Kowalski Sebastian, Allard Sybille, Scherf Ullrich
Bergische Universität Wuppertal, makrobuw and Institute for Polymer Technology, Gauss-Str. 20, D-42119, Wuppertal, Germany.
Macromol Rapid Commun. 2015 Jun;36(11):1061-8. doi: 10.1002/marc.201400557. Epub 2014 Dec 4.
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.
直接芳基化缩聚反应是目前用于共轭聚合物合成的芳基-芳基偶联方案的一种有前景的替代方法，其特点是对环境的潜在影响较小且成本降低。然而，到目前为止，这种新方法的适用范围和局限性尚未完全了解。在此，有两个主要方面：i）在未活化的二卤代芳族单体偶联过程中发生的副反应的化学性质，以及ii）空间和电子因素对单体反应性的影响。在本通讯中，研究了用于直接芳基化合成交替共聚物聚（4,4-（2-乙基己基）-环戊并[2,1-b：3,4-b']二噻吩-alt-2,1,3-苯并噻二唑）（PCPDTBT）的4,4-双（2-乙基己基）-环戊并[1,2-b：5,4-b']二噻吩（CPDT）/2,1,3-苯并噻二唑（BT）单体对，并确定均偶联为主要的副反应。该研究表明，通过巧妙选择反应条件，几乎可以完全抑制均偶联。最后，研究结果表明，主要是电子因素控制了两种单体的反应性。
