1-乙基-3-甲基咪唑双（三氟甲基磺酰基）亚胺中氧气溶解度

Oxygen is the third-most abundant element on this planet and is essential to life, the lifestyle of humans and virtually all sentient life. We need O2 to live and additionally use it for both heating and transportation. Since O2 is so essential in our everyday life, there are several applications where the oxygen levels need to be controlled or maintained within a certain range. To make sure that the O2 level is within the necessary range, devices are needed that can monitor and feedback/communicate O2 levels continuously. There are several types of chemical gas sensors for O2 which include chemoresistive gas sensors and electrochemical gas sensors. The Clark-type electrochemical sensor is the oldest and probably the most used sensor for oxygen especially in medical applications. One of the most well-known industrial applications for gas-phase oxygen sensors is probably the control of oxygen levels in combustion engines with the help of a Lambda probe, a solid-state electrochemical cell operated in amperometric and potentiometric modes. Electrochemical sensors have evolved over the past decades. By finding the suitable combination of electrolyte, electrode material, cell design and operation conditions, electrochemical sensors are tunable to meet the specific requirements of the many different applications. For example, by changing the electrode material from gold to platinum while keeping everything else the same, you can reduce the response to CO by orders of magnitude improving the selectivity in low level measurements. Further, by adjusting the thermodynamic voltage of the sensing electrode, the electrochemical reactivity is adjusted to maximize the sensor’s selectivity for the target analyte. While these developments have occurred over time, recent work implements room temperature ionic liquids (RTILs) as electrolytes. This idea has some serious merit to it for multiple reasons. Firstly, many electrochemical sensors have aqueous electrolytes which freeze at low temperatures and rapidly evaporate at elevated temperatures. Additionally, aqueous electrolytes can change in real time with variations in background humidity levels. To be more exact, aqueous electrolytes dry out when operated in low humidity backgrounds and significantly increase in volume (swell) in high humidity background levels. While drying out is an issue because this leads to poor ionic conductivities, swelling is an issue because the electrolyte needs expansion room in the sensor, typically an extensive cavity within the cell body. RTILs have shown promise because they can extend the operating temperature range as well as lead to new sensor designs operatable over a wider range of environmental conditions. The implementation of RTILs might even allow for smaller sensor designs due to a smaller volume change of the electrolyte in dependence of changing humidity levels. Several research groups have investigated the oxygen sensing capabilities of RTILs in electrochemical devices. Silvester et al. investigated the oxygen solubility in several different imidazolium cations combined with [bis(trifluoromethylsulfonyl)imide] ([NTf2]-) anions and found a high oxygen solubility in 3-butyl-1-methyl imidazolium [NTf2]- [1]. They further investigated the influence of humidity on the oxygen reduction reaction and found the most stable behavior for [3-etyhl-1-methyl imidiazolium] [NTf2]- over a broad range of different humidity levels [2]. Yin et al. investigated 1-butyl-1-methylpyrrolidinium [NTf2]- as an electrolyte in oxygen sensors and found good linear correlation of the sensor output to the oxygen concentration [3]. In this work, we investigated different RTILs, including the before mentioned 1-butyl-1-methylpyrrolidinium [NTf2]- and 3-butyl-1-methyl imidazolium [NTf2]-, regarding their suitability for thin layer electrochemical oxygen sensors in a background of mostly nitrogen. The performance was investigated using CV (cyclic voltammetry) and other time dependent voltametric techniques. The ability to detect oxygen of sensors with different RTILs as electrolyte was compared to that of aqueous H2SO4. [1] S. Doblinger, D.S. Silvester, M. Costa Gomes, Functionalized Imidazolium Bis(trifluoromethylsulfonyl)-imide Ionic Liquids for Gas Sensors: Solubility of H2, O2 and SO2, Fluid Phase Equilib. 549 (2021). https://doi.org/10.1016/j.fluid.2021.113211. [2] S. Doblinger, J. Lee, D.S. Silvester, Effect of Ionic Liquid Structure on the Oxygen Reduction Reaction under Humidified Conditions, Journal of Physical Chemistry C. 123 (2019) 10727–10737. https://doi.org/10.1021/acs.jpcc.8b12123. [3] H. Yin, H. Wan, L. Lin, X. Zeng, A.J. Mason, Miniaturized Planar RTIL-based Electrochemical Gas Sensor for Real-Time Point-of-Exposure Monitoring, 2016 IEEE Healthcare Innovation Point-Of-Care Technologies Conference (HI-POCT). (2016) 85–88. https://doi.org/10.1109/HIC.2016.7797703.

A robust, miniaturised electrochemical gas sensor for oxygen (O2) has been constructed using a commercially available Pt microarray thin-film electrode (MATFE) with a gellified electrolyte containing the room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]) and poly(methyl methacrylate) (PMMA) in a 50 : 50 mass ratio. Diffusion coefficients and solubilities for oxygen in mixtures of PMMA/RTIL at different PMMA doping concentrations (0-50% mass) were derived from potential step chronoamperometry (PSCA) on a Pt microdisk electrode. The MATFE was then used with both the neat RTIL and 50% (by mass) PMMA/RTIL gel, to study the analytical behavior over a wide concentration range (0.1 to 100 vol% O2). Cyclic voltammetry (CV) and long-term chronoamperometry (LTCA) techniques were employed and it was determined that the gentler CV technique is better at higher O2 concentrations (above 60 vol%), but LTCA is more reliable and accurate at lower concentrations (especially below 0.5% O2). In particular, there was much less potential shifting (from the unstable Pt quasi-reference electrode) evident in the 50% PMMA/RTIL gel than in the neat RTIL, making this a much more suitable electrolyte for long-term continuous oxygen monitoring. The mass production and low-cost of the electrode array, along with the minimal amounts of RTIL/PMMA required, make this a viable sensing device for oxygen detection on a bulk scale in a wide range of environmental conditions.

No abstract available

No abstract available

We have determined the temperature dependence of the solvation behavior of a large collection of important light gases in imidazolium-based ionic liquids with the help of extensive molecular dynamics simulations. The motivation of our study is to unravel common features of the temperature dependent solvation under well controlled conditions, and to provide a guidance for cases, where experimental data from different sources disagree significantly. The solubility of molecular hydrogen, oxygen, nitrogen, methane, krypton, argon, neon and carbon dioxide in the imidazolium based ionic liquids of type 1-n-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Cnmim][NTf2]) with varying alkyl side chain lengths n = 2, 4, 6, 8 is computed for a temperature range between 300 K and 500 K at 1 bar. By applying Widom's particle insertion technique and Bennet's overlapping distribution method, we are able to determine the temperature dependent solvation free energies of those selected light gases in simulated imidazolium based ionic liquids with high statistical accuracy. Our simulations demonstrate that the magnitude of the solvation free energy of a gas molecule at a chosen reference temperature and that of its temperature-derivatives are intimately related to one another. We conclude that this "universal" behavior is rooted in a solvation entropy-enthalpy compensation effect, which seems to be a defining feature of the solvation of small molecules in ionic liquids. The observations lead to simple analytical relations, determining the temperature dependence of the solubility data based on the absolute solubility at a certain reference temperature. By comparing our results with available experimental data from many sources, we can show that our approach is particularly helpful for providing reliable estimates for the solvation behavior of very light gases, such as hydrogen, where conflicting experimental data exist.

Understanding the thermodynamic interactions between an analyte and the sample phase is of paramount importance when choosing a co-solvent in headspace analysis. A sample phase - gas phase equilibrium partition coefficient (Kp) is used fundamentally to describe the distribution of the analyte between the two phases. Kp determinations by headspace gas chromatography (HS-GC) were acquired by two methods: vapor phase calibration (VPC) and phase ratio variation (PRV). Here, we demonstrated a pressurized - loop headspace system in conjunction with gas chromatography vacuum ultraviolet detection (HS-GC-VUV) to directly calculate the concentration of analytes in the gas phase from room temperature ionic liquids (RTILs) sample phases, using pseudo-absolute quantification (PAQ). PAQ, an attribute of VUV detection, allowed for quick determination of Kp and other thermodynamic properties, such as enthalpy (ΔH) and entropy (ΔS) of the system through the use of van't Hoff plots in the temperature range of 70-110 °C. The Kp determinations by PAQ were comparable to those obtained using the VPC method with percent difference ranging from ≤ 1-33%. Kp determinations were made for analytes (cyclohexane, benzene, octane, toluene, chlorobenzene, ethylbenzene, m-,p-, and o-xylene) at the varying temperatures (70-110 °C) using different RTILs (1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][ESO4]), 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), and tris(2-hydroxyethyl)methylammonium methylsulfate ([MTEOA][MeOSO3])) and (1-ethyl-3-methylimidazolium bis(trisfluoromethanesulfonyl)imide ([EMIM] [NTF2])). The results from the van't Hoff analysis revealed that [EMIM] cation-based RTILs exhibit strong solute-solvent interactions with analytes that have π- electrons.

Four new di(hydroperoxy)cycloalkane adducts (Ahn adducts) of p-Tol3PO (1) and o-Tol3PO (2), namely, p-Tol3PO·(HOO)2C(CH2)5 (3), o-Tol3PO·(HOO)2C(CH2)5 (4), p-Tol3PO·(HOO)2C(CH2)6 (5), and o-Tol3PO·(HOO)2C(CH2)6 (6), have been synthesized and fully characterized. Their single crystal X-ray structures have been determined and analyzed. The 31P NMR data are in accordance with hydrogen bonding of the di(hydroperoxy)alkanes to the P═O groups of the phosphine oxides. Due to their high solubility in organic solvents, natural abundance 17O NMR spectra of 1-6 could be recorded, providing the signals for the P═O groups and additionally the two different oxygen nuclei in the O-OH groups in the adducts 3-6. The association and mobility of 3-6 were explored by 1H DOSY (diffusion ordered spectroscopy) NMR, which indicated persistent hydrogen bonding of the adducts in solution. Competition experiments with phosphine oxides allowed ranking of the affinities of the di(hydroperoxy)cycloalkanes for the different phosphine oxide carriers. On the basis of variable temperature 31P NMR investigations, the Gibbs energies of activation ΔG‡ for the adduct dissociation processes of 3-6 at different temperatures, as well as the enthalpy ΔH‡ and entropy ΔS‡ of activation, have been determined. IR spectroscopy of 3-6 corroborated the hydrogen bonding, and in the Raman spectra, the ν(O-O) stretching bands have been identified, confirming the presence of peroxy groups in the solid materials. The high solubilities in selected organic solvents have been quantified.

No abstract available

The use of ions as therapeutic agents has the potential to minimize the use of small-molecule drugs and biologics for the same purpose, thus providing a potentially more economic and less adverse means of treating, ameliorating or preventing a number of diseases. Hydroxyapatite (HAp) is a solid compound capable of accommodating foreign ions with a broad range of sizes and charges and its properties can dramatically change with the incorporation of these ionic additives. While most ionic substitutes in HAp have been monatomic cations, their lesser atomic weight, higher diffusivity, chaotropy and a lesser residence time on surfaces theoretically makes them prone to exert a lesser influence on the material/cell interaction than the more kosmotropic oxyanions. Selenite ion as an anionic substitution in HAp was explored in this study for its ability to affect the short-range and the long-range crystalline symmetry and solubility as well as for its ability to affect the osteoclast activity. We combined microstructural, crystallographic and spectroscopic analyses with quantum mechanical calculations to understand the structural effects of doping HAp with selenite. Integration of selenite ions into the crystal structure of HAp elongated the crystals along the c-axis, but isotropically lowered the crystallinity. It also increased the roughness of the material in direct proportion with the content of the selenite dopant, thus having a potentially positive effect on cell adhesion and integration with the host tissue. Selenite in total acted as a crystal structure breaker, but was also able to bring about symmetry at the local and global scales within specific concentration windows, indicating a variety of often mutually antagonistic crystallographic effects that it can induce in a concentration-dependent manner. Experimental determination of the lattice strain coupled with ab initio calculations on three different forms of carbonated HAp (A-type, B-type, AB-type) demonstrated that selenite ions initially substitute carbonates in the crystal structure of carbonated HAp, before substituting phosphates at higher concentrations. The most energetically favored selenite-doped HAp is of AB-type, followed by the B-type and only then by the A-type. This order of stability was entailed by the variation in the geometry and orientation of both the selenite ion and its neighboring phosphates and/or carbonates. The incorporation of selenite in different types of carbonated HAp also caused variations of different thermodynamic parameters, including entropy, enthalpy, heat capacity, and the Gibbs free energy. Solubility of HAp accommodating 1.2 wt% of selenite was 2.5 times higher than that of undoped HAp and the ensuing release of the selenite ion was directly responsible for inhibiting RAW264.7 osteoclasts. Dose-response curves demonstrated that the inhibition of osteoclasts was directly proportional to the concentration of selenite-doped HAp and to the selenite content in it. Meanwhile, selenite-doped HAp had a significantly less adverse effect on osteoblastic K7M2 and MC3T3-E1 cells than on RAW264.7 osteoclasts. The therapeutically promising osteoblast vs. osteoclast selectivity of inhibition was absent when the cells were challenged with undoped HAp, indicating that it is caused by selenite ions in HAp rather than by HAp alone. It is concluded that like three oxygens building the selenite pyramid, the coupling of (1) experimental materials science, (2) quantum mechanical modeling and (3) biological assaying is a triad from which a deeper understanding of ion-doped HAp and other biomaterials can emanate.

No abstract available

No abstract available

No abstract available

No abstract available

The stoichiometric and thermodynamic properties of nitrogen (N2) binding to human deoxyhemoglobin (Hb) at N2 saturation pressures up to 400 atm were derived from measured N2 solubilities in protein-free buffers (pH 7.1) and in corresponding buffer + Hb (6.5% w/w) solutions at 20.0, 25.0, and 37.0 degrees C. At each temperature, approximately 3 N2 molecules bind per Hb tetramer at N2 pressures of 100 atm, while about 7 N2 molecules bind per tetramer at 400 atm N2 pressure, where available binding sites are still not fully saturated. Calculated N2-Hb binding isotherms are well described by a simple binding model with 12 independent and equivalent binding sites/Hb tetramer. N2 binding at each of the sites is hydrophobic, exhibiting the typical increase of the dissociation enthalpy with temperature. Enthalpies of dissociation are slightly more negative, while corresponding unitary entropies are somewhat less negative than those for the transfer of N2 from olive oil to water. Calculated partial molar volumes of N2 in Hb are positive but less than the corresponding partial molar volumes of N2 in buffer. Results indicate that N2 binding to Hb is accompanied by only small protein conformational changes which entail slight structural destabilization and loss of free volume in the protein that partially accommodates the volume of the N2 ligand. Results are related to previously reported effects of high pressure and high-pressure N2 on HbO2 affinity, illuminating essential features of the molecular mechanisms for these effects.

No abstract available

The progress of rechargeable Li-O2 battery (LOB) is hampered due to the number of challenges its components present. Among various critical challenges, the choice of electrolyte has always been a bottleneck impeding the breakthrough in the development of LOB. Various electrolytes, including organic solvents and room-temperature ionic liquids (RTILs) have been developed and studied. Each electrolyte comes with various limitations, which restrict its application in the LOB. These include thermal and electrochemical stability, volatility, viscosity, flammability, capability to dissolve incoming oxygen, diffusivity, and ionic conductivity. Consequently, no electrolyte could be regarded as an ideal electrolyte. Nonetheless, efforts have been made to tune the physiochemical properties of the electrolyte by blending two or more miscible solvents. High thermal and electrochemical stability and negligible volatility of RTILs can be combined with high diffusivity and ionic conductivity of organic solvents by merely blending them with optimized volume ratios. In this study, we comprehensively investigated the effects of operating temperature (20°C, 40°C and 60°C) on the electrochemical performance of LOBs incorporated with RTIL and organic solvent binary electrolyte. We designed and investigated, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2C1im][Tf2N]) RTIL and dimethyl sulfoxide (DMSO) organic solvent at various volume ratios ((4:1), (1:1), (1:4)). Among the binary electrolytes, ([C2C1im][Tf2N]/DMSO (1:4)) delivered the highest discharge capacities of 3.70 Ah g-1 (20°C), 4.0 Ah g-1 (40°C) and 3.65 Ah g-1 (60°C) as compared with pure [C2C1im][Tf2N] and DMSO. Cycling stability tests showed superior stability of the binary electrolyte ([C2C1im][Tf2N]/DMSO (1:4)) irrespective of the operating temperature. From viscosity and ionic conductivity measurements (at 20-60°C), [C2C1im][Tf2N]/DMSO (1:4) exhibited the highest ionic conductivity and the lowest viscosity compared with other binary electrolytes and pure RTIL at any given temperature. Cyclic voltammetry (CV) tests revealed a higher reaction rate with [C2C1im][Tf2N]/DMSO (1:4) binary electrolytes than pure electrolytes. The superior performance of [C2C1im][Tf2N]/DMSO (1:4) binary electrolyte was ascribed to enhanced stability against reactive intermediate species during oxygen reduction reaction (ORR), increased ionic conductivity, low viscosity (comparable with organic electrolytes), improved oxygen solubility, and relatively low evaporation rates. The detailed results and discussion will be presented during the presentation.

Ionic liquid (IL)-based solid polymer electrolytes (SPE) with stable thermal properties and low electrical resistivity have been evaluated. Two candidates for the polymer component of the SPE, poly(ethylene glycol) diacrylate (PEGDA) and Nafion, were considered. Differential scanning calorimetry analysis and electrical resistivity tests revealed that PEGDA, in comparison to Nafion, enables the formation of uniform SPEs with lower electrical resistivity and better thermal stability within a range of 25 °C-170 °C. Therefore, PEDGA was selected for further evaluation of the IL component effect on the resulting SPE. Six IL candidates, including 1-butyl-3-methylimidazolium methanesulfonate ± methanesulfonic acid (BMIM.MS ± MSA), diethylmethylammonium triflate ±bis(trifluoromethanesulfonyl)imine (Dema.OTF±HTFSI), and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ± bis(trifluoromethanesulfonyl)imine (BMIM.TFSI ± HTFSI), were selected to test the effect of hydrophobicity/hydrophilicity of the IL on the resulting SPE. Fourier transformation infrared spectrometer analysis revealed that the BMIM.MSA-based electrolytes have the highest tendency to absorb from the environment and keep the moisture, while Dema.OTF has the fastest curing time. The SPE candidates were further evaluated for absorption characteristics of different gasses and vapors, such as N2, O2, ethanol vapor, and diluted CO/N2, that were tested with the in situ quartz crystal microbalance (QCM) technique. Among all six candidates, BMIM.MS showed the largest N2 and O2 absorption capacity from the environment. Dema.OTF + HTFSI, meanwhile, demonstrated a higher level of interactions with the ethanol vapor. In the case of CO/N2, QCM analysis revealed that BMIM.MS+MSA has the largest, ∼13 µg/cm2, absorption capacity that is reached within 400 s of being exposed to the gas mixture.

No abstract available

Effect of ionic liquids, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI) and 1-butyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide (BDMITFSI), on the Li-O2 cell performance was investigated by mixing ionic liquids with LiTFSI in TEGDME electrolyte at a specific volume ratio. Addition of ionic liquids improved the discharge/charge cycleability and optimum mixing ratio of LiTFSI in TEGDME to ionic liquid was 9 to 1. EMITFSI and BDMITFSI ionic liquids reduced the overpotential of oxygen evolution reaction occurred during charging process and BDMITFSI is more effective than EMITFSI. Successive linear sweep voltammetry is in agreement with the observed discharge/charge cycleability.

Ionic liquids (ILs) are highly promising, tuneable materials that have the potential to replace volatile electrolytes in amperometric gas sensors in a 'membrane-free' sensor design. However, the drawback of removing the membrane is that the liquid ILs can readily leak or flow from the sensor device when moved/agitated in different orientations. A strategy to overcome the flowing nature of ILs is to mix them with polymers to stabilise them on the surface in the form of membranes. In this research, the room temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]), has been mixed with the poly(ionic liquid) (poly(IL), poly(diallyldimethylammonium bis(trifluoromethylsulfonyl)imide), poly[DADMA][NTf2]) to form stable membranes on miniaturised, planar electrode devices. Different mixing ratios of the IL/poly(IL) have been explored to find the optimum membrane that gives both high robustness (non-flowing material) and adequate conductivity for measuring redox currents, with the IL/poly(IL) 60/40 wt% proving to give the best responses. After assessing the blank potential windows on both platinum and gold electrodes, followed by the kinetics of the cobaltocenium/cobaltocene redox couple, the voltammetry of oxygen, sulfur dioxide and ammonia gases have been studied. Not only were the membranes highly robust and non-flowing, but the analytical responses towards the gases were excellent and highly reproducible. The presence of the poly(IL) negatively affected the sensitivity, however the electron transfer kinetics and the limit of detection were actually improved for O2 and SO2, combined with the poly(IL) experiencing less reference potential shifting. These promising results show that membranes containing conductive poly(IL)s mixed with ionic liquids could be used as new 'designer' gas sensor materials in robust membrane free amperometric gas sensor devices.

No abstract available

No abstract available