Synthesis And Application Of Fluorescent Conjugated Polymers Containing Diketopyrrolopyrrole (DPP) Building Blocks

In recent years,with the development of science,technology and economy,the research on fluorescent conjugated polymers have been further developed.Because of its special advantages of conjugate structure,it has a wide range of applications in the field of photoelectrics,fluorescence sensing and bio-detection.Based on literature and our research group's previous work in this filed,the structure of diketopyrrolopyrrole(DPP)was introduced into the main chain of the conjugated polymer to prepare novel fluorescent conjugated polymers;and the properites of polymer in solutions were studied and application of synthetic conjugated polymers in fluorescence sensing were carried out.Moreover,the fluorescence color tuning of the conjugated polymer were achieved by adjusting the structure of the conjugated main chain.The specific contents are as follows:System 1:Two brominated substituted diketopyrrolopyrrole(DPP)monomers with different side chains were designed and synthesized.With 1,4-diethynyl-p-phenoxydiacetate dodecanoate,two kinds of conjugated polymers containing diketopyrrolopyrrole(DPP)in the main chain and the side chains contained different groups were synthesized by Sonogashira coupling.The side chains contained tert-butoxycarbonyl group of PPE-DPP1 and side chains contained long alkanes group of PPE-DPP2.These polymers were characterized by 1H NMR,FTIR,elemental analysis and GPC.The results show that we successfully synthesized the expected two conjugated polymers.We characterized the photophysical properties of polymers such as UV absorption and fluorescence emission in different organic solvents,indicating that the two conjugated polymers have good luminescence properties.Due to the difference in the structure of the two polymer side chains,we explored the effects of different side chain structures on the solubility and photophysical properties of polymer.The application of polymer synthesized above in fluorescence sensing were explored.The polymer PPE-DPP1 had different detection responses to common anions(including OH-,F-,Cl-,Br-,I-and AcO-)within 24 hours.Meanwhile,Same exploration were also carried out on PPE-DPP2.The results show that the polymer PPE-DPP2 has different detection responses from PPE-DPP1 to anions(including OH-,F-,Cl-,and Br-)in 24 hours.System 2:Based on the successful synthesized monomer containing diketopyrrolopyrrole(DPP)structure in first part,and considering the better solubility of the side chain polymers containing long alkyl groups in organic solvents,diketopyrrolopyrrole(DPP)monomers containing long alkyl chains were chosen for copolymerization.Introduced the structure of diketopyrrolopyrrole(DPP)into the conjugated backbone structure by Suzuki coupling copolymerization with 2,7-dibromo-9,9-dioctylfluorene monomer and 1,4-benzenediborate.Six conjugated polymers were synthesized by adjusting the feeding ratio between diketopyrrolopyrrole(DPP)monomer and 2,7-dibromo-9,9-dioctylfluorene monomer.to realize the tuning of the fluorescent color of the conjugated polymers.Six polymers were characterized by 1H NMR,FTIR,elemental analysis and GPC.The results showed that these conjugated polymers were successfully synthesized.The photophysical properties of these six polymers showed that the fluorescent color tuning of the conjugated polymers were achieved.Combined with the digital photograph of the polymer solution,it can be seen that the fluorescent color of the polymer solution range from the yellow to blue,meeting our expectation.