Synthesis And Properties Of Conjugated Polymers Containing Ethylenedioxythiophene Substituted Acenaphthenequinoxaline

Compounds with quinoxaline aromatic rings which have an electron-deficient nature are used as raw materials for organic light-emitting devices, light-emitting cells and optoelectronic devices. Although preparation and electrochromic properties of quinoxaline containing polymers have drawn a wide interest, planar fused acenaphthene substituted quinoxaline unit has not been paid much attention. On the other hand, thiophenes are belonging to the most typical electron-rich aromatic rings used in CT-type structure. Compared with thiophene, while the polymerization of 3,4-ethylenedioxythiophene theα-βandβ-βmislinkage are forbidden by blocking theβpositions of the thiophene units with the electron donating oxygen atoms, and the ethylene bridges minimize steric distortion effects resulting in a high stereo regularity of the polymer chain so that goodπ-conjugation is guaranteed. Hence in this paper we have successfully synthesized bis-3,4-ethylenedioxythiophene substituted acenaphthe -nequinoxaline. The main content is as follows:A new EDOT-substituted acenaphthenequinoxaline was synthesized via Stille coupling reaction, which has a low oxidation potential of 0.73 V vs. Ag/Ag+, and was electrochemically polymerized. The electrochemically coated polymer film exhibited electrochromic behavior between -2 V and +1.5 V vs. Ag/Ag+. The film color changed from more green (neutral) to transmissive light blue in the oxidized state and reddish in the reduced state. Considering these properties, this polymer can be utilized in electrochromic device applications.Poly (8,11-bis(3, 4-ethylenedioxy -thiophen-2-yl) acenaphtho [1, 2-b]quinoxaline) (PBEAQ) was synthesized by oxidative solution or solid-state polymerization using ferric chloride (Ⅲ) as an oxidant. The optimum mole ratios of monomer to oxidant and polymerization method were selected by comparison of the conductivity and electrochemical performances of the obtained polymers. Results show that the solid-state polymerized polymer using monomer/oxidant mole ratio of 1/2 possessed high specific capacitance and good cyclic performance, having the initial capacity of 114 F.g-1 and kept 94% of the initial value at 1000th cycle. For the purpose of increasing conductivity of the polymer, using the optimum condition of solid-state polymerization we synthesized polymers doped with some of sulfonic acids. Results show that when the naphthalene sulfonic acid was used as a dopant the conductivity of the polymer increased by 10000 times. But other electrochemical properties were remaining almost unchanged.Two copolymers of 5,8-bis(3,4-ethylenedioxythiophenyl)-acenaphthenequino -xaline with 1,4-Diethynyl-2,5-dialkoxybenze were synthesized by Sonogashira reaction. The obtained copolymers are soluble in common organic solvents and have a certain thermal stability and were electrochemically active.