Lithium Chlorides and Bromides as Promising Solid‐State Chemistries for Fast Ion Conductors with Good Electrochemical Stability

Enabling all‐solid‐state Li‐ion batteries requires solid electrolytes with high Li ionic conductivity and good electrochemical stability. Following recent experimental reports of Li₃YCl₆ and Li₃YBr₆ as promising new solid electrolytes, we used first principles computation to investigate the Li‐ion diffusion, electrochemical stability, and interface stability of chloride and bromide materials and elucidated the origin of their high ionic conductivities and good electrochemical stabilities. Chloride and bromide chemistries intrinsically exhibit low migration energy barriers, wide electrochemical windows, and are not constrained to previous design principles for sulfide and oxide Li‐ion conductors, allowing for much greater freedom in structure, chemistry, composition, and Li sublattice for developing fast Li‐ion conductors. Our study highlights chloride and bromide chemistries as a promising new research direction for solid electrolytes with high ionic conductivity and good stability.     

Bacteriophage Tail‐Tube Assembly Studied by Proton‐Detected 4D Solid‐State NMR

Obtaining unambiguous resonance assignments remains a major bottleneck in solid‐state NMR studies of protein structure and dynamics. Particularly for supramolecular assemblies with large subunits (>150 residues), the analysis of crowded spectral data presents a challenge, even if three‐dimensional (3D) spectra are used. Here, we present a proton‐detected 4D solid‐state NMR assignment procedure that is tailored for large assemblies. The key to recording 4D spectra with three indirect carbon or nitrogen dimensions with their inherently large chemical shift dispersion lies in the use of sparse non‐uniform sampling (as low as 2 %). As a proof of principle, we acquired 4D (H)COCANH, (H)CACONH, and (H)CBCANH spectra of the 20 kDa bacteriophage tail‐tube protein gp17.1 in a total time of two and a half weeks. These spectra were sufficient to obtain complete resonance assignments in a straightforward manner without use of previous solution NMR data.     

Water‐Mediated Synthesis of a Superionic Halide Solid Electrolyte

To promote the development of solid‐state batteries, polymer‐, oxide‐, and sulfide‐based solid‐state electrolytes (SSEs) have been extensively investigated. However, the disadvantages of these SSEs, such as high‐temperature sintering of oxides, air instability of sulfides, and narrow electrochemical windows of polymers electrolytes, significantly hinder their practical application. Therefore, developing SSEs that have a high ionic conductivity (>10^?3 S cm^?1), good air stability, wide electrochemical window, excellent electrode interface stability, low‐cost mass production is required. Herein we report a halide Li⁺ superionic conductor, Li₃InCl₆, that can be synthesized in water. Most importantly, the as‐synthesized Li₃InCl₆ shows a high ionic conductivity of 2.04×10^?3 S cm^?1 at 25 °C. Furthermore, the ionic conductivity can be recovered after dissolution in water. Combined with a LiNi_0.8Co_0.1Mn_0.1O₂ cathode, the solid‐state Li battery shows good cycling stability.     

DNP‐Supported Solid‐State NMR Spectroscopy of Proteins Inside Mammalian Cells

Elucidating at atomic level how proteins interact and are chemically modified in cells represents a leading frontier in structural biology. We have developed a tailored solid‐state NMR spectroscopic approach that allows studying protein structure inside human cells at atomic level under high‐sensitivity dynamic nuclear polarization (DNP) conditions. We demonstrate the method using ubiquitin (Ub), which is critically involved in cellular functioning. Our results pave the way for structural studies of larger proteins or protein complexes inside human cells, which have remained elusive to in‐cell solution‐state NMR spectroscopy due to molecular size limitations.     

Single Benzene Green Fluorophore: Solid‐State Emissive,Water‐Soluble,and Solvent‐ and pH‐Independent Fluorescence with Large Stokes Shifts

Benzene is the simplest aromatic hydrocarbon with a six‐membered ring. It is one of the most basic structural units for the construction of π conjugated systems, which are widely used as fluorescent dyes and other luminescent materials for imaging applications and displays because of their enhanced spectroscopic signal. Presented herein is 2,5‐bis(methylsulfonyl)‐1,4‐diaminobenzene as a novel architecture for green fluorophores, established based on an effective push–pull system supported by intramolecular hydrogen bonding. This compound demonstrates high fluorescence emission and photostability and is solid‐state emissive, water‐soluble, and solvent‐ and pH‐independent with quantum yields of Φ=0.67 and Stokes shift of 140 nm (in water). This architecture is a significant departure from conventional extended π‐conjugated systems based on a flat and rigid molecular design and provides a minimum requirement for green fluorophores comprising a single benzene ring.     

High Accuracy Protein Structures from Minimal Sparse Paramagnetic Solid‐State NMR Restraints

There is a pressing need for new computational tools to integrate data from diverse experimental approaches in structural biology. We present a strategy that combines sparse paramagnetic solid‐state NMR restraints with physics‐based atomistic simulations. Our approach explicitly accounts for uncertainty in the interpretation of experimental data through the use of a semi‐quantitative mapping between the data and the restraint energy that is calibrated by extensive simulations. We apply our approach to solid‐state NMR data for the model protein GB1 labeled with Cu²⁺‐EDTA at six different sites. We are able to determine the structure to 0.9 Å accuracy within a single day of computation on a GPU cluster. We further show that in some cases, the data from only a single paramagnetic tag are sufficient for accurate folding.     

Reversible Encapsulation of Xenon and CH2Cl2 in a Solid‐State Molecular Organometallic Framework (Guest@SMOM)

Reversible encapsulation of CH₂Cl₂ or Xe in a non‐porous solid‐state molecular organometallic framework of [Rh(Cy₂PCH₂PCy₂)(NBD)][BAr^F₄] occurs in single‐crystal to single‐crystal transformations. These processes are probed by solid‐state NMR spectroscopy, including ¹²⁹Xe SSNMR. Non‐covalent interactions with the ‐CF₃ groups, and hydrophobic channels formed, of [BAr^F₄]^? anions are shown to be important, and thus have similarity to the transport of substrates and products to and from the active site in metalloenzymes.