Latest ArticlesA nickel(Ⅱ)-catalyzed asymmetric alkylation of acyclic oxocarbenium ions generated in situ from corresponding acetals with carboxylic acid derivatives to prepare β-alkoxyl carbonyl moieties with diverse α-substituents has been disclosed. The method exhibited broad scope of acetals and carboxylic acid derivatives with excellent enantioselectivity and good functional group compatibility, and can be conducted in a gram-scale without obvious loss of efficiency.
A template-free carbonization-activation route is developed to fabricate sub-nanopore-containing porous carbon by using a novel polypyrrole (PPy) hydrogel as a precursor. This design of PPy hydrogel precursor containing molecular-scale grids (diameter ~2.0 nm) allows for homogeneous N, O-codoping into the porous carbon scaffold during the pyrolysis process. A subsequent activation step produces activated porous carbons (APCs) with tailored pore structures, which renders the APCs abundant sub-nanopores on their surface to increase the specific capacitance as extra capacitance sites. Coupled with large specific surface area and abundant heteroatoms, the optimized APC4/1 displays excellent specific capacitance of 379 F/g for liquid-state supercapacitor and 230 F/g for solid-state supercapacitor. The solid-state supercapacitor shows a high energy density of 22.99 Wh/kg at power density of 420 W/kg, which is higher than most reported porous carbon materials and satisfy the urgent requirements of elementary power source for electric vehicles. Moreover, this method can be easily modified to fabricate sub-nanopore-containing porous carbons with preferred structures and compositions for many applications.
p-TsOH catalyzed Diels-Alder reaction of 3-(indol-3-yl)maleimides with 3-phenacylideneoxindoles in toluene at 80 ℃ for two hours afforded cis/trans isomers of 3a', 4′, 6′, 10c'-tetrahydrospiro[indoline-3, 5′-pyrrolo[3, 4-c]carbazoles] in nearly comparable yields, which could be easily converted to the corresponding 4′, 6′-dihydrospiro[indoline-3, 5′-pyrrolo[3, 4-c]carbazole] in high yields and with high diastereoselectivity by further DDQ oxidation., the similar reaction of 3-(indol-3-yl)maAdditionallyleimides with 2-arylidene-1, 3-indanediones in toluene 80 ℃ and sequential DDQ oxidation afforded functionalized dihydrospiro[indene-2, 5′-pyrrolo[3, 4-c]carbazoles] as major products.
Lithium sulfur batteries with high energy density are thought to be the most potential energy storage technology that can be commercialized. However, the shuttle effect of polysulfides deteriorates its electrochemical performance. Herein, a novel Co9S8 nanostructure derived from metal organic framework material (MOF) was explored by simple liquid phase reaction and heat vulcanization of 2-methylimidazole and Co(NO3)2·6H2O on the surface of the original PP separator. The Co9S8 nano-flower cluster array wall was vertically and closely arranged with the thickness of 200 nm, and the polysulfide can be adsorbed by its physical and chemical action to slow down the "shuttle effect". It is found that the cell with the modified separator can achieve an ideal discharge capacity of about 600 mAh/g at 1 C. The specific capacity is maintained at 500 mAh/g after 200 cycles, with only 0.11% of capacity decay per cycle. It provides a new way for the utilization of MOF material derivatives to modify the separator in order to improve the electrochemical performance of lithium-sulfur batteries.
Non-enzymatic electrochemical sensors for the determination of hydrogen peroxide (H2O2) have attracted more and more concerns. A series of nickel and cobalt double oxides (NixCoy-DO) with the different ratios of Ni/Co have been prepared by a polyol-mediated solvothermal method for H2O2 detection. The obtained products exhibit honeycomb-like open porous microtubes constituted with the low-dimensional nanostructured NixCoy-DO blocks after the calcination treatment. Compared with nickel oxides, the introduced Co ions in NixCoy-DO can induce the production of surficial oxygen vacancies, and further enhance the electrode surface activity. In particular, the NiCo-DO sample (with an atomic ratio of Ni/Co = 4:3) shows the richest surficial oxygen vacancies and presents the highest H2O2 detection activity among all the as-prepared samples, demonstrating an excellent sensitivity of 698.60 μA L mmol-1 cm-2 (0 ~ 0.4 mmol/L), low detection limit (0.28 μmol/L, S/N = 3), as well as long stability, high selectivity and good reproducibility. This work lends a new impetus to the potential application of double metal oxides for the next generation of non-enzymatic sensors.
Catalytic transfer hydrogenation (CTH) of furfural (FF) to furfuryl alcohol (FFA) has received great interest in recent years. Herein, Cu-Cs bimetallic supported catalyst, CuCs(2)-MCM, was developed for the CTH of FF to FFA using formic as hydrogen donor. CuCs(2)-MCM achieved a 99.6% FFA yield at an optimized reaction conditions of 170 ℃, 1 h. Cu species in CuCs(2)-MCM had dual functions in catalytically decomposing formic acid to generate hydrogen and hydrogenating FF to FFA. The doping of Cs made the size of Cu particles smaller and improved the dispersion of the Cu active sites. Importantly, the Cs species played a favorable role in enhancing the hydrogenation activity as a promoter by adjusting the surface acidity of Cu species to an appropriate level. Correlation analysis showed that surface acidity is the primary factor to affect the catalytic activity of CuCs(2)-MCM.
Azithromycin loaded fumaryl diketopiperazine (FDKP) dry powder inhalationwas designed and prepared for the treatment of community-acquired pneumonia. The solubility of FDKP and stability of azithromycin solution was investigated. Formulation of azithromycin loaded FDKP microparticle was investigated and optimized by the single factor experiment. High-pressure homogenization and spray drying conditions were also optimized to prepare the particles by spray drying azithromycin dissolved FDKP microparticle suspension at pH 4.5. The in vitro antibacterial efficiency and in vitro dispersion performance was also investigated to confirm the antibacterial efficiency, dispersion and deposition behavers. FDKP/azithromycin mass ratio (3:2) was the optimized formulation of azithromycin loaded FDKP microparticle with the maximal drug loading efficiency. High-pressure homogenization and spray drying conditions were also optimized. The in vitro antibacterial results indicated that only with the antibiotic concentration higher than mutant prevention concentration could totally inhibit the reproduction of bacteria. In vitro dispersion performance of azithromycin loaded FDKP microparticles (AZM@FDKP-MPs) also shows remarkable improvement of dispersion and deposition behavers of AZM. AZM@FDKP-MPs dry powder inhalation as a targeting delivery route has better potential for lung infection treatment.
A multifunctional nanocomposite of AgNPs@GQDs is prepared by synergistic in-situ growth of silver nanoparticles (AgNPs) on the complex of tannic acid (TA) and graphene quantum dots (GQDs) for the construction of dual-mode biosensing platform and cancer theranostics. The nanocomposite exhibits a hydrogen peroxide (H2O2)-responsive degradation, in which Ag0 is oxidized to Ag+ along with the release of oxidized TA and GQDs. The degradation induces the decreased absorbance and enhanced fluorescence (FL) intensity due to the suppression of Förster resonance energy transfer (FRET) in AgNPs@GQDs, which is employed for colorimetric/fluorescence dual-mode sensing of H2O2. The intrinsic peroxidase-like activity of GQDs nanozyme can effectively catalyze the oxidation reaction, enhancing the detection sensitivity significantly. Based on the generation of H2O2 from the oxidation of glucose with the catalysis of glucose oxidase (GOx), this nanoprobe is versatilely used for the determination of glucose in human serum. Further, through combining the H2O2-responsive degradation of AgNPs@GQDs with high H2O2 level in cancer cells, the nanocomposites exhibit good performance in cancer cell recognition and therapy, in which the synergistic anticancer effect of Ag+ and oxidized TA contribute to effective cell death, and the liberated GQDs are used to monitor the therapeutic effect by cell imaging.
Selective separation of CO2/CH4 and C2H2/CH4 are promising for their high-purity industrial demand and scientific research on account of the similar molecular radius and physical properties. In this work, a unique 3D microporous MOF material [Cu(SiF6)(sdi)2] solvents (1, sdi = 1, 1'-sulfonyldiimidazole) was successfully constructed by cross-linking 1D coordination polymer chains. The dense functional active sites on the inner walls of the channel of 1a can provide strong binding affinities to CO2, C2H2, and thus effectively improve the gas separation performance of CO2/CH4 and C2H2/CH4.
Functional groups in the molecule play an important role in the molecular organization process. To reveal the influence of functional groups on the self-assembly at interface, herein, the self-assembly structures of three liquid crystal molecules, which only differ in the functional groups, are explicitly characterized by using scanning tunneling microscopy (STM). The high-resolution STM images demonstrate the difference between the supramolecular assembly structures of three liquid crystal molecules, which attribute to the hydrogen bonding interaction and π-π stacking interaction between different functional groups. The density functional theory (DFT) results also confirm the influence of these functional groups on the self-assemblies. The effort on the self-assembly of liquid crystal molecules at interface could enhance the understanding of the supramolecular assembly mechanism and benefit the further application of liquid crystals.
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