Stereoselective Synthesis of Oxabicyclo[2.2.1]heptenes via a Tandem Dirhodium(II)-Catalyzed Triazole Denitrogenation and [3 + 2] Cycloaddition

A novel synthetic strategy for the diastereoselective synthesis of structurally diverse oxabicyclo[2.2.1]­heptenes has been developed, featuring a tandem reaction combining a Rh-catalyzed triazole denitrogenation and a novel type of [3 + 2] cycloaddition reaction. This tandem reaction was thought to proceed via a five-membered oxonium ylide intermediate, which was formed by the intramolecular nucleophilic attack of the carbonyl group on the α-imino metallocarbene followed by an inter- or intramolecular [3 + 2] dipolar cycloaddition with a range of alkynes and alkenes

Patients' demographic and clinical characteristics.

<p>RTA: Road Traffic Accidence.</p><p>PV: Personal Violence.</p><p>All 31 patients showed malocclusion, which was one indication for open reduction and internal fixation. Patients without malocclusion were excluded from this group.</p

Stereoselective Synthesis of Oxabicyclo[2.2.1]heptenes via a Tandem Dirhodium(II)-Catalyzed Triazole Denitrogenation and [3 + 2] Cycloaddition

A novel synthetic strategy for the diastereoselective synthesis of structurally diverse oxabicyclo[2.2.1]­heptenes has been developed, featuring a tandem reaction combining a Rh-catalyzed triazole denitrogenation and a novel type of [3 + 2] cycloaddition reaction. This tandem reaction was thought to proceed via a five-membered oxonium ylide intermediate, which was formed by the intramolecular nucleophilic attack of the carbonyl group on the α-imino metallocarbene followed by an inter- or intramolecular [3 + 2] dipolar cycloaddition with a range of alkynes and alkenes

Stereoselective Synthesis of Oxabicyclo[2.2.1]heptenes via a Tandem Dirhodium(II)-Catalyzed Triazole Denitrogenation and [3 + 2] Cycloaddition

A novel synthetic strategy for the diastereoselective synthesis of structurally diverse oxabicyclo[2.2.1]­heptenes has been developed, featuring a tandem reaction combining a Rh-catalyzed triazole denitrogenation and a novel type of [3 + 2] cycloaddition reaction. This tandem reaction was thought to proceed via a five-membered oxonium ylide intermediate, which was formed by the intramolecular nucleophilic attack of the carbonyl group on the α-imino metallocarbene followed by an inter- or intramolecular [3 + 2] dipolar cycloaddition with a range of alkynes and alkenes

Photographs show a 25-year-old male patient undergoing open reduction and rigid internal fixation of right condylar fracture under general anaesthesia.

<p>A: Design; B: Incision; C: Flap elevation and exposure of the SMAS fascia; D: Exposure of condylar fracture; E: Rigid internal fixation; F: Suture.</p

Two-Photon Acid Generation Systems Based on Dibenzylidene Ketone Dyes Intermolecular Sensitization

A couple of two-photon absorption dyes containing triphenylamine groups as the electron donor were synthesized. They were combined with commonly used photoacid generator <i>N</i>-(trifluoromethanesulfonyloxy)-1,8-naphthalimide (NIOTf) to build two-photon acid generation systems (2PAGs). The photochemical and photophysical properties of these dyes as well as their photosensitizing mechanism were investigated. Both of the two dyes have a greatly enhanced two-photon absorption cross-section over 1000 GM. The photoacid quantum yields of 2PAGs were measured in acetonitrile solution by one-photon process. Fluorescence quenching experiments were carried out and confirmed the electron transfer mechanism in resin films. Also, the acid-catalyzed chemical amplification processes in resin films were studied with a Ti/sapphire regenerative amplifier by attenuated total reflectance Fourier transform infrared spectroscopy, and both 2PAGs exhibited superior efficiencies via two-photon absorption in comparison with isopropylthioxanthone/NIOTf system and NIOTf itself. The two-photon lithography (TPL) was carried out on a Ti/sapphire femtosecond laser system successfully with chemically amplified positive resists based on the achieved 2PAGs and the proceeding power for TPL was as low as 0.24 mW. The results suggest that these 2PAGs can be used as high-efficiency initiator for two-photon chemically amplified positive resist

Ni-Based Janus Pentagonal Monolayers as Promising Water-Splitting Photocatalysts

Photocatalysts which can efficiently promote water splitting to generate hydrogen without using sacrificial reagents and cocatalysts are highly desirable. In this study, on the basis of first-principles calculations, we predict that a series of Ni-based Janus monolayers with a pentagonal structure are promising photocatalysts, where the hydrogen evolution reaction can solely be driven by photon-excited electrons. The stability of the investigated monolayers is affirmed through energetic analysis, phonon band structure calculations, and ab initio molecular dynamics simulations. From the perspective of the photocatalytic process, their high absorption coefficients (∼105 cm–1) guarantee strong light absorption, their intrinsic electric fields generated by the Janus structure are beneficial to charge transfer, and their high catalytic activity speeds up the hydrogen evolution reaction. Moreover, strain engineering turns out to be effective for tuning band alignment and improving the catalytic performance. This study provides a new type of photocatalyst with high solar-to-hydrogen efficiency

Discovery of a Metalloenzyme-like Cooperative Catalytic System of Metal Nanoclusters and Catechol Derivatives for the Aerobic Oxidation of Amines

We have discovered a new class of cooperative catalytic system, consisting of heterogeneous polymer-immobilized bimetallic Pt/Ir alloyed nanoclusters (NCs) and 4-<i>tert</i>-butylcatechol, for the aerobic oxidation of amines to imines under ambient conditions. After optimization, the desired imines were obtained in good to excellent yields with broad substrate scope. The reaction rate was determined to be first-order with respect to the substrate and catechol and zero-order for the alloyed Pt/Ir NC catalyst. Control studies revealed that both the heterogeneous NC catalyst and 4-<i>tert</i>-butylcatechol are essential and act cooperatively to facilitate the aerobic oxidation under mild conditions

Synthesis of 2,3-Disubstituted Indoles and Benzofurans by the Tandem Reaction of Rhodium(II)-Catalyzed Intramolecular C–H Insertion and Oxygen-Mediated Oxidation

A highly effective and straightforward method to construct a wide range of functionalized 2,3-disubstituted indoles has been developed. The method involves the tandem reaction of rhodium­(II)-catalyzed denitrogenative annulation of triazole-based benzyl anilines and oxygen-mediated oxidative aromatization. The developed method can also be used to synthesize 2,3-disubstituted benzofurans by replacing the benzyl anilines with benzyl phenols

Amino Acid Double-Passivation-Enhanced Quantum Dot Coupling for High-Efficiency FAPbI₃ Perovskite Quantum Dot Solar Cells

Formamidinium lead triiodide (FAPbI3) perovskite quantum dot has outstanding durability, reasonable carrier lifetime, and long carrier diffusion length for a new generation of highly efficient solar cells. However, ligand engineering is a dilemma because of the highly ionized and dynamic characteristics of quantum dots. To circumvent this issue, herein, we employed a mild solution-phase ligand-exchange approach through adding short-chain amino acids that contain amino and carboxyl groups to modify quantum dots and passivate their surface defects during the purification process. As a result, the photoelectric conversion efficiency of FAPbI3 perovskite quantum dot solar cells (PQDSCs) increased from 11.23 to 12.97% with an open-circuit voltage of 1.09 V, a short-circuit current density of 16.37 mA cm–2, and a filling factor of 72.13%. Furthermore, the stability of the device modified by amino acids retains over 80% of the initial efficiency upon being exposed to 20–30% relative humidity for 240 h of aging treatment. This work may offer an innovative concept and approach for surface ligand treatment to improve the photovoltaic performance of PQDSCs toward large-scale manufacture