Zinc(ii)-mediated stereoselective construction of 1,2- 2-azido-2-deoxy glycosidic linkage: assembly of K48 capsular pentasaccharide derivative.

The capsular polysaccharide (CPS) is a major virulence factor of the pathogenic and a promising target for vaccine development. However, the synthesis of the 1,2--2-amino-2-deoxyglycoside core of CPS remains challenging to date. Here we develop a highly α-selective ZnI-mediated 1,2- 2-azido-2-deoxy chemical glycosylation strategy using 2-azido-2-deoxy glucosyl donors equipped with various 4,6--tethered groups.

Helical fused 1,2:8,9-dibenzozethrene oligomers with up to 201° end-to-end twist: "one-pot" synthesis and chiral resolution.

Twisted polyarenes with persistent chirality are desirable but their synthesis has remained a challenge. In this study, we present a "one-pot" synthesis of 1,2:8,9-dibenzozethrene (DBZ) and its vertically fused dimers and trimers using nickel-catalyzed cyclo-oligomerization reactions. X-ray crystallographic analysis confirmed highly twisted helical structures that consist of equal parts left- and right-handed enantiomers.

A cationic thorium-organic framework with triple single-crystal-to-single-crystal transformation peculiarities for ultrasensitive anion recognition.

Single-crystal-to-single-crystal transformation of metal-organic frameworks has been met with great interest, as it allows for the creation of new materials in a stepwise manner and direct visualization of structural transitions when subjected to external stimuli. However, it remains a peculiarity among numerous metal-organic frameworks, particularly for the ones constructed from tetravalent metal cations. Herein, we present a cationic thorium-organic framework displaying unprecedented triple single-crystal-to-single-crystal transformations in organic solvents, water, and NaIO solution.

Stereo-controlled -hydromagnesiation of aryl alkynes by magnesium hydrides.

A concise protocol for -hydromagnesiation of aryl alkynes was established using 1 : 1 molar combination of sodium hydride (NaH) and magnesium iodide (MgI) without the aid of any transition metal catalysts. The resulting alkenylmagnesium intermediates could be trapped with a series of electrophiles, thus providing facile accesses to stereochemically well-defined functionalized alkenes. Mechanistic studies by experimental and theoretical approaches imply that polar hydride addition from magnesium hydride (MgH) is responsible for the process.

A mild one-pot synthesis of 2-iminothiazolines from thioureas and 1-bromo-1-nitroalkenes.

A mild method to access functionalized 2-iminothiazolines in a facile and efficient manner has been developed. The reaction started from 1,3-disubstituted thioureas and 1-bromo-1-nitroalkenes in the presence of triethylamine in THF and proceeded smoothly in air to afford 2-iminothiazoline derivatives in moderate to good yields.

Surface modifications of carbon nanodots reveal the chemical source of their bright fluorescence.

Fluorescent carbon nanodots (CNDs) have drawn increasing attention in recent years. These cost-effective and eco-friendly nanomaterials with bright fluorescence have been investigated as promising materials for electrooptic and bioimaging applications. However, the chemical source stimulating their strong fluorescence has not been completely identified to date.

New Metallic Ordered Phase of Perovskite CsPbI under Pressure.

Pressure-induced electronic structure transition from insulating phase to metal state is a potential new paradigm for halide perovskites. The metallization based on these materials may afford a novel motif toward realizing new electronic properties even superconductivity phenomenon. Herein, how static compression modulates the crystal and electronic structure of typical perovskite semiconductors cesium lead iodine (CsPbI) by both experimental and theoretical studies is reported.

Divergent Protosilylation and Protoborylation of Polar Enynes.

Copper-catalyzed divergent conjugate protosilylation and protoborylation of polar enynes were developed. The corresponding β-boryldienoates and β-silyldienotes were obtained in moderate to good yields and with good stereoselectivity. In this protocol, novel cascade double protoborylation/protodeboronation processes of polar enynoates enabled access of the useful trisubstituted vinylboronates in up to 80% yield and with up to 98:2 Z/ E ratio.

Synthesis of (-)-Cytisine Using a 6- endo aza-Michael Addition.

An asymmetric synthesis of (-)-cytisine has been achieved. The piperidine C-ring was formed using a stereodivergent intramolecular 6- endo aza-Michael addition. The B-ring was established by intramolecular pyridine N-alkylation.

Monolayer Molybdenum Disulfide Transistors with Single-Atom-Thick Gates.

Two-dimensional transition-metal dichalcogenides (TMDs) are unique candidates for the development of next-generation electronic devices. However, the large contact resistance between metal and the monolayer TMDs have significantly limited the devices' performance. Also, the integration of ultrathin high- k dielectric layers with TMDs remains difficult due to the lack of dangling bonds on the surface of TMDs.

Synchronized oscillations and acoustic fluidization in confined granular materials.

According to the acoustic fluidization hypothesis, elastic waves at a characteristic frequency form inside seismic faults even in the absence of an external perturbation. These waves are able to generate a normal stress which contrasts the confining pressure and promotes failure. Here, we study the mechanisms responsible for this wave activation via numerical simulations of a granular fault model.

Spin Order and Phase Transitions in Chains of Polariton Condensates.

We demonstrate that multiply coupled spinor polariton condensates can be optically tuned through a sequence of spin-ordered phases by changing the coupling strength between nearest neighbors. For closed four-condensate chains these phases span from ferromagnetic (FM) to antiferromagnetic (AFM), separated by an unexpected crossover phase. This crossover phase is composed of alternating FM-AFM bonds.

Synthesis and Optimization of MoS@FeO-ICG/Pt(IV) Nanoflowers for MR/IR/PA Bioimaging and Combined PTT/PDT/Chemotherapy Triggered by 808 nm Laser.

Elaborately designed biocompatible nanoplatforms simultaneously achieving multimodal bioimaging and therapeutic functions are highly desirable for modern biomedical applications. Herein, uniform MoS nanoflowers with a broad size range of 80-180 nm have been synthesized through a facile, controllable, and scalable hydrothermal method. The strong absorbance of MoS nanoflowers at 808 nm imparts them with high efficiency and stability of photothermal conversion.

Bistability in bosonic terahertz lasers.

We study theoretically terahertz (THz) lasing in a system consisting of a quantum well placed inside an optical microcavity and a THz cavity in the regime of two-photon excitation of 2p dark exciton states. The stability of the system with varying parameters of the microcavity under coherent pumping is analyzed. We show that the nonlinearity provided by two-photon absorption can give rise to bistability and hysteresis in the THz output.