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

Quinoxaline is a typical electron-deficient type compounds, and widely used in Photovoltaic cells, organic light emitting due to the features of electro activity. Recently, synthesizing and preparing the quinoxaline-containing polymers and application in organic solar cells and Electrochromic is being one of the interesting research topics. However, there are some published papers about quinoxaline series polymers, the quinoxiline monomers side chain attached with more planer and rich electron rings are rare. Thiophine is a typical electron-rich unit, and linking with some electron-deficient unit electron-transfer type structures can be achieved. Compare thiophene with selenophene, research about selenophene is not so abundant. Selenophene is a simple five-member Heterocyclic aromatic ring, widely used in organic synthesizing, organic electronics and nonlinear materials. chemical structures of the selenophene and thiophe are very close each other, but also has some differences, advantages are; intermolecular interaction between selenophene atoms can facilitates the electron transfer; redox potential of the selenophene is more lower than thiophene; selenophene atoms are more easy to polarize than thiophene; atom radius of the selenophene is larger than thiophene. Thus photoelectric properties of the selenophene are most show some unique feature than thiophene compounds. According to the opinion above mentioned, we synthesized the doner(D) acceptor(A) doner(D)type conjugated molecules, 5, 8- di(selenophen-2-yl) acenaphtho [1,2-b] quinoxaline and 5, 8- di(selenophen- 2-yl) dibenzo [a,c] phenazine, 2, 3- di(4?-octyloxyphenyl)- 5, 8- di(selenophen- 2- yl) quinoxaline and their polymers.1. The 4, 7- dibrom- 2, 1, 3 Benzothiadiazole as a primary material, 5, 8- di(selenophen-2-yl) acenaphtho [1,2-b] quinoxaline(M1) and 5, 8- di(selenophen-2-yl) dibenzo [a,c] phenazine were synthesized. P1 and P2 were prepared by electrochemical polymerization. Test monomers M1 and M2 for acid sensitive, results showed that two acid monomers have good Acid photochromic effect. The optical and electrochemical band gap energies calculated from UV-vis spectrophotometry and cyclic voltammogram of polymer film are 1.49 e V,1.37 e V and 1.19 e V,1.02 e V, respectively. We learned From Cyclic voltammograms of polymer film that the polymer has a p-type and n-type doping behavior. From Spectroelectro-chemistry results, it can be seen that polymers P1,P2 have good electrochromic behavior. Spectroelectrochemistry analysis and kinetic studies indicated that P1 possesses 42.9% optical contrast at 940 nm with a switching time of 1.1 s, while P2 has 20 % optical contrast at 990 nm with a switching time of 1.7 s.2. The 4, 7- dibrom- 2, 1, 3 Benzothiadiazole as a primary material, 2, 3- di(4?-octyloxyphenyl)- 5, 8- di(selenophen- 2- yl) quinoxaline(M4) was synthesized as a primary material 2, 3- di(4?- octyloxyphenyl)- 5, 8- di(selenophen- 2- yl) quinoxaline was synthesized. The optical and electrochemical band gap energies calculated from UV-vis spectrophotometry and cyclic voltammogram of polymer film are 1.45 e V and 1.48 e V, respectively. We learned From Cyclic voltammograms of polymer film that the polymer has a p-type and n-type doping behavior. From Spectroelectro- chemistry results, it can be seen that polymer exhibited electrochromism and the polymer film was changed from dark blue color(neutral state) to transparent pale yelleow color(oxidation state) while potential stepped between 0 V and 1.0 V. As the potential stepwise increased, UV-vis absorption of polymer film at 603 nm decreased and the intensity of new absorption band at 863 nm enhanced. Optical contrast and the response time of the polymer film at 863 nm are 59 % and 1.74 s, respectively.3. Through the bromination of the resulting monomer 2, 3- di(4?- octyloxyphenyl)-5, 8- di(selenophen- 2- yl) quinoxaline obtained 2,3- di(4?- octyloxyphenyl) 5,8-bis(5-dibromo selenophenes yl) quinoxaline(M5). Copolymers P4, P5, P6 were synthesized by alternating copolymerization of p-diethynylbenzene, 9,9 –dioctylfuorene, N-butyl 3,6-dibromo-N-carbazole with monomer through Sonogashira reaction, Suzuki reaction. Monomers and polymers were characterized by FT-IR, 1H-NMR. by UV-visible absorption, fluorescence spectra and cyclic voltammetry and other means to study the photoelectric properties and Acid Induced Discoloration of polymers. Finally, we discuss the relationship between the structure and optoelectronic properties. P4, P5, P6 onset oxidation potentials were 0.98 V, 1.02 V, 0.76 V, the optical band gap of 1.98 e V, 1.93 e V, 1.87 e V.