Latest ArticlesTrifluoromethylation/sulfonylation of alkynes from trifluoromethyl thianthrenium triflate and sulfur dioxide under extremely mild reaction conditions provides a facile access to trifluoromethyl-substituted vinyl sulfonohydrazides in moderate to good yields. This multicomponent reaction of trifluoromethyl thianthrenium triflate, alkynes, sulfur dioxide and hydrazines proceeds efficiently under visible light irradiation in the presence of photocatalyst at room temperature with broad substrate scope and excellent functional group compatibility. This reaction is highly stereoselective, and only (E)-isomers are obtained. Additionally, these trifluoromethyl-substituted vinyl sulfonohydrazides are further evaluated for anti-bacteria activity. In vitro activities of these compounds against Staphylococcus aureus (G+) and Escherichia coli (G−) are examined.
Artificial photosynthesis of valuable chemicals from CO2 is a potential way to achieve sustainable carbon cycle. The CO2 conversion activity is still inhibited by the sluggish charge kinetics and poor CO2 activation. Herein, Ag nanoparticles coupled BiOBr have been constructed by in-situ photoreduction strategy. The crafting of interface between Ag nanoparticles and BiOBr nanosheets, achieving an ultra-fast charge transfer. The BiOBr semiconductor excited electrons and plasmonic Ag nanoparticles generated high-energy hot electrons synchronous accelerates the C=O double bond activation. Thus, the optimized Ag/BiOBr-2 heterostructure shows excellent CO2 photoreduction activity with CO production of 133.75 and 6.83 µmol/g under 5 h of 300 W Xe lamp and visible light (λ > 400 nm) irradiation, which is 1.51 and 2.81 folds versus the pristine BiOBr, respectively. The mechanism of CO2 photoreduction was in-depth understood through in-situ FT-IR spectrum and density functional theory calculations. This study provides some new perspectives into efficient photocatalytic CO2 reduction.
A facile and elegant method for synthesis of novel N–aryl phenothiazine derivatives from 2-phenylindolizines and phenothiazines through direct electrochemical oxidation has been developed. This approach was performed smoothly at room temperature without external oxidant and catalyst. Cyclic voltammetry and in situ FTIR techniques were applied to analyze the cross-coupling process of phenothiazines and 2-phenylindolizines, which helped to select the appropriate reaction potential. Under the optimized conditions, a broad range of substrates were well tolerated, affording the desired products in moderate to excellent isolated yields (up to 91%) with high regioselectivity. Meanwhile, a plausible mechanism involving a radical pathway has been proposed.
Diketopyrrolopyrrole (DPP) and related derivatives have drawn great attention due to their applications in organic optical /electronic materials. Progress in these materials is associated with developments in the syntheses of the DPP family. Chemical modification of DPP at nitrogen atom, including N-alkylation and N-arylation, is an effective strategy to improve its physical and chemical properties, such as solubility, optical and semiconducting properties. However, N-arylation of DPPs remains challenging compared to the easily accessible N-alkylation. Herein, the synthesis of N-aryl DPP derivatives and correlated π-expanded DPPs are summarized, and their optical/electronic properties are introduced. The future perspectives of N-aryl DPP derivatives are also discussed.
Nitrate (NO3−) is widely found in wastewater, which is harmful to human health and water environmental. Electrochemical reduction can convert NO3− to high value-added ammonia (NH3)/ammonium (NH4+) for pollutant removal and resource recovery. Currently, electrochemical nitrate reduction to produce ammonia (ENRA) is mostly focused on the preparation of high-performance catalysts, while ignoring the prerequisite for industrial application as the stable operation and optimal regulation of the process. Therefore, the review focused on wastewater treatment, based on the mechanism of electrochemical nitrate reduction for ammonia production and reactor construction (reactor, power supply system), then summarized the operation control strategies (such as reduction potential, nitrate concentration, inorganic ions, pH) that should be noted for ENRA. Finally, the challenges (system structure, economy) and prospects (ammonia recovery process, construction of large-scale ENRA system, application of real wastewater) of the field as it moves towards commercialization were discussed. It is hoped that this review will facilitate the scaling up of ENRA in the wastewater treatment field.
Two-dimensional electride Ca2N has strong electron transfer ability and low work function, which is a potential candidate for hydrogen evolution reaction (HER) catalyst. In this work, based on density functional theory calculations, we adopt two strategies to improve the HER catalytic activity of Ca2N monolayer: introducing Ca or N vacancy and doping transition metal atoms (TM, refers to Ti, V, Cr, Mn, Fe, Zr, Nb, Mo, Ru, Hf, Ta and W). Interestingly, the Gibbs free energy ΔGH* of Ca2N monolayer after introducing N vacancy is reduced to -0.146 eV, showing good HER catalytic activity. It is highlighted that, the HER catalytic activity of Ca2N monolayer can be further enhanced with TM doping, the Gibbs free energy ΔGH* of single Mo and double Mn doped Ca2N are predicted to be 0.119 and 0.139 eV, respectively. The present results will provide good theoretical guidance for the HER catalysis applications of two-dimensional electride Ca2N monolayer.
By introducing a naphthothiadiazole (NT) unit as the main building block, a non-doped and red emissive conjugated polymer poly(9,9-dihexylfluorene-alt-naphthothiadiazole) (PFNT) is readily obtained through a two-step synthesis. Since the NT unit has a large twist angle with its neighboring segment, the aggregation-induced quenching (AIQ) effect of PFNT can be effectively suppressed in the condensed state. As a result, the corresponding PFNT polymer dot (Pdot) exhibits a high fluorescence quantum yield of 53.2% with peak emission at 616 nm, which is one of the most efficient red Pdots known. PFNT Pdot shows good biocompatibility and can be employed for living cell fluorescent imaging with high brightness. It also can be used for specific subcellular organelle imaging through immunofluorescence labeling. Furthermore, the PFNT Pdot demonstrates much better photostability for long-time cell fluorescence imaging than commercial red dyes. The high performances of PFNT Pdot make it a promising fluorescent probe for practical bioapplications.
Herein we report a covalent cage TPE-Zn4 based on a tetraphenylethylene molecule via subcomponent self-assembly, which is templated by zinc ions. TPE-Zn4 features a quadrangular prismatic cage structure, which is characterized by NMR, mass spectrum, and single-crystal X-ray diffractions. TPE-Zn4 emitted orange fluorescence (λem = 620 nm) in DMSO solution under the irradiation of UV light (λex = 395 nm) and can be applied as a fluorescence sensor for selectively detecting Pd2+. The fluorescence of TPE-Zn4 was quenched by Pd2+ in DMSO solution, and a very low detection limit of 62.3 nM was achieved. Mechanism studies reveal that the Pd2+ can replace the Zn2+, and the heavy atom effect and chelation-enhanced quenching effect between the Pd2+ and the cage probably cause the fluorescence quenching.
Glioma is a malignant primary brain tumor that is extremely harmful to human beings. Therefore, studying the invasiveness of glioma cells is of great significance for the diagnosis and treatment of glioma. In this work, TiO2/Nb2C was prepared as a SERS substrate and combined with microfluidic chip to construct an invasion model capable of monitoring glioma invasion in real time. Both experimental data and density function theory (DFT) calculations showed that the significant SERS-enhancing effect of TiO2/Nb2C on methylene blue (MB) originated from the chemical magnification (CM) mechanism when MB was used as the adsorbed molecule. Based on this, we achieved a highly sensitive and targeted detection of vascular endothelial growth factor (VEGF), a biomarker for glioma with a low detection limit of 3.7 pg/mL, then quantified the invasive process in real time by detecting VEGF. Meanwhile, the depletion of reactive oxygen species (ROS) by TiO2/Nb2C can inhibit the invasion of glioma cells. For the first time, the invasion model combines SERS technology with microfluidic technology, while monitoring the cell invasion process in real time, the invasion process can be quantified by detecting the VEGF secreted by glioma cells during the invasion process, realizing the integration of diagnosis and treatment, and establish a new model for the biomedical analysis, clinical diagnosis and treatment of glioma.
The application of metal-organic frameworks (MOFs) nanozymes in biosensing has been extensively investigated, however, till now there is still no report on photoelectrochemical (PEC) sensing based on enzyme memetic properties of MOFs. To further expand the utilization of MOFs nanozymes in biosensing, we developed a label-free homogenous PEC aptasensor for the detection of VEGF165, an important cancer biomarker, based on the DNA-regulated peroxidase-mimetic activity of Fe-MIL-88, a type of MOFs. In this strategy, the peroxidase-mimetic property of MOFs is integrated with the label-free homogeneous PEC sensing approach, and highly sensitive detection of VEGF165 is obtained with a detection limit down to 33 fg/mL, superior or comparable to the previously reported values. Moreover, this approach displays outstanding specificity, and has been successfully used to detect VEGF165 added in diluted serum samples. As far as we know, it is the first example to employ the peroxidase-like activity of MOFs in PEC biosensing, which may find potential application in bioanalysis and early disease diagnosis.
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