Bis Amide Research Articles

Synthesis and Characterization of Solvated Lanthanide(II) Bis(triisopropylsilyl)phosphide Complexes.

Lanthanide (Ln) silylamide chemistry is well-developed, but the corresponding silylphosphide chemistry is immature; there are only ten structurally characterized examples of Ln(II) bis(trimethylsilyl)phosphide complexes to date and no reported derivatives with bulkier R-groups. Here, we report the synthesis of the first f-block bis(triisopropylsilyl)phosphide complexes, [Ln{P(SiiPr3)2}2(THF)x] (1-Ln; Ln = Sm, Eu, x = 3; Ln = Yb, x = 2), by the respective salt metathesis reactions of parent [LnI2(THF)2] with 2 equiv of [Na{P(SiiPr3)2}]n in toluene. Complexes 1-Ln were characterized by a combination of NMR, EPR, ATR-IR, electronic absorption and emission spectroscopies, elemental analysis, SQUID magnetometry, and single crystal X-ray diffraction. These data contrast with those obtained for related Ln(II) bis(trimethylsilyl)phosphide complexes due to the bulkier ligands in 1-Ln and also with Ln(II) bis(triisopropylsilyl)amide complexes due to a combination of longer Ln-P vs. Ln-N bonds and the softer nature of P- vs. N-donor ligands.

Modeling High Concentration Bisalt-in-Sulfolane Electrolytes and the Observation of Ligand-Bridged Cation-Pair Complexes.

Despite the abundance of sodium over lithium in Earth's crust and the copious amounts of expensive lithium salt required to make Li-ion high-concentration electrolytes (HCEs), studies of HCEs made from sodium salts remain sparse. A comparative molecular-level study of Li- and Na-ion HCEs and mixed cation or bisalt HCEs in an organic solvent is missing. To fill this gap, we studied model HCEs of pure and mixed Li and Na salts of bis(fluorosulfonyl)amide (FSI) in sulfolane using a confluence of classical molecular dynamics (MD), ab initio MD (AIMD) simulations, and quantum chemical cluster calculations. While Li-ion HCEs display transport properties superior to those of Na-ion HCEs, the latter's performance can be considerably improved by replacing even 25% of Na-ions with Li-ions. While the effects of doping are largely systemic, a larger sensitivity of the identity of solvation shells of Li-ions to the Li-content of the HCE is observed; in contrast, those of Na-ions are more oblivious to it. Fascinating ligand-bridged, short-distance cation pairs observed in the classical MD simulations are confirmed using density functional theory-based AIMD simulations. Quantum chemical calculations in the gas phase reveal the thermodynamic stability of such cation pairs complexed with multiple anions and solvent molecules.

A Mixed Aryl/Amide Complex of Iron(II)

The combined incorporation of a labile and a stabilizing ligand in a metal‐organic precursor is of interest for the synthesis of low valent ligated (hetero)metallic clusters. The heteroleptic aryl/amide iron (II) complex [Fe2(Mes)2(BTSA)2] (1) was synthesized by equimolar mixing of [Fe2(Mes)4] with [Fe2(BTSA)4]. (VT)‐NMR‐, UV‐Vis‐ and SC‐XRD‐analysis combined with DFT calculations revealed a dimeric structure with terminal bis(trimethylsilyl)amide‐ and bridging mesityl‐ligands in solution and as well in the solid phase. The treatment of [Fe2(BTSA)4] with the carbenoid group 13 metallo‐ligand GaCp* is known to yield simply adducts. In contrast, monitoring the reactions of [Fe2(Mes)4] and [Fe2(Mes)2(BTSA)2] (1) with GaCp* by liquid injection field desorption mass spectrometry (LIFDI‐MS) suggest formation of a broader variety of bimetallic Fe‐Ga‐species with iron formally reduced to iron (I) or iron (0). However, the product distribution obtained using the heteroleptic compound 1 indicates combined reactivity of the homoleptic congeners by showing larger species with variations of Fe/Ga ratios towards the formation of Fe/Ga clusters. This blended behavior is assigned to the more labile mesityl ligand and the more stabilizing BTSA‐ligand.

Investigating the ions emitted by multiply charged ionic liquids from a porous electrospray ion source

A porous electrospray ion source was tested with three ionic liquids in order to investigate the effects of ionic liquid properties on the sizes of ion clusters emitted by purely ionic electrospray sources. Two of the ionic liquids, bis(1-ethyl-3-methylimidazolium) tetrathiocyanatocobaltate and 1,6-bis(3-methylimidazolium-1-yl)hexane bis(trifluoromethylsulfonyl)amide, were selected due to them having a dication or dianion, which were termed multiply charged ionic liquids due to them containing anions or cations with more than one charge within them. These were selected in order to investigate ionic clustering within electrospray ion emission and were compared against one of the most common ionic liquids, EMI-BF4. The current–voltage data showed that EMI-BF4 emitted similar levels of current to bis(1-ethyl-3-methylimidazolium) tetrathiocyanatocobaltate, even though the latter liquid had significantly lower conductivity and higher viscosity, suggesting an improvement in current speculated to be due to the extra charges contained by the ions. Time-of-flight and retarding potential analysis data are provided, showing all three liquids emitting ions comprising of monomers, dimers, trimers, and quadramers, with some of the 1,6-bis(3-methylimidazolium-1-yl)hexane bis(trifluoromethylsulfonyl)amide data showing heavier species emission. The data also suggested that the multiply charged ionic liquids produced ions that have two anions or cations attached, termed “double ions,” with these ions not been previously reported using porous electrospray sources. Furthermore, it was found that the dimers emitted by both of the multiply charged ionic liquids seemed to be more stable than EMI-BF4 dimers, providing insight into ion cluster formation.

Correlation between Electrolyte Concentration and Lithium Morphology during Lithium Bis(fluorosulfonyl)amide–Tetraglyme Electrolyte Deposition–Dissolution Reactions

Electrodeposition and chemical dissolution reactions of Li are strongly affected by the electrolyte concentration at the electrode surface. In this study, we investigated the processes involved in the formation of Li deposits at various electrolyte concentrations and different numbers of deposition–dissolution cycles. Growth of the deposits during the cycles was assessed using a digital microscope. The thickness of the fibrous layer was strongly dependent on the electrolyte solute–solvent molar ratio. The thickness of the fibrous layer increased as the number of cycles increased when the electrolyte solute–solvent molar ratio was low but decreased when the molar ratio was high. Temporal changes in the electrolyte concentration and in the diffusion layers near the electrode were identified using a laser interference microscope. The results led us to conclude that there are three fibrous Li deposit growth models that occur at different solvent–solute molar ratios.

Mn-Based Transition Metal Oxide Positive Electrode for K-Ion Battery Using an FSA-based Ionic Liquid Electrolyte

Layered Mn-based transition metal oxides have gained interest as positive electrode materials for K-ion batteries due to their high capacity, excellent structural stability, and abundant resources. However, their practical utility is significantly hindered by insufficient electrochemical performances during operations. This study reports the successful synthesis of P3-K0.46MnO2 via the solid-state method and investigates its charge–discharge behavior as a positive electrode working in an FSA-based (FSA= bis(fluorosulfonyl)amide) ionic liquid electrolyte at 298 K. The K0.46MnO2 electrode demonstrates superior performance compared to previously reported K x MnO2 counterparts, delivering a reversible discharge capacity of about 100 mAh g−1 at a current density of 20 mA g−1 and a capacity retention of 68.3% over 400 cycles at 100 mA g−1. Ex situ X-ray diffraction analyses confirm the occurrence of reversible structural changes during the charge–discharge process. Further, we explore potassium storage mechanisms through ex situ synchrotron soft X-ray absorption spectroscopy. Spectra obtained in Mn L-edge region suggest that Mn is reversibly oxidized and reduced during K+ deintercalation and intercalation processes. Remarkably, discharging the electrode below 2.3 V induces reversible formation of Mn2+ from Mn3+/4+ on the electrode surface. The study demonstrates superior electrochemical performance of K0.46MnO2 positive electrode for K-ion battery using ionic liquid electrolyte.

Anti-Cancer Activity, DFT and molecular docking study of new BisThiazolidine amide

In this study, a series of bis amide thiazolidine derivatives (Q1-Q6) were synthesized and their anticancer activity was evaluated against prostate (PC3) and breast (MCF7) cancer cells and normal cells line activity was evaluated against breast (MCF10), prostate (PNT1A) and living human cells (HUVEC) cancer cells. The thiazolidine rings were built from penicillamine and aromatic aldehydes (A1-A6), then converted to acetyl thiazolidines (B1-B6) using acetic anhydride, and finally linked with phenylene diamine to form the final compounds (Q1-Q6). Notably, compounds Q1 and Q3 displayed the highest activity against PC3, with IC50 values of 81 and 89 µg/ml, respectively. Docking simulations were performed for Q1, Q4, and Q5 against protein structures related to cancer (2FVD and 1SJ0). Additionally, DFT calculations were used to determine various molecular properties like HOMO/LUMO energies, band gap, and other descriptors, providing insights into the compounds’ stability and reactivity.

Solvation structure and thermodynamics for Ln(III), (Ln = Pr, Nd, Tb, and Dy) complexes in phosphonium-based ionic liquids evaluated by Raman spectroscopy and DFT calculation

The coordination states of trivalent praseodymium, neodymium, terbium, and dysprosium complexes in triethyl-n-octylphosphonium bis(trifluoromethylsulfonyl)amide ([P2228][TFSA]) ionic liquid were examined using Raman spectroscopy. In [P2228][TFSA], the concentration dependence of lanthanide (Ln) ions on the Raman spectrum was investigated in the range of 0.24–0.48 mol kg−1 of Ln(III), (Ln = Pr, Nd, Tb, and Dy) in [P2228][TFSA]. Based on classical analysis, solvation numbers n of Ln(III) (Ln = Pr, Nd, Tb, and Dy) in [P2228][TFSA] were determined as 4.80 ± 0.04, 5.08 ± 0.03, 5.15 ± 0.04, and 4.92 ± 0.03, respectively, at 373 K.Based on the temperature dependence of the Raman spectrum measured at temperatures between 298 and 398 K, thermodynamic parameters with ΔisoG, ΔisoH, and ΔisoS for the isomerism of [TFSA]− from the trans- to the cis-coordinated isomer in the bulk and first solvation sphere of the centered Ln3+ (Ln = Pr, Nd, Tb, and Dy) cation in [P2228][TFSA] were evaluated in this study. As indicated by the positive value of ΔisoH(bulk) = 6.86 kJ mol−1, the trans-[TFSA]− was found to be the dominant contributor to enthalpy. In [P2228][TFSA], the value of TΔisoS(bulk) = 7.92 kJ mol−1 was slightly larger than that of ΔisoH(bulk), indicating that cis-[TFSA]− was entropy controlled. Conversely, in the first solvation sphere of the Ln3+ cation, ΔisoH(Ln) became significantly negative, indicating stabilization of cis-[TFSA]− isomers via enthalpic contributions. This result clearly indicates that the cis-[TFSA]− conformer bound to Ln3+ cation is the preferred coordination state of [Ln(III)(cis–TFSA)5]2− in [P2228][TFSA], because ΔisoH(Ln) contributes to a significant decrease in ΔisoG(Ln).Furthermore, DFT calculations using the Amsterdam Density Functional package were used to investigate the optimized geometries and binding energies of [Ln(III)(cis-TFSA)5]2−, (Ln = Pr, Nd, Tb, and Dy) clusters. The bonding energy, ΔEb, was calculated as ΔEb = Etot(cluster) − Etot(Ln3+) − nEtot([TFSA]−), and ΔEb ([Ln(III)(cis-TFSA)5]2−), (Ln = Pr, Nd, Tb, and Dy) were calculated as −4349.2 ± 7.2, −4354.6 ± 7.6, −4278.6 ± 7.2, and −4296.4 ± 7.8 kJ mol−1, respectively. The thermodynamic properties were consistent with the average atomic charges and bond distances of these clusters. Additionally, the highest occupied molecular orbital and lowest unoccupied molecular orbital estimated from DFT methods were consistent with the coordination states of [Ln(III)(cis-TFSA)5]2−, (Ln = Pr, Nd, Tb, and Dy) analyzed by Raman spectroscopy.

Anodic Dissolution and Electropolishing of Titanium in an Amide-Type Ionic Liquid Containing Halide Ions

Anodic dissolution of titanium was investigated in an amide-type ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethyl-sulfonyl)amide (BMPTFSA) in the presence of halide ions, Cl– and Br–. Electropolishing of Ti was possible in the presence of Cl– at 353 K, suggesting that the surface of a Ti electrode with the native oxide layer was activated by Cl–. The dissolved species of Ti after anodic dissolution of Ti at 0 V vs. Ag|Ag(I) was found to be tetravalent [TiCl6]2–, because the applied potential was more positive than the redox potential of [TiCl6]2–/[TiCl6]3–. The morphology of a Ti electrode changed after potentiostatic anodic oxidation at –0.5 V in BMPTFSA containing BMPBr, indicating that anodic dissolution of Ti was possible in the presence of Br–.

Redox Reaction of Some Nitroxyl Radicals in 1-Butyl-1-Methylpyrrolidinium Bis(fluorosulfonyl)amide in the Presence and Absence of Lithium Ion

The electrochemical behavior of 2,2,6,6,-tetramethylpiperidine-1-oxyl (TEMPO) and 4-oxo-TEMPO was investigated in 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)amide (BMPFSA) in the absence and presence of LiFSA. The redox reactions of TEMPO+/TEMPO and 4-oxo-TEMPO+/4-oxo-TEMPO were observed on a platinum electrode in the absence and presence of 0.5 M LiFSA. The formal potentials of TEMPO+/TEMPO and 4-oxo-TEMPO+/4-oxo-TEMPO were positively shifted in the presence of LiFSA, indicating that the interaction of TEMPO and 4-oxo-TEMPO with Li+ altered the energies of the singly occupied molecular orbitals of TEMPO and 4-oxo-TEMPO. The diffusion coefficients and standard rate constants were evaluated by chronoamperometry and electrochemical impedance spectroscopy, respectively. The diffusion coefficient and the standard rate constant were suggested to be controlled not only by the viscosity but also by the interaction between the nitroxyl radicals and Li+.

1H, 13C, 15N NMR, and DFT Studies on Complex Formation of Zinc(II) Ion with Ethylenediamine in Ionic Liquid [C2mIm][TFSA

In bis(trifluoromethylsulfonyl)amide (TFSA-)-based ionic liquid (IL), 1-ethyl-3-methylimidazolium TFSA- ([C2mIm][TFSA]), the complex formation equilibria of zinc(II) ion (Zn2+) with ethylenediamine (EN) have been investigated. An EN molecule may coordinate with Zn2+ as a bidentate ligand. First, the formation of Zn2+-EN complexes in [C2mIm][TFSA] was confirmed from the difference of 1H and 13C NMR chemical shift values of EN molecules between [C2mIm][TFSA]-EN binary solvents and the 0.1 mol dm-3 Zn(TFSA)2/[C2mIm][TFSA]-EN solutions as a function of EN mole fraction xEN. Second, the stability constants of Zn2+-EN complexes formed in the IL were determined from the concentration ratio [EN]/[Zn2+] dependence of 15N NMR chemical shift values of the TFSA- N atom in the Zn2+/IL-EN solutions. In the IL, mono-, bis-, and tris-EN complexes are successively formed by 1:1 replacement of TFSA- anions coordinated with Zn2+ by EN molecules with increasing EN content. Third, 1H and 13C NMR measurements with the help of density functional theory (DFT) calculations were made on [C2mIm][TFSA]-EN binary solvents as a function of xEN to clarify key interactions to the mechanism of the complex formation. Fourth, the stability constants of Zn2+-EN complexes in the IL were compared with those in aqueous solutions. It was suggested that the hydrogen bonding of the EN molecule with the imidazolium ring H atoms and the TFSA- O atoms reduces the stability of the mono-EN complex in the IL. In contrast, the intracomplex hydrogen bonds between EN and TFSA- in the first coordination shell contribute to the higher stability of the bis-EN complex in the IL than that in aqueous solutions. The difference in the stability constants between the tris-EN complexes and hexaacetonitrile complexes, where acetonitrile (AN) molecules act as monodentate ligands, was interpreted in terms of the higher electron donicity of EN. Finally, to verify the present evaluation, the experimental 13C NMR chemical shift values of EN molecules in the solutions were compared with the theoretical values calculated by DFT using the stability constants determined.

Isolation and Electronic Structures of Lanthanide(II) Bis(trimethylsilyl)phosphide Complexes.

While lanthanide (Ln) silylamide chemistry is mature, the corresponding silylphosphide chemistry is underdeveloped, with [Sm{P(SiMe3)2}{μ-P(SiMe3)2}3Sm(THF)3] being the sole example of a structurally authenticated Ln(II) silylphosphide complex. Here, we expand the Ln(II) {P(SiMe3)2} chemistry through the synthesis and characterization of nine complexes. The dinuclear "ate" salt-occluded complexes [{Ln[P(SiMe3)2]3(THF)}2(μ-I)K3(THF)] (1-Ln; Ln = Sm, Eu) and polymeric "ate" complex [KYb{P(SiMe3)2}3{μ-K[P(SiMe3)2]}2]∞ (2-Yb) were prepared by the respective salt metathesis reactions of parent [LnI2(THF)2] (Ln = Sm, Eu, Yb) with 2 or 3 equiv of K{P(SiMe3)2} in diethyl ether. The separate treatment of these complexes with either pyridine or 18-crown-6 led to the formation of the mononuclear solvated adducts trans-[Ln{P(SiMe3)2}2(py)4] (3-Ln; Ln = Sm, Eu, Yb) and [Ln{P(SiMe3)2}2(18-crown-6)] (4-Ln; Ln = Sm, Eu, Yb), with concomitant loss of K{P(SiMe3)2}. The complexes were characterized by a combination of NMR, electron paramagnetic resonance (EPR), attenuated total reflectance infrared (ATR-IR), electronic absorption and emission spectroscopies, elemental analysis, SQUID magnetometry, and single crystal X-ray diffraction. We find that these complexes contrast with those of related Ln(II) bis(silyl)amide complexes due to differences in ligand donor atom hardness and ligand steric requirements from Ln-P bonds being longer than Ln-N bonds. This leads to higher coordination numbers, shorter luminescence lifetimes, and smaller easy-axis magnetic anisotropy parameters.

Entropy-Driven 60mol% Li Electrolyte for Li Metal-Free Batteries.

Highly Li-concentrated electrolytes are acknowledged for their compatibility with Li metal negative electrodes and high voltage positive electrodes to achieve high-energy Li metal batteries, showcasing stable and facile interfaces for Li deposition/dissolution and high anodic stability. This study aims to explore a highly concentrated electrolyte by adopting entropy-driven chemistry for Li metal-free (so-called anode-free) batteries. The combination of lithium bis(fluorosulfonyl)amide (LiFSA) and lithium trifluoromethanesulfonate (LiOTf)salts in a pyrrolidinium-based ionic liquid is found to significantly modify the coordination structure, resulting in an unprecedented 60mol% Li concentration and a low solvent-to-salt ratio of 0.67:1 in the electrolyte system. This novel 60mol% Li electrolyte demonstrates unique coordination stricture, featuring a high ratio of monodentate-anion structures and aggregates, which facilitates an enhanced Li+ transference number and improved anodic stability. Moreover, the developed electrolyte provides a facile de-coordination process and leads to the formation of an anion-based solid electrolyte interface, which enables stable Li deposition/dissolution properties and demonstrates excellent cycling stability in the Li metal-free full cell with a Li[Ni0.8Co0.1Mn0.1]O2 (NCM811) positive electrode.

Effect of Ionic Liquids with Different Structures on Rheological Properties of Water-Based Drilling Fluids and Mechanism Research at Ultra-High Temperatures.

The rheology control of water-based drilling fluids at ultra-high temperatures has been one of the major challenges in deep or ultra-deep resource exploration. In this paper, the effects of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonimide) (ILA), 1-ethyl-3-methylimidazolium tetrafluoroborate (ILB) and N-methyl, butylpyrrolidinium bis(trifluoromethanesulfonimide) (ILC) on the rheological properties and filtration loss of polymer-based slurries at ultra-high temperatures (200 °C and 240 °C) are investigated by the American Petroleum Institute (API) standards. The results show that ionic liquids with different structures could improve the high-temperature rheological properties of polymer-based drilling fluids. The rheological parameter value (YP/PV) of the polymer-based slurry formulated with ILC is slightly higher than that with ILA at the same concentration, while the YP/PV value of the polymer-based slurry with ILA is slightly higher than that with ILB, which is consistent with the TGA thermal stability of ILA, ILB, and ILC; the thermal stability of ILC with pyrrolidine cations is higher than that of ILA with imidazole cations, and the thermal stability of ILA with bis(trifluorosulfonyl)amide anions is higher than that of ILB with tetrafluoroborate anions. Cation interlayer exchange between organic cation and sodium montmorillonite can improve the rheological properties of water-based drilling fluids. And meantime, the S=O bond in bis(trifluorosulfonyl)amide ions and the hydroxyl group of sodium montmorillonite may form hydrogen bonds, which also may increase the rheological properties of water-based drilling fluids. ILA, ILB, and ILC cannot reduce the filtration loss of polymer-based drilling fluids at ultra-high temperatures.

Effects of Heterogeneous Mixing of Imidazolium-Based Ionic Liquids with Alcohols on Complex Formation of Ni(II) Ion.

Understanding the complex formation of metal ions in room-temperature ionic liquids (ILs) is essential for the application of ILs in solvent extraction. Nevertheless, the research on metal complex formation in ILs lags behind other applications. The complex formation equilibria may be influenced by specific interactions among the metal ion, ligand molecule, and IL cation and anion. In the present investigation, the complex formation of Ni2+ with ethanol (EtOH) and methanol (MeOH) molecules in ILs, 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([CNmim][TFSA], where N represents the alkyl chain lengths of 2 and 8) was discussed in terms of the microscopic interactions among alcohol molecules, [CNmim]+ and [TFSA]-, and the mesoscopic mixing states of alcohols in [CNmim][TFSA], with N = 2-12. The microscopic interaction of alcohol molecules with the imidazolium ring H atoms in the ILs was evaluated by using ATR-IR and 1H and 13C NMR spectroscopies. The self-hydrogen bonding of alcohol molecules was clarified from the O-H stretching vibration of alcohol molecules. MeOH molecules can be more strongly hydrogen-bonded with themselves than EtOH molecules due to the less steric hindrance and the weaker dispersion force of MeOH with the IL cation's alkyl chain. In fact, small-angle neutron scattering (SANS) experiments revealed the more heterogeneous mixing of MeOH with the ILs by the self-hydrogen bonding among MeOH molecules than EtOH. The longer the IL cation's alkyl chain, the more the MeOH clusters significantly form. In contrast, the formation of EtOH clusters becomes weaker with elongating the alkyl chain. Ultraviolet (UV)-visible spectroscopic measurements on Ni2+-[CNmim][TFSA]-alcohol solutions with N = 2 and 8 revealed that di-, tetra-, and hexa-alcohol-Ni2+ complexes are formed in both the ILs. With N = 2, the stabilities of Ni2+-EtOH and Ni2+-MeOH complexes are comparable in the IL. However, with N = 8, the complexes are more stable in the EtOH solutions than in the MeOH solutions. This is because the less heterogeneous mixing of EtOH molecules with the IL results in the larger enthalpic contribution in the complex formation, as shown by the thermodynamic parameters estimated by the van't Hoff plots on the stability constants at several temperatures.

Heterogeneous dynamics of diffusive motion in organic ionic plastic crystal studied using spin–spin relaxation time: N,N-diethylpyrrolidinium bis(fluorosulfonyl)amide

Abstract The temperature dependences of the spin–spin relaxation times (T2) of 1H and 19F nuclei were measured for N,N-diethylpyrrolidinium bis(fluorosulfonyl)amide with a plastic crystal phase. In the plastic crystal phase, 2 types of T2 were observed in both 1H and 19F experiments, which were considered to be the appearance of heterogeneous dynamics of diffusive motion. By examining temperature dependences of the T2 values and the existence ratios, the following conclusions were reached. (i) The prepared plastic crystal sample was in a polycrystalline state, and each crystallite comprised 2 phases: the core phase (plastic crystal phase) and the surface phase formed to relieve surface stress. (ii) The 1H-T2 (19F-T2) values of the 2 phases differed, and ions in the surface phase were more mobile. The 1H-T2 (19F-T2) values for the 2 phases increased with temperature rise. In particular, the 1H-T2 (19F-T2) values of the surface phase were smoothly connected to the liquid T2 values. (iii) The cations and anions exhibited a cooperative diffusive motion. (iv) When the temperature was considerably lower than the melting point, the ratio of the surface phase did not significantly differ from when it first formed. However, it rapidly increased near the melting point and became liquid.

Monitoring the Solid-Electrolyte Interphase Formation in Bis(fluorosulfonyl)Amide Ionic Liquid Electrolyte Using a Redox Probe Method

The solid-electrolyte interphase (SEI) has been considered to be formed on the negative electrode surface by reductive decomposition of electrolyte components. In the case of the electrolytes containing lithium ions, the SEI can be regarded as the Li+ conductor that enables the negative electrode reactions and prevents the further decomposition of the electrolytes. The structure of the SEI is often explained by the mosaic model, in which the SEI is a composite of several different inorganic and organic domains [1]. On the other hand, we have proposed the formation of the gelled SEI in bis(fluorosulfonyl)amide (FSA–) ionic liquid electrolytes containing a high concentration of LiFSA [2,3]. Furthermore, we have reported that the SEI formation can be detected by monitoring the redox reaction of ferrocene (Fc) and ferrocenium (Fc+) [4,5]. In the present study, the time-dependent transition of the SEI formed on a Pt electrode was investigated by the redox probe method in BMPFSA (BMP+ = 1-butyl-1-methylpyrrolidinium) containing LiFSA.The formation of SEI by holding a Pt electrode at a negative potential was confirmed by a shift in the anodic peak potential of the cyclic voltammogram for Fc+/Fc couple in LiFSA/BMPFSA. The anodic peak disappeared when the electrode was held at the negative potential for a few hours, indicating the formation of a thick SEI. However, the anodic peak was observed again after keeping the electrode at the open circuit potential for a few hours, indicating the disappearance of the SEI. These results suggest that the SEI is formed by dissolution and/or dispersion of the decomposed products, which form at the electrode surface and diffuse into the electrolyte. Thus, the SEI formed at the potential is considered to exist as a metastable phase in the balance between the formation and diffusion of the decomposition products. This work was partly supported by GteX Program Japan Grant Number JPMJGX23S0.[1] E. Peled, D. Golodnitsky, and G. Ardel, J. Electrochem. Soc., 144, L208 (1997).[2] R. Furuya, T. Hara, T. Fukunaga, K. Kawakami, N. Serizawa, and Y. Katayama, J. Electrochem. Soc., 168, 100516 (2021).[3] N. Serizawa, R. Yamashita, and Y. Katayama, J. Phys. Chem. C, 127, 10434 (2023).[4] S. Kato, N. Serizawa, and Y. Katayama, J. Electrochem. Soc., 169, 076509 (2022).[5] S. Kato, N. Serizawa, and Y. Katayama, J. Electrochem. Soc., 170, 056504 (2023).

Computational and Machine Learning‐Assisted Discovery and Experimental Validation of Conjugated Sulfonamide Cathodes for Lithium‐Ion Batteries

AbstractConjugated sulfonamides (CSAs) stand out for their propitious electroactivity and notable stability in ambient conditions, making them suitable candidates for high‐potential cathode materials in lithium‐ion batteries (LIBs). This study employs a combination of machine learning, semi‐empirical quantum mechanics, and density functional theory methods to evaluate a large library of 11 432 CSA molecules, focusing on material properties crucial for application in batteries, such as synthetic complexity, redox potential, gravimetric charge capacity, and energy density. After applying the thresholds for the synthetic complexity score at 2.62 and the redox potential at 3.25 V versus Li/Li+, we identify 50 CSA molecules that are easy to synthesize and suitable for the positive electrode in LIBs. By ranking on the basis of redox potential, 13 CSA molecules having potentials greater than 3.50 V versus Li/Li+ are identified. Through further investigations using molecular dynamics simulations on these reactant molecules and their lithiated products, a molecule is singled out for synthesis and electrochemical evaluation. This molecule, lithium (2,5‐dicyano‐1,4‐phenylene)bis((methylsulfonyl)amide)(Li2‐DCN‐PDSA), demonstrates a redox potential surpassing those previously reported within the class of CSA molecules. Moreover, the study explores the quantitative structure‐property relations of CSAs, yielding insights for the development of CSA‐based LIB cathode materials, informed by the comprehensive data assembled.

Silylation-Driven Volatility Enhancement in Mononuclear Calcium, Magnesium, and Barium Complexes with Monomethyl or Silyl Ether and Bis(diketonate).

Magnesium, calcium, and barium heteroleptic complexes were synthesized by the substitution reaction of the bis(trimethylsilyl)amide of Mg(btsa)2·DME, Ca(btsa)2·DME, and Ba(btsa)2·2DME with an ethereal group and hfac ligands (btsa = bis(trimethylsilyl)amide, DME = dimethoxyethane). The compounds Mg(dts)(hfac)2 (1), Ca(dts)(hfac)2 (2), Mg(dmts)(hfac)2 (3), Ca(dmts)(hfac)2 (4), and Ba(dmts)(hfac)2 (5) were fabricated and analyzed using various techniques, including Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, thermogravimetric analyses, and elemental analysis (dts = 2,2-dimethyl-3,6,9-trioxa-2-siladecane, dmts = 2,2-dimethyl-3,6,9,12-tetraoxa-2-silatridecane, hfac = hexafluoroacetylacetonate). The structures of complexes 2, 4, and 5 were confirmed using single-crystal X-ray crystallography; all complexes display monomeric structures. All compounds underwent trimethylsilylation of the coordinating ethereal alcohols (meeH and tmgeH) in the presence of HMDS as byproducts because of their increasing acidity originating from the electron-withdrawing hfac ligands. (meeH = 2-(2-methoxyethoxy)ethan-1-ol, tmgeH = tri(ethylene glycol) monoethyl ether, HMDS = hexamethyldisilazane).

Dimensionality Control of Li Transport by MOFs Based Quasi‐Solid to Solid Electrolyte (Q‐SSEs) for Li−Metal Batteries

AbstractNowadays, lithium‐ion batteries (LIBs) are widely used in all walks of life and play a very important role. As complex systems composed of multiple materials with diverse chemical compositions, where different electrochemical reactions take place, battery interfaces are essential for determining the operation, performance, durability and safety of the battery. This work, set out to study the incorporation of lithium bis(fluorosulfonyl)amide (LiFSI) doped 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIm][TFSI]) ionic liquid into an archetype Ti‐based Metal Organic Framework (MOF) ((Ti) MIL125−NH2) to create a solid to quasi‐solid (depending on the amount of IL in the system), and how it affects not only ionic transport but also the structural properties of the IL/MOF electrolyte. Remarkably high ionic conductivity values (2.13×10−3 S ⋅ cm−1 at room temperature) as well as a lithium transference number (tLi=0.58) were achieved, supported by pulsed field gradient (PFG) NMR experiments. Electrochemical characterization revealed reversible plating‐stripping of lithium and lower overpotential after 750 h at 50 °C. Additionally, a proof‐of‐concept solid state battery was fabricated resulting in a discharge capacity of 160 mAh ⋅ g−1 at 50 °C and 0.1 C rate after 50 cycles. This work presents a suitable strategy to dendrite suppression capability, allowing its implementation as interface modifiers in next‐generation solid‐state batteries.