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Dielectric Interpretation of Specificity of Ion Pairing in Water

Lund, Mikael LU ; Jagoda-Cwiklik, Barbara; Woodward, Clifford E.; Vácha, Robert and Jungwirth, Pavel (2010) In The Journal of Physical Chemistry Letters 1(1). p.300-303
Abstract
We present a dielectric continuum model that, at a semiquantitative level, explains why ion pair formation in water is favored by like-sized ions over unlike-sized pairs. Using both classical and ab initio continuum approaches, we show that the now well-established empirical rule, the so-called “law of matching water affinities”, can be rationalized in terms of ion solvation. Namely, pairing of differently sized ions is weakened due to a shadowing effect where the larger ion shields the smaller ion from the solvent. It is shown that this empirical law ceases to be valid for less polar solvents where strong ion−ion coulomb interactions dominate the pairing free energy. The presented model demonstrates that certain ion-specific effects, such... (More)
We present a dielectric continuum model that, at a semiquantitative level, explains why ion pair formation in water is favored by like-sized ions over unlike-sized pairs. Using both classical and ab initio continuum approaches, we show that the now well-established empirical rule, the so-called “law of matching water affinities”, can be rationalized in terms of ion solvation. Namely, pairing of differently sized ions is weakened due to a shadowing effect where the larger ion shields the smaller ion from the solvent. It is shown that this empirical law ceases to be valid for less polar solvents where strong ion−ion coulomb interactions dominate the pairing free energy. The presented model demonstrates that certain ion-specific effects, such as those connected with the Hofmeister series, can be qualitatively captured by classical continuum electrostatics, although a fully quantitative description would require explicit molecular treatment of the solvent. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
ion pairing, Hofmeister series, dielectric continuum, ion specificity, primitive model of electrolytes, solvation, electrolyte solutions
in
The Journal of Physical Chemistry Letters
volume
1
issue
1
pages
300 - 303
publisher
The American Chemical Society
external identifiers
  • wos:000276905600064
  • scopus:84962376834
ISSN
1948-7185
DOI
10.1021/jz900151f
language
English
LU publication?
yes
id
82a7d83e-e90d-45e4-b5f4-8ac49f2c8cf6 (old id 7763578)
date added to LUP
2010-05-20 10:18:56
date last changed
2018-06-10 04:02:59
@article{82a7d83e-e90d-45e4-b5f4-8ac49f2c8cf6,
  abstract     = {We present a dielectric continuum model that, at a semiquantitative level, explains why ion pair formation in water is favored by like-sized ions over unlike-sized pairs. Using both classical and ab initio continuum approaches, we show that the now well-established empirical rule, the so-called “law of matching water affinities”, can be rationalized in terms of ion solvation. Namely, pairing of differently sized ions is weakened due to a shadowing effect where the larger ion shields the smaller ion from the solvent. It is shown that this empirical law ceases to be valid for less polar solvents where strong ion−ion coulomb interactions dominate the pairing free energy. The presented model demonstrates that certain ion-specific effects, such as those connected with the Hofmeister series, can be qualitatively captured by classical continuum electrostatics, although a fully quantitative description would require explicit molecular treatment of the solvent.},
  author       = {Lund, Mikael and Jagoda-Cwiklik, Barbara and Woodward, Clifford E. and Vácha, Robert and Jungwirth, Pavel},
  issn         = {1948-7185},
  keyword      = {ion pairing,Hofmeister series,dielectric continuum,ion specificity,primitive model of electrolytes,solvation,electrolyte solutions},
  language     = {eng},
  number       = {1},
  pages        = {300--303},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Letters},
  title        = {Dielectric Interpretation of Specificity of Ion Pairing in Water},
  url          = {http://dx.doi.org/10.1021/jz900151f},
  volume       = {1},
  year         = {2010},
}