Molecular Structure, Vibrational Spectra, and Hydrogen Bonding of the Ionic Liquid 1‐Ethyl‐3‐methyl‐1<i>H</i>‐imidazolium Tetrafluoroborate

Katsyuba, Sergey A.; Dyson, Paul J.; Vandyukova, Elena; Чернова, А. В.; Vidiš, Ana

doi:10.1002/hlca.200490228

Cited by 197 publications

(185 citation statements)

References 22 publications

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“…Combined, these data indicate the ion pairing persists in the CD 3 CN solvent, at least to some extent, and the main contact is between the anion and the ring proton at the 2-position as expected. [30,31] In addition, the IR spectra of salts 2-7 show characteristic absorptions of the imidazolium ring. It has been reported that ionic liquids tend to form cation-anion aggregates and these aggregates have been investigated by ESIMS.…”

Section: Resultsmentioning

confidence: 98%

An Internal Fluorescent Probe Based on Anthracene to Evaluate Cation–Anion Interactions in Imidazolium Salts

Fei

Zhu

Yang

et al. 2010

Chemistry A European J

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A series of fluorescent imidazolium-based salts containing the cation [AnCH(2)MeIm](+) (in which An = anthracene and Im = the imidazolium cation) with Cl(-), BF(4)(-), PF(6)(-), SO(3)CF(3)(-), [N(CN)(2)](-), [N(SO(2)CF(3))(2)](-), or PhBF(3)(-) anions have been prepared and characterized. X-ray diffraction analysis of four of the salts reveals a number of C-H...X-type (X = O, N, F) hydrogen bonds between the hydrogen atoms from the imidazolium ring and in some cases from the anthracene ring with the electronegative atoms of the anions. Additionally, C-H...pi interactions can be found in all the salts analyzed by X-ray diffraction, whereas pi-pi stacking is observed only in the salt containing the phenyltrifluoroborate anion. Fluorescence emission analysis in acetonitrile shows that the fluorescence of these salts varies significantly according to the nature of the anion, and correlates to the extent of ion pairing present in solution. Photodimerization of these salts was observed, and in one case a dimer has been isolated and characterized by X-ray crystallography.

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Section: Resultsmentioning

confidence: 98%

An Internal Fluorescent Probe Based on Anthracene to Evaluate Cation–Anion Interactions in Imidazolium Salts

Fei

Zhu

Yang

et al. 2010

Chemistry A European J

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“…À anion in neat [C 2 mim][BF 4 ]; a finding that was later confirmed by IR and Raman spectroscopy [67]. The degree of hydrogen bonding between the ringbound hydrogen atoms and the anion seems to change significantly when going from e.g., a neat chloride to a hexafluorophosphate.…”

Section: N]mentioning

confidence: 85%

“…Similarly, studies were done on [C 2 mim][BF 4 ] and other 1-ethyl-3-methylimidazolium liquid salts [67,127,137]. In the Raman spectral range 200-500 cm À1 , Umebayashi et al [137] for liquids contain- [127].…”

Section: Assigned To Vibrations Associated With the Imidazolium Ring mentioning

confidence: 99%

Raman Spectroscopy and Ab-Initio Model Calculations on Ionic Liquids

2007

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Summary.A review of the recent developments in the study and understanding of room temperature ionic liquids are given. An intimate picture of how and why these liquids are not crystals at ambient conditions is attempted, based on evidence from crystallographical results combined with vibrational spectroscopy and ab-initio molecular orbital calculations. A discussion is given, based mainly on some recent FT-Raman spectroscopic results on the model ionic liquid system of 1-butyl-3-methylimidazolium ([C 4 mim][X]) salts. The rotational isomerism of the [C 4 mim] þ cation is described: the presence of anti and gauche conformers that has been elucidated in remarkable papers by Hamaguchi et al. Such presence of a conformational equilibrium seems to be a general feature of the room temperature liquids. Then the ''localized structure features'' that apparently exist in ionic liquids are described. It is hoped that the structural resolving power of Raman spectroscopy will be appreciated by the reader. It is of remarkable use on crystals of known different conformations and on the corresponding liquids, especially in combination with modern quantum mechanics calculations. It is hoped that these interdisciplinary methods will be applied to many more systems in the future. A few examples will be discussed.

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“…71−81 Spectral bands in the region from 3200 to 3000 cm −1 are attributed to the coupled aromatic ring C−H stretching vibrations of the imidazolium hydrogen atoms, while those between 3000 and 2850 cm −1 can be assigned to the aliphatic C−H stretches of the CH 2 and CH 3 groups of the ethyl chain and of the CH 3 group bonded directly to the [C 2 MIM + ] ring. [71][72][73][74][75][76][77][78]81 4 ] thin films to water vapor in the sealed ATR cell at different levels of RH at 295 K. After each RH adjustment, spectra were collected until the band intensities stopped changing to ensure that equilibrium was attained. It typically took ∼20 min for the system to equilibrate.…”

Section: ■ Introductionmentioning

confidence: 99%

Interaction of Water Vapor with the Surfaces of Imidazolium-Based Ionic Liquid Nanoparticles and Thin Films

et al. 2012

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Understanding the interactions of humid air with ionic liquids (ILs) is critical for predicting how their physicochemical properties are affected by water. Using experimental and theoretical techniques, water vapor's interaction with aerosolized nanoparticles and thin films of [C 2 MIM][Cl] and [C 2 MIM][BF 4 ] was studied. Solutions were electrosprayed to produce dry particles. Particles' hygroscopic growth was quantified using tandem nanodifferential mobility analysis as a function of relative humidity (RH). This is the first report of the interaction of water with aerosolized IL nanoparticles. The particles' small size allows true IL−water vapor equilibrium achieved quickly. Growth curves for both ILs show steady water uptake with increasing RH. Water vapor uptake by IL thin films was also examined using ATR-FTIR spectroscopy. . They represent a large class of molecules that have unique and widely tunable physical and chemical properties. 1−3 For example, there is a significant interest in the use of ILs in green chemistry, 2,4,5 due to their negligible vapor pressure at room temperature, 6 and for many other applications including solvents in synthesis and catalysis, 1,6 chemical extraction, 1,2,5 and fuel cells. 7 Physical properties such as conductivity, viscosity, density, and surface tension of ILs are known to depend on the presence of water, both adsorbed and absorbed. 3,8 Water is ubiquitous in the environment, and hygroscopic ILs such as those with imidazolium-based cations can uptake significant amounts of water vapor from ambient air, which alters their physical and chemical properties. 1,3 Thus, quantification of water uptake by hygroscopic ILs and understanding how the presence of water affects the nature of the ion−ion and ion−water interactions are critical for use of ILs in future applications. 8−14 Numerous experimental and theoretical studies have investigated the interaction of imidazolium-based ILs with water. 3,8−35 It is understood that both the cation and the anion have an effect on how ILs interact with water, with the anion having a stronger effect. 3,17,19 Early experimental work by Seddon et al. investigated the miscibility of water with ILs containing 1-nalkyl-3-methylimidazolium ([C n MIM + ], n = number of carbons on the linear alkyl chain) cations and various anions at room temperature. 3 It was determined that, regardless of the alkyl chain length, all halide anions were fully soluble in water and all hexafluorophosphate ([PF 6 − ]) anions were insoluble. 3 However, alkyl chain length did have an effect on water miscibility of [C n MIM + ]-based ILs with tetrafluoroborate ([BF 4 − ]) anions; for chain lengths of n = 2 or 4, the ILs were fully miscible, but for n > 4, the ILs formed biphasic systems. 3 Cammarata et al. performed early attenuated total reflection (ATR) infrared (IR) studies on the molecular states of water

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Molecular Structure, Vibrational Spectra, and Hydrogen Bonding of the Ionic Liquid 1‐Ethyl‐3‐methyl‐1H‐imidazolium Tetrafluoroborate

Cited by 197 publications

References 22 publications

An Internal Fluorescent Probe Based on Anthracene to Evaluate Cation–Anion Interactions in Imidazolium Salts

An Internal Fluorescent Probe Based on Anthracene to Evaluate Cation–Anion Interactions in Imidazolium Salts

Raman Spectroscopy and Ab-Initio Model Calculations on Ionic Liquids

Interaction of Water Vapor with the Surfaces of Imidazolium-Based Ionic Liquid Nanoparticles and Thin Films

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