Irreversible Conversion of a Water–Ethanol Solution into an Organized Two‐Dimensional Network of Alternating Supramolecular Units in a Hydrophobic Zeolite under Pressure

Turning disorder into organization is a key issue in science. By making use of X‐ray powder diffraction and modeling studies, we show herein that high pressures in combination with the shape and space constraints of the hydrophobic all‐silica zeolite ferrierite separate an ethanol–water liquid mixture into ethanol dimer wires and water tetramer squares. The confined supramolecular blocks alternate in a binary two‐dimensional (2D) architecture that remains stable upon complete pressure release. These results support the combined use of high pressures and porous networks as a viable strategy for driving the organization of molecules or nano‐objects towards complex, pre‐defined patterns relevant for the realization of novel functional nanocomposites.     

Modulated Structure Calculated for Superconducting Hydrogen Sulfide

Compression of hydrogen sulfide using first principles metadynamics and molecular dynamics calculations revealed a modulated structure with high proton mobility which exhibits a diffraction pattern matching well with experiment. The structure consists of a sublattice of rectangular meandering SH⁻ chains and molecular‐like H₃S⁺ stacked alternately in tetragonal and cubic slabs forming a long‐period modulation. The novel structure offers a new perspective on the possible origin of the superconductivity at very high temperatures in which the conducting electrons in the SH chains are perturbed by the fluxional motions of the H₃S resulting in strong electron‐phonon coupling.     

Pressure‐Induced Intersite Bi?M (M=Ru, Ir) Valence Transitions in Hexagonal Perovskites

Pressure‐induced charge transfer from Bi to Ir/Ru is observed in the hexagonal perovskites Ba_3+nBiM_2+nO_9+3n (n=0,1; M=Ir,Ru). These compounds show first‐order, circa 1 % volume contractions at room temperature above 5 GPa, which are due to the large reduction in the effective ionic radius of Bi when the 6s shell is emptied on oxidation, compared to the relatively negligible effect of reduction on the radii of Ir or Ru. They are the first such transitions involving 4d and 5d compounds, and they double the total number of cases known. Ab initio calculations suggest that magnetic interactions through very short (ca. 2.6 Å) M M bonds contribute to the finely balanced nature of their electronic states.     

An Anti CuO2‐type Metal Hydride Square Net Structure in Ln2M2As2Hx (Ln=La or Sm,M=Ti,V, Cr,or Mn)

Using a high pressure technique and the strong donating nature of H⁻, a new series of tetragonal La₂Fe₂Se₂O₃‐type layered mixed‐anion arsenides, Ln₂M₂As₂H_x, was synthesized (Ln=La or Sm, M=Ti, V, Cr, or Mn; x≈3). In these compounds, an unusual M₂H square net, which has anti CuO₂ square net structures accompanying two As³⁻ ions, is sandwiched by (LaH)₂ fluorite layers. Notably, strong metal–metal bonding with a distance of 2.80 Å was confirmed in La₂Ti₂As₂H_2.3, which has metallic properties. In fact, these compounds are situated near the boundary between salt‐like ionic hydrides and transition‐metal hydrides with metallic characters.