Latest ArticlesA facile and metal-free visible-light-enabled three-component reaction of quinoxalin-2(1H)-ones, alkenes and CF3SO2Na has been developed under air at room temperature. This photocatalytic tandem reaction using 4CzIPN as the photocatalyst and air as the green oxidant, provides a mild and environmentally friendly approach to access a series of 3-trifluoroalkylated quinoxalin-2(1H)-ones.
A high efficiency and low toxicity radiosensitizer, OsN(PhenOH)Cl3, was designed and synthesized through substituent regulation. To the best of our knowledge, this is the first osmium-based coordination complex radiosensitizer. The experimental results shown that this radiosensitizer induced G2/M cell cycle arrest mainly through induction of intracellular ROS overproduction.
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.
Oxygen evolution reaction (OER) is admitted to an important half reaction in water splitting for sustainable hydrogen production. The sluggish four-electron process is known to be the bottleneck for enhancing the efficiency of OER. In this regard, tremendous efforts have been devoted to developing effective catalysts for OER. In addition to Ir- or Ru-based oxides taken as the benchmark, transition metal carbides have attracted ever-increasing interest due to the high activity and stability as low-cost OER electrocatalysts. In this review, the transition metal carbides for water oxidation electrocatalysis concerning design strategies and synthesis are briefly summarized. Some typical applications for various carbides are also highlighted. Besides, the development trends and outlook are also discussed.
As a novel family of macrocyclic molecules, cucurbit[n]urils (CB[n]s) have emerged as promising building blocks of supramolecular nano drug delivery systems (SNDDS) in recent years. Direct encapsulation of amphiphilic guests by CB[6] and CB[7] can modulate their amphiphilicity, resulting in formation of supramolecular amphiphiles that self-assemble into supramolecular nanoparticles for drug delivery. Additionally, CB[n]'s host-guest chemistry on the surface of mesoporous nanoparticles makes CB[n] an ideal blocking agent to control drug release from delivery vehicles. These SNDDS possess intrinsic stimuli responsiveness towards external guest or host, which can further incorporate responsiveness to a variety of other stimuli including pH, thermal, redox, photo and enzyme, to realize multiple stimuli-responsive drug release. Moreover, the recent breakthrough in direct functionalization of CB[n]s has provided a feasible method for preparing superior CB[6] and CB[7] derivatives that can be employed to build multifunctional SNDDS with unoccupied macrocycles located on surface, which could be decorated with various functional "tags" through host-guest chemistry. In this review, we summarized the recent progress of CB[6] and CB[7] based SNDDS through formation of supramolecular amphiphiles, supramolecular nanovalves as well as supramolecularly tailorable surface, which we hope to further promote the development of CB[n]s family as building blocks for advanced SNDDS.
Metal-free direct α-C(sp3)—H intramolecular cyclization of 2-alkylthiobenzoic acid in the presence of Selectfluor is described. This novel strategy provides a facile and efficient method to access important 1, 3-benzooxathiin-4-one derivatives with good functional groups tolerance and yields.
A Si-substituted rhodamine based water-soluble fluorescent probe bearing a tetrathia-azacrown was designed for fluorescence imaging of Cu+ with substantial affinity and selectivity. In physiological condition, the developed probe with outstanding water-solubility exhibits ultrahigh sensitivity to Cu+, ensuring the reliable fluorescence imaging in vivo.
For bone regenerative engineering, it is a promising method to form skeletal tissues differentiating from human bone morrow mesenchyme stem cells (hBMSCs). However, it is still a critical challenge to efficiently control ostogenesis and clearly reveal the influence factor. To this end, the fluorescent gold nanodots (Au NDs) with highly negative charges as osteogenic induction reagent are successfully synthesized, which display better than commercial osteogenic induction medium through the investigations of ALP activity (2.5 folds) and cytoskeleton staining (1.5 folds). Two kinds of oligopeptides with different bio-structures (cysteine, Cys and glutathione, GSH) are selected for providing surficial charges on Au NDs. It is revealed that Au-Cys with more negative charges (-51 mV) play better role than Au-GSH (-19 mV) in osteogenic differentiation, when both of them have same size (~2 nm), sphere shape and show similar cell uptake amount. To explore deeply, osteogenesis related signaling pathways are monitored, revealing that the enhancement of osteogenic differentiation was through autophagy signaling pathway triggered by Au-Cys. And the promotion of highly negative charges in osteogenic differentiation was further proved via sliver nanodots (Ag NDs, Ag-Cys and Ag-GSH) and carbon nanodots (CDs, Cys-CDs and GSH-CDs). This work indicates part of insights during hBMSCs differentiation and provides a novel strategy in osteogenic differentiation process.
Porous carbon spheres represent an ideal family of electrode materials for supercapacitors because of the high surface area, ideal conductivity, negligible aggregation, and ability to achieve space efficient packing. However, the development of new synthetic methods towards porous carbon spheres still remains a great challenge. Herein, N-doped hollow carbon spheres with an ultrahigh surface area of 2044 m2/g have been designed based on the phenylenediamine-formaldehyde chemistry. When applied in symmetric supercapacitors with ionic electrolyte (EMIBF4), the obtained N-doped hollow carbon spheres demonstrate a high capacitance of 234 F/g, affording an ultrahigh energy density of 114.8 Wh/kg. Excellent cycling stability has also been achieved. The impressive capacitive performances make the phenylenediamine-formaldehyde resin derived N-doped carbon a promising candidate electrode material for supercapacitors.
Low-cost silicon microparticles (SiMP), as a substitute for nanostructured silicon, easily suffer from cracks and fractured during the electrochemical cycle. A novel n-type conductive polymer binder with excellent electronic and ionic conductivities as well as good adhesion, has been successfully designed and applied for high-performance SiMP anodes in lithium-ion batteries to address this problem. Its unique features are attributed to the strong electron-withdrawing oxadiazole ring structure with sulfonate polar groups. The combination of rigid and flexible components in the polymer ensures its good mechanical strength and ductility, which is beneficial to suppress the expansion and contraction of SiMP s during the charge/discharge process. By fine-tuning the monomer ratio, the conjugation and sulfonation degrees of the polymer can be precisely controlled to regulate its ionic and electronic conductivities, which has been systematically analyzed with the help of an electrochemical test method, filling in the gap on the conductivity measurement of the polymer in the doping state. The experimental results indicate that the cell with the developed n-type polymer binder and SiMP (~0.5 μm) anodes achieves much better cycling performance than traditional non-conductive binders. It has been considered that the initial capacity of the SiMP anode is controlled by the synergetic effect of ionic and electronic conductivity of the binder, and the capacity retention mainly depends on its electronic conductivity when the ionic conductivity is sufficient. It is worth noting that the fundamental research of this work is also applicable to other battery systems using conductive polymers in order to achieve high energy density, broadening their practical applications.