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Atropisomeric Hydrogen Bonding Control for CO2 Binding and Electrocatalytic Reduction Enhancement at Iron Porphyrins.
Angewandte Chemie International Edition ( IF 16.1 ) Pub Date : 2020-09-09 , DOI: 10.1002/anie.202010859
Philipp Gotico 1, 2 , Loïc Roupnel 1 , Regis Guillot 1 , Marie Sircoglou 1 , Winfried Leibl 2 , Zakaria Halime 1 , Ally Aukauloo 1, 2
Affiliation  

The manipulation of the second coordination sphere for improving the electrocatalytic CO2 reduction has led to breakthroughs with hydrogen bonding, local proton source, or electrostatic effects. We have developed two atropisomers of an iron porphyrin complex with two urea functions acting as multiple hydrogen‐bonding tweezers to lock the metal‐bound CO2 in a similar fashion found in the carbon monoxide dehydrogenase (CODH) enzyme. The αα topological isomer with the two urea groups on the same side of the porphyrin provides a stronger binding affinity to tether the incoming CO2 in comparison to the αβ disposition. However, the electrocatalytic activity of the αβ atropisomer outperforms its congener with one of the highest reported turnover frequencies at low overpotential. The strong H/D kinetic isotope effect (KIE) observed for the αα system indicates the existence of a tight water hydrogen‐bonding network for proton delivery which is disrupted by addition of an acid source. The small H/D KIE for the αβ isomer and the enhanced electrocatalytic performance on addition of stronger acid indicate the free access of protons to the bound CO2 on the opposite side of the urea arm.

中文翻译:

阻转异构氢键控制二氧化碳结合和电催化还原铁卟啉。

为了改善电催化CO 2还原而对第二配位球的操纵已导致氢键,局部质子源或静电效应方面的突破。我们已经开发了具有两个尿素功能的卟啉铁配合物的两个阻转异构体,它们充当多个氢键镊子,以一氧化碳脱氢酶(CODH)酶的相似方式锁定金属结合的CO 2。卟啉同一侧带有两个脲基的αα拓扑异构体对引入的CO 2束缚更强的结合亲和力与αβ的布置相比。但是,αβ阻转异构体的电催化活性在低超电势下表现出最高的转换频率之一,优于同类产品。对αα系统观察到的强H / D动力学同位素效应(KIE)表明存在一个紧密的氢氢键网络,用于质子传递,但会因添加酸源而被破坏。αβ异构体的H / D KIE小,加入强酸后电催化性能增强,表明质子可自由进入尿素臂另一侧的结合CO 2
更新日期:2020-09-09
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