Latest ArticlesMXenes, a new family of functional two-dimensional (2D) materials, have shown great potential for an extensive variety of applications within the last decade. Atomic defects and functional groups in MXenes are known to have a tremendous influence on the functional properties. In this review, we focus on recent progress in the characterization of atomic defects and functional group chemistry in MXenes, and how to control them to directly influence various properties (e.g., electron transport, Li+ adsorption, hydrogen evolution reaction (HER) activity, and magnetism) of 2D MXenes materials. Dynamic structural transformations such as oxidation and growth induced by atomic defects in MXenes are also discussed. The review thus provides perspectives on property optimization through atomic defect engineering, and bottom-up synthesis methods based on defect-assisted homoepitaxial growth of MXenes.
We report herein a new fluorescent probe for the selective recognition and determination of dodine among 20 different pesticides. This fluorescent probe was assembled through host-guest complexation between cucurbit[10]uril (Q[10]) and aminopropyl-1-pyrenebutanamide (PBA) and is designated as PBA@Q[10]. Addition of dodine to PBA@Q[10] results in a dramatic enhancement of fluorescence intensity at 390 nm, accompanied by fluorescence quenching at 488 nm. On this basis, the detection limit is 6.78×10-7 mol/L. The response mechanism is a competitive interaction: dodine occupies the cavity of Q[10] and forces PBA to leave.
Two sulfonated seco C20-diterpenoid alkaloids, aconapelsulfonines A (1) and B (2), were isolated from an aqueous extract of the raw material of "Fu Zi" (the Aconitum carmichaelii lateral roots), of which the structures were elucidated by various spectroscopic data, combined with X-ray crystallographic analysis. The unprecedented skeletons are biogenetically proposed to be derived via Criegee rearrangements of the napelline-type architecture. The two compounds exhibited dose-depended analgesic activities on an acetic acid-induced mice writhing test.
Recent advances in non-fullerene acceptors (NFAs), typically Y6, have driven power conversion efficiency (PCE) of single-junction organic solar cells (OSCs) over 16%. Meanwhile, it becomes essential to know how to adopt simple strategies to further improve device performance. In this work, a new A-DA'D-A acceptor derivative, Y19-N3 employing 3-ethylheptyl branched at the 3rd-position instead of 2-ethylhexyl on the pyrroles of Y19 is reported. The selection of an appropriate solvent in casting device is implemented to maximize the photovoltaic performance. PBDB-T: Y19-N3-based OSCs treated with a ternary solvent of CF/CB (1:3, v/v) and 0.8% DIO exhibit the optimal PCE of 13.77% here, with the significantly improved Voc (0.78 V) and FF (0.72) as well as the high Jsc (24.46 mA/cm2). Further characterizations indicate that this ternary solvent-treated PBDB-T/Y19-N3 film exhibits the more appropriate morphological features with the highly efficient charge generation and collection as well as the more balanced electron and hole mobilities. This work combines molecular design and device engineering to improve the photovoltaic properties, which is important to the development of OSCs.
Nickel- and palladium-catalyzed cross-coupling reactions have attracted wide attentions, while ligandcontrolled selectivity in these reactions are still elusive, and calculations can help obtain possible catalytic cycles to generate different products and provide insights into key factors of selectivity, which facilitates the development of new catalyst systems to control reaction selectivity. This review covers our efforts and some significant achievements from other groups on ligand-controlled reaction selectivity of coupling reactions, including introduction, computational methods, selectivity control by ligands in Ni- and Pd-catalyzed coupling reactions, as well as summary and future perspectives.
Caspases are a family of proteases that play critical roles in controlling inflammation and cell death. Apoptosis is a caspase-3 mainly controlled behavior to avoid inflammation and damage to surrounding cells, whereas anomalistic cell apoptosis may be associated with many diseases. The detection and imaging of caspase-3 will be of great significance in evaluating the early therapeutic effect of tumors. Developing smart fluorescent probes may be helpful for the visualization of therapeutic effect compared with palways onq probes. Thus, more and more works toward activatable fluorescent probes for caspase-3 imaging have been reported. In addition, multifunctional probes have also been designed to further improve the imaging of caspase-3. Herein, this review systematically summarized the representative work of caspase-3 from the perspective of molecular design that it will play a guiding role in the design of probes that respond to caspase-3. Also, challenges and perspectives toward the field for imaging of cell apoptosis (caspase-3) are also discussed.
Highly efficient Co3O4/TiO2 monolithic catalysts with enhanced stability were in-situ grown on Ti mesh for CO oxidation, which could completely oxidize CO at 120 ℃. The comprehensive catalytic performance is competitive to some noble metal catalysts and conventional Co3O4 powder catalysts, which holds great potential toward industrial applications. Meanwhile, the in-situ synthesis strategy of Co3O4/TiO2 monolithic catalysts on flexible mesh substrate in this work can be extended to the development of a variety of oxide-based monolithic catalysts towards diverse catalysis applications.
A cascade carbonylative ring expansion and [2 + 2]/[4 + 2] cycloaddition of strained 1-iminylphosphirane complexes with aryl allenes were reported. The carbonylative ring expansion of 1-iminylphosphirane complexes provides an azaphosphacyclohexone complex intermediate with a C＝P double bond. The following [2 + 2] or dearomatic [4 + 2] cycloaddition of this intermediate with allenes is modulated by the aryl substituents on the imino carbon. The regioselective [2 + 2] cycloaddition with 1, 1-diarylallene provides an entry to bicyclo[4.2.0]octan-4-one skeletons featuring a four-membered phosphacyclobu-tane moiety. While dearomatic [4 + 2] cycloaddition was preferred with less aromatic naphthalene and yielded octahydrochrysene skeleton containing heteroatoms.
S-Monofluoromethyl phosphorothioates represent an important class of organofluorine compounds and are reported here for the first time. A series of S-monofluoromethyl phosphorothioates are conveniently synthesized from different PV-H compounds and PhSO2SCH2F under mild conditions. The method is compatible with common functional groups and provides potential opportunities to synthesize new bioactive molecules for medicinal chemistry.
Metal-nitrogen-carbon materials (M-N-C) are non-noble-metal-based alternatives to platinum-based catalysts and have attracted tremendous attention due to their low-cost, high abundance, and efficient catalytic performance towards the oxygen reduction reaction (ORR). Among them, Fe-based materials show remarkable ORR activity, but they are limited by low selectivity and low stability. To address these issues, herein, we have synthesized FeCu-based M-N-C catalysts, inspired by the bimetal center of cytochrome c oxidase (CcO). In acidic media, the selectivity was notably improved compared with Fe-based materials, with peroxide yields less than 1.2% (< 1/3 of the hydrogen peroxide yields of Fe-N-C catalysts). In addition to Cu-N-C catalysts which can catalytically reduce hydrogen peroxide, the reduction current of hydrogen peroxide using FeCu-N-C-20 exceeded that of Fe-N-C by about 6% when the potential was greater than 0.4 V. Furthermore, FeCu-based M-N-C catalysts suffered from only a 15 mV attenuation in their half-wave potentials after 10, 000 cycles of accelerated degradation tests (ADT), while there was a 30 mV negative shift for Fe-N-C. Therefore, we propose that the H2O2 released from Fe-Nx sites or N-doped carbon sites would be reduced by adjacent Cu-Nx sites, resulting in low H2O2 yields and high stability.
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