Cong Christina, Kim Jaehwan, Gannett Cara N, Abruña Héctor D, Milner Phillip J
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14850, United States.
ACS Appl Polym Mater. 2023 Jan 13;5(1):1056-1066. doi: 10.1021/acsapm.2c02047. Epub 2022 Dec 28.
Strategies for the sustainable synthesis of redox-active organic polymers could lead to next-generation organic electrode materials for electrochemical energy storage, electrocatalysis, and electro-swing chemical separations. Among redox-active moieties, benzils or aromatic 1,2-diones are particularly attractive due to their high theoretical gravimetric capacities and fast charge/discharge rates. Herein, we demonstrate that the cyanide-catalyzed polymerization of simple dialdehyde monomers unexpectedly leads to insoluble redox-active benzil-linked polymers instead of the expected benzoin polymers, as supported by solid-state nuclear magnetic resonance spectroscopy and electrochemical characterization. Mechanistic studies suggest that cyanide-mediated benzoin oxidation occurs by hydride transfer to the solvent, and that the insolubility of the benzil-linked polymers protects them from subsequent cyanolysis. The thiophene-based polymer is an intriguing organic electrode material that demonstrates two reversible one-electron reductions with monovalent cations such as Li and Na but one two-electron reduction with divalent Mg. As such, the tandem benzoin-oxidation polymerization reported herein represents a sustainable method for the synthesis of highly tunable and redox-active organic materials.
氧化还原活性有机聚合物的可持续合成策略可能会催生用于电化学储能、电催化和电摆动化学分离的下一代有机电极材料。在氧化还原活性部分中，联苯甲酰或芳香族1,2 - 二酮因其高理论重量容量和快速充放电速率而特别具有吸引力。在此，我们证明，简单二醛单体的氰化物催化聚合意外地产生了不溶性的氧化还原活性联苯甲酰连接聚合物，而非预期的安息香聚合物，这得到了固态核磁共振光谱和电化学表征的支持。机理研究表明，氰化物介导的安息香氧化是通过氢化物转移到溶剂中发生的，并且联苯甲酰连接聚合物的不溶性保护它们免受随后的氰醇解。基于噻吩的聚合物是一种有趣的有机电极材料，它对诸如Li和Na等单价阳离子表现出两个可逆的单电子还原，但对二价Mg表现出一个双电子还原。因此，本文报道的松香醛氧化聚合串联反应代表了一种合成高度可调谐且具有氧化还原活性的有机材料的可持续方法。
