Organophosphorus -adenosyl--methionine mimetics: synthesis, stability, and substrate properties.

-Adenosyl-l-methionine (SAM)-mediated methylation of biomolecules controls their function and regulates numerous vital intracellular processes. Analogs of SAM with a reporter group in place of the -methyl group are widely used to study these processes. However, many of these analogs are chemically unstable that largely limits their practical application.

Study of the RNA splicing kinetics via in vivo 5-EU labeling.

Splicing is an important step of gene expression in all eukaryotes. Splice sites might be used with different efficiency, giving rise to alternative splicing products. At the same time, splice sites might be used at a variable rate.

Phylogeny and structural modeling of the transcription factor CsqR (YihW) from Escherichia coli.

CsqR (YihW) is a local transcription factor that controls expression of yih genes involved in degradation of sulfoquinovose in Escherichia coli. We recently showed that expression of the respective gene cassette might be regulated by lactose. Here, we explore the phylogenetic and functional traits of CsqR.

Synthesis of Ultra-Incompressible and Recoverable Carbon Nitrides Featuring CN Tetrahedra.

Carbon nitrides featuring three-dimensional frameworks of CN tetrahedra are one of the great aspirations of materials science, expected to have a hardness greater than or comparable to diamond. After more than three decades of efforts to synthesize them, no unambiguous evidence of their existence has been delivered. Here, the high-pressure high-temperature synthesis of three carbon-nitrogen compounds, tI14-C N , hP126-C N , and tI24-CN , in laser-heated diamond anvil cells, is reported.

Quantum Spin Hall States and Topological Phase Transition in Germanene.

We present the first experimental evidence of a topological phase transition in a monoelemental quantum spin Hall insulator. Particularly, we show that low-buckled epitaxial germanene is a quantum spin Hall insulator with a large bulk gap and robust metallic edges. Applying a critical perpendicular electric field closes the topological gap and makes germanene a Dirac semimetal.

Gating Orbital Memory with an Atomic Donor.

Orbital memory is defined by two stable valencies that can be electrically switched and read out. To explore the influence of an electric field on orbital memory, we studied the distance-dependent influence of an atomic Cu donor on the state favorability of an individual Co atom on black phosphorus. Using low temperature scanning tunneling microscopy and spectroscopy, we characterized the electronic properties of individual Cu donors, corroborating this behavior with ab initio calculations based on density functional theory.

Electronic Tuning in WSe/Au via van der Waals Interface Twisting and Intercalation.

The transition metal dichalcogenide (TMD)-metal interfaces constitute an active part of TMD-based electronic devices with optimized performances. Despite their decisive role, current strategies for nanoscale electronic tuning remain limited. Here, we demonstrate electronic tuning in the WSe/Au interface by twist engineering, capable of modulating the WSe carrier doping from an intrinsic p-type to n-type.

High-Pressure Synthesis of Dirac Materials: Layered van der Waals Bonded BeN_{4} Polymorph.

High-pressure chemistry is known to inspire the creation of unexpected new classes of compounds with exceptional properties. Here, we employ the laser-heated diamond anvil cell technique for synthesis of a Dirac material BeN_{4}. A triclinic phase of beryllium tetranitride tr-BeN_{4} was synthesized from elements at ∼85  GPa.

Redox Condensations of -Nitrobenzaldehydes with Amines under Mild Conditions: Total Synthesis of the Vasicinone Family.

A total synthesis of the vasicinone family of natural products from bulk chemicals was developed. Reductive condensation of nitrobenzaldehydes with amines utilizing iron pentacarbonyl as a reducing agent followed by subsequent oxidation leads to a great variety of polycyclic nitrogen-containing heterocycles under mild conditions. Enantiomerically pure vasicinone, rutaecarpine, isaindigotone, and luotonin were synthesized from readily available starting materials like hydroxyproline, nitrobenzaldehyde, pyrrolidine, and piperidine in two to four operational steps without chromatography.

Anisotropic Two-Dimensional Screening at the Surface of Black Phosphorus.

Electronic screening can have direct consequences for structural arrangements on the nanoscale, such as on the periodic ordering of adatoms on a surface. So far, such ordering phenomena have been explained in terms of isotropic screening of free electronlike systems. Here, we directly illustrate the structural consequences of anisotropic screening, making use of a highly anisotropic two-dimensional electron gas (2DEG) near the surface of black phosphorous.

Anisotropic ultraviolet-plasmon dispersion in black phosphorus.

By means of momentum-resolved electron energy loss spectroscopy (EELS) coupled with scanning transmission electron microscopy, we have studied the dispersion relation of interband plasmonic modes in the ultraviolet in black phosphorus. We find that the dispersion of the interband plasmons is anisotropic. Experimental results are reproduced by density functional theory, by taking into account both the anisotropy of the single-particle response function, arising from the anisotropic band structure, and the damping.

An orbitally derived single-atom magnetic memory.

A magnetic atom epitomizes the scaling limit for magnetic information storage. Individual atomic spins have recently exhibited magnetic remanence, a requirement for magnetic memory. However, such memory has been only realized on thin insulating surfaces, removing potential tunability via electronic gating or exchange-driven magnetic coupling.

Observing Imperfection in Atomic Interfaces for van der Waals Heterostructures.

Vertically stacked van der Waals heterostructures are a lucrative platform for exploring the rich electronic and optoelectronic phenomena in two-dimensional materials. Their performance will be strongly affected by impurities and defects at the interfaces. Here we present the first systematic study of interfaces in van der Waals heterostructure using cross-sectional scanning transmission electron microscope (STEM) imaging.

Probing Single Vacancies in Black Phosphorus at the Atomic Level.

Utilizing a combination of low-temperature scanning tunneling microscopy/spectroscopy (STM/STS) and electronic structure calculations, we characterize the structural and electronic properties of single atomic vacancies within several monolayers of the surface of black phosphorus. We illustrate, with experimental analysis and tight-binding calculations, that we can depth profile these vacancies and assign them to specific sublattices within the unit cell. Measurements reveal that the single vacancies exhibit strongly anisotropic and highly delocalized charge density, laterally extended up to 20 atomic unit cells.