Latest ArticlesA palladium-catalyzed formal [2 + 2 + 1] cyclization of 1-alkynyl-8-iodonaphthalene with double isocyanides is developed herein. The transformation worked well to produce a series of 7H-acenaphtho[1,2-b]pyrrole with a broad reaction scope. Isocyanides play a dual role in the reaction. One is a C1 building block, and another is used as C1N1 component. In the process, the [2 + 2 + 1] cyclization involves imidoylation, regioselective addition of imidoylpalladium species into alkyne, double imidoylation, and another addition of the resulting imidoylpalladium species into imine bonds.
Herein we report a new general method for one-step synthesis of four kinds of fluoroiodane(Ⅲ) reagents by treating the corresponding aryl iodides with silver difluoride (AgF2). This is the first method applicable for the synthesis of all four fluoroiodane(Ⅲ) reagents including p-iodotoluene difluoride (1), fluoro-benziodoxole (2), fluoro-benziodoxolone (3), and fluoro-N-acetylbenziodazole (4). AgF2 was firstly employed in the direct oxidative fluorination of iodobenzene and thus has shown its outstanding oxidation and fluorine-transfer ability. The use of AgF2 has improved the synthesis of fluoroiodane(Ⅲ) reagents by shortening the reaction steps, avoiding the use of hazardous reagents, and simplifying the experimental operations. It was worth noting that we have developed the first one-step direct synthetic method for 3, while 3 can only be synthesized through Cl→F ligand exchange reaction previously.
An efficient and catalytic protocol for highly stereoselective construction of β-mannopyranosylation has been developed. Glycosylation of 2,6-lactone-bridged mannopyranosyl ortho-hexynylbenzoate with various acceptors proceeded smoothly in the presence of 5% Hg(Ⅱ) at room temperature, resulting in the corresponding β-mannosides in high yield and exclusive β-stereoselectivity.
Wastewater treatment and reclamation from wastewater are essential for the sustainable use of water resource. Zeolite-based heterogeneous catalysis shows great potential in circumventing the current limitations on pollutant removal and transformation to useful chemicals, inspiring advancements towards practical water treatment. This paper summarizes the methods for synthesizing zeolite-based catalyst, and the corresponding advantages and disadvantages. In comparison with traditional Fenton-like reaction, the superiority of zeolite-based catalysis lies in less sludge, wide pH range and easy recyclability. Accordingly, applications of zeolite-based Fenton-like catalysis (ZFCs) in pollutant removal and reclamation of wastewater were reviewed. Emphasis was placed on the methodological strategies in improving ZFCs, including the combination of external driving force (e.g., photocatalysis or electrochemistry), as well as the introduction of various transition metals into zeolite-based catalyst. Possible challenges and future perspectives for ZFCs were proposed.
α, β-Unsaturated primary amides are important intermediates and building blocks in organic synthesis. Herein, we report a ligand-free iron-catalyzed hydroaminocarbonylation of alkynes using NH4HCO3 as the ammonia source, enabling the highly efficient and regioselective synthesis of linear α, β-unsaturated primary amides. Various aromatic and aliphatic alkynes are transformed into the desired linear α, β-unsaturated primary amides in good to excellent yields. Further studies show that using NH4HCO3 as the ammonia source is key to obtain good yields and selectivity. The utility of this route is demonstrated with the synthesis of linear α, β-unsaturated amides including vanilloid receptor-1 antagonist TRPV-1.
We construct MUC1 vaccines using β-cyclodextrin grafted chitosan (CS-g-CD) as carrier via host-guest interaction. These vaccines based on non-covalent assembling can provoke robust immune responses, including high level of specific antibodies and cytokines. The induced antibodies can specifically recognize tumor cells and mediate cytotoxicity against tumor cells. These results indicate that CS-g-CD with strong immunostimulatory activities can be a straightforward platform for peptide-based vaccine construction.
One goal of supramolecular chemistry is the creation of synthetic receptors that have a high affinity for hydrophilic molecules in water. We found that cavitands with upper rims extended by pyridyl groups coax hydrophilic guests into the cavity where they are shielded from the aqueous environment. The ability of Pd(Ⅱ) to coordinate adjacent pyridyl groups leads to increased selectivity for highly hydrophilic solvent molecules such as acetone, 1, 4-dioxane and tetrahydrofuran in water. Analysis of the binding behavior indicated that metal-coordination restricts the container entrance, shrinks the effective cavity volume and increases the energetic barrier to guest exchange.
The flow-through electro-Fenton (EF-T) reactor with WBC cathode was designed to remove florfenicol (FF). The activated WBC cathode was prepared by facile carbonization and activation methods, and featured high specific surface area, natural multi-channel structure, abundant oxygen-containing groups, good hydrophilicity, and excellent O2 reducing capacity. WBC cathode was located above Ti/Ru-IrO2 mesh anode. O2 evolved at the anode was carried to the inner wall of channel of WBC by the force of buoyancy and water flow, which increases oxygen source of H2O2 generation at the cathode. The flow-through system by using WBC electrode promote the mass transfer of O2 and FF. The production amount of H2O2 at activated WBC was 32.2 mg/L, which was almost twice as much as that at non-activated WBC (15.0 mg/L). FF removal ratio in EF-T system was 98%, which was much higher than that of traditional flow-by electro-Fenton (EF-B, 33%) or single electrooxidation system (EO, 16%). EF-T system has the lowest energy consumption (4.367 kWh/kg) among the three electrochemical systems. The cathodic adsorption, anodic electrooxidation, and EF reaction are responsible for the degradation of FF. After five consecutive cycle experiments, FF removal ratio was still 98%, indicating WBC has the good stability.
Since the discovery of aggregation induced emission (AIE) phenomenon, various stimuli-responsive materials have been rapidly developed, but there are still great challenges in the application of ink printing due to the bad water solubility. In this research, a new cationic amphiphilic TPE-functionalized pyridine salt (TPE-OTs) was designed, which shows good water solubility and hydrochromic properties. The optical properties of the compound have been studied, which is equipped with the typical AIEE characteristics and TICT effect. The compound can self-assemble to form aggregates with a particle size of about 30 nm in water. What is more, the compound is responsive to the environmental humidity, whose fluorescent color changes from green to yellow as the humidity gradually increased. Based on this characteristic, we applied it to the fluorescent anti-counterfeiting ink, realizing the protection and encryption of information.
Accurate detection of important biomarkers with ultra-low levels in complex biological matrix is one of the frontier scientific issues because of possible signal interference of potential reductive agents and protein molecules. Herein, a self-powered anti-interference photoelectrochemical (PEC) immunosensor was explored for sensitive and specific detection of model target of cardiac troponin I (cTnI). Specifically, a novel ternary heterojunction served as the photocathode to offer a remarkable current output and a zwitterionic peptide was introduced to build a robust antifouling biointerface. CuInS2 (CIS) film with porous network nanostructure was first prepared and then modified in order with ZnIn2S4 (ZIS) nanocrystals and Au nanoparticles to fabricate the Au/ZIS/CIS heterojunction photocathode. After capture cTnI antibody (Ab) was immobilized, the zwitterionic peptide KAEAKAEAPPPPC was then anchored to compete the immunosensor. The elaborated PEC immunosensor exhibited high sensitivity for target cTnI antigen (Ag) detection, with good anti-interference against reductive agents and nonspecific proteins. This integration strategy of heterojunction photocathode with zwitterionic peptide provides a new sight to develop advanced PEC immunosensors applying in practical biosamples.
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