Low‐Frequency Vibrational Modes of Protic Molten Salts and Ionic Liquids: Detecting and Quantifying Hydrogen Bonds

Fumino, Koichi; Reichert, Elena; Wittler, Kai; Hempelmann, Rolf; Ludwig, Ralf

doi:10.1002/anie.201200508

Cited by 104 publications

(139 citation statements)

References 45 publications

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“…[12][13][14][15] Owing to the inductive effect of the fluorine atoms within the anion, the cation-anion interaction is significantly lowered indicated by a 20 cm À1 shift to lower wavenumbers for TEATF. [13] The location and absorbance of this vibrational band is sensitive for the interaction strength between the PIL constituents.…”

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confidence: 99%

Non‐Ideal Mixing Behaviour of Hydrogen Bonding in Mixtures of Protic Ionic Liquids

et al. 2014

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Ionic liquids (ILs) attract interest in science and technology as a result of their unique properties. Binary and ternary mixtures of ILs significantly increase the number of possible cation/anion combinations, resulting in targeted physical and chemical properties. In this work, we study the mixing behaviour of two protic ILs: triethyl ammonium methylsulfonate [Et3 NH][CH3 SO3 ] and triethylammonium triflate [Et3 NH][CF3 SO3 ]. We find a characteristic deviation from ideal mixing by means of low-frequency infrared spectroscopy. By using molecular dynamics simulations, we explain this behaviour as being the result of different strengths of anion/cation hydrogen bonding. This non-ideality of non-random H-bond mixing is also reflected in macroscopic properties such as the viscosity. Mixing suitable ILs may, thus, result in new ILs with targeted physical properties.

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confidence: 99%

Non‐Ideal Mixing Behaviour of Hydrogen Bonding in Mixtures of Protic Ionic Liquids

et al. 2014

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“…The use of a correlation consistent basis set augmented with diffuse functions, such as aug (augmented)-cc-pVTZ, would give much better results, but great computer resources are required to complete the calculation. Frequency calculations at the B3LYP level using the 6-31+G(d) basis set gives sufficient results for large cluster systems, like ionic liquids [120,126,134]. Here, the anharmonicity described in the next section is corrected by the standard scaling factor, 0.96, and Grimme's dispersion-corrected method (DFT-D3), described in the next section, is recommended for the calculation of THz vibrations.…”

Section: Computational Methods To Analyze the Thz Spectra Of Hydrogenmentioning

confidence: 99%

“…It turns out that the translational vibration mixed with the stretching vibration of the hydrogen bond, as in PHB, is higher in frequency than the unmixed translational vibrations, as in benzoic acid. Low-frequency vibrational modes of protic ionic liquids (PIL) and ionic liquids (ILs) detect and quantify hydrogen bonds [120]. PILs are a subset of ILs and are formed by the combination of equimolar amounts of a Brønsted acid and a Brønsted base [121][122][123][124][125][126][127][128].…”

Section: Thz Vibrations Of Hydrogen-bonded Moleculesmentioning

confidence: 99%

Terahertz Vibrations and Hydrogen-Bonded Networks in Crystals

Takahashi

2014

Crystals

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Abstract:The development of terahertz technology in the last few decades has made it possible to obtain a clear terahertz (THz) spectrum. THz vibrations clearly show the formation of weak bonds in crystals. The simultaneous progress in the code of first-principles calculations treating noncovalent interactions has established the position of THz spectroscopy as a powerful tool for detecting the weak bonding in crystals. In this review, we are going to introduce, briefly, the contribution of weak bonds in the construction of molecular crystals first, and then, we will review THz spectroscopy as a powerful tool for detecting the formation of weak bonds and will show the significant contribution of advanced computational codes in treating noncovalent interactions. From the second section, following the Introduction, to the seventh section, before the conclusions, we describe: (1) the crystal packing forces, the hydrogen-bonded networks and their contribution to the construction of organic crystals; (2) the THz vibrations observed in hydrogen-bonded molecules; (3) the computational methods for analyzing the THz vibrations of hydrogen-bonded molecules; (4) the dispersion correction and anharmonicity incorporated into the first-principles calculations and their effect on the peak assignment of the THz spectrum (5) the temperature dependence; and (6) the polarization dependence of the THz spectrum.

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“…2 Besides ionic interactions, whether supramolecular interactions also govern the organization of imidazoliumbased ILs is still hotly debated with a vast number of important contributions. [24][25][26][27][28][29] Despite their importance, the number of significant contributions specifically discussing the supramolecular organization and interactions of TSILs is much scarcer [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] when compared to nonfunctionalized ILs. TSILs have become one of the most important strategies for furthering IL chemistry, 1 as noted for the large and increasing number of innovative applications described for these ionic compounds.…”

Section: Introductionmentioning

confidence: 99%

“…[24][25][26][27][28][29] Despite their importance, the number of significant contributions specifically discussing the supramolecular organization and interactions of TSILs is much scarcer 30-45 when compared to nonfunctionalized ILs. TSILs have become one of the most important strategies for furthering IL chemistry, 1 as noted for the large and increasing number of innovative applications described for these ionic compounds.…”

mentioning

confidence: 99%

Solid, Solution and Gas Phase Interactions of an Imidazolium-Based Task-Specific Ionic Liquid Derived from Natural Kojic Acid

Neto¹,

Mota²,

Gatto³

et al. 2014

Journal of the Brazilian Chemical Society

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Um líquido iônico imidazólio de função específica derivado do ácido kójico natural teve suas interações supramoleculares investigadas no estado sólido, em solução e em fase gasosa. Diferentes técnicas como difração de raios X de monocristal, espectroscopia de ressonância magnética nuclear (NMR), espectrofotometria UV-Vis, medidas de condutividade, espalhamento de raios X em baixo ângulo (SAXS), espectrometria de massas (tandem) com ionização por electrospray (ESI-MS(/MS)) e cálculos teóricos permitiram uma investigação estrutural aprofundada desse líquido iônico de função específica e suas interações supramoleculares. An imidazolium-based task-specific ionic liquid derived from the natural kojic acid had its supramolecular interactions investigated in solid, solution and gas phase. The use of a set of techniques formed by single-crystal X-ray diffraction, nuclear magnetic resonance (NMR) spectroscopy, UV-Vis spectrophotometry, conductivity measurements, small angle X-ray scattering (SAXS), electrospray (tandem) mass spectrometry (ESI-MS(/MS)), and theoretical calculations allowed a deep investigation of the structural organization of the task-specific ionic liquid and its supramolecular interactions.Keywords: ionic liquids, imidazolium, task-specific ionic liquids, supramolecular interactions, organization, X-ray, SAXS, UV-Vis, NMR, ESI-MS IntroductionIonic liquids (ILs) and task-specific ionic liquids (TSILs), especially those based on the imidazolium cation, are part of a class of attractive compounds of widespread use in many scientific and technological areas.1-3 These organic salts have already been successfully used in the chemical industry for many years. 4 Their prominence is exemplified by many review articles recently published regarding several features of these unique chemical species. 5-21The possibility of tuning the physical and chemical properties of ILs and TSILs associated with their attractive physicochemical properties, such as very low vapor pressure, large electrochemical window, good thermal and chemical stabilities, have also opened a wealth of other applications for these ionic materials. Despite all progress already reached by ILs, fine details about their supramolecular organization, the importance of H-bonds and a deep understanding on the directionality of imidazolium-based derivatives are only now emerging. Each IL/TSIL has unique physicochemical properties and it has been estimated that ca. 10 6 combinations of known Neto et al. 2281 Vol. 25, No. 12, 2014 cations and anions may afford a new type of such ionic compounds. 22 The effort towards a better comprehension on the physicochemical properties of such materials is therefore very challenging; and each new structure demands specific efforts and a set of characterizations to depict its unique structural features and properties. Despite the diversity, some general trends have been established, and it is, for instance, known that the physicochemical properties of ILs/TSILs are intimately associated with their ionic structures, 23...

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Low‐Frequency Vibrational Modes of Protic Molten Salts and Ionic Liquids: Detecting and Quantifying Hydrogen Bonds

Cited by 104 publications

References 45 publications

Non‐Ideal Mixing Behaviour of Hydrogen Bonding in Mixtures of Protic Ionic Liquids

Non‐Ideal Mixing Behaviour of Hydrogen Bonding in Mixtures of Protic Ionic Liquids

Terahertz Vibrations and Hydrogen-Bonded Networks in Crystals

Solid, Solution and Gas Phase Interactions of an Imidazolium-Based Task-Specific Ionic Liquid Derived from Natural Kojic Acid

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