Certain molten complexes of Li salts and solvents can be regarded as ionic liquids. In this study, the local structure of Li(+) ions in equimolar mixtures ([Li(glyme)]X) of glymes (G3: triglyme and G4: tetraglyme) and Li salts (LiX: lithium bis(trifluoromethanesulfonyl)amide (Li[TFSA]), lithium bis(pentafluoroethanesulfonyl)amide (Li[BETI]), lithium trifluoromethanesulfonate (Li[OTf]), LiBF4, LiClO4, LiNO3, and lithium trifluoroacetate (Li[TFA])) was investigated to discriminate between solvate ionic liquids and concentrated solutions. Raman spectra and ab initio molecular orbital calculations have shown that the glyme molecules adopt a crown-ether like conformation to form a monomeric [Li(glyme)](+) in the molten state. Further, Raman spectroscopic analysis allowed us to estimate the fraction of the free glyme in [Li(glyme)]X. The amount of free glyme was estimated to be a few percent in [Li(glyme)]X with perfluorosulfonylamide type anions, and thereby could be regarded as solvate ionic liquids. Other equimolar mixtures of [Li(glyme)]X were found to contain a considerable amount of free glyme, and they were categorized as traditional concentrated solutions. The activity of Li(+) in the glyme-Li salt mixtures was also evaluated by measuring the electrode potential of Li/Li(+) as a function of concentration, by using concentration cells against a reference electrode. At a higher concentration of Li salt, the amount of free glyme diminishes and affects the electrode reaction, leading to a drastic increase in the electrode potential. Unlike conventional electrolytes (dilute and concentrated solutions), the significantly high electrode potential found in the solvate ILs indicates that the solvation of Li(+) by the glyme forms stable and discrete solvate ions ([Li(glyme)](+)) in the molten state. This anomalous Li(+) solvation may have a great impact on the electrode reactions in Li batteries.

The structure and interactions of different (Li salt + glyme) mixtures, namely equimolar mixtures of lithium bis(trifluoromethylsulfonyl)imide, nitrate or trifluoroacetate salts combined with either triglyme or tetraglyme molecules, are probed using Molecular Dynamics simulations. structure factor functions, calculated from the MD trajectories, confirmed the presence of different amounts of lithium-glyme solvates in the aforementioned systems. The MD results are corroborated by S(q) functions derived from diffraction and scattering data (HEXRD and SAXS/WAXS). The competition between the glyme molecules and the salt anions for the coordination to the lithium cations is quantified by comprehensive aggregate analyses. Lithium-glyme solvates are dominant in the lithium bis(trifluoromethylsulfonyl)imide systems and much less so in systems based on the other two salts. The aggregation studies also emphasize the existence of complex coordination patterns between the different species (cations, anions, glyme molecules) present in the studied fluid media. The analysis of such complex behavior is extended to the conformational landscape of the anions and glyme molecules and to the dynamics (solvate diffusion) of the bis(trifluoromethylsulfonyl)imide plus triglyme system.

Hydrofluoroethers have recently been used as the diluent to a lithium battery electrolyte solution to increase and decrease the ionic conductivity and the solution viscosity, respectively. In order to clarify the Li(+) local structure in the 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (HFE) diluted [Li(G4)][TFSA] (G4, tetraglyme; TFSA, bis(trifluoromethanesulfonyl)amide) solvate ionic liquid, Raman spectroscopic study has been done with the DFT calculations. It has turned out that the HFE never coordinates to the Li(+) directly, and that the solvent (G4) shared ion pair of Li(+) with TFSA anion (SSIP) and the contact ion pair between Li(+) and TFSA anion (CIP) are found in the neat and HFE diluted [Li(G4)][TFSA] solvate ionic liquid. It is also revealed that the two kinds of the CIP in which TFSA anion coordinates to the Li(+) in monodentate and bidentate manners (hereafter, we call them the monodentate CIP and the bidentate CIP, respectively) exist with the SSIP of predominant [Li(G4)](+) ion-pair species in the neat [Li(G4)][TFSA] solvate ionic liquid, and that the monodentate CIP decreases as diluting with the HFE. To obtain further insight, X-ray total scattering experiments (HEXTS) were carried out with the aid of MD simulations, where the intermolecular force field parameters, mainly partial atomic charges, have been newly proposed for the HFE and glymes. A new peak appeared at around 0.6-0.7 Å(-1) in X-ray structure factors, which was ascribed to the correlation between the [Li(G4)][TFSA] ion pairs. Furthermore, MD simulations were in good agreement with the experiments, from which it is suggested that the terminal oxygen atoms of the G4 in [Li(G4)](+) solvated cation frequently repeat coordinating/uncoordinating to the Li(+), although almost all of the G4 coordinates to the Li(+) to form [Li(G4)](+) solvated cation in the neat and HFE diluted [Li(G4)][TFSA] solvate ionic liquid.

Neutron diffraction measurements have been carried out at 25 °C for 9.6 mol% *LiPF 6 -deutrerated dimethyl carbonate (DMC-d 6 ) solutions in which the isotopic ratio of 6 Li/ 7 Li was changed. Local structure of Li + in the solution was derived from the least squares fitting analysis of observed difference function, Δ Li (Q). It was revealed that Li + is surrounded by ca. 3 DMC molecules and ca. 1 PF 6 with intermolecular distances of r(Li +… O(DMC)) = 2.08 ± 0.02 Å and r(Li +… F(PF 6 -)) = 2.03 ± 0.06 Å, respectively. Raman experimental study and DFT calculations agree well with neutron structure analysis.

Equimolar mixtures of lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) and tetraglyme (G4: CH3O-(CH2CH2O)4-CH3) yield the solvate (or chelate) ionic liquid [Li(G4)][TFSA], which is a homogeneous transparent solution at room temperature. Solvate ionic liquids (SILs) are currently attracting increasing research interest, especially as new electrolytes for Li-sulfur batteries. Here, we performed neutron total scattering experiments with (6/7)Li isotopic substitution to reveal the Li(+) solvation/local structure in [Li(G4)][TFSA] SILs. The experimental interference function and radial distribution function around Li(+) agree well with predictions from ab initio calculations and MD simulations. The model solvation/local structure was optimized with nonlinear least-squares analysis to yield structural parameters. The refined Li(+) solvation/local structure in the [Li(G4)][TFSA] SIL shows that lithium cations are not coordinated to all five oxygen atoms of the G4 molecule (deficient five-coordination) but only to four of them (actual four-coordination). The solvate cation is thus considerably distorted, which can be ascribed to the limited phase space of the ethylene oxide chain and competition for coordination sites from the TFSA anion.

a b s t r a c t Keywords:Hydrogen bond Protic ionic liquids X-ray scattering MD simulations Liquid structure of bis-(trifluoromethanesulfonyl)amide TFSA − based protic and aprotic ionic liquids composed of imidazolium [h 2 Im + ], N-methylimidazolium [C 1 hIm + ] and N,N'-dimethylimidazolium [C 1 mIm + ] were investigated by high-energy total scattering (HETS) experiments. The nearest neighboring cation-anon orientation variations by the N-methyl groups substitution to proton were suggested based on the peaks at around 6 and 9 Å in the differential radial distribution functions as the form of r 2 {G X-ray (r) -1} for these ionic liquids. It was supposed that the NH · · · O hydrogen bond causes the cation-anion orientation variations. To obtain further insight into the hydrogen bond in the PIL, MD simulations performed and agreed well with the experiments. According to spatial distribution functions (SDF) for the three ionic liquids, the O atom of TFSA − prefers the NH hydrogen of the imidazolium that has the most positive partial atomic charge in the cation, while the F atom locates right above and right below the imidazolium ring plane. In addition, the NH · · · O hydrogen bond has short bond lengths and linear bond angles, while the C 2 H · ·O interaction is long and bent. The NH · · · O hydrogen bond in the PIL was discussed based on structural aspect accompanied by a thermodynamic viewpoint.

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CRP 24 Abbreviations: H 2 S, hydrogen sulfide; Cys, L-cysteine; Km r , kanamycin 25 resistance; Cm r , chloramphenicol resistance; ORFs, open reading frames 26 3 Summary 27 Many organisms produce endogenous hydrogen sulfide (H 2 S) as a by-product of 28 protein, peptide, or L-cysteine degradation. Recent reports concerning mammalian cells 29 have demonstrated that H 2 S acts as a signaling molecule playing important roles in 30 various biological processes. In contrast to mammals, bacterial H 2 S signaling remains 31 unclear. In this work, we demonstrate that Escherichia coli generates H 2 S through the 32 assimilation of inorganic sulfur, without L-cysteine degradation. Comparison of 33 phenotypes and genomes between laboratory E. coli K-12 strains revealed a major 34 contribution of CRP (a protein that controls the expression of numerous genes involved 35in glycolysis) to H 2 S generation. We found that H 2 S was produced by cells growing in a 36 synthetic minimal medium containing thiosulfate as a sole inorganic sulfur source, but 37 not in a medium only containing sulfate. Furthermore, E. coli generated H 2 S in a 38 CRP-dependent manner as a response to glucose starvation. These results indicate that 39 CRP plays a key role in the generation of H 2 S coupled to thiosulfate assimilation, whose 40 molecular mechanisms remains to be elucidated. Here, we propose a potential biological 41 role of the H 2 S as a signaling mediator for a cross-talk between carbon and sulfur 42 metabolism in E. coli. 43 44 45