Latest ArticlesThe textile industry spreads globally with the challenges of its wastewater treatment, especially dyes, which are difficult to degrade. To improve coagulation-flocculation process in dye wastewater treatment, an intercalation process was employed to prepare a new efficient coagulant of lithium borohydride-iron oxychloride (LiBH4_FeOCl) in this study. The layered crystal pristine iron oxychloride (FeOCl) material was prepared by chemical gas phase migration. LiBH4 was introduced into the layers of two dimensional (2D) FeOCl nanosheets by a simple method of liquid phase insertion. The samples were characterized by a field emitting scanning electron microscopy (SEM), a rotating anode X-ray powder diffractometer (XRD), etc. The cationic dye was employed as the simulated pollutant. A coagulation and decolorization experimental device was built to study the coagulation performance of the new coagulant LiBH4_FeOCl. It is found that the intercalation modified LiBH4_FeOCl exhibits the characteristics of crystal structure, and the layered structure of FeOCl is preserved. LiBH4_FeOCl, as an insoluble inorganic solid coagulant, performs well for dye pollutants of methyl red, basic yellow 1, methylene blue, rhodamine B, ethyl violet and Janus green B. The reaction rate is significantly 68% higher than the current commercial coagulants of Al2(SO4)3. The mechanism analysis reveals that LiBH4_FeOCl breaks and disperses rapidly in the water environment. Its negatively charged material particles can be electrostatically adsorbed with dye pollutant molecules through electrostatic action. The above collaborative actions of breaking, dispersion and electrostatic adsorption are the main coagulation mechanisms of LiBH4_FeOCl. The solid inorganic coagulant of LiBH4_FeOCl provides a competitive alternative for traditional inorganic salts and organic coagulants.
Ynamides are electron-rich alkynes with unique reactivities and act as flexible building blocks in organic synthesis. Therefore, the investigation for transformation of ynamides with exceptional selectivity and efficiency is attractive and interesting. Herein, we report an oxoarylation of ynamides with N-aryl hydroxamic acids. In the presence of catalytic Cu(OTf)2, both the terminal and internal ynamides could undergo an addition/[3,3] sigmatropic rearrangement cascade with N-aryl hydroxamic acids to achieve oxoarylation, along with providing selective entry to (ortho-amino)arylacetamides and oxindoles. Moreover, deuterium-labelling reaction and gram-scale reaction were conducted to probe the mechanism and showcase the scalability.
An N-heterocyclic carbene (NHC)-catalysed retro-aldol/aldol cascade reaction of spirooxindole-based β-hydroxyaldehyde has been developed. The ring opening-closure process enables the diastereodivergent synthesis of spirocyclopentaneoxindole products with four consecutive stereocenters by simply changing the reaction solvents (THF or DCE). The Michael/aldol/retro-aldol/aldol sequential protocol allows the diastereodivergent synthesis of spirocyclopentaneoxindoles from 3-substituted oxindole and α, β-unsaturated aldehyde under the relay catalysis of a chiral secondary amine and an NHC catalyst. Moreover, four stereoisomers of the product can be selectively provided by using different combinations of a chiral secondary amine and a solvent.
Morphology and dispersity are key factors for activating peroxymonosulfate (PMS). In this study, we designed a recyclable open-type NiCo2O4 hollow microsphere via a simple hydrothermal method with the assistance of an NH3 vesicle. The physical structure and chemical properties were characterized using techniques such as scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), N2 adsorption and X-ray photoelectron spectroscopy (XPS). The test results confirm that the inner and outer surfaces of open-type NiCo2O4 hollow-sphere can be efficiently utilized because of the hole on the surface of the catalyst, which can minimize the diffusion resistance of the reactants and products. Under optimized conditions, the total organic carbon (TOC) removal efficiency of rhodamine B (RhB) can reach up to 80% in 40 min, which is almost 50% shorter than the reported values. The reactive radicals were identified and the proposed reaction mechanism was well described. Moreover, the disturbances of HCO3−, NO3−, Cl− and H2PO4− were further investigated. As a result, HCO3− and NO3− suppressed the reaction while Cl− and H2PO4− had a double effect on reaction.
A visible light and base promoted O-H insertion/cyclization of para-quinone methides with aryl diazoacetates is developed. This one-pot two step reaction offers a mild and efficient approach for the synthesis of biologically important 2, 3-dihydrobenzofuran derivatives in good yields and moderate diastereoselectivities.
In this paper, the host-guest interaction of cucurbit[7]uril (Q[7]) and chromone (CMO) has been developed as a fluorescent probe for the highly selective detection of Zn2+ and Cd2+ in water based on a chelation-enhanced fluorescence (CHEF) mechanism. There was a good linear relationship between the fluorescence intensity of the CMO@Q[7] probe and the concentration of Zn2+ or Cd2+ in the range of 0–3.0 × 10–5 mol/L and the detection limit for Zn2+ and Cd2+ was found to be 2.03 × 10–6 mol/L and 1.89 × 10–6 mol/L, respectively. The X-ray crystal structure indicated that different coordination fashions were triggered by Zn2+ and Cd2+ in the CMO@Q[7] complexes, respectively. However, both metal ions coordinated with the carbonyl oxygen of CMO, which was encapsulated in the cavity of Q[7], thus leading to the enhancement of recognition fluorescence emission of CMO.
Bi draws increasing attention as anode materials for lithium-ion batteries and sodium-ion batteries due to its unique layered crystal structure, which is in favor of achieving fast ionic diffusion kinetics during cycling. However, the dramatic volume expansion upon lithiation/sodiation and an insufficient theoretical capacity of Bi greatly hinder its practical application. Herein, we report the Fe2O3 nanoparticle-pinning Bi-encapsulated carbon fiber composites through the electrospinning technique. The introduction of Fe2O3 nanoparticles can prevent the growth and aggregation of Bi nanoparticles during synthetic and cycling processes, respectively. Fe2O3 with high specific capacity also contributes to the specific capacity of the composites. Consequently, the as-prepared Bi-Fe2O3/carbon fiber composite exhibits outstanding long-term stability, which delivers reversible capacities 504 and 175 mAh/g after 1000 cycles at 1 A/g for lithium-ion and sodium-ion batteries, respectively.
Visible-light-driven photochemical Cadogan-type cyclization has been discovered. The organic D-A type photosensitizer 4CzIPN found to be an efficient mediator to transfer energy from photons to the transient intermediate that breaks the barriers of deoxygenation in Cadogan reaction and enables a mild metal-free access to carbazoles and related heterocycles. DFT calculation results indicate mildly endergonic formation of the intermediate complex of nitrobiarenes and PPh3, which corresponds with experimental findings regarding reaction temperature. The robust synthetic capacity of the photoredox Cadogan reaction systems has been demonstrated by the viable productivity of a broad range of carbazoles and related N-heterocycles with good tolerance of various functionalities.
Bimetallic nanoparticles modified hollow-structured nanoporous carbons (NPCs) have been fabricated via a convenient one-step carbonizing strategy derived from covalent organic framework. The Pd/Fe/NPCs, Pt/Fe/NPCs and Rh/Fe/NPCs were obtained and can be used as Fenton-like catalysts with good stability and reusability. The catalytic activity was evaluated by the degradation of 2, 4-dichlorophenl (2, 4-DCP). These fabricated bimetallic catalysts exhibited much higher catalytic activity than Fe/NPCs at room temperature. The enhancement of catalytic ability was benefited from synergetic catalytic effect of bimetallic nanoparticles and accelerated mass transfer of hollow structure. Additionally, the enhanced catalytic mechanism of bimetallic catalysts was studied in detail and the reasonable reaction pathway was proposed. Besides, the bimetallic catalysts were successfully used for degradation of 2, 4-DCP in actual industrial wastewater and the removal efficiency could reach 74.3% within 120 min, which demonstrated the promising potential application of bimetallic catalysts in the removal of pollutants in environment.
Gold nanovesicles (GVs) with unique plasmonic property and large cavity hold great potential as a stimuli-responsive nanocarrier to deliver drugs for efficient tumor chemotherapy and other therapies synergistically. Herein, we developed doxorubicin-loaded gold nanovesicles (DGVs), offering infrared thermal (IRT) and photoacoustic (PA) dual-modal imaging guided mild hyperthermia-enhanced chemo-photothermal cancer synergistic therapy. The DGVs are self-assembled by gold nanoparticles modified with amphiphilic copolymer in a predetermined concentration of doxorubicin through film rehydration method. Under the influence of laser excitation, the as-prepared DGVs exhibited good photothermal effect, which triggered the structural disruption of GVs and thus, allowed the efficient release of encapsulated DOX to enhance cell uptake for fluorescence imaging and tumor chemotherapy, respectively. In addition, DGVs also showed a strong PA and IRT signals in vivo. Our study demonstrated the potential of DGVs as stimuli-responsive drug delivery systems and cancer theranostics.
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