Theoretical Chemistry Division Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria.
J Phys Chem B. 2010 Mar 25;114(11):3921-6. doi: 10.1021/jp911860y.
An ab initio quantum mechanical charge field simulation has been carried out in order to obtain molecular level insight into the hydration behavior of HAsO4(-2), one of the major biologically active components of As(V) oxoanion in neutral to slightly alkaline aqueous medium. Moreover, a geometrical definition of hydrogen bonding has been used to probe and characterize both solute-solvent and solvent-solvent hydrogen bonding present in the system. The asymmetry of the anion induced by the protonation of one of the oxygens of the arsenate anion causes rather irregular hydration structure. The nonprotonated oxygen atoms preferably form relatively stable hydrogen bonds with two to three water molecules in their vicinity, while the protonated oxygen forms one or two hydrogen bonds, weaker than water-water hydrogen bonds. The two types of As-O distances obtained from the simulation (1.68 and 1.78 A for the protonated and nonprotonated oxygens, respectively) are in good agreement with the experimental data. The two types of As-O stretching frequencies obtained from the simulation (855 and 660 cm(-1) reproduce well the experimental ATR-FTIR results (859 and 680-700 cm(-1)).
为了深入了解砷（V）氧阴离子在中性到弱碱性水介质中的主要生物活性成分 HAsO4(-2) 的水合行为，我们进行了从头量子力学电荷场模拟。此外，我们还使用了氢键的几何定义来探测和描述系统中存在的溶质-溶剂和溶剂-溶剂氢键。由于砷酸盐阴离子的一个氧原子质子化引起的阴离子不对称性导致了相当不规则的水合结构。未质子化的氧原子与附近的两到三个水分子优先形成相对稳定的氢键，而质子化的氧原子则形成一个或两个氢键，强度弱于水-水氢键。模拟得到的两种类型的 As-O 距离（质子化和非质子化氧的分别为 1.68 和 1.78Å）与实验数据吻合良好。模拟得到的两种类型的 As-O 伸缩振动频率（855 和 660cm(-1)）很好地再现了实验 ATR-FTIR 结果（859 和 680-700cm(-1)）。
