Insights into the Solvation and Mobility of the Hydroxyl Radical in Aqueous Solution.
Insights into the Solvation and Mobility of the Hydroxyl Radical in Aqueous Solution.
复制标题
深入了解水溶液中羟基自由基的溶剂化和迁移性。
DOI：
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发表时间：
2011
影响因子：
5.5
通讯作者：
P. Kusalik
中科院分区：
文献类型：
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作者：
Edelsys Codorniu;P. Kusalik
通过Car-Parrinello分子动力学模拟，详细描述了近环境条件下水溶液中羟基自由基（OH*）的局部溶剂化结构和迁移率。在这里，我们证明了对于HCTH/120和BLYP泛函，较小的系统（即，31·H2O-OH*）受到系统尺寸效应的污染，由于水分子的氧原子和自由基之间存在三电子两中心半键结构而偏置。相对较大的63·H2O-OH* 体系的径向和空间分布函数揭示了存在一个4重配位的“非活性”OH* 结构，该结构具有三个氢键供体邻居和一个强配位的氢键受体邻居。自由基周围的局部水合结构表现出更多的H-键有序比最近的模拟采用经典力场预测。局部结构波动可以以来自最近的H-键供体水分子的自发H-转移反应结束，通过形成“活性”OH* 状态促进，类似于水合OH（-）的质子转移机制（即，（H3 O2）* 络合物的轻微极化）。还提供了由DFT泛函和两种系统尺寸获得的H-转移反应的自由能垒的比较，表明这可以是一个非常快速的过程中的水。
A detailed description of the local solvation structure and mobility of hydroxyl radicals (OH*) in aqueous solution near ambient conditions is provided by Car-Parrinello molecular dynamics simulations. Here, we demonstrate that for HCTH/120 and BLYP functionals, smaller systems (i.e., 31·H2O-OH*) are contaminated by system size effects, being biased for the presence of a three-electron two-centered hemibond structure between the oxygen atoms of a water molecule and the radical. Radial and spatial distribution functions of relatively large 63·H2O-OH* systems reveal the existence of a 4-fold coordinated "inactive" OH* structure with three H-bond donating neighbors and a strongly coordinated H-bond accepting neighbor. The local hydration structure around the radical exhibits more H-bond ordering than has been predicted by recent simulations employing classical force fields. Local structural fluctuations can end with spontaneous H-transfer reactions from the nearest H-bond donor water molecule, facilitated by the formation of an "active" OH* state, resembling the proton transfer mechanism of hydrated OH(-) (i.e., slight polarization of the (H3O2)* complex). A comparison of the free energy barriers for the H-transfer reaction obtained by both DFT functionals and for both system sizes is also provided, demonstrating that this can be a very rapid process in water.
影响因子：
2.9
作者：
Allodi, Marco A.;Dunn, Meghan E.;Shields, George C.
通讯作者：
Shields, George C.