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Burba CM, Frech R. Existence of optical phonons in the room temperature ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate. J Chem Phys 2011; 134:134503. [PMID: 21476760 DOI: 10.1063/1.3571458] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The technologically important properties of room temperature ionic liquids (RTILs) are fundamentally linked to the ion-ion interactions present among the constituent ions. These ion-ion interactions in one RTIL (1-ethyl-3-methylimidazolium trifluoromethanesulfonate, [C(2)mim]CF(3)SO(3)) are characterized with transmission FTIR spectroscopy and polarized attenuated total reflection (ATR) FTIR spectroscopy. A quasilattice model is determined to be the best framework for understanding the ionic interactions. A novel spectroscopic approach is proposed to characterize the degree of order that is present in the quasilattice by comparing the dipole moment derivative calculated from two independent spectroscopic measurements: (1) the TO-LO splitting of a vibrational mode using dipolar coupling theory and (2) the optical constants of the material derived from polarized ATR experiments. In principle, dipole moment derivatives calculated from dipolar coupling theory should be similar to those calculated from the optical constants if the quasilattice of the RTIL is highly structured. However, a significant disparity for the two calculations is noted for [C(2)mim]CF(3)SO(3), indicating that the quasilattice of [C(2)mim]CF(3)SO(3) is somewhat disorganized. The potential ability to spectroscopically characterize the structure of the quasilattice, which governs the long-range ion-ion interactions in a RTIL, is a major step forward in understanding the interrelationship between the molecular-level interactions among the constituent ions of an ionic liquid and the important physical properties of the RTIL.
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Affiliation(s)
- Christopher M Burba
- Department of Natural Sciences, Northeastern State University, Tahlequah, Oklahoma 74464-2302, USA.
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Burba CM, Rocher NM, Frech R. Hydrogen-Bonding and Ion−Ion Interactions in Solutions of Triflic Acid and 1-Ethyl-3-methylimidazolium Triflate. J Phys Chem B 2009; 113:11453-8. [DOI: 10.1021/jp902276b] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christopher M. Burba
- Department of Natural Sciences, Northeastern State University, Tahlequah, Oklahoma 74464-2302, Department of Materials Engineering, Monash University, Clayton, Victoria 3800 Australia, and Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019-3051
| | - Nathalie M. Rocher
- Department of Natural Sciences, Northeastern State University, Tahlequah, Oklahoma 74464-2302, Department of Materials Engineering, Monash University, Clayton, Victoria 3800 Australia, and Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019-3051
| | - Roger Frech
- Department of Natural Sciences, Northeastern State University, Tahlequah, Oklahoma 74464-2302, Department of Materials Engineering, Monash University, Clayton, Victoria 3800 Australia, and Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019-3051
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Burba CM, Rocher NM, Frech R, Powell DR. Cation−Anion Interactions in 1-Ethyl-3-Methylimidazolium Trifluoromethanesulfonate-Based Ionic Liquid Electrolytes. J Phys Chem B 2008; 112:2991-5. [DOI: 10.1021/jp076577l] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christopher M. Burba
- Department of Natural Sciences, Northeastern State University, Tahlequah, Oklahoma 74464-2302, Department of Materials Engineering, Monash University, Clayton, Victoria 3800, Australia, and Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019-3051
| | - Nathalie M. Rocher
- Department of Natural Sciences, Northeastern State University, Tahlequah, Oklahoma 74464-2302, Department of Materials Engineering, Monash University, Clayton, Victoria 3800, Australia, and Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019-3051
| | - Roger Frech
- Department of Natural Sciences, Northeastern State University, Tahlequah, Oklahoma 74464-2302, Department of Materials Engineering, Monash University, Clayton, Victoria 3800, Australia, and Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019-3051
| | - Douglas R. Powell
- Department of Natural Sciences, Northeastern State University, Tahlequah, Oklahoma 74464-2302, Department of Materials Engineering, Monash University, Clayton, Victoria 3800, Australia, and Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019-3051
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Rocher NM, Frech R, Powell DR. Crystalline and Solution Phases of N,N-Dimethylethylenediamine Complexed with Lithium Triflate and Sodium Triflate: Intramolecular and Intermolecular Hydrogen Bonding. J Phys Chem B 2006; 110:15117-26. [PMID: 16884224 DOI: 10.1021/jp061143w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Infrared and Raman spectroscopy were used to study hydrogen-bonding interactions and the cation coordination effect in solutions of N,N-dimethylethylenediamine (DMEDA) with lithium triflate (LiTf) and sodium triflate (NaTf). A comparison of pure DMEDA with DMEDA dissolved in carbon tetrachloride enabled the separation of the relative contributions of intermolecular and intramolecular hydrogen-bonding interactions to the N-H stretching frequencies. The addition of LiTf and NaTf to DMEDA shifts the N-H stretching frequencies through two competing effects: the cation coordination effect lowers the frequencies, while the disruption of the hydrogen-bonding interactions increases the frequencies. These two effects were distinguished in a study of the concentration dependence of both salts dissolved in DMEDA; the differentiation was based on the difference in the spectral sensitivities of the symmetric and the antisymmetric stretch in both the Raman and infrared spectra. During this study, DMEDA-LiTf and DMEDA-NaTf crystals were discovered, and their structures were solved by X-ray diffraction techniques. The analysis of the vibrational spectra of these crystals was greatly enhanced by unambiguous knowledge of the structural details of cation-molecule and anion-cation interactions. These structure-spectra correlations were used to complement analogous spectroscopic studies in the solution phases. Analysis of spectral regions in both crystalline and solution phases particularly sensitive to the nature and strength of cation-molecule interactions clearly established that the interaction of the lithium ion with the nitrogen atoms of DMEDA was stronger than the sodium ion-DMEDA interaction, as expected from charge density arguments.
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Affiliation(s)
- Nathalie M Rocher
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, USA
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Spectroscopic studies of polymer electrolytes based on poly(N-ethylethylenimine) and poly(N-methylethylenimine). Electrochim Acta 2005. [DOI: 10.1016/j.electacta.2005.02.051] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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