Synthesis of well-defined polythiophene with oxyethylene side chain: Effect of phosphine ligands on catalyst-transfer polycondensation
Synthesis of well-defined polythiophene with oxyethylene side chain: Effect of phosphine ligands on catalyst-transfer polycondensation
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DOI：
10.1021/ma061809k
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发表时间：
2006-11-14
期刊：
影响因子：
5.5
通讯作者：
Yokozawa, Tsutomu
中科院分区：
文献类型：
--
作者：
Adachi, Isao;Miyakoshi, Ryo;Yokozawa, Tsutomu
聚（3-烷基噻吩）S1是众所周知的导电聚合物，并且它们的区域选择性合成由McCullough等人2和Rieke等人3开发。聚合被认为通过逐步增长聚合机理进行，但是我们最近报道了2-溴-5-氯镁基-3-己基噻吩与Ni（dppp）-Cl 2（dppp）1的缩聚，3-双（二苯基膦基）丙烷）通过链增长缩聚机理进行，得到具有低多分散性和可控分子量的头-尾聚（3-己基噻吩）（HT-P3 HT）。4对缩聚反应的详细研究表明，聚合物的一端由溴原子封端，另一端由所有聚合物分子中的氢原子封端，并且一个Ni催化剂分子形成一个聚合物链。在此基础上，我们提出了催化转移缩聚反应作为链增长缩聚反应的一种新机理。5，6虽然区域规则的聚（3-烷基噻吩）由于其有用的电子和光学性质而受到广泛关注，但具有醚侧链的聚噻吩显示出独特和有趣的特性。7-11例如，Walree及其同事报道了在ZnSe晶体表面上的聚{3-[2-（2-甲氧基乙氧基）乙氧基]甲基噻吩}（PMEEMT）薄膜表现出适用于LED的氧化电位。11醚官能化聚噻吩的区域选择性合成在与用于聚（3-烷基噻吩）的那些条件类似的条件下进行，8但链生长聚合尚未报道。本文介绍了镍催化剂中膦配体对2-溴-5-氯镁基-3-[2-（2-甲氧基乙氧基）乙氧基]-甲基噻吩（1）聚合的影响。研究发现，配体的选择对1的链增长聚合至关重要，并且1的链增长聚合的最佳配体是1，2-双（二苯基膦基）乙烷（dppe），而不是用于合成聚（3-己基噻吩）的链增长聚合的dppp。McCullough及其同事研究了金属和配体对合成PHT的区域选择性的影响，但是Ni催化剂的配体对链增长聚合的影响还没有报道。（2-甲氧基乙氧基）乙氧基]-甲基噻吩（2）与1当量异丙基氯化镁在0 ℃下反应1小时，通过镁-碘交换反应得到1，13的反应混合物中进行聚合反应，并通过向反应混合物中加入Ni催化剂进行聚合反应（方案1）。我们首先在室温下将1与Ni（dppp）Cl 2在THF中聚合。
Poly (3-alkylthiophene) s1 are well-known conductive polymers, and their regioselective synthesis was developed by McCullough et al. 2 and Rieke et al. 3 The polymerization had been believed to proceed via a step-growth polymerization mechanism, but we recently reported that the polycondensation of 2-bromo-5-chloromagnesio-3-hexylthiophene with Ni (dppp)-Cl2 (dppp) 1, 3-bis (diphenylphosphino) propane) proceeds via a chain-growth polycondensation mechanism to yield head-totail poly (3-hexylthiophene)(HT-P3HT) with low polydispersity and controlled molecular weight. 4 Detailed studies of this polycondensation revealed that one end of the polymer is terminated by a bromine atom and the other end by a hydrogen atom in all the polymer molecules and that one Ni catalyst molecule forms one polymer chain. On the basis of these results, we have proposed catalyst-transfer polycondensation as a new mechanism of chain-growth polycondensation. 5, 6 While regioregular poly (3-alkylthiophene) s have received much attention because of their useful electronic and optical properties, polythiophenes with etheric side chains showed unique and interesting characteristics. 7-11 For example, Walree and coworkers reported that a thin film of poly {3-[2-(2-methoxyethoxy) ethoxy] methylthiophene}(PMEEMT) on a ZnSe singlecrystal surface exhibited suitable oxidative potentials for application in LEDs. 11 The regioselective synthesis of etherfunctionalized polythiophenes was carried out under conditions similar to those used for poly (3-alkylthiophene), 8 but chaingrowth polymerization has not been reported. In this Communication, we describe the effect of the phosphine ligand of the Ni catalyst on the polymerization of 2-bromo-5-chloromagnesio-3-[2-(2-methoxyethoxy) ethoxy]-methylthiophene (1). We found that ligand choice was critical for the chain-growth polymerization of 1 and that the best ligand for the chain-growth polymerization of 1 was 1, 2-bis (diphenylphosphino) ethane (dppe), not dppp, which was used in the chain-growth polymerization for the synthesis of poly (3-hexylthiophene). McCullough and co-workers have examined the effects of metals and ligands on the regioselectivity for the synthesis of PHT, 12 but the influence of the ligand of the Ni catalyst on the chain-growth polymerization has not been reported.Treatment of 2-bromo-5-iodo-3-[2-(2-methoxyethoxy) ethoxy]-methylthiophene (2) with 1 equiv of isopropylmagnesium chloride at 0 C for 1 h gave 1 via magnesium-iodine exchange reaction, 13 and the polymerization was carried out by the addition of Ni catalyst to the reaction mixture (Scheme 1). We first polymerized 1 with Ni (dppp) Cl2 in THF at room temper-