Locally Concentrated Ionic Liquid Electrolytes for Wide-Temperature-Range Aluminum-Sulfur Batteries.

Aluminum-sulfur (Al-S) batteries are promising energy storage devices due to their high theoretical capacity, low cost, and high safety. However, the high viscosity and inferior ion transport of conventionally used ionic liquid electrolytes (ILEs) limit the kinetics of Al-S batteries, especially at sub-zero temperatures. Herein, locally concentrated ionic liquid electrolytes (LCILE) formed via diluting the ILEs with non-solvating 1,2-difluorobenzene (dFBn) co-solvent are proposed for wide-temperature-range Al-S batteries. The addition of dFBn effectively promotes the fluidity and ionic conductivity without affecting the AlCl4 - /Al2 Cl7 - equilibrium, which preserves the reversible stripping/plating of aluminum and further promotes the overall kinetics of Al-S batteries. As a result, Al-S cells employing the LCILE exhibit higher specific capacity, better cyclability, and lower polarization with respect to the neat ILE in a wide temperature range from -20 to 40 °C. For instance, Al-S batteries employing the LCILE sustain a remarkable capacity of 507 mAh g-1 after 300 cycles at 20 °C, while only 229 mAh g-1 is delivered with the dFBn-free electrolyte under the same condition. This work demonstrates the favorable use of LCILEs for wide-temperature Al-S batteries.

Reinforcing the Electrode/Electrolyte Interphases of Lithium Metal Batteries Employing Locally Concentrated Ionic Liquid Electrolytes.

Lithium metal batteries (LMBs) with nickel-rich cathodes are promising candidates for next-generation high-energy-density batteries, but the lack of sufficiently protective electrode/electrolyte interphases (EEIs) limits their cyclability. Herein, trifluoromethoxybenzene is proposed as a cosolvent for locally concentrated ionic liquid electrolytes (LCILEs) to reinforce the EEIs. With a comparative study of a neat ionic liquid electrolyte (ILE) and three LCILEs employing fluorobenzene, trifluoromethylbenzene, or trifluoromethoxybenzene as cosolvents, it is revealed that the fluorinated groups tethered to the benzene ring of the cosolvents not only affect the electrolytes' ionic conductivity and fluidity, but also the EEIs' composition via adjusting the contribution of the 1-ethyl-3-methylimidazolium cation (Emim+ ) and bis(fluorosulfonyl)imide anion. Trifluoromethoxybenzene, as the optimal cosolvent, leads to a stable cycling of LMBs employing 5 mAh cm-2 lithium metal anodes (LMAs), 21 mg cm-2 LiNi0.8 Co0.15 Al0.05 (NCA) cathodes, and 4.2 µL mAh-1 electrolytes for 150 cycles with a remarkable capacity retention of 71%, thanks to a solid electrolyte interphase rich in inorganic species on LMAs and, particularly, a uniform cathode/electrolyte interphase rich in Emim+ -derived species on NCA cathodes. By contrast, the capacity retention under the same condition is only 16%, 46%, and 18% for the neat ILE and the LCILEs based on fluorobenzene and benzotrifluoride, respectively.

Recycling of used vegetable oils by powder adsorption.

The treatment of used vegetable oil (UVO) with seven different adsorbents and through two different procedures (stirring and gravity filtration) was explored. Important differences in terms of density, turbidity, electrical resistance, free fatty acids (FFAs) content and relative fatty acid distribution were observed. Different outcomes were shown depending both on the adsorbent and on the procedure. Lower values of density and FFAs were registered for oils treated by gravity filtration with portland (respectively 0.6% and 0.81 g/ml) and celite (respectively 0.7% and 0.72 g/ml). Considering the undesired leaching from the powder to the oil, related to the turbidity, the celite resulted more suitable for the oil recycling (241 Nephelometric Turbidity Unit (NTU) for portland vs 184 NTU for celite). In addition, Fourier-transform infrared spectroscopy combined with multivariate analysis allowed to determine a chemical fingerprint relative characteristic of vegetable oils recycled by gravity or by adsorption by stirring.

Insights into the Effect of Lithium Doping on the Deep Eutectic Solvent Choline Chloride:Urea.

Choline-based deep eutectic solvents (DESs) are potential candidates to replace flammable organic solvent electrolytes in lithium-ion batteries (LIBs). The effect of the addition of a lithium salt on the structure and dynamics of the material needs to be clarified before it enters the battery. Here, the archetypical DES choline chloride:urea at 1:2 mole fraction has been added with lithium chloride at two different concentrations and the effect of the additional cation has been evaluated with respect to the non-doped system via multinuclear NMR techniques. 1H and 7Li spin-lattice relaxation times and diffusion coefficients have been measured between 298 K and 373 K and revealed a decrease in both rotational and translational mobility of the species after LiCl doping at a given temperature. Temperature dependent 35Cl linewidths reflect the viscosity increase upon LiCl addition, yet keep track of the lithium complexation. Quantitative indicators such as correlation times and activation energies give indirect insights into the intermolecular interactions of the mixtures, while lithium single-jump distance and transference number shed light into the lithium transport, being then of help in the design of future DES electrolytes.

Locally Concentrated Ionic Liquid Electrolyte with Partially Solvating Diluent for Lithium/Sulfurized Polyacrylonitrile Batteries.

The development of Li/sulfurized polyacrylonitrile (SPAN) batteries requires electrolytes that can form stable electrolyte/electrode interphases simultaneously on lithium-metal anodes (LMAs) and SPAN cathodes. Herein, a low-flammability locally concentrated ionic liquid electrolyte (LCILE) employing monofluorobenzene (mFBn) as the diluent is proposed for Li/SPAN cells. Unlike non-solvating diluents in other LCILEs, mFBn partially solvates Li+ , decreasing the coordination between Li+ and bis(fluorosulfonyl)imide (FSI- ). In turn, this triggers a more substantial decomposition of FSI- and consequently results in the formation of a solid electrolyte interphase (SEI) rich in inorganic compounds, which enables a remarkable Coulombic efficiency (99.72%) of LMAs. Meanwhile, a protective cathode electrolyte interphase (CEI), derived mainly from FSI- and organic cations, is generated on the SPAN cathodes, preventing the dissolution of polysulfides. Benefiting from the robust interphases simultaneously formed on both the electrodes, a highly stable cycling of Li/SPAN cells for 250 cycles with a capacity retention of 71% is achieved employing the LCILE and only 80% lithium-metal excess.

Implications of Anion Structure on Physicochemical Properties of DBU-Based Protic Ionic Liquids.

Protic ionic liquids (PILs) are potential candidates as electrolyte components in energy storage devices. When replacing flammable and volatile organic solvents, PILs are expected to improve the safety and performance of electrochemical devices. Considering their technical application, a challenging task is the understanding of the key factors governing their intermolecular interactions and physicochemical properties. The present work intends to investigate the effects of the structural features on the properties of a promising PIL based on the 1,8-diazabicyclo[5.4.0]undec-7-ene (DBUH+) cation and the (trifluoromethanesulfonyl)(nonafluorobutanesulfonyl)imide (IM14-) anion, the latter being a remarkably large anion with an uneven distribution of the C-F pool between the two sides of the sulfonylimide moieties. For comparison purposes, the experimental investigations were extended to PILs composed of the same DBU-based cation and the trifluoromethanesulfonate (TFO-) or bis(trifluoromethanesulfonyl)imide (TFSI-) anion. The combined use of multiple NMR methods, thermal analyses, density, viscosity, and conductivity measurements provides a deep characterization of the PILs, unveiling peculiar behaviors in DBUH-IM14, which cannot be predicted solely on the basis of differences between aqueous pKa values of the protonated base and the acid (ΔpKa). Interestingly, the thermal and electrochemical properties of DBUH-IM14 turn out to be markedly governed by the size and asymmetric nature of the anion. This observation highlights that the structural features of the precursors are an important tool to tailor the PIL's properties according to the specific application.

The Intermolecular NOE Depends on Isotope Selection: Short Range vs Long Range Behavior.

The nuclear Overhauser effect (NOE) is a powerful tool in molecular structure elucidation, combining the subtle chemical shift of NMR and three-dimensional information independent of chemical connectivity. Its usage for intermolecular studies, however, is fundamentally limited by an unspecific long-ranged interaction behavior. This joint experimental and computational work shows that proper selection of interacting isotopes can overcome these limitations: Isotopes with strongly differing gyromagnetic ratios give rise to short-ranged intermolecular NOEs. In this light, existing NOE experiments need to be re-evaluated and future ones can be designed accordingly. Thus, a new chapter on intermolecular structure elucidation is opened.

Liquid structure and dynamics in the choline acetate:urea 1:2 deep eutectic solvent.

We report on the thermodynamic, structural, and dynamic properties of a recently proposed deep eutectic solvent, formed by choline acetate (ChAc) and urea (U) at the stoichiometric ratio 1:2, hereinafter indicated as ChAc:U. Although the crystalline phase melts at 36-38 °C depending on the heating rate, ChAc:U can be easily supercooled at sub-ambient conditions, thus maintaining at the liquid state, with a glass-liquid transition at about -50 °C. Synchrotron high energy x-ray scattering experiments provide the experimental data for supporting a reverse Monte Carlo analysis to extract structural information at the atomistic level. This exploration of the liquid structure of ChAc:U reveals the major role played by hydrogen bonding in determining interspecies correlations: both acetate and urea are strong hydrogen bond acceptor sites, while both choline hydroxyl and urea act as HB donors. All ChAc:U moieties are involved in mutual interactions, with acetate and urea strongly interacting through hydrogen bonding, while choline being mostly involved in van der Waals mediated interactions. Such a structural situation is mirrored by the dynamic evidences obtained by means of 1H nuclear magnetic resonance techniques, which show how urea and acetate species experience higher translational activation energy than choline, fingerprinting their stronger commitments into the extended hydrogen bonding network established in ChAc:U.

Connecting chloride solvation with hydration in deep eutectic systems.

The Deep Eutectic Solvents/Systems (DESs) choline chloride:urea (xChCl = 0.33) and choline chloride:glycolic acid (xChCl = 0.5) were investigated using viscosity-corrected 35Cl NMR spectroscopy and molecular dynamics simulations to probe the role of chloride as a function of water content. Three Cl- solvation regimes are revealed, with high-symmetry environments for pure and highly dilute DES, and an unusual low-symmetry interstitial region where the primary coordination sphere is most disordered.

13C NMR-Based Chemical Fingerprint for the Varietal and Geographical Discrimination of Wines.

A fast, economic, and eco-friendly methodology for the wine variety and geographical origin differentiation using 13C nuclear magnetic resonance (NMR) data in combination with machine learning was developed. Wine samples of different grape varieties cultivated in different regions in Greece were subjected to 13C NMR analysis. The relative integrals of the 13C spectral window were processed and extracted to build a chemical fingerprint for the characterization of each specific wine variety, and then subjected to factor analysis, multivariate analysis of variance, and k-nearest neighbors analysis. The statistical analysis results showed that the 13C NMR fingerprint could be used as a rapid and accurate indicator of the wine variety differentiation. An almost perfect classification rate based on training (99.8%) and holdout methods (99.9%) was obtained. Results were further tested on the basis of Cronbach's alpha reliability analysis, where a very low random error (0.30) was estimated, indicating the accuracy and strength of the aforementioned methodology for the discrimination of the wine variety. The obtained data were grouped according to the geographical origin of wine samples and further subjected to principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA). The PLS-DA and variable importance in projection (VIP) allowed the determination of a chemical fingerprint characteristic of each geographical group. The statistical analysis revealed the possibility of acquiring useful information on wines, by simply processing the 13C NMR raw data, without the need to determine any specific metabolomic profile. In total, the obtained fingerprint can be used for the development of rapid quality-control methodologies concerning wine.

Inclusion complexes of tricyclic drugs and ß-cyclodextrin: Inherent chirality and dynamic behaviour.

Amitriptyline (AMT) and cyclobenzaprine (CBZ) are tricyclic drugs used as antidepressant and muscle relaxant, respectively. They show inherently chirality, i.e. they are chiral due to the lack of any symmetry element. As they are used as racemic mixture, diastereomeric inclusion complexes are formed via encapsulation in homochiral ßCD. In this work we show that a suitable combination of NMR methods easily provides details on the chiral recognition, geometry of complexation, rotational dynamics and spatial proximity of selected atom pairs. In particular, we show that 13C NMR can be used to unambiguously assess chiral recognition, demonstrating a higher performance over 1H NMR. The mole fraction of the bound drug and the association constant can be worked out through diffusion experiments, whereas the combination of non-selective, selective and bi-selective relaxation spectra gave insights into the rotational motion of the complexed drug and the spatial proximity of selected proton pairs. The toolkit here proposed provides a thorough characterization of CD/drug inclusion complexes from a physicochemical point of view. This can constructively complement the conventional pharmacological and pharmacokinetic experiments, and can shed light on the understanding of CD/drug formulations.

Urinary Metabolic Profile of Patients with Transfusion-Dependent ß-Thalassemia Major Undergoing Deferasirox Therapy.

INTRODUCTION: Renal dysfunction is a frequent complication in patients suffering from ß-thalassemia major (ß-TM). The aim of this study was to analyze the renal function and urine metabolomic profile of ß-TM patients undergoing transfusions and deferasirox (DFX) therapy, in order to better characterize and shed light on the pathogenesis of renal disease in this setting. METHODS AND SUBJECTS: 40 patients affected by ß-TM treated with DFX and 35 age- and gender-matched healthy controls were enrolled in the study. Renal function was assessed. Glomerular filtration rate (GFR) was estimated with CKD-EPI and Schwartz formula for adults and children, respectively. Renal tubular function and maximal urine concentration ability were tested. Urine specimens were analyzed by nuclear magnetic resonance spectroscopy to identify the urinary metabolite profiles. RESULTS: The study of renal function in ß-TM patients revealed normal estimated (e)GFR mean values and the albumin-to-creatinine ratio was <30 mg/g. The analysis of tubular function showed normal basal plasma electrolyte levels; 60% of patients presented hypercalciuria and many subjects showed defective urine concentration. Several amino acids, N-methyl compounds, and organic acids were overexcreted in the urine of thalassemic patients compared with controls. DISCUSSION: The major finding of this work is that ß-TM patients and controls exhibit different concentrations of some metabolites in the urine. Early recognition of urinary abnormalities may be useful to detect and prevent kidney damage.

Band-Gap Energies of Choline Chloride and Triphenylmethylphosphoniumbromide-Based Systems.

UV-VIS spectroscopy analysis of six mixtures containing choline chloride or triphenylmethylphosphonium bromide as the hydrogen bond acceptor (HBA) and different hydrogen bond donors (HBDs, nickel sulphate, imidazole, d-glucose, ethylene glycol, and glycerol) allowed to determine the indirect and direct band-gap energies through the Tauc plot method. Band-gap energies were compared to those relative to known choline chloride-containing deep band-gap systems. The measurements reported here confirmed the tendency of alcohols or Lewis acids to increment band-gap energy when employed as HBDs. Indirect band-gap energy of 3.74 eV was obtained in the case of the triphenylmethylphosphonium bromide/ethylene glycol system, which represents the smallest transition energy ever reported to date for such kind of systems.

Anions as Dynamic Probes for Ionic Liquid Mixtures.

Ionic liquid (IL) mixtures have been proposed as a viable alternative to rationally fine-tune the physicochemical properties of ILs for a variety of applications. The understanding of the effects of mixing ILs on the properties of the mixtures is however only in the very early stages. Two series of ionic liquid mixtures, based on the 1-ethyl-3-methylimidazolium and 1-dodecyl-3-methylimidazolium cations, and having a common anion (tetrafluoroborate or bis(trifluoromethylsulfonyl)imide), have been prepared and deeply characterized via multiple NMR techniques. Diffusion and relaxation methods combined with 2D ion-ion correlation (nuclear Overhauser enhancement) experiments have been used for a better understanding of the interplay between dynamics and structure of IL mixtures. A crucial role of the anion in driving the mixture's behavior emerged, making them important "dynamic probes" for gaining information of the polar and nonpolar regions of ionic liquids and their mixtures.

Probing Long-Range Anisotropic Interactions: a General and Sign-Sensitive Strategy to Measure 1 H-1 H Residual Dipolar Couplings as a Key Advance for Organic Structure Determination.

Residual dipolar couplings (RDCs) are amongst the most powerful NMR parameters for organic structure elucidation. In order to maximize their effectiveness in increasingly complex cases such as flexible compounds, a maximum of RDCs between nuclei sampling a large distribution of orientations is needed, including sign information. For this, the easily accessible one-bond 1 H-13 C RDCs alone often fall short. Long-range 1 H-1 H RDCs are both abundant and typically sample highly complementary orientations, but accessing them in a sign-sensitive way has been severely obstructed due to the overflow of 1 H-1 H couplings. Here, we present a generally applicable strategy that allows the measurement of a large number of 1 H-1 H RDCs, including their signs, which is based on a combination of an improved PSYCHEDELIC method and a new selective constant-time ß-COSY experiment. The potential of 1 H-1 H RDCs to better determine molecular alignment and to discriminate between enantiomers and diastereomers is demonstrated.

A combined LX-NMR and molecular dynamics investigation of the bulk and local structure of ionic liquid crystals.

The unique power of NMR spectroscopy in anisotropic media (LX-NMR) as a tool to obtain local and bulk structural information, combined with the effectiveness of molecular dynamics simulations at the atomistic level, shows very attractive potentialities for the study of interesting, even though still poorly understood, materials such as Ionic Liquid Crystals (ILCs). In this work, we focused our attention, in particular, on the orientational ordering of two mesophases: 1-dodecyl-3-methylimidazolium chloride, [C12C1im]Cl, and 1-dodecyl-3-methylimidazolium tetrafluoroborate, [C12C1im][BF4]. Both ILCs were studied by a 2H NMR direct investigation of the molecules forming the phases, suitably deuterated, and by 1H NMR spectroscopy, using the small rigid probe-solutes 1,4-dichlorobenzene (DCB), dissolved in [C12C1im][BF4] and [C12C1im]Cl, and 1,4-dibromobenzene (DBB) dissolved in [C12C1im][BF4], to probe the local, internal structure and organization of the mesophases. The experimental results were then compared with the predictions, by atomistic MD simulations, of the structure of the smectic phase of the two salts, at two selected temperatures, containing a single DCB molecule as a probe. The MD simulations show that the DCB solute is distributed only within the hydrophobic layers of the ILC. Orientational order parameters of the imidazolium cations and of the DCB molecule were obtained and compared with the experiments, showing a general good agreement and allowing a deeper understanding of the microscopic structure of the systems.

Assessing the stable conformations of ibuprofen in solution by means of Residual Dipolar Couplings.

Detailing the conformational equilibria between global and local minimum energy structures of anti-inflammatory α-arylpropionic acids directly in solution is of the utmost importance for a better understanding of the structure-activity relationships, hence providing valuable clues for rational structure-based drug design studies. Here the conformational preferences of the widely used pharmaceutical ibuprofen were investigated in solution by NMR spectroscopy in weakly ordering phases. A thorough theoretical treatment of the anisotropic interactions that are relevant for NMR spectra led to a conformational model characterized by six pairs of symmetry-related conformers, in particular four couples of gauche structures, with a total probability of 93%, and 2 couples of trans structures, counting for the remaining 7%.

Doped ionic liquid crystals as effective weakly alignment media for polar solutes.

The ionic liquid crystal 1-dodecyl-3-methylimidazolium tetrafluoroborate slightly doped with water is presented as a promising NMR alignment medium for the measurement of residual dipolar couplings for polar molecules dissolved therein.

Detection of Significant Aprotic Solvent Effects on the Conformational Distribution of Methyl 4-Nitrophenyl Sulfoxide: From Gas-Phase Rotational to Liquid-Crystal NMR Spectroscopy.

The conformational equilibrium of methyl 4-nitrophenyl sulfoxide (MNPSO) was experimentally investigated in the gas phase by using microwave spectroscopy and in isotropic and nematic liquid-crystal solutions, in which the solvents are nonaqueous and aprotic, by using NMR spectroscopy; moreover, it was theoretically studied in vacuo and in solution at different levels of theory. The overall set of results indicates a significant dependence of the solute conformational distribution on the solvent dielectric permittivity constant: when dissolved in low-polarity media, the most stable conformation of MNPSO proved to be strongly twisted with respect to that in more polar solvents, in which the conformational distribution maximum essentially coincides with that obtained in the gas phase. We discuss a possible explanation of this behavior, which rests on electrostatic solute-solvent interactions and is supported by calculations of the solute electric dipole moment as a function of the torsional angle. This function shows that the least polar conformation of MNPSO is located at a twist angle close to that of the conformational distribution maximum found in less-polar solvents. This fact, associated with a relatively flat torsional potential, can justify the stabilization of the twisted conformation by the less-polar solvents.

Conformational investigation in solution of a fluorinated anti-inflammatory drug by NMR spectroscopy in weakly ordering media.

The structural and conformational elucidation of flexible bioactive molecules in solution is currently a crucial goal for the scientific community, but it is rarely achievable by available techniques. The anti-inflammatory drug diflunisal is presented here as a model case for supporting the efficiency of NMR spectroscopy combined with the use of weakly ordering media as a promising methodology for the conformational investigation of small bioactive molecules. Starting from NMR anisotropic data (40 independent dipolar couplings), a quite accurate description of its torsional distribution around the inter-ring C-C bond was found, characterized by a pair of two couples of conformers. According to the relative configuration of the carboxylic group and the fluorine atom in the ortho position to the inter-ring C-C bond, the more stable couple of conformers are defined as "trans" type conformers (F opposite to the carboxylic group) whereas the less stable couple are "cis" type conformers (F and carboxylic group on the same side). In order to study the influence of fluorine nuclei on the structure and conformational distribution, the same analytical strategy has been applied to investigate the phenylsalicylic acid, its nonfluorinated analogue.