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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Effect of Cycling Ion and Solvent on the Redox Chemistry of Substituted Quinones and Solvent-Induced Breakdown of the Correlation between Redox Potential and Electron-Withdrawing Power of Substituents
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Effect of Cycling Ion and Solvent on the Redox Chemistry of Substituted Quinones and Solvent-Induced Breakdown of the Correlation between Redox Potential and Electron-Withdrawing Power of Substituents

机译：循环离子和溶剂对取代醌氧化还原化学的影响及溶剂诱导的氧化还原电位与取代基电子抽取力的相关性分解

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摘要

Quinones have a capacity for high energy storage and exhibit facile and reversible electrochemistry in several widely different electrolytes. They are, therefore, one of the most popular compounds currently used in organic materials based electrical energy storage. Quinone electrochemistry is, however, strongly affected by the composition of the electrolyte. This report summarizes our systematic investigation of the redox chemistry of a series of quinones with electron-withdrawing and electron-donating substituents in aqueous solution and in acetonitrile (MeCN) with tetrabutylammonium (TBA(+))-, Li+-, and H+-based electrolytes. As a general trend, proton cycling, TBA(+) cycling, and Li+ cycling resulted in the highest, the lowest, and intermediate redox potentials, respectively. We attribute this trend to stabilization of the reduced state, namely benzene-1,4-bis(olate) (Q(2-)), by the different counterions. Density functional theory (DFT) calculations showed that, in the fully reduced state, two Li+ counterions accommodated 35% of the injected electron charges while proton counterions accommodated 69% of the injected charge, thus significantly stabilizing the reduced state. However, with the bulky TBA+ as the cycling ion, this stabilization was not possible and the reduction potential was decreased. In addition, we showed that stabilization of the counterion also affected the Coulombic interaction between the successively injected charges, resulting in the well-known disproportionation of the semiquinone radical intermediate state with proton cycling, while Li+ and TBA(+) cycling generally resulted in two consecutive redox reactions. Finally, we showed that the electrolyte strongly influences the effects of substitution with electron-donating and electron-withdrawing substituents. A strong relationship between the redox potential and the electron-withdrawing power of the substituent was observed in the MeCN solution. However, this relationship was completely lost in aqueous solution. The reason for the loss of the relationship was addressed using a DFT explicit-solvent model and is discussed.
机译：Quinones在几个不同的电解质中具有高能量储存和表现出便利和可逆电化学的能力。因此，它们是目前用于基于有机材料的电能存储的最受欢迎的化合物之一。然而，醌电化学受电解质的组成受到强烈影响。本报告总结了我们对水溶液中的一系列醌的氧化还原化学的系统研究和用四丁基铵（TBA（+）） - ，Li + - 和H +基于乙腈（Mecn）的氧丙酮和乙腈（Mecn）的氧化还原化学物质电解质。作为一般趋势，质子循环，TBA（+）循环，Li +循环分别导致最高，最低和中间氧化还原电位。我们将这种趋势归因于稳定的状态，即苯-1,4-双（olate）（Q（2-）），由不同的抗衡度。密度函数理论（DFT）计算显示，在完全降低的状态下，两个Li +抗衡部容纳35％的注入的电子电荷，而质子抗体容纳69％的注入电荷，从而显着稳定降低状态。然而，对于庞大的TBA +作为循环离子，不可能这种稳定化，降低潜力降低。此外，我们表明，抗衡静电也影响了依次注入的电荷之间的库仑相互作用，导致半醌自由基中间状态与质子循环的众所周知的歧化，而Li +和TBA（+）循环通常导致两个连续的氧化还原反应。最后，我们表明电解质强烈影响取代与电子提取取代基的影响。在Mecn溶液中观察到氧化还原电位与取代基的吸电子功率之间的强烈关系。然而，这种关系在水溶液中完全丧失。使用DFT显式溶剂模型解决了丧失关系的原因，并讨论了。

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