The Design, Synthesis And Properties Of Novel Fluorescent Fe³⁺ Film Sensing Materials

The detection of trace metal ions is of great significance to human health and ecological environment. At present, the methods used for the detection of metal ions are numerous, the fluorescence detection is one of the most practical application methods because of its simple operation, high sensitivity, short response time, and so on. The fluorescence detection is mainly divided into flurescence enhancement (turn-on) and quenching (turn-off), the mechanism of fluorescence quenching method for metal ion is electron-transfer or energy-transfer from donor to accepter (metal ion) which leads fluorescence quenching.Fluorescence conjugated polymers show special molecular wires effect which can realize rapid metal ions detection. When the excited electron transfers from conjugated polymer to metal ions, the fluorescence of whole polymer would be quenched to realize the detection of trace metal ions.Fluorescent film used for trace metal ions detection has more practical application than in liquid, based on the mechanism of fluorescence quenching metal ion detection, in order to improve the response of metal ions recognition ability and control the state of aggregation structure, we have designed and synthesized a series of fluorescent materials containing carbazole and triphenylamine groups. It demonstrates that these fluorescent films fabricated by carbazole compounds can detect Fe3+ both in water phase and actual environment with stable recognition sensitivity, high selectivity and great repeatability. The research is mainly composed of three parts:1. In order to improve the response ability of metal ions, we introduced the metal ions recognition units in molecular (2,2’-bipyridine and 1,10-phenanthroline), On the one hand, to control the state of aggregation structure, eletropolymerization films are first used to metal ion film fluorescence sensing field by carbazole groups with electrochemical activity. Two EP films (TCLC, TCFC) have been demonstrated to be sensitive and selective to Fe3+. The cross-linking cavity structure formed by carbazole groups in the process of electrochemical polymerization not only ensures that metal ions can quickly diffuse in the films, but also enlarges the contact area between the EP films and Fe3+.2. Combining with the results of part 1, to further improve the response of the metal ions recognition ability and the state of aggregation structure, we designed and synthesized fluorescent molecules PTCFC EP flims. Conjugated polymer PTCFC EP fluorescent films have been demonstrated to be more sensitive and selective to Fe3+ than TCLC, TCFC EP films both in water phase and actual environment. Furthermore, we have compared PTCFC EP flims with PTCFC spin-coating films and analyzed the relationship between the molecular structure and Fe3+.3. Compared to the fluorescence small molecules, dendrimer macromolecules in single molecule has more metal ions recognition unit can capture more metal ions and lead to more fluorophore quenched, having advantage in the response ability of metal ions sensing and sensitivity for metal ions identification. We designed and synthesized a dendrimer macromolecule PYTPAG2 with pyrene group as luminescent interior core and peripheral triphenylamine groups as metal ion recognition units. Finally, we got a fluorescent sensor for Fe3+ with a specific selectivity both in solution and as film. The detection limits in solution and as film are 6.5 × 10-7 M and 5× 10-7 M, respectively. Moreover, PYTPAG2 could not be disturbed by pH, interference with other metal ions, counter anions, and the real environment. In addition, biological fluorescence imaging studies of Fe3+ in living roundworms demonstrated its value practical application.