Synthesis And Studies On The Properties Of Conjugated Polymers Containing Thiophene-substituted Quinoxaline

In the past few decades,conjugated polymers have been widely used in the preparation of all kinds of organic optoelectronic devices because of their advantages of high luminous efficiency,good flexibility,light weight and good solution processability.Among them,it is a hot spot in recent years.The structure contains the energy level and band gap of the N-heterocyclic ring,which has high electron affinity and high electron mobility.Therefore,its own and its derivatives are a kind of potential luminescent and photoluminescence materials.In comparison with inorganic materials,conjugated polymers provide unique advantage that band gap,luminous efficiency;solubility can be changed by structural adjustment or chemical modifications.For the above reasons,we brought the advantages of thiophene or 2,2'-bithiophene moiety into the quinoxaline(Qx)polymers and synthetic with rich electron cell that phenylacetylene,fluorene and carbazole respectively in metal catalysis.We got two series,six kinds of Alternate conjugate polymers.are as follows: In addition,using a method based on electrochemical synthesis of Qx polymer unit.The structure of the target polymer was characterized,and the properties of its optical,electrochemistry,acid Chromism,electrochromic and aggregations were tested and discussed one by one.The detailed research content and results are as follows:(1)Through the dehydration cyclization of the resulting monomer 1,2-bis(5-oct-ylthiophen-2-yl)ethane-1,2-dione and 3,6-dibromobenzene-1,2-diamine obtained 5,8-dibromo-2,3-bis(5-oct ylthiophcn-2-yl)quinoxaline(M1).The Sonogashira and Suzuki methods were selected to make M1 alternately copolymerized with phenylene acetylene monomer(M2),9,9-two octyl fluorene monomer(M3)and 3,6-Di bromine-N-noctyl carbazole monomer(M4),and three kinds of polymer P1,P2 and P3 were synthesized.The structure of the target monomers and target polymers were characterized and its photoelectric properties and acid induced discoloration were investigated.P1,P2,P3 onset oxidation potentials were 1.05 V,1.45 V,1.09 V,optical band gap were 2.14 eV,2.49 eV,2.37 eV.(2)Through the dehydration cyclization of the resulting monomer 1,2-bis(5'-octyl-[2,2'-bithiophen]-5-yl)ethane-1,2-dione and 3,6-dibromobenzene-1,2-diamine obtained(M5).M2,M3 and M4 were copolymerized by Sonogashira and Suzuki respectively to get P4,P5 and P6.It is characterized by a series of means,and then its photoelectric properties and acid Chromism properties are discussed.The initial oxidation potentials of P4,P5 and P6 are 1.25 V,1.53 V and 1.31 V,respectively.The spectral gap is 2.16 eV,2.37 eV and 2,27 eV.(3)P7 was synthesized by M5,and then P7 was obtained by electrochemical polymerization.The optical gap and electrochemical energy gap of P7 are 1.40 eV and 1.82 eV.P7 has p and n doping behavior and electrochromic behavior.The optical contrast of P7 at 620 nm is 20 %,and the response time is 1.43 s.