Proton-Coupled Electron Transfer Drives Long-Range Proton Translocation in Bioinspired Systems
Proton-Coupled Electron Transfer Drives Long-Range Proton Translocation in Bioinspired Systems
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DOI：
10.1021/jacs.9b06978
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发表时间：
2019-09-11
影响因子：
15
通讯作者：
Moore, Ana L.
中科院分区：
文献类型：
--
作者：
Odella, Emmanuel;Wadsworth, Brian L.;Moore, Ana L.
质子耦合电子转移（PCET）结合了基本带电物质的运动，形成了生物能量学和催化中电子和质子传输反应之间的重要联系。质子运输可能发生在PCET过程中的长度尺度和由此产生的质子化学势对驱动这些PCET过程的氧化反应的热力学后果尚未普遍建立。在这里，我们报告的生物启发分子的设计，采用氧化还原过程可逆地移动两个，三个和四个质子通过格罗特胡斯型机制沿着氢键网络高达类似于16埃的长度。这些分子由苯并咪唑部分组成，将苯酚连接到最终的质子受体环己基亚胺。苯酚电化学氧化后，在1660 cm（-1）处出现红外带，表明质子到达了末端碱性位点。将电极电位切换到还原条件逆转质子移位并将结构重置为初始物质。除了模拟光系统II中Tyr（z）-His 190氧化还原继电器用于氧化水的标志性PCET过程的第一步之外，这项工作还在理论上和实验上具体解决了PCET过程可能发生的长度尺度。从这些氧化还原驱动的，生物启发的“质子线”的热力学研究结果有影响的理解和合理设计的泵产生的质子动力在人工和再造光合作用，以及管理质子活性周围的催化位点，包括水的氧化和氧还原。
Proton-coupled electron transfer (PCET) combines the movement of fundamental charged species to form an essential link between electron- and proton-transport reactions in bioenergetics and catalysis in general. The length scale over which proton transport may occur within PCET processes and the thermodynamic consequences of the resulting proton chemical potential to the oxidation reaction driving these PCET processes have not been generally established. Here we report the design of bioinspired molecules that employ oxidation-reduction processes to move reversibly two, three, and four protons via a Grotthuss-type mechanism along hydrogen-bonded networks up to similar to 16 angstrom in length. These molecules are composed of benzimidazole moieties linking a phenol to the final proton acceptor, a cyclohexylimine. Following electrochemical oxidation of the phenol, the appearance of an infrared band at 1660 cm(-1) signals proton arrival at the terminal basic site. Switching the electrode potential to reducing conditions reverses the proton translocation and resets the structure to the initial species. In addition to mimicking the first step of the iconic PCET process used by the Tyr(z)-His190 redox relay in photosystem II to oxidize water, this work specifically addresses theoretically and experimentally the length scale over which PCET processes may occur. The thermodynamic findings from these redox-driven, bioinspired "proton wires" have implications for understanding and rationally designing pumps for the generation of proton-motive force in artificial and reengineered photosynthesis, as well as for management of proton activity around catalytic sites, including those for water oxidation and oxygen reduction.