Microscopic hydration of the sodium chloride ion pair.
Microscopic hydration of the sodium chloride ion pair.
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DOI：
10.1021/ja028522x
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发表时间：
2003-01
影响因子：
15
通讯作者：
A. Mizoguchi;Y. Ohshima;Y. Endo
中科院分区：
文献类型：
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作者：
A. Mizoguchi;Y. Ohshima;Y. Endo
离子对的水合是溶液中发生的各种物理化学现象的重要过程。与有限数量的水溶剂化的离子对的孤立簇被认为是对该过程中涉及的微观相互作用进行批判性评估的模型系统，并且迄今为止的理论研究仅对该主题做出了贡献。在这里，我们报告了水合离子对 NaCl-(H2O)n (n = 1-3) 的结构和内部动力学的首次实验表征。其旋转光谱的测量证明，团簇具有环状形式，其中Na+和Cl-离子分别与溶剂分子的O和H原子发生强烈相互作用。随着水分子的连续添加，Na-Cl距离显着增加。 n = 3 的分离接近最近分子动力学模拟对水溶液中接触离子对状态的预测值。
Hydration of ion pairs is an essential process in various physicochemical phenomena occurring in solutions. Isolated clusters of an ion pair solvated with finite number of waters have been considered as a model system for the critical evaluation of microscopic interactions involved in the process, and theoretical studies have contributed exclusively to the subject up to now. Here we report the first experimental characterization of structure and internal dynamics of hydrated ion pairs, NaCl-(H2O)n (n = 1-3). The measurements of their rotational spectra have proven that the clusters have cyclic forms, in which Na+ and Cl- ions are strongly interacted with the O and H atoms of the solvent molecules, respectively. The Na-Cl distance shows a pronounced increase with the successive addition of water molecules. The separation for n = 3 approaches the value predicted for the contact ion-pair state in aqueous solution by recent molecular dynamics simulations.