Conjugated Polymer Based Dual-functional Fluorescent-magnetic Nanocomposites: Synthesis And Investigation

Mercury pollution is a global problem because of its deleterious effects onhuman health and environment. In this thesis, a class of fluorescent-magnetic dual-function nanocomposites was constructed and applied as optical detection platform.These nanocomposites are based on carbazole/aromatic amines-based conjugatedpolymers. The heavy atom effect of iodide (I-) was employed to quench thefluorescence of nanocomposites. By utilizing the high association constants andcomposition ratios between I-and mercury ions (Hg2+) to distract I-from the quenchedsystems, the fluorescence signal of nanocomposites I-assembly toward Hg2+could betracked via a “turn-on” mode. Recycling of fluorescent-magnetic nanocompositesprobe was readily achieved by practical-simple magnetic separation. The sensitivity,selectivity and reusability of these fluorescent-magnetic nanocomposites probe wereinvestigated systematically through UV-vis and PL investigation. The main contentsand results of this work are shown below:1. A kind of benzo-2,1,3-thiadiazole-based conjugated polymer with tetheredtriazoles and thymines (P-3) was successfully synthesized by Cu(I)-catalyzed clickreaction between the acetylene-substituted polymer precursor (P-2) and3’-azido-3’-deoxythymidine. The structure of polymers was confirmed by NMR, IR, and UV-visanalyses. The optical responses of P-3toward various metal ions were investigatedsystematically under various conditions of different pH values and buffer solutions.2. A type of fluorescent-magnetic dual-function nanocomposites,Fe3O4@SiO2@P-5, was successfully obtained by Cu+-catalyzed click reactionbetween acetylene (C≡C-H) substituted carbazole-based conjugated polymer (P-4)and azide-terminated silica-coated magnetic iron oxide nanoparticles (Fe3O4@SiO2-N3). The analysis results of NMR, IR, TEM, SEM, UV-vis and PL spectrademonstrated that this nanocomposite was successfully synthesized. The opticalresponses of Fe3O4@SiO2@P-5I-toward Hg2+were investigated and indicated thatthe nanocomposites system can sensitively and selectively detect Hg2+(with thedetection limit of~4.17×10-7mol·L-1). 3. A type of green-emitting magnetic nanocomposites, Fe3O4@SiO2@P-7, wasobtained by click reaction between acetylene-substituted benzo-2,1,3-thiadiazole-based conjugated polymer (P-6) and Fe3O4@SiO2-N3. The structure of nanocompositewas confirmed by NMR, IR and UV-vis analyses. The optical responses ofFe3O4@SiO2@P-7I-toward Hg2+were investigated and shown that thenanocomposite system can be used as a high sensitive, selective and reusable Hg2+probe (with the detection limit of~1.9×10-7mol·L-1).