Hydrogen-bonding organic acid−base salts are promising candidates for the chemical design of high-performance anhydrous proton conductors. The simple molecular crystals between the π-planar molecules of 2,2′-diaminobithiazolium (DABT) derivative and hydrogen-bonding H 3 PO 4 formed the proton-transferred salts with proton conductivities above ∼10 −4 S cm −1 and anisotropic behavior. Controlling the crystallization condition facilitated the formation of binary salts between di-cationic H2DABT 2+ and (H 3 PO 4 − ) 2 or mixed proton-transferred (H 2 PO 4 − ) 2 (H 3 PO 4 ) 2 with different hydrogen-bonding networks, including one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) networks. The structural isomers of 2,2′diamino-4,4′-bithiazolium (2,4-DABT) and 2,2′-diamino-5,5′-bithiazolium (2,5-DABT) formed a different type of packing structure even with the same crystal stoichiometry of (H2DABT 2+ )(H 2 PO 4 − ) 2 and/or (H2DABT 2+ )(H 2 PO 4 − ) 2 (H 3 PO 4 ) 2 where the latter salt had different protonated species of H 2 PO 4 − and H 3 PO 4 in the hydrogenbonding network. Four and 10 protons per H2DABT 2+ molecule (H + : carrier concentration) were present in the (H2DABT 2+ )(H 2 PO 4 − ) 2 and (H2DABT 2+ )(H 2 PO 4 − ) 2 (H 3 PO 4 ) 2 salts, respectively, which accounted for the highly protonconducting behavior in the latter mixed protonated crystal. To design anhydrous intrinsic H + conductors, both the mixed proton transfer state and uniform O−H•••O hydrogen-bonding interaction are essential factors that must be considered.

Bis-urea macrocycle 1 forms N–H···O= hydrogen-bonded one-dimensional (1D) channels, and the acetic acid (AcOH) dimer can be introduced into the 1D tubular channels, forming a 1D guest adsorption crystal (S1). The guest AcOH was easily desorped from the 1D channel to generate an empty 1D channel (S1′), which was further transformed into a thermodynamically stable two-dimensional (2D) hydrogen-bonding zigzag layer (S2) at temperatures above 520 K. The formation of host–guest molecular complexes with 1–dichloroacetic acid, tetrahydrofuran, pyrrole, pyridine, 3,4-difluoroaniline, and 1,4-diaminoalkanes was confirmed by X-ray crystal structural analyses, and molecular assembly structures of isolated monomers (S0), 1D channels (S1), 2D layers (S2), and dimeric 2D layers (S3), respectively, were observed depending on the size and shape of guest molecules. Guest desorption from the S0, S1, S2, and S3 assemblies resulted in a structural transformation to the thermodynamically stable guest-free S2′. Of these structures, a transformation from 1D guest-filled channel S1 to guest-free S1′ was observed for linear guests of (AcOH)2 dimers and NH2(CH2) n NH2 (n = 3, 5, and 7) with a molecular length longer than ca. 1 nm. The guest-filled 2D layer of S2 was transformed to S2′ after the guest desorption and also to S1 through AcOH readsorption, suggesting a reversible S1–S2′ structural transformation by stepwise thermal treatment and guest adsorption–desorption processes. Both the N2 and CO2 adsorption behaviors were not observed in thermodynamically stable S2′, whereas selective CO2 adsorption was confirmed in S1′.

Enhancing the energy density of high-voltage lithium-ion battery cathodes is challenging. Cathode surface coating can effectively suppress the irreversible side reactions occurring at the cathode/electrolyte interface. Recent high-throughput theoretical studies have demonstrated the potential of a ternary lithium fluoride, β-Li3AlF6, as a coating agent owing to its high anodic limit, sufficient stability against various cathode materials, and sufficient Li+-ion conductivity. This study improves the cathode performance by the surface coating of β-Li3AlF6 on LiNi0.5Mn1.5O4 and LiCoO2 cathodes using a simple sol–gel calcination process. β-Li3AlF6-coated LiNi0.5Mn1.5O4 shows superior cycle performance, with a capacity retention of 98.2% and a coulombic efficiency of 99% at the 100th cycle. Further, β-Li3AlF6-coated LiCoO2 can be cycled at a high voltage of 4.5 V with a capacity retention of 95% at the 100th cycle. These results demonstrate the potential of β-Li3AlF6 as a high-voltage cathode coating agent.

An alkylamide-substituted (−NHCOC10H21) hydrogen-bonded dibenzo[18]crown-6 derivative (1) was prepared to stabilise the ionic channel structure in a discotic hexagonal columnar (Colh) liquid crystal.