Kumar Divyaratan, Gueskine Viktor, Khan Ziyauddin, Crispin Reverant, Vagin Mikhail
Laboratory of Organic Electronics, Department of Science and Technology, Linköping University, Norrköping SE-60174, Sweden.
Wallenberg Wood Science Center, ITN, Linköping University, Norrköping SE-60174, Sweden.
ACS Omega. 2024 Sep 5;9(37):38498-38505. doi: 10.1021/acsomega.4c03621. eCollection 2024 Sep 17.
Quinol/quinone equilibria are ubiquitous in nature and find multiple technological applications, most recently in electrical charge storage. Much research has been devoted to proton-coupled electron transfer (PCET) in such systems and to bidentate complexation of -quinol (catechol) ligands with multivalent metal ions but rarely to the interplay of these two reactions. Here, we investigate the impact of a redox-inactive metal ion, as a complexing and charge-compensating agent, on redox processes of catechol in aqueous solutions, that is, in the presence of proton equilibria. We pay separate attention to their thermodynamics and kinetics, which can be regulated by the pH and buffer capacity. As the proton buffer concentration decreases, proton equilibria during catechol PCET are slower to establish, thus kinetically prioritizing the participation of the metal ion rather than the proton in the redox charge compensation. Making use of this kinetic interplay can be a general strategy to conceive organic battery cathodes for proton-free metal-ion aqueous batteries.
醌醇/醌平衡在自然界中普遍存在，并具有多种技术应用，最近在电荷存储方面有所应用。许多研究致力于此类体系中的质子耦合电子转移（PCET）以及醌醇（儿茶酚）配体与多价金属离子的双齿络合，但很少关注这两个反应之间的相互作用。在这里，我们研究了一种氧化还原惰性金属离子作为络合剂和电荷补偿剂对水溶液中儿茶酚氧化还原过程的影响，即在存在质子平衡的情况下。我们分别关注它们的热力学和动力学，这可以通过pH值和缓冲容量来调节。随着质子缓冲剂浓度降低，儿茶酚PCET过程中的质子平衡建立得较慢，因此在动力学上优先考虑金属离子而非质子参与氧化还原电荷补偿。利用这种动力学相互作用可能是构思无质子金属离子水系电池有机电池阴极的通用策略。
