Effect of Bulky Anion around the Dication on the Electronic Structure and Normal Frequencies in 1,3-Bis(3-methylimidazolium-1-yl)propane Bis(trifluoromethanesulfonyl)imide Ionic Liquid.

A manifestation of hydrogen bonding between the dication and anions attributed to their relative position of the anions around the cation can influence both the conformational equilibrium and the physical properties of ionic liquids. With this view, we studied the electronic structure and normal frequencies using density functional theory calculations to analyze the hydrogen-bonding interactions in dicationic ionic liquids. The conformers are distinguished based on the hydrogen-bonding sites of the cation and anion.

Theoretical Study of Alkylsulfonic Acids: Force-Field Development and Molecular Dynamics Simulations.

Potential model descriptions for alkylsulfonic acids, methanesulfonic, ethanesulfonic, and propanesulfonic acids, are developed based on CHARMM and OPLS parameters and protocols. Thermodynamic, structural, and transport properties of these alkylsulfonic acids, including density, heat of vaporization, radial and spatial distribution functions, hydrogen bond structure, shear viscosity, and translational diffusion coefficients, are examined via molecular dynamics simulations using these potential models. The results are compared with the predictions of ab initio molecular dynamics simulations as well as with available experimental information.

Dielectric Relaxation of the Ionic Liquid 1-Ethyl-3-methylimidazolium Ethyl Sulfate: Microwave and Far-IR Properties.

Dielectric relaxation of the ionic liquid, 1-ethyl-3-methylimidazolium ethyl sulfate (EMIETS), is studied using molecular dynamics (MD) simulations. The collective dynamics of polarization arising from cations and anions are examined. Characteristics of the rovibrational and translational components of polarization dynamics are analyzed to understand their respective roles in the microwave and terahertz regions of dielectric relaxation.

CO capture in ionic liquid 1-alkyl-3-methylimidazolium acetate: a concerted mechanism without carbene.

Ionic liquids (ILs) provide a promising medium for CO capture. Recently, the family of ILs comprising imidazolium-based cations and acetate anions, such as 1-ethyl-3-methylimidazolium acetate (EMIOAc), has been found to react with CO and form carboxylate compounds. N-Heterocyclic carbene (NHC) is widely assumed to be responsible by directly reacting with CO though NHC has not been detected in these ILs.

Computer Simulation Study of Graphene Oxide Supercapacitors: Charge Screening Mechanism.

Graphene oxide supercapacitors in the parallel plate configuration are studied via molecular dynamics (MD) simulations. The full range of electrode oxidation from 0 to 100% is examined by oxidizing the graphene surface with hydroxyl groups. Two different electrolytes, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI(+)BF4(-)) as an ionic liquid and its 1.

Theoretical study of interactions of a Li(+)(CF3SO2)2N(-) ion pair with CR3(OCR2CR2)nOCR3 (R = H or F).

Interactions of a lithium bis(trifluoromethane sulfonyl)imide (Li(+)Tf2N(-)) ion pair with oligoethers are investigated via density functional theory (DFT). As a model for polymer electrolytes polyethyleneoxide (PEO) and perfluoropolyether (PFPE), CR3(OCR2CR2)n=1-5OCR3 (R = H or F) is considered. Topographical analysis of the molecular electrostatic potential (MESP) is performed to determine preferential binding sites of Li(+).

Revisiting the Aqueous Solutions of Dimethyl Sulfoxide by Spectroscopy in the Mid- and Near-Infrared: Experiments and Car-Parrinello Simulations.

The infrared and near-infrared spectra of the aqueous solutions of dimethyl sulfoxide are revisited. Experimental and computational vibrational spectra are analyzed and compared. The latter are determined as the Fourier transformation of the velocity autocorrelation function of data obtained from Car-Parrinello molecular dynamics simulations.

Molecular structure and interactions in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide.

Electronic structure theory (density functional and Møller-Plesset perturbation theory) and vibrational spectroscopy (FT-IR and Raman) are employed to study molecular interactions in the room-temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. Different conformers of a cation-anion pair based on their molecular interactions are simulated in the gas phase and in a dielectric continuum solvent environment. Although the ordering of conformers in energy varies with theoretical methods, their predictions for three lowest energy conformers in the gas phase are similar.

Electronic structure, molecular electrostatic potential and hydrogen bonding in DMSO-X complexes (X = ethanol, methanol and water).

In the present work, we have studied the electronic structure, molecular electrostatic potential (MEP) and hydrogen bonding in DMSO-ethanol, DMSO-methanol and DMSO-water complexes by employing the MP2 method. Different conformers were simulated on the basis of possible binding sites guided by molecular electrostatic potential topology. The stronger hydrogen bonded interaction lowers the energy of the conformer.

Electronic structure and normal vibrations of the 1-ethyl-3-methylimidazolium ethyl sulfate ion pair.

Electronic and structural properties of the ion pair 1-ethyl-3-methylimidazolium ethyl sulfate are studied using density functional methods. Three locally stable conformers of the ion pair complex are considered to analyze molecular interactions between its cation and anion. Manifestations of these interactions in the vibrational spectra are discussed and compared with experimental IR and Raman spectroscopy data.

Molecular interactions in 1-ethyl-3-methylimidazolium acetate ion pair: a density functional study.

The density functional method is used to obtain the molecular structure, electron density topography, and vibrational frequencies of the ion pair 1-ethyl-3-methylimidazolium acetate. Different conformers are simulated on the basis of molecular interactions between the 1-ethyl-3-methylimidazolium cation and acetate anion. The lowest energy conformers exhibit strong C-H.

Theoretical studies on NMR chemical shifts in azacubanes.

Successive substitution of CH groups of cubane (CH)(8), by isoelectronic nitrogen atoms leads to a class of energy-rich azacubanes (CH)(8-alpha)N(alpha) (with alpha=1-8). In the present work, we systematically investigate how substitution of nitrogen in a cubanoid influence deshielding of carbon and manifest in the chemical shift in NMR spectra calculated using the second order Møller-Plesset (MP2) perturbation level of theory. PMR spectra predict a large downshift of delta(H)=7.

Electronic structure and normal vibrations of CH3(OCH2CH2)nOCH3-M+-CF3SO3- (n = 2-4, M = Li, Na, and K).

Electronic structure and the vibrational frequencies of CH(3)(OCH(2)CH(2))(n)OCH(3)-M(+)-CF(3)SO(3)(-) (n = 2-4, M = Li, Na, and K) complexes have been derived from ab initio Hartree-Fock calculations. The metal ion shows varying coordination from 5 to 7 in these complexes. In tetraglyme-lithium triflate, Li(+) binds to one of the oxygens of CF(3)SO(3)(-) (triflate or Tf(-)) unlike for potassium or sodium ions, which possess bidentate coordination.

Theoretical studies on blue versus red shifts in diglyme-M+-X- (M=Li, Na, and K and X=CF3SO3, PF6, and (CF3SO2)2N)).

Ab initio Hartree-Fock calculations have been used to obtain the electronic structure and the frequencies of normal vibrations in the 1:1:1 solid polymer electrolytes CH3(OCH2CH2)2OCH3-M+-X- (M=Li, Na, and K and X=CF3SO3, PF6, (CF3SO2)2N). These calculations predict stronger binding for the lithium ion toward the ether oxygens of diglyme in these electrolytes. Consequences of diglyme-MX interactions to the infrared spectra have been presented.

Molecular electrostatic potentials and electron densities in nitroazacubanes.

Successive introduction of nitrogen atoms in the cubyl corners instead of C-NO2 groups of octanitrocubane (CNO2)8, the most powerful explosives known to date, leads to a class of energy-rich compounds known as nitroazacubanes. In present work the ab initio Hartree-Fock and hybrid density functional calculations have been carried out on the possible conformers of (CNO2)(8-alpha)Nalpha (with alpha=0-8), nitroazacubanes. The charge distributions in these systems have been derived using the topography of the molecular electrostatic potential and electron density.