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X‐ray Photoelectron Spectroscopy of Pyridinium‐Based Ionic Liquids: Comparison to Imidazolium‐ and Pyrrolidinium‐Based Analogues 下载免费PDF全文
Shuang Men Daniel S. Mitchell Kevin R. J. Lovelock Peter Licence 《Chemphyschem》2015,16(10):2211-2218
We investigate eight 1‐alkylpyridinium‐based ionic liquids of the form [CnPy][A] by using X‐ray photoelectron spectroscopy (XPS). The electronic environment of each element of the ionic liquids is analyzed. In particular, a reliable fitting model is developed for the C 1s region that applies to each of the ionic liquids. This model allows the accurate charge correction of binding energies and the determination of reliable and reproducible binding energies for each ionic liquid. Shake‐up/off phenomena are determinedfor both C 1s and N 1s spectra. The electronic interaction between cations and anions is investigated for both simple ionic liquids and an example of an ionic‐liquid mixture; the effect of the anion on the electronic environment of the cation is also explored. Throughout the study, a detailed comparison is made between [C8Py][A] and analogues including 1‐octyl‐1‐methylpyrrolidinium‐ ([C8C1Pyrr][A]), and 1‐octyl‐3‐methylimidazolium‐ ([C8C1Im][A]) based samples, where X is common to all ionic liquids. 相似文献
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Charge‐Scaling Effect in Ionic Liquids from the Charge‐Density Analysis of N,N′‐Dimethylimidazolium Methylsulfate 下载免费PDF全文
Dr. Witali Beichel Dr. Nils Trapp Dipl.‐Phys. Christoph Hauf Dipl.‐Ing. Oliver Kohler Dr. Georg Eickerling Prof. Dr. Wolfgang Scherer Prof. Dr. Ingo Krossing 《Angewandte Chemie (International ed. in English)》2014,53(12):3143-3146
The charge scaling effect in ionic liquids was explored on the basis of experimental and theoretical charge‐density analyses of [C1MIM][C1SO4] employing the quantum theory of atoms in molecules (QTAIM) approach. Integrated QTAIM charges of the experimental (calculated) charge density of the cation and anion resulted in non‐integer values of ±0.90 (±0.87) e. Efficient charge transfer along the bond paths of the hydrogen bonds between the imidazolium ring and the anion was considered as the origin of these reduced charges. In addition, a detailed QTAIM analysis of the bonding situation in the [C1SO4]? anion revealed the presence of negative πO→σ*S‐O hyperconjugation. 相似文献
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Exploring the Molecular Structure of Imidazolium–Silica‐Based Nanoparticle Networks by Combining Solid‐State NMR Spectroscopy and First‐Principles Calculations 下载免费PDF全文
Dr. Marie‐Alexandra Neouze Martin Kronstein Dr. Marco Litschauer Dr. Michael Puchberger Dr. Cristina Coelho Prof. Christian Bonhomme Prof. Christel Gervais Dr. Frederik Tielens 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):15188-15196
A DFT‐based molecular model for imidazolium–silica‐based nanoparticle networks (INNs) is presented. The INNs were synthesized and characterized by using small‐angle X‐ray scattering (SAXS), NMR spectroscopy, and theoretical ab initio calculations. 11B and 31P HETCOR CP MAS experiments were recorded. Calculated 19F NMR spectroscopy results, combined with the calculated anion–imidazolium (IM) distances, predicted the IM chain density in the INN, which was also confirmed from thermogravimetric analysis/mass spectrometry results. The presence of water molecules trapped between the nanoparticles is also suggested. First considerations on possible π–π stacking between the IM rings are presented. The predicted electronic properties confirm the photoluminescence emissions in the correct spectral domain. 相似文献
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Alexander B. A. Rupp Petra Klose Dr. Harald Scherer Prof. Dr. Ingo Krossing 《Chemphyschem》2014,15(17):3729-3731
Several new ionic liquids (ILs) were prepared from Na[B(tfe)4] (tfe=OCH2CF3) via metathesis, including one room temperature IL (RTIL). Prior to synthesis, suitable cations were chosen via predictive quantum‐chemical calculations. Nuclear magnetic resonance monitoring over almost a month showed a total stability of the anion in the presence of water. The temperature‐dependent viscosities and melting points of all the new ILs were determined. The data indicate that [B(tfe)4]? ILs may be too viscous for electrochemical applications, but are interesting candidates for lubricant research. 相似文献
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Frank Haarmann Dr. Katrin Koch Dipl.‐Phys. Daniel Grüner Dr. Walter Schnelle Dr. Oliver Pecher Dipl.‐Chem. Raul Cardoso‐Gil Dr. Horst Borrmann Dr. Helge Rosner Dr. Yuri Grin Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(7):1673-1684
Delving into digallides : The characteristics of the chemical bonding of the digallides of the alkaline‐earth metals (see figure) have been studied by application of experimental methods, such as single‐crystal X‐ray diffraction and solid‐state NMR spectroscopy, in combination with quantum mechanical calculations.
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An Abnormal N‐Heterocyclic Carbene–Carbon Dioxide Adduct from Imidazolium Acetate Ionic Liquids: The Importance of Basicity 下载免费PDF全文
Zsolt Kelemen Barbara Péter‐Szabó Dr. Edit Székely Dr. Oldamur Hollóczki Dzmitry S. Firaha Prof. Dr. Barbara Kirchner Dr. József Nagy Prof. Dr. László Nyulászi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(40):13002-13008
In the reaction of 1‐ethyl‐3‐methylimidazolium acetate [C2C1Im][OAc] ionic liquid with carbon dioxide at 125 °C and 10 MPa, not only the known N‐heterocyclic carbene (NHC)–CO2 adduct I , but also isomeric aNHC‐CO2 adducts II and III were obtained. The abnormal NHC‐CO2 adducts are stabilized by the presence of the polarizing basic acetate anion, according to static DFT calculations and ab initio molecular dynamics studies. A further possible reaction pathway is facilitated by the high basicity of the system, deprotonating the initially formed NHC‐CO2 adduct I , which can then be converted in the presence of the excess of CO2 to the more stable 2‐deprotonated anionic abnormal NHC–CO2 adduct via the anionic imidazolium‐2,4‐dicarboxylate according to DFT calculations on model compounds. This suggests a generalizable pathway to abnormal NHC complex formation. 相似文献
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Superstructure of a Substituted Zeolitic Imidazolate Metal–Organic Framework Determined by Combining Proton Solid‐State NMR Spectroscopy and DFT Calculations 下载免费PDF全文
Dr. Maria Baias Dr. Anne Lesage Dr. Sonia Aguado Dr. Jerome Canivet Dr. Virginie Moizan‐Basle Dr. Nathalie Audebrand Dr. David Farrusseng Prof. Lyndon Emsley 《Angewandte Chemie (International ed. in English)》2015,54(20):5971-5976
We report the supercell crystal structure of a ZIF‐8 analog substituted imidazolate metal–organic framework (SIM‐1) obtained by combining solid‐state nuclear magnetic resonance and powder X‐ray diffraction experiments with density functional theory calculations. 相似文献
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Ion Pairing in Protic Ionic Liquids Probed by Far‐Infrared Spectroscopy: Effects of Solvent Polarity and Temperature 下载免费PDF全文
Dr. Koichi Fumino Verlaine Fossog Peter Stange Kai Wittler Wigbert Polet Prof. Dr. Rolf Hempelmann Prof. Dr. Ralf Ludwig 《Chemphyschem》2014,15(12):2604-2609
The cation–anion and cation–solvent interactions in solutions of the protic ionic liquid (PIL) [Et3NH][I] dissolved in solvents of different polarities are studied by means of far infrared vibrational (FIR) spectroscopy and density functional theory (DFT) calculations. The dissociation of contact ion pairs (CIPs) and the resulting formation of solvent‐separated ion pairs (SIPs) can be observed and analyzed as a function of solvent concentration, solvent polarity, and temperature. In apolar environments, the CIPs dominate for all solvent concentrations and temperatures. At high concentrations of polar solvents, SIPs are favored over CIPs. For these PIL/solvent mixtures, CIPs are reformed by increasing the temperature due to the reduced polarity of the solvent. Overall, this approach provides equilibrium constants, free energies, enthalpies, and entropies for ion‐pair formation in trialkylammonium‐containing PILs. These results have important implications for the understanding of solvation chemistry and the reactivity of ionic liquids. 相似文献
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Maarten Goesten Dr. Eli Stavitski Dr. Evgeny A. Pidko Canan Gücüyener Bart Boshuizen Dr. Steven N. Ehrlich Prof. Emiel J. M. Hensen Prof. Freek Kapteijn Dr. Jorge Gascon 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(24):7809-7816
We present an in situ small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) and quick‐scanning extended X‐ray absorption fine‐structure (QEXAFS) spectroscopy study on the crystallization of the metal–organic framework ZIF‐7. In combination with DFT calculations, the self‐assembly and growth of ZIF‐7 microrods together with the chemical function of the crystal growth modulator (diethylamine) are revealed at all relevant length scales, from the atomic to the full crystal size. 相似文献
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Prof. Aleksei B. Sheremetev Nataly S. Aleksandrova Nadezhda V. Palysaeva Marina I. Struchkova Vladimir A. Tartakovsky Kyrill Yu. Suponitsky 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(37):12446-12457
An efficient two‐step one‐pot protocol for the synthesis of N‐nitrated trinitroethylamino furazans in an ionic liquid has been developed involving the condensation of aminofurazans with trinitroethanol and the N‐nitration of an intermediate Mannich base. Trinitroethylnitramino derivatives have been synthesized and characterized by multinuclear NMR spectroscopy and X‐ray crystallography. A role of the N,2,2,2‐tetranitroethylamino group for stabilization of the high‐density crystal‐packing motif is described. The performance calculations gave detonation pressures and velocities for the furazan derivatives in a range of about 31–36 GPa and 8330–8745 ms?1, respectively, which makes them competitive energetic materials. Furthermore, due to the positive oxygen balance, the compounds could be potential oxidizers for energetic formulations. 相似文献
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Methoxy and Methyl Group Rotation: Solid‐State NMR 1H Spin‐Lattice Relaxation,Electronic Structure Calculations,X‐ray Diffractometry,and Scanning Electron Microscopy 下载免费PDF全文
Prof. Peter A. Beckmann Dr. Clelia W. Mallory Prof. Frank B. Mallory Prof. Arnold L. Rheingold Dr. Xianlong Wang 《Chemphyschem》2015,16(7):1509-1519
We report solid‐state 1H nuclear magnetic resonance (NMR) spin‐lattice relaxation experiments, X‐ray diffractometry, field‐emission scanning electron microscopy, and both single‐molecule and cluster ab initio electronic structure calculations on 1‐methoxyphenanthrene ( 1 ) and 3‐methoxyphenanthrene ( 2 ) to investigate the rotation of the methoxy groups and their constituent methyl groups. The electronic structure calculations and the 1H NMR relaxation measurements can be used together to determine barriers for the rotation of a methoxy group and its constituent methyl group and to develop models for the two coupled motions. 相似文献
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Structure elucidation of configurational isomers of nitrile‐substituted spirocyclopropyloxindoles by NMR spectroscopy,molecular modeling,and X‐ray crystallography 下载免费PDF全文
J. Benjamín García‐Vázquez Daphne E. González‐Juárez Martha S. Morales‐Ríos Oscar R. Suárez‐Castillo Yolanda Mora‐Pérez 《Magnetic resonance in chemistry : MRC》2015,53(12):1061-1070