Microsolvation of the Potassium Ion with Aromatic Rings: Comparison between Hexafluorobenzene and Benzene
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- 作者：J. M. C. Marques ; J. L. Llanio-Trujillo ; M. Albert铆 ; A. Aguilar ; F. Pirani
- 刊名：The Journal of Physical Chemistry A
- 出版年：2013
- 出版时间：August 22, 2013
- 年：2013
- 卷：117
- 期：33
- 页码：8043-8053
- 全文大小：471K
- 年卷期：v.117,no.33(August 22, 2013)
- ISSN：1520-5215
文摘
We employ a recently developed methodology to study structural and energetic properties of the first solvation shells of the potassium ion in nonpolar environments due to aromatic rings, which is important to understand the selectivity of several biochemical phenomena. Our evolutionary algorithm is used in the global optimization study of clusters formed of K+ solvated with hexafluorobenzene (HFBz) molecules. The global intermolecular interaction for these clusters has been decomposed in HFBz鈥揌FBz and in K+鈥揌FBz contributions, using a potential model based on different decompositions of the molecular polarizability of hexafluorobenzene. Putative global minimum structures of microsolvation clusters up to 21 hexafluorobenzene molecules were obtained and compared with the analogous K+鈥揵enzene clusters reported in our previous work (J. Phys. Chem. A 2012, 116, 4947鈥?956). We have found that both K+鈥?Bz)n and K+鈥?HFBz)n clusters show a strong magic number around the closure of the first solvation shell. Nonetheless, all K+鈥揵enzene clusters have essentially the same first solvation shell geometry with four solvent molecules around the ion, whereas the corresponding one for K+鈥?HFBz)n is completed with nine HFBz species, and its structural motif varies as n increases. This is attributed to the ion鈥搒olvent interaction that has a larger magnitude for K+鈥揃z than in the case of K+鈥揌FBz. In addition, the ability of having more HFBz than Bz molecules around K+ in the first solvation shell is intimately related to the inversion in the sign of the quadrupole moment of the two solvent species, which leads to a distinct ion鈥搒olvent geometry of approach.