Water (in Water) as an Intrinsically Efficient Proton Acceptor in Concerted Proton Electron Transfers
Water (in Water) as an Intrinsically Efficient Proton Acceptor in Concerted Proton Electron Transfers
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DOI：
10.1021/ja110935c
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发表时间：
2011-05-04
影响因子：
15
通讯作者：
Saveant, Jean-Michel
中科院分区：
文献类型：
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作者：
Bonin, Julien;Costentin, Cyrille;Saveant, Jean-Michel
以光化学生成的Ru-III（bpy）（3）氧化水中的PhOH为原型，揭示了水在溶剂水中作为质子受体参与协同质子-电子转移反应的特殊性质。速率常数随温度和驱动力的变化，以及随温度的变化的H/D动力学同位素效应，允许确定的反应机制，其特征在于由三个内在参数，重组能，一个指前因子测量的电子态的振动耦合在平衡距离，和距离敏感性参数。分析这些特性并与标准碱磷酸氢盐进行比较，发现电子转移与Grotthus型质子易位相一致，导致电荷在涉及几个水分子的簇上离域。因此，一个机制，可能有助于了解质子可以运输沿着水链在大的距离与电子转移在生物系统中。
The oxidation of PhOH in water by photochemically generated Ru-III(bpy)(3) is taken as prototypal example disclosing the special character of water, in the solvent water, as proton acceptor in concerted proton-electron transfer reactions. The variation of the rate constant with temperature and driving force, as well as the variation of the H/D kinetic isotope effect with temperature, allowed the determination of the reaction mechanism characterized by three intrinsic parameters, the reorganization energy, a pre-exponential factor measuring the vibronic coupling of electronic states at equilibrium distance, and a distance-sensitivity parameter. Analysis of these characteristics and comparison with a standard base, hydrogen phosphate, revealed that electron transfer is concerted with a Grotthus-type proton translocation, leading to a charge delocalized over a cluster involving several water molecules. A mechanism is thus uncovered that may help in understanding how protons could be transported along water chains over large distances in concert with electron transfer in biological systems.