2,2′‐Bipyridine Equipped with a Disulfide/Dithiol Switch for Coupled Two‐Electron and Two‐Proton Transfer,Chemistry - A European Journal

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2,2′‐Bipyridine Equipped with a Disulfide/Dithiol Switch for Coupled Two‐Electron and Two‐Proton Transfer
Chemistry - A European Journal ( IF 3.9 ) Pub Date : 2018-03-06 , DOI: 10.1002/chem.201705022
Mauricio Cattaneo _{1,

2} , Christine E. Schiewer ₁ , Anne Schober ₁ , Sebastian Dechert ₁ , Inke Siewert _{1,

3} , Franc Meyer _{1,

3}

Affiliation

[1,2]Dithiino[4,3‐b:5,6‐b′]dipyridine (1) and its protonated open form 3,3′‐dithiol‐2,2′‐bipyridine (2) were synthesised and their interconversion investigated. The X‐ray structure of 2 revealed an anti orientation of the two pyridine units and a zwitterionic form. In depth electrochemical studies in combination with DFT calculations lead to a comprehensive picture of the redox chemistry of 1 in the absence and presence of protons. Initial one‐electron reduction at E₁=−1.20 V results in the formation of the radical anion 1^red with much elongated S−S bond, which readily undergoes further reduction at E₂=−1.38 V. Water triggers a potential inversion (E≥−1.13 V for the second reduction) as the radical anion 1^red is protonated at its basic N atom. DFT studies revealed that S−S bond breaking and twisting of the pyridine units generally occurs after the second reduction step, whereas the potential inversion induced by protonation is a result of charge compensation. The CV data were simulated to derive rate constants for the individual chemical and electrochemical reactions for both scenarios in the absence and presence of protons.

中文翻译：

配有二硫键/二硫键开关的2,2'-联吡啶，用于双电子和双质子耦合转移

[1,2] Dithiino [4,3-b：5,6-b']双吡啶（1）及其质子化开放形式3,3'-二硫醇-2,2'-联吡啶（2）调查。X射线结构2显示两个吡啶单元的反方向和两性离子形式。深入的电化学研究与DFT计算相结合，可以得出在质子不存在和不存在的情况下1的氧化还原化学的全面情况。在E ₁ = -1.20 V时的初始单电子还原导致形成带有很多S-S键的自由基阴离子1^红色，并易于在E ₂处进一步还原= -1.38 V.水触发电位反转（Ë ≥-1.13 V代表第二减速）作为自由基阴离子1个^红在其基本的N原子质子化。DFT研究表明，吡啶单元的S-S键断裂和扭曲通常发生在第二步还原步骤之后，而质子化诱导的电势反转是电荷补偿的结果。对CV数据进行了仿真，以得出在不存在和存在质子的情况下两种情况下单个化学和电化学反应的速率常数。

更新日期：2018-03-06

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