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Ionic Liquid Vapors in Vacuum: Possibility to Derive Anodic Stabilities from DFT and UPS

[Image: see text] Ultraviolet photoelectron spectroscopy (UPS) investigations of several gas-phase ionic liquid (IL) ion pairs have been conducted. [EMIM][OTF], [PYR(14)][OTF], [EMIM][DCA], [PYR(14)][DCA], [PYR(14)][TCM], [PYR(14)][FSI], [PYR(14)][PF(6)], [S(222)][TFSI], [P(4441)][TFSI], and [EMMIM]...

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Autores principales: Kuusik, Ivar, Kook, Mati, Pärna, Rainer, Kisand, Vambola
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2021
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7931180/
https://www.ncbi.nlm.nih.gov/pubmed/33681566
http://dx.doi.org/10.1021/acsomega.0c05369
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author Kuusik, Ivar
Kook, Mati
Pärna, Rainer
Kisand, Vambola
author_facet Kuusik, Ivar
Kook, Mati
Pärna, Rainer
Kisand, Vambola
author_sort Kuusik, Ivar
collection PubMed
description [Image: see text] Ultraviolet photoelectron spectroscopy (UPS) investigations of several gas-phase ionic liquid (IL) ion pairs have been conducted. [EMIM][OTF], [PYR(14)][OTF], [EMIM][DCA], [PYR(14)][DCA], [PYR(14)][TCM], [PYR(14)][FSI], [PYR(14)][PF(6)], [S(222)][TFSI], [P(4441)][TFSI], and [EMMIM][TFSI] vapor UPS spectra are presented for the first time. The experimental low-binding-energy cutoff value (highest occupied molecular orbital, HOMO energy) of the ionic liquid ion pairs, which is of great interest, has been measured. Many studies use calculated gas-phase electronic properties to estimate the liquid-phase electrochemical stability. Hybrid density functional theory (DFT) calculations have been used to interpret the experimental data. The gas-phase photoelectron spectra in conjunction with the theoretical calculations are able to verify most HOMO energies and assign them to the cation or anion. The hybrid M06 functional is shown to offer a very good description of the ionic liquid electronic structure. In some cases, the excellent agreement between the UPS spectra and the M06 calculation validates the conformer found and constitutes as a first indirect experimental determination of ionic liquid ion-pair structure. Comparisons with recent theoretical studies are made, and implications for electrochemical applications are discussed. The new data provide a much-needed reference for future ab initio calculations and support the argument that modeling of IL cations and anions separately is incorrect.
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spelling pubmed-79311802021-03-05 Ionic Liquid Vapors in Vacuum: Possibility to Derive Anodic Stabilities from DFT and UPS Kuusik, Ivar Kook, Mati Pärna, Rainer Kisand, Vambola ACS Omega [Image: see text] Ultraviolet photoelectron spectroscopy (UPS) investigations of several gas-phase ionic liquid (IL) ion pairs have been conducted. [EMIM][OTF], [PYR(14)][OTF], [EMIM][DCA], [PYR(14)][DCA], [PYR(14)][TCM], [PYR(14)][FSI], [PYR(14)][PF(6)], [S(222)][TFSI], [P(4441)][TFSI], and [EMMIM][TFSI] vapor UPS spectra are presented for the first time. The experimental low-binding-energy cutoff value (highest occupied molecular orbital, HOMO energy) of the ionic liquid ion pairs, which is of great interest, has been measured. Many studies use calculated gas-phase electronic properties to estimate the liquid-phase electrochemical stability. Hybrid density functional theory (DFT) calculations have been used to interpret the experimental data. The gas-phase photoelectron spectra in conjunction with the theoretical calculations are able to verify most HOMO energies and assign them to the cation or anion. The hybrid M06 functional is shown to offer a very good description of the ionic liquid electronic structure. In some cases, the excellent agreement between the UPS spectra and the M06 calculation validates the conformer found and constitutes as a first indirect experimental determination of ionic liquid ion-pair structure. Comparisons with recent theoretical studies are made, and implications for electrochemical applications are discussed. The new data provide a much-needed reference for future ab initio calculations and support the argument that modeling of IL cations and anions separately is incorrect. American Chemical Society 2021-02-15 /pmc/articles/PMC7931180/ /pubmed/33681566 http://dx.doi.org/10.1021/acsomega.0c05369 Text en © 2021 The Authors. Published by American Chemical Society This is an open access article published under an ACS AuthorChoice License (https://creativecommons.org/licenses/by/4.0/) , which permits copying and redistribution of the article or any adaptations for non-commercial purposes.
spellingShingle Kuusik, Ivar
Kook, Mati
Pärna, Rainer
Kisand, Vambola
Ionic Liquid Vapors in Vacuum: Possibility to Derive Anodic Stabilities from DFT and UPS
title Ionic Liquid Vapors in Vacuum: Possibility to Derive Anodic Stabilities from DFT and UPS
title_full Ionic Liquid Vapors in Vacuum: Possibility to Derive Anodic Stabilities from DFT and UPS
title_fullStr Ionic Liquid Vapors in Vacuum: Possibility to Derive Anodic Stabilities from DFT and UPS
title_full_unstemmed Ionic Liquid Vapors in Vacuum: Possibility to Derive Anodic Stabilities from DFT and UPS
title_short Ionic Liquid Vapors in Vacuum: Possibility to Derive Anodic Stabilities from DFT and UPS
title_sort ionic liquid vapors in vacuum: possibility to derive anodic stabilities from dft and ups
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7931180/
https://www.ncbi.nlm.nih.gov/pubmed/33681566
http://dx.doi.org/10.1021/acsomega.0c05369
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