Unusual Influence of Fluorinated Anions on the Stretching Vibrations of Liquid Water

Maciej Śmiechowski

doi:10.1021/acs.jpcb.7b11334

Unusual Influence of Fluorinated Anions on the Stretching Vibrations of Liquid Water

Abstract

Infrared (IR) spectroscopy is a commonly used and invaluable tool in the studies of solvation phenomena in aqueous solutions. Concurrently, ab initio molecular dynamics (AIMD) simulations deliver the solvation shell picture at a molecular detail level and allow for a consistent decomposition of the theoretical IR spectrum into underlying spatial correlations. Here, we demonstrate how the novel spectral decomposition techniques can extract important information from the computed IR spectra of aqueous solutions of BF₄⁻ and PF₆⁻, interesting weakly coordinating anions that have been known for a long time to alter the IR spectrum of water in an unusual manner. The distance-dependent spectra of both ions are analyzed using the spectral similarity method that provides a quantitative picture of both the spectrum of the solute-affected solvent and the number of solvent molecules thus altered. We find, in accordance with previous experiments, a considerable blue shift of the ν_OH stretching band of liquid water by 264 cm⁻¹ for BF₄⁻ and 306 cm⁻¹ for PF₆⁻ , with the affected numbers being 3.7 and 4.2, respectively. Considering also the additional information on solute−solvent dipolar couplings delivered by radially and spatially resolved IR spectra, the computational IR spectroscopy based on AIMD simulations is shown to be a viable predictive tool with strong interpretative power.

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Maciej Śmiechowski dr hab. inż.

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Publication version: Accepted or Published Version
DOI:: Digital Object Identifier (open in new tab) 10.1021/acs.jpcb.7b11334
License: Copyright (2018 American Chemical Society)

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Category:: Articles
Type:: artykuł w czasopiśmie wyróżnionym w JCR
Published in:: JOURNAL OF PHYSICAL CHEMISTRY B no. 122, edition 12, pages 3141 - 3152,
ISSN: 1520-6106
Language:: English
Publication year:: 2018
Bibliographic description:: Śmiechowski M.: Unusual Influence of Fluorinated Anions on the Stretching Vibrations of Liquid Water// JOURNAL OF PHYSICAL CHEMISTRY B. -Vol. 122, iss. 12 (2018), s.3141-3152
DOI:: Digital Object Identifier (open in new tab) 10.1021/acs.jpcb.7b11334
Verified by:: Gdańsk University of Technology