY in1,2-dichloroethane at-15℃. The temperature of mixture reaction was increased to30℃and kept stirring for12h. The yield could reach as high as95%.In this thesis, all intermediates and target products were well characterized with nuclear magnetic resonance spectroscopy (NMR) and mass spectroscopy (MS) experiments. Additionally, the fluorescence properties and selective recognition ability towards ions of compounds A and B were further systematically investigated through fluorescence spectrum and UV spectrum. It was found that compound A could not recognize selectively have no selective, can not be as a chemosensor. Coumpoud B is a fluorescent molecule with high selectivity and sensitivity for hexavalent chromium in the DMF/H2O (7:3, v/v) system with no interference from other ions and insensitive to pH. The fluorescence intensity of B exhibited linear increase trend with increased hexavalent chromium concentration. Moreover, the fluorescence was obviously observed after compound B was added into cells for one hour in the cellular imaging experiments. The1H NMR titration experiments indicated that coumpound B was reduced to P-formyl-BODIPY when added hexavalent chromium for one hour. Therefore coumpound B is candidated to be an excellent fluorescent chemosensor for the detection of hexavalent chromium.