Quantifying intermolecular interactions of ionic liquids using cohesive energy densities
For ionic liquids (ILs), both the large number of possible cation + anion combinations and their ionic nature provide a unique challenge for understanding intermolecular interactions. Cohesive energy density, ced, is used to quantify the strength of intermolecular interactions for molecular liquids,...
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| Format: | Article |
| Language: | English |
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The Royal Society
2017-01-01
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| Series: | Royal Society Open Science |
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| Online Access: | https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.171223 |
| _version_ | 1818187658300489728 |
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| author | Kevin R. J. Lovelock |
| author_facet | Kevin R. J. Lovelock |
| author_sort | Kevin R. J. Lovelock |
| collection | DOAJ |
| description | For ionic liquids (ILs), both the large number of possible cation + anion combinations and their ionic nature provide a unique challenge for understanding intermolecular interactions. Cohesive energy density, ced, is used to quantify the strength of intermolecular interactions for molecular liquids, and is determined using the enthalpy of vaporization. A critical analysis of the experimental challenges and data to obtain ced for ILs is provided. For ILs there are two methods to judge the strength of intermolecular interactions, due to the presence of multiple constituents in the vapour phase of ILs. Firstly, cedIP, where the ionic vapour constituent is neutral ion pairs, the major constituent of the IL vapour. Secondly, cedC+A, where the ionic vapour constituents are isolated ions. A cedIP dataset is presented for 64 ILs. For the first time an experimental cedC+A, a measure of the strength of the total intermolecular interaction for an IL, is presented. cedC+A is significantly larger for ILs than ced for most molecular liquids, reflecting the need to break all of the relatively strong electrostatic interactions present in ILs. However, the van der Waals interactions contribute significantly to IL volatility due to the very strong electrostatic interaction in the neutral ion pair ionic vapour. An excellent linear correlation is found between cedIP and the inverse of the molecular volume. A good linear correlation is found between IL cedIP and IL Gordon parameter (which are dependent primarily on surface tension). ced values obtained through indirect methods gave similar magnitude values to cedIP. These findings show that cedIP is very important for understanding IL intermolecular interactions, in spite of cedIP not being a measure of the total intermolecular interactions of an IL. In the outlook section, remaining challenges for understanding IL intermolecular interactions are outlined. |
| first_indexed | 2024-12-11T23:14:32Z |
| format | Article |
| id | doaj.art-ea9dc3f396b64f26a895a67234c25e9c |
| institution | Directory Open Access Journal |
| issn | 2054-5703 |
| language | English |
| last_indexed | 2024-12-11T23:14:32Z |
| publishDate | 2017-01-01 |
| publisher | The Royal Society |
| record_format | Article |
| series | Royal Society Open Science |
| spelling | doaj.art-ea9dc3f396b64f26a895a67234c25e9c2022-12-22T00:46:35ZengThe Royal SocietyRoyal Society Open Science2054-57032017-01-0141210.1098/rsos.171223171223Quantifying intermolecular interactions of ionic liquids using cohesive energy densitiesKevin R. J. LovelockFor ionic liquids (ILs), both the large number of possible cation + anion combinations and their ionic nature provide a unique challenge for understanding intermolecular interactions. Cohesive energy density, ced, is used to quantify the strength of intermolecular interactions for molecular liquids, and is determined using the enthalpy of vaporization. A critical analysis of the experimental challenges and data to obtain ced for ILs is provided. For ILs there are two methods to judge the strength of intermolecular interactions, due to the presence of multiple constituents in the vapour phase of ILs. Firstly, cedIP, where the ionic vapour constituent is neutral ion pairs, the major constituent of the IL vapour. Secondly, cedC+A, where the ionic vapour constituents are isolated ions. A cedIP dataset is presented for 64 ILs. For the first time an experimental cedC+A, a measure of the strength of the total intermolecular interaction for an IL, is presented. cedC+A is significantly larger for ILs than ced for most molecular liquids, reflecting the need to break all of the relatively strong electrostatic interactions present in ILs. However, the van der Waals interactions contribute significantly to IL volatility due to the very strong electrostatic interaction in the neutral ion pair ionic vapour. An excellent linear correlation is found between cedIP and the inverse of the molecular volume. A good linear correlation is found between IL cedIP and IL Gordon parameter (which are dependent primarily on surface tension). ced values obtained through indirect methods gave similar magnitude values to cedIP. These findings show that cedIP is very important for understanding IL intermolecular interactions, in spite of cedIP not being a measure of the total intermolecular interactions of an IL. In the outlook section, remaining challenges for understanding IL intermolecular interactions are outlined.https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.171223ionic liquidscohesive energy densityintermolecular interactions |
| spellingShingle | Kevin R. J. Lovelock Quantifying intermolecular interactions of ionic liquids using cohesive energy densities Royal Society Open Science ionic liquids cohesive energy density intermolecular interactions |
| title | Quantifying intermolecular interactions of ionic liquids using cohesive energy densities |
| title_full | Quantifying intermolecular interactions of ionic liquids using cohesive energy densities |
| title_fullStr | Quantifying intermolecular interactions of ionic liquids using cohesive energy densities |
| title_full_unstemmed | Quantifying intermolecular interactions of ionic liquids using cohesive energy densities |
| title_short | Quantifying intermolecular interactions of ionic liquids using cohesive energy densities |
| title_sort | quantifying intermolecular interactions of ionic liquids using cohesive energy densities |
| topic | ionic liquids cohesive energy density intermolecular interactions |
| url | https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.171223 |
| work_keys_str_mv | AT kevinrjlovelock quantifyingintermolecularinteractionsofionicliquidsusingcohesiveenergydensities |