Scope and Limitations of a Direct Arylation Polycondensation Scheme in the Synthesis of PCPDTBT-Type Copolymers
Scope and Limitations of a Direct Arylation Polycondensation Scheme in the Synthesis of PCPDTBT-Type Copolymers
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DOI：
10.1002/marc.201400557
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发表时间：
2015-06-01
影响因子：
4.6
通讯作者：
Scherf, Ullrich
中科院分区：
文献类型：
--
作者：
Kowalski, Sebastian;Allard, Sybille;Scherf, Ullrich
直接芳基化缩聚代表了目前用于共轭聚合物合成的芳基-芳基偶联方案的有前途的替代方案，其特征在于对环境的潜在影响较低并且降低了成本。然而，这种新协议的范围和局限性到现在还没有完全理解。因此，两个主要方面是i）在非活化和二卤代芳族单体的偶联期间发生的副反应的化学性质，和ii）空间和电子因素对单体反应性的影响。本文研究了4，4-双（2-乙基己基）-环戊二烯并[1，2-B：5，4-B]二噻吩（CPDT）/2，1，3-苯并噻二唑（BT）单体对直接芳基化合成交替共聚物聚（4，4-（2-乙基己基）-环戊二烯并[2，1-B：3，4-B]二噻吩-alt-2，1，3-苯并噻二唑）（PCPDTBT），并确定了同偶联为主要副反应。该研究表明，通过巧妙选择反应条件，可以几乎完全抑制同偶联。最后，研究结果表明，主要是电子因素控制两种单体的反应性。
Direct arylation polycondensation represents a promising alternative to the currently used aryl-aryl coupling schemes for conjugated polymer synthesis that is characterized by a potentially lower impact on the environment and reduced costs. However, scope and limitations of this novel protocol are not fully understood until now. Two main aspects are, hereby, i) the chemical nature of side reactions that occur during coupling of nonactivated and dihalogenated aromatic monomers, and ii) the influence of steric and electronic factors on the reactivity of the monomers. Within this communication, the 4,4-bis(2-ethylhexyl)-cyclopenta[1,2-b:5,4-b]dithiophene (CPDT)/2,1,3-benzothiadiazole (BT) monomer couple for direct arylation synthesis of the alternating copolymer poly(4,4-(2-ethylhexyl)-cyclopenta[2,1-b:3,4-b]dithiophene-alt-2,1,3-benzothiadiazole) (PCPDTBT) is studied and homocoupling identified as the dominating side reaction. The study demonstrates that homocoupling can be almost completely suppressed through a clever choice of the reaction conditions. Finally, the findings implicate that mainly electronic factors control the reactivity of both monomers.