Latest ArticlesTwo new hydrostable two-dimensional (2D) uranyl coordination complexes [(UO2)5(μ3-O)2(nbca)2]·7H2O (1) and [(UO2)3(nbca)2(H2O)3]·2H2O (2) (H3nbca = 5-nitro-1,2,3-benzenetricarboxylic acid) were hydrothermal synthesized. Single-crystal structural refinements reveal that both of the two complexes were formed by the packing of 2D uranyl coordination sheets via the hydrogen bonds. The nbca ligand coordinating to the uranyl polyhedron centers constructed the 2D sheets. There are UO8 hexagonal bipyramids and UO7 pentagonal bipyramids in 1 while only UO7 pentagonal bipyramids in 2. Photocatalytic degradation of rhodamine B (RhB) in aqueous solution was studied. Complex 2 possesses better performance than 1 with 96.2 % of the RhB was degraded in only 60 min. Mechanism studies reveal that the dissolved oxygens are essential to the RhB degradation. The photocurrent density of 2 is more stable than that of 1, which indicating the stronger ability to separate photoexcited electrons and hole pairs of 2.
The series of heterodinuclear metal oxide carbonyls in the form of TaNiO(CO) n- (n = 5–8) are generated in the pulsed-laser vaporization source and characterized by mass-selected photoelectron velocity-map spectroscopy. During the consecutive CO adsorption, the μ2-O-bent structure initially is the most favorable for TaNiO(CO)5-, and subsequently both μ2-O-bent and μ2-O-linear structures are degenerate for TaNiO(CO)6-, then the μ2-O-linear structure is most preferential for TaNiO(CO)7-, and finally the η2-CO2-tagged structure is the most energetically competitive one for TaNiO(CO)8-, i.e., the CO oxidation occurs at n = 8. In contrast to the literature reported CO oxidation on heteronuclear metal oxide complexes generally proceeding via Langmuir–Hinshelwood-like mechanism, complementary theoretical calculations suggest that both Langmuir–Hinshelwood-like and Eley–Rideal-like mechanisms prevail for the CO oxidation reaction on TaNiO(CO)8- complex. Our findings provide new insight into the composition-selective mechanism of CO oxidation on heteronuclear metal complexes, of which the composition be tailored to fulfill the desired chemical behaviors.
The abuse of antibiotics will cause an increase of drug-resistant strains and environmental pollution, which in turn will affect human health. Therefore, it is important to develop effective detection techniques to determine the level of antibiotics contamination in various fields. Compared with traditional detection methods, electrochemical sensors have received extensive attention due to their advantages such as high sensitivity, low detection limit, and good selectivity. In this mini review, we summarized the latest developments and new trends in electrochemical sensors for antibiotics. Here, modification methods and materials of electrode are discussed. We also pay more attention to the practical applications of antibiotics electrochemical sensors in different fields. In addition, the existing problems and the future challenges ahead have been proposed. We hope that this review can provide new ideas for the development of electrochemical sensors for antibiotics in the future.
An unprecedented chiral secondary amine-catalyzed [3 + 3] annulation of isatin N,N'-cyclic azomethine imines with α,β-unsaturated aldehydes was developed. This strategy allowed the construction of structurally novel spiro N-heterocyclic oxindole derivatives in good yields (up to 91%) and good to excellent enantioselectivities (up to >99% ee), albeit with modest diastereoselectivities (up to 3.1:1 dr).
A novel Pd-Fe/α-Al2O3 catalyst was synthesized by incipient-wetness impregnation method with bayberry tannin as chelating promoter and commercial hollow column Raschig ring α-Al2O3 as support for the synthesis of diethyl oxalate from CO and ethyl nitrite. A variety of characterization techniques including N2 physical adsorption, optical microscopy, scanning electron microscopy and energy dispersive system (SEM-EDS), inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), were employed to explore the relationship between the physicochemical properties and activity of catalysts. It indicated that a large number of phenolic hydroxyl groups in bayberry tannin can efficiently anchor the active component Pd, reduce the particle size and make the active Pd as a multi-ring distribution on the commercial α-Al2O3 support, which were beneficial to improve the catalytic activity for the production of diethyl oxalate from CO and ethyl nitrite. 0.3 wt% Pd-Fe/α-Al2O3 showed excellent catalytic activity and selectivity in a continuous flow, fixed-bed reactor with the loading amount of 10 mL catalysts. Under the mild reaction conditions, the space-time yield of diethyl oxalate was 978 g L-1 h-1 and CO conversion was 44% with the selectivity to diethyl oxalate of 95.5%.
All-solid-state Li metal battery has been regarded as a promising battery technology due to its high energy density based on the high capacity of lithium metal anode and high safety based on the all solid state electrolyte without inflammable solvent. However, challenges still exist mainly in the poor contact and unstable interface between electrolyte and electrodes. Herein, we demonstrate an asymmetric design of the composite polymer electrolyte with two different layers to overcome the interface issues at both the cathode and the anode side simultaneously. At the cathode side, the polypropylene carbonate layer has enough viscosity and flexibility to reduce the inter-facial resistance, while at the Li anode side, the polyethylene oxide layer modified with hexagonal boron nitride has high mechanical strength to suppress the Li dendrite growth. Owing to the synergetic effect between different components, the as-prepared double layer composite polymer electrolyte demonstrates a large electrochemical window of 5.17 V, a high ionic conductivity of 6.1×10-4 S/cm, and a transference number of 0.56, featuring excellent ion transport kinetics and good chemical stability. All-solid-state Li metal battery assembled with LiFePO4 cathode and Li anode delivers a high capacity of 150.9 mAh/g at 25 ℃ and 0.1 C-rate, showing great potential for practical applications.
Carbon nitride (CN) photocatalysts have attracted much attention due to their excellent photocatalytic properties. And hydrothermal fluorination is a common method to improve the photocatalytic effect of CN photocatalyst. Here, the influence of the band gap was first revealed of fluorination and hydroxylation of CN photocatalyst based on the first theoretical principle. Here, the effect of fluorination and hydroxylation on the CN band gap was discussed for the first time using the first theoretical principle. With F atoms and OH doping, the band gap of CN was significantly improved, conduction band and valence band moved up. Then, F—CN photocatalyst with F atoms and OH was successfully synthesized by a hydrothermal fluorinated method. Next, the reasons why F—CN photocatalyst was more effective than that of traditional CN photocatalyst were fully discussed. From the photocatalytic effect of photocatalyst (12, 593.2 μmol g-1 h-1 to the morphology (super-small nanosheets), structure (homojunctions), composition (metal-free), specific surface area (54.1 m2/g), visible light absorption response (AQE is 10.9% at 420 nm) and photo-induced carrier life (14.13 ns). Therefore, this work has a great guiding effect on the development of CN photocatalyst.
Five novel biscembranoids, ximaolides H–L (1–5), along with four known related compounds (6–9) were isolated from the Hainan soft coral Sarcophyton tortuosum. The structures of the new compounds were determined by extensive spectroscopic analysis, quantum chemical calculations, and/or by comparing their CD spectra with those of the known compounds. Compounds 1 and 2 are the first examples of biscembranoids bearing a 1,35-bridged lactone moiety, 4 is the first biscembranoid comprising an uncommon oxetane ring, and 5 represents the first 36-peroxyl biscembranoid. Ximaolides I (2), K (4) and F (9) exhibited interesting anti-inflammatory activity by the inhibition of LPS-induced TNF-α protein release in RAW264.7 macrophages.
Sulfonium salts and sulfur ylides are important S(Ⅳ) motifs, and have displayed many unique reactivities to provide simple, effective, and often stereoselective synthesis toward sulfur containing compounds. Impressive developments have been witnessed within this field during the past several years. In light of the increasing demand of organosulfur compounds across the range of chemical sciences, our aim of this review is to provide a concise overview of recent advances of sulfonium salt and sulfur ylide chemistry. Selected examples are organized in three parts on the basis of their role in organic reactions (reactants, intermediates and catalysts).
Rheumatoid arthritis (RA), as a chronic autoimmune disease, damages the bone and cartilage of patients, and even leads to disability. Therefore, the diagnosis and treatment of RA is particularly important. However, due to the complexity of RA, it is difficult to make effective early diagnosis of RA, which is detrimental to RA treatment. Besides, long-term intake of anti-RA drugs can also cause damage to patients' organs. The emergence of nanotechnology provides the new train of thoughts for the diagnosis and treatment of RA. And the combination of diagnosis and therapy is an ideal method to solve the problem of disease management of RA patients. In this review, we summarize the mechanism and microenvironment of RA, discuss the commonly used diagnostic techniques and therapeutic drugs for RA, and review their advantages and disadvantages. New nanotherapy strategies such as drug-carrying nanoparticles, PTT, PDT are listed, and their applications in RA treatment are also summarized. In addition, multimodal imaging, combined therapy and responsive diagnosis and treatment are also summarized as important contents. At last, we also review typical nanocarriers that can be used in the integration of diagnosis and therapy, and discussed their potential applications in RA theranostics.
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