Latest ArticlesA general, facile and eco-friendly iron catalysis enables oxidation of unstrained tertiary aromatic alcohols to ketones through C−C bond cleavage even with H2O2 as the oxidant. Notably, this transformation can tolerate oxidation-labile functional groups. The robustness of this method is further demonstrated on the late-stage oxidation of complex bioactive molecules.
The rapid and precise fabrication of multiscale supramolecular assemblies using micro/nanofluidic techniques has emerged as a dynamic area of research in supramolecular chemistry, materials chemistry, and organic chemistry. This review summarizes the application of micro/nanofluidic techniques in constructing supramolecular assemblies, including nanoscale supramolecular assemblies such as macrocycles and cages, microscale supramolecular assemblies such as metal organic frameworks (MOFs) and covalent organic frameworks (COFs), and macroscale supramolecular assemblies such as supramolecular hydrogels. Compared to conventional synthesis methods, micro/nanofluidic techniques for the production of supramolecular assemblies have significant advantages, including enhanced safety, high reaction rates, improved selectivity/yield, and scalability. Additionally, micro/nanofluidic systems facilitate the creation of precisely controllable micro/nanoconfined environments, allowing for a unique flow behavior that improves our understanding of the supramolecular self-assembly process. Such systems may also lead to the development of novel supramolecular assemblies that differ from those generated via traditional methods.
Droplet manipulation on an open surface has great potential in chemical analysis and biomedicine engineering. However, most of the reported platforms designed for the manipulation of water droplets cannot thoroughly solve the problem of droplet evaporation. Herein, we report a shape-reconfigurable micropillar array chip for the manipulation of water droplets, oil droplets and water-in-oil droplets. Water-in-oil droplets provide an enclosed space for water droplets, preventing the evaporation in an open environment. Perfluoropolyether coated on the surface of the chip effectively reduces the droplet movement resistance. The micropillar array chip has light and magnetic dual-response due to the Fe3O4 nanoparticles and the reduced iron powder mixed in the shape-memory polymer. The micropillars irradiated by a near-infrared laser bend under the magnetic force, while the unirradiated micropillars still keep their original shape. In the absence of a magnetic field, when the micropillars in a temporary shape are irradiated by the near-infrared laser to the transition temperature, the micropillars return to their initial shape. In this process, the surface morphology gradient caused by the deformation of the micropillars and the surface tension gradient caused by the temperature change jointly produce the driving force of droplet movement.
Folding of molecules is an essential process in nature, and various molecular machines achieve their chemical and mechanical function via controlled folding of molecular conformations. The electric field offers a unique strategy to drive the folding of molecular conformation and to control charge transport through single molecules but remains unexplored. The single-molecule break junction technique provides access to detect the conformational changes via the monitoring of single-molecule conductance, and the electric field between two metal electrodes with nanoscale spacing can provide an extremely strong to achieve in-situ control and detection of molecular folding at the single-molecule level. Here, we use the electric field to control the single-molecule folding using the scanning tunneling microscope break junction (STM-BJ) technique. The electric fields induced folding could lead to a ~1400% conductance change of the single-molecule junctions, and the folding/unfolding process can be in-situ switched at the scale of milliseconds. DFT calculations suggest the conformational control originates from the electric field-induced charge injection, and the formation of homoconjugated conformation with the overlapped orbitals. This work provides the first demonstration of electric field-driven molecular folding, which is essential for the understanding of molecular machines in nature and for the design of artificial molecular machines.
The chemoselective hydrogenation of structurally diverse nitroaromatics is a challenging process. Generally, catalyst activity tends to decrease when excellent selectivity is guaranteed. We here present a novel photocatalyst combining amino-functionalized carbon dots (N-CDs) with copper selenite nanoparticles (N-CDs@CuSeO3) for simultaneously improving selectivity and activity. Under visible light irradiation, the prepared N-CDs@CuSeO3 exhibits 100% catalytic selectivity for the formation of 4-aminostyrene at full conversion of 4-nitrostyrene in aqueous solvent within a few minutes. Such excellent photocatalytic performance is mainly attributed to the precise control of the hydrogen species released from the ammonia borane by means of light-converted electrons upon N-CDs@CuSeO3. Besides, the defect states at the interface of N-CDs and CuSeO3 enable holes to be trapped for promoting separation and transfer of photogenerated charges, allowing more hydrogen species to participate in catalytic reaction.
As a new concept having emerged in last few years, the "deep eutectic solvents" (DESs) effect integrated into the imprinting technology inevitably exposes design limitations of stimuli-responsive molecularly imprinted polymers (MIPs), as well as inadequate analysis of the adsorption performance of MIPs. Herein, a simple yet defined N-isopropylacrylamide/(3-acrylamidopropyl) trimethylammonium chloride (NIPAM/APTMAC) binary DESs system was proposed to prepare intelligent MIPs with thermo-sensitivity. Accordingly, magnetic and thermo-responsive MIPs based on functional monomers-derived DESs (TM-DESs-MIPs1) were synthesized, revealing DESs effect-regulated affinity/kinetics for the enhanced adsorption capability, eco-friendly thermo-regulated elution for high release efficiency, and simple magnetic separation, along with superior selectivity to rhein (RH) and good regeneration ability. TM-DESs-MIPs1 were utilized to extract RH from Cassiae semen samples coupled with high performance liquid chromatography (HPLC), yielding satisfactory recoveries (79.47%−110.82%) and low limits of detection (LOD) (16.67 µg/L). Another two kinds of MIPs adopting the thermo-responsive moiety-derived DESs effect strategy further demonstrated great applicability of such intelligent MIPs for analyses of complicated samples.
Methane chemistry is one of the "Holy Grails of catalysis". It is highly desirable but challenge to transform methane into value-added chemicals, because of its high C-H bonding energy (435 kJ/mol), lack of π bonding or unpaired electrons. Currently, commercial methane conversion is usually carried out in harsh conditions with enormous energy input. Photocatalytic partial oxidation of methane to liquid oxygenates (PPOMO) is a future-oriented technology towards realizing high efficiency and high selectivity under mild conditions. The selection of oxidant is crucial to the PPOMO performance. Hence, attentions are paid to the research progress of PPOMO with various oxidants (O2, H2O, H2O2 and other oxidants). Moreover, the activation of the selected oxidants is also highly emphasized. Meanwhile, we summarized the methane activation mechanisms focusing on the C-H bond that was broken mainly by •OH radical, O− specie or photogenerated hole (h+). Finally, the challenges and prospects in this subject are briefly discussed.
NH3 in ambient air directly leads to an increase in the aerosol content in the air. These substances lead to the formation of haze to various environmental problems after atmospheric circulation and diffusion. Controlling NH3 emissions caused by ammonia escaping from mobile and industrial sources can effectively reduce the NH3 content in ambient air. Among the various NH3 removal methods, the selective catalytic oxygen method (NH3-SCO) is committed to oxidizing NH3 to environmentally harmless H2O and N2; therefore, it is the most valuable and ideal ammonia removal method. In this review, the characteristics of loaded and core-shell catalysts in NH3-SCO have been reviewed in the context of catalyst structure-activity relationships, and the H2O resistance and SO2 resistance of the catalysts are discussed in the context of practical application conditions. Then the effects of the valence state of the active center, oxygen species on the catalyst surface, dispersion of the active center and acidic sites on the catalyst performance are discussed comprehensively. Finally, the shortcomings of the existing catalysts are summarized and the catalyst development is discussed based on the existing studies.
Malignant tumors are the main diseases threatening human life. Using precise theranostics to diagnose and cure tumors has emerged as a new method to improve patient survival. Based on the current development of precise tumor imaging, image-guided tumor therapy has received widespread attention because it is beneficial for developing precise treatment of tumors, has the potential to improve the efficacy of tumor therapy and reduce the incidence of adverse side effects. Nanoprobes, which are nanomaterial functionalized with specific biomolecules, have intrigued intense interest due to their great potential in monitoring biorecognition and biodetection evens. Benefiting from the unique advantages of nanomaterials, including the easy surface functionalization, the unique imaging performances, and the high drug loading capacity, nanoprobes have become a powerful tool to simultaneously realize tumor precise imaging, diagnosis, and therapy. This review introduces the non-invasive tumor precise imaging and highlights the recent advances of image-guided oncotherapy mediated by nanoprobes in anti-tumor drug delivery, tumor precise surgical navigation, chemodynamic therapy, and phototherapy. Finally, a perspective on the challenge and future direction of nanoprobes in imaging-guided tumor theranostics is also discussed.
Aqueous zinc-ion batteries (AZIBs) have become a hotspot for electrochemical energy storage owing to the high safety, low cost, environmental friendliness, and favorable rate performance. However, the serious dissolution of cathode materials in aqueous electrolytes would lead to poor cyclability, which should be addressed before commercialization. Herein, we designed a Ti-doped V2O5 with yolk-shell microspherical structure for AZIBs. The Ti doping stabilizes the crystal structure and relieves the dissolution of V2O5 in aqueous ZnSO4 electrolyte. The optimized sample, Ti0.2V1.8O4.9, delivers a high capacity (355 mAh/g at 0.05 A/g) as well as good capacity retention (89% after 2500 cycles at 1.0 A/g). This work provides an effective strategy to mitigate the dissolution of cathode material in aqueous ZnSO4 electrolyte for cyclability enhancement.
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