Self-trapped emissions in 2D lead-free halide perovskites driven by divalent spacer cations.

The mono- and divalent spacer cation investigation in sodium/indium-based 2D double perovskites revealed significant impacts on optoelectronic properties due to distortions in the inorganic layers. The strong electron-phonon coupling in a novel lead-free Dion-Jacobson phase highlights a promising class for broad-emission devices based on self-trapped excitons (STE), offering enhanced structural stability.

Rashba Spin Splitting Limiting the Application of 2D Halide Perovskites for UV-Emitting Devices.

Layered lead halide perovskites have attracted much attention as promising materials for a new generation of optoelectronic devices. To make progress in applications, a full understanding of the basic properties is essential. Here, we study 2D-layered (BA)PbX by using different halide anions (X = I, Br, and Cl) along with quantum confinement.

Chiral Cation Doping for Modulating Structural Symmetry of 2D Perovskites.

Cation mixing in two-dimensional (2D) hybrid organic-inorganic perovskite (HOIP) structures represents an important degree of freedom for modifying organic templating effects and tailoring inorganic structures. However, the limited number of known cation-mixed 2D HOIP systems generally employ a 1:1 cation ratio for stabilizing the 2D perovskite structure. Here, we demonstrate a chiral-chiral mixed-cation system wherein a controlled small amount (<10%) of chiral cation S-2-MeBA (S-2-MeBA = ()-(-)-2-methylbutylammonium) can be doped into (S-BrMBA)PbI (S-BrMBA = ()-(-)-4-bromo-α-methylbenzylammonium), modulating the structural symmetry from a higher symmetry (2) to the lowest symmetry state (1).

insights into the stabilization and binding mechanisms of MoS nanoflakes supported on graphene.

An atomistic understanding of transition-metal dichalcogenide (TMD) nanoflakes supported on graphene (Gr) plays an important role in the tuning of the physicochemical properties of two-dimensional (2D) materials; however, our current atom-level understanding of 2D-TMD nanoflakes on Gr is far from satisfactory. Thus, we report a density functional theory investigation into the stabilization and binding mechanisms of (MoS2)n/Gr, where n = 1, 4, 6, 9, 12 and 16. We found an evolution of the (MoS2)n…Gr interactions from covalent and hybridization contributions for smaller nanoflakes (n = 1, 4) to vdW interactions for larger (MoS2)n nanoflakes (n ≥ 6); however, the coupling of the (MoS2)n and Gr electronic states for n = 1 and 4 is not intense enough to change the Dirac cones at the Gr monolayer.

Edge, size, and shape effects on WS, WSe, and WTe nanoflake stability: design principles from an ab initio investigation.

An improved atomistic understanding of the W-based two-dimensional transition-metal dichalcogenides (2D TMDs) is crucial for technological applications of 2D materials, since the presence of tungsten endows these materials with distinctive properties. However, our atomistic knowledge on the evolution of the structural, electronic, and energetic properties and on the nanoflake stability of such materials is not properly addressed hitherto. Thus, we present a density functional theory (DFT) study of stoichiometric (WQ2)n nanoflakes, with Q = S, Se, Te, and n = 1,…,16, 36, 66, and 105.

Palladium-Mediated Catalysis Leads to Intramolecular Narcissistic Self-Sorting on a Cavitand Platform.

Palladium-catalyzed aminocarbonylation reactions have been used to directly convert a tetraiodocavitand intermediate into the corresponding carboxamides and 2-ketocarboxamides. When complex mixtures of the amine reactants are employed in competition experiments using polar solvents, such as DMF, no "mixed" products possessing structurally different amide fragments are detected either by H or C NMR. Only highly symmetrical cavitands are sorted out of a large number of potentially feasible products, which represents a rare example of intramolecular, narcissistic self-sorting.

Influence of Metal, Ligand and Solvent on Supramolecular Polymerizations with Transition-Metal Compounds: A Theoretical Study.

The nature of intermolecular interactions governing supramolecular polymerizations is very important for controlling their cooperativity. In order to address this problem, supramolecular columns made of Pt and Pd complexes of oligo(phenylene ethynylene)-based pyridine (OPE) and tetrazolylpyridine ligands (TEP) were investigated through the dispersion-corrected PM6 method. Aromatic, CH-π, M-Cl and metallophilic interactions helped stabilize the supramolecules studied, and their geometries and associated cooperativities were in excellent agreement with experimental data.