Proton hydration in aqueous solution: Fourier transform infrared studies of HDO spectra
Proton hydration in aqueous solution: Fourier transform infrared studies of HDO spectra
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DOI：
10.1063/1.2374891
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发表时间：
2006-11-28
影响因子：
4.4
通讯作者：
Stangret, Janusz
中科院分区：
文献类型：
--
作者：
Smiechowski, Maciej;Stangret, Janusz
本文试图阐明水溶液中质子周围水合球的数量和性质。这种现象进行了研究，在选定的酸的水溶液中，通过傅里叶变换红外光谱的半重水（HDO），同位素稀释在H2O。首次将差谱定量方法应用于此类体系的研究。它允许去除本体水的贡献和分离的光谱溶质影响的HDO。所获得的光谱数据面临的小气相和极化连续模型（PCM）的溶剂化水溶液团簇，H+（H2O）（n），n=2-8的从头计算结构，以帮助建立连续水合质子的水合球的结构和能量状态。这是通过比较计算出的最佳几何结构与来自HDO带位置的原子间距离来实现的。第一水合球体外的质子水合壳层的结构基本上遵循其他水合阳离子的模型结构，先前通过受影响的HDO光谱揭示。稀释的水溶液中的第一水合球络合物被鉴定为常规Zundel阳离子的不对称变体[The Hydrogen Bond：Recent Developments in Theory and Experiments，edited by P. Schuster，G. Zundel和C. Sandorfy（North-Holland，Amsterdam，1976），Vol. II，p. 683]，介于理想的Zundel和Eigen结构之间[E. Wicke，Z. Phys. Chem. Neue Folge 1，340（1954）]。实验测得的氧-氧距离平均为2.435A，PCM计算值约为2.41- 2.44A。首次证明了质子具有四个明确的水化球，并根据氢键的长度和排列对其进行了表征。此外，外部水化层，共享的阴离子，以及松散结合的水分子与自由电子对的中心复杂的受影响的光谱中检测。(c)2006年，美国物理学会。
This paper attempts to elucidate the number and nature of the hydration spheres around the proton in an aqueous solution. This phenomenon was studied in aqueous solutions of selected acids by means of Fourier transform infrared spectroscopy of semiheavy water (HDO), isotopically diluted in H2O. The quantitative version of difference spectrum procedure was applied for the first time to investigate such systems. It allowed removal of bulk water contribution and separation of the spectra of solute-affected HDO. The obtained spectral data were confronted with ab initio calculated structures of small gas-phase and polarizable continuum model (PCM) solvated aqueous clusters, H+(H2O)(n), n=2-8, in order to help in establishing the structural and energetic states of the consecutive hydration spheres of the hydrated proton. This was achieved by comparison of the calculated optimal geometries with the interatomic distances derived from HDO band positions. The structure of proton hydration shells outside the first hydration sphere essentially follows the model structure of other hydrated cations, previously revealed by affected HDO spectra. The first hydration sphere complex in diluted aqueous solutions was identified as an asymmetric variant of the regular Zundel cation [The Hydrogen Bond: Recent Developments in Theory and Experiments, edited by P. Schuster, G. Zundel, and C. Sandorfy (North-Holland, Amsterdam, 1976), Vol. II, p. 683], intermediate between the ideal Zundel and Eigen structures [E. Wicke , Z. Phys. Chem. Neue Folge 1, 340 (1954)]. Evidence was found for the existence of strong and short hydrogen bonds, with oxygen-oxygen distance derived from the experimental affected spectra equal 2.435 A on average and in the PCM calculations about 2.41-2.44 A. It was also evidenced for the first time that the proton possesses four well-defined hydration spheres, which were characterized in terms of hydrogen bonds' lengths and arrangements. Additionally, an outer hydration layer, shared with the anion, as well as loosely bound water molecules interacting with free electron pairs of the central complex were detected in the affected spectra. (c) 2006 American Institute of Physics.