From Two‐ to Three‐Dimensional Structures of a Supertetrahedral Boran Using Density Functional Calculations

With help of the DFT calculations and imposing of periodic boundary conditions the geometrical and electronic structures were investigated of two‐ and three‐dimensional boron systems designed on the basis of graphane and diamond lattices in which carbons were replaced with boron tetrahedrons. The consequent studies of two‐ and three‐layer systems resulted in the construction of a three‐dimensional supertetrahedral borane crystal structure. The two‐dimensional supertetrahedral borane structures with less than seven layers are dynamically unstable. At the same time the three‐dimensional superborane systems were found to be dynamically stable. Lack of the forbidden electronic zone for the studied boron systems testifies that these structures can behave as good conductors. The low density of the supertetrahedral borane crystal structures (0.9 g cm⁻³) is close to that of water, which offers the perspective for their application as aerospace and cosmic materials.     

Mixed‐Valence Nickel Bis(azamacrocycle) Compounds with Ghost‐Leg‐type Sheets

The fabrication of so‐called ghost‐leg sheets and their electronic properties is reported. This unique sheet structure is composed of one‐dimensional mixed‐valence nickel chains, which are linked with one another by bis(azamacrocycle) ligands. They are also topologically unique Ni^II/Ni^III mixed‐valence complexes, as confirmed by X‐ray and optical measurements. Moreover, their magnetic susceptibilities indicated two‐dimensional antiferromagnetic behavior following the Fisher 1D chain model with interchain interactions, where spins on Ni^III sites mutually interact antiferromagnetically in the sheets.     

Synthetic Nanosheets of Natural van der Waals Heterostructures

Creation of new van der Waals heterostructures by stacking different two dimensional (2D) crystals on top of each other in a chosen sequence is the next challenge after the discovery of graphene, mono/few layer of h ‐BN, and transition‐metal dichalcogenides. However, chemical syntheses of van der Waals heterostructures are rarer than the physical preparation techniques. Herein, we demonstrate the kinetic stabilization of 2D ultrathin heterostructure (ca. 1.13–2.35 nm thick) nanosheets of layered intergrowth SnBi₂Te₄, SnBi₄Te₇, and SnBi₆Te₁₀, which belong to the Sn_m Bi_2n Te_{3n +m} homologous series, by a simple solution based synthesis. Few‐layer nanosheets exhibit ultralow lattice thermal conductivity (κ _lat) of 0.3–0.5 W m⁻¹ K⁻¹ and semiconducting electron‐transport properties with high carrier mobility.