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Title: Counter-ion binding and mobility in the presence of hydrophobic polyions – combining molecular dynamics simulations and NMR

Abstract

Counter-ion binding and mobility in aqueous solutions of partially hydrophobic ionene oligoions is studied here by a combination of all-atomic molecular dynamics (MD) simulations and NMR ({sup 19}F and {sup 81}Br nuclei) measurements. We present results for 12, 12–ionenes in the presence of different halide ions (F{sup −}, Cl{sup −}, Br{sup −} and I{sup −}), as well as their mixtures; the latter allowing us to probe counter-ion selectivity of these oligoions. We consolidate both structural and dynamic information, in particular simulated radial distribution functions and average residence times of counter-ions in the vicinity of ionenes and NMR data in the form of counter-ion chemical shift and self-diffusion coefficients. On one hand, previously reported enthalpy of dilution and mixing measurements show a reverse counter-ion sequence for 12, 12–ionenes with respect to their less hydrophobic 3, 3– and 6, 6– analogues. On the other hand, the current MD and NMR data, reflecting the counter-ion binding tendencies to the ionene chain, give evidence for the same ordering as that observed by MD for 3, 3–ionenes. This is not seen as a contradiction and can be rationalized on the basis of increasing chain hydrophobicity, which has different consequences for enthalpy and ion-binding. The lattermore » is reflecting free energy changes and as such includes both enthalpic and entropic contributions.« less

Authors:
 [1]; ;  [2];  [3]
  1. Institute for Condensed Matter Physics, Svientsitskii 1, 79011 Lviv (Ukraine)
  2. Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8234, PHENIX, F-75005, Paris (France)
  3. Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana (Slovenia)
Publication Date:
OSTI Identifier:
22611553
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 6; Journal Issue: 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; AQUEOUS SOLUTIONS; BROMINE 81; COMPUTERIZED SIMULATION; DISTRIBUTION FUNCTIONS; ENTHALPY; FLUORINE 19; FREE ENERGY; HALIDES; IONS; MOBILITY; MOLECULAR DYNAMICS METHOD; NUCLEAR MAGNETIC RESONANCE; SELF-DIFFUSION; SPATIAL DISTRIBUTION

Citation Formats

Druchok, Maksym, Malikova, Natalie, Rollet, Anne-Laure, and Vlachy, Vojko, E-mail: vojko.vlachy@fkkt.uni-lj.si. Counter-ion binding and mobility in the presence of hydrophobic polyions – combining molecular dynamics simulations and NMR. United States: N. p., 2016. Web. doi:10.1063/1.4954292.
Druchok, Maksym, Malikova, Natalie, Rollet, Anne-Laure, & Vlachy, Vojko, E-mail: vojko.vlachy@fkkt.uni-lj.si. Counter-ion binding and mobility in the presence of hydrophobic polyions – combining molecular dynamics simulations and NMR. United States. doi:10.1063/1.4954292.
Druchok, Maksym, Malikova, Natalie, Rollet, Anne-Laure, and Vlachy, Vojko, E-mail: vojko.vlachy@fkkt.uni-lj.si. 2016. "Counter-ion binding and mobility in the presence of hydrophobic polyions – combining molecular dynamics simulations and NMR". United States. doi:10.1063/1.4954292.
@article{osti_22611553,
title = {Counter-ion binding and mobility in the presence of hydrophobic polyions – combining molecular dynamics simulations and NMR},
author = {Druchok, Maksym and Malikova, Natalie and Rollet, Anne-Laure and Vlachy, Vojko, E-mail: vojko.vlachy@fkkt.uni-lj.si},
abstractNote = {Counter-ion binding and mobility in aqueous solutions of partially hydrophobic ionene oligoions is studied here by a combination of all-atomic molecular dynamics (MD) simulations and NMR ({sup 19}F and {sup 81}Br nuclei) measurements. We present results for 12, 12–ionenes in the presence of different halide ions (F{sup −}, Cl{sup −}, Br{sup −} and I{sup −}), as well as their mixtures; the latter allowing us to probe counter-ion selectivity of these oligoions. We consolidate both structural and dynamic information, in particular simulated radial distribution functions and average residence times of counter-ions in the vicinity of ionenes and NMR data in the form of counter-ion chemical shift and self-diffusion coefficients. On one hand, previously reported enthalpy of dilution and mixing measurements show a reverse counter-ion sequence for 12, 12–ionenes with respect to their less hydrophobic 3, 3– and 6, 6– analogues. On the other hand, the current MD and NMR data, reflecting the counter-ion binding tendencies to the ionene chain, give evidence for the same ordering as that observed by MD for 3, 3–ionenes. This is not seen as a contradiction and can be rationalized on the basis of increasing chain hydrophobicity, which has different consequences for enthalpy and ion-binding. The latter is reflecting free energy changes and as such includes both enthalpic and entropic contributions.},
doi = {10.1063/1.4954292},
journal = {AIP Advances},
number = 6,
volume = 6,
place = {United States},
year = 2016,
month = 6
}
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