Dynamic Chelate Effect on the Li+-Ion Conduction in Solvate Ionic Liquids

Lithium-glyme solvate ionic liquids (Li-G SILs), which typically consist of a lithium-ion (Li+) solvated by glymes of oligoethers and its counter anion, are expected as promising electrolytes for lithium secondary batteries. Additionally, a specific ligand-exchange Li+ conduction mechanism was proposed at the electrode/electrolyte interface of the cell using Li-G SILs. To reveal Li+ conduction in SILs, Li-G SILs with varying ethylene oxide chain lengths were investigated using various techniques that are sensitive to solution structure and dynamics. We found good correlations between the relaxation time of the slowest dielectric mode and the ionic conductivity as well as viscosity. We propose that a dynamic chelate effect, which is closely related to solvent exchange and/or contact ion-pair formation/dissociation, is important for Li+ conduction in these Li-G SILs

Li⁺ Local Structure in Li–Tetraglyme Solvate Ionic Liquid Revealed by Neutron Total Scattering Experiments with the ^6/7Li Isotopic Substitution Technique

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 ^6/7Li 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

Liver autophagy contributes to the maintenance of blood glucose and amino acid levels

Both anabolism and catabolism of the amino acids released by starvation-induced autophagy are essential for cell survival, but their actual metabolic contributions in adult animals are poorly understood. Herein, we report that, in mice, liver autophagy makes a significant contribution to the maintenance of blood glucose by converting amino acids to glucose via gluconeogenesis. Under a synchronous fasting-initiation regimen, autophagy was induced concomitantly with a fall in plasma insulin in the presence of stable glucagon levels, resulting in a robust amino acid release. In liver-specific autophagy (Atg7)-deficient mice, no amino acid release occurred and blood glucose levels continued to decrease in contrast to those of wild-type mice. Administration of serine (30 mg/animal) exerted a comparable effect, raising the blood glucose levels in both control wild-type and mutant mice under starvation. Thus, the absence of the amino acids that were released by autophagic proteolysis is a major reason for a decrease in blood glucose. Autophagic amino acid release in control wild-type livers was significantly suppressed by the prior administration of glucose, which elicited a prompt increase in plasma insulin levels. This indicates that insulin plays a dominant role over glucagon in controlling liver autophagy. These results are the first to show that liver-specific autophagy plays a role in blood glucose regulation