Unique Electron-Transfer-Mediated Electrochemiluminescence of AuPt Bimetallic Nanoclusters and the Application in Cancer Immunoassay.

Noble Metal nanoclusters (NCs) are promising electrochemiluminescence (ECL) emitters due to their amazing optical properties and excellent biocompatibility. They have been widely used in the detection of ions, pollutant molecules, biomolecules, etc. Herein, we found that glutathione-capped AuPt bimetallic NCs (GSH-AuPt NCs) emitted strong anodic ECL signals with triethylamine as co-reactants which had no fluorescence (FL) response. Due to the synergistic effect of bimetallic structures, the ECL signals of AuPt NCs were 6.8 and 94 times higher than those of monometallic Au and Pt NCs, respectively. The electric and optical properties of GSH-AuPt NCs differed from those of Au and Pt NCs completely. An electron-transfer mediated ECL mechanism was proposed. The excited electrons may be neutralized by Pt(II) in GSH-Pt and GSH-AuPt NCs, resulting in the vanished FL. Furthermore, abundant TEA radicals formed on the anode contributed electrons to the highest unoccupied molecular orbital of GSH-Au2.5Pt NCs and Pt(II), booming intense ECL signals. Because of the ligand effect and ensemble effect, bimetallic AuPt NCs exhibited much stronger ECL than GSH-Au NCs. A sandwich-type immunoassay for alpha fetoprotein (AFP) cancer biomarkers was fabricated with GSH-AuPt NCs as signal tags, which displayed a wide linear range from 0.01 to 1000 ng·mL-1 and a limit of detection (LOD) down to 1.0 pg·mL-1 at 3S/N. Compared to previous ECL AFP immunoassays, this method not only had a wider linear range but also a lower LOD. The recoveries of AFP in human serum were around 108%, providing a wonderful strategy for fast, sensitive, and accurate cancer diagnosis.

2-Hydroxypropyl Group Linked Derivatives of Indole Azoles as Potential Multifunctional Antibacterial Candidates for Effectively Inhibiting the Activity of MRSA and Responding Inflammatory Factors.

The increasing resistance of methicillin-resistant Staphylococcus aureus (MRSA) to antibiotics has led to escalating efforts to design and synthesize new structural agents with significant antimicrobial potential. A novel class of 2-hydroxypropyl group linked derivatives of indole azoles was developed as potential antibacterial agents. Bioactivity screening results demonstrated that metronidazole-modified indole derivative 4 a had excellent antibacterial capacity against MRSA (MIC=6 µM), which was about 4 times that of norfloxacin (MIC=25 µM). Highly active hybrid 4 a did not cause obvious drug-resistance in MRSA after multiple generations (15 passage operations). Compound 4 a showed low toxicity to normal mammalian cells (RAW 264.7). Molecular docking and molecular electrostatic potential (MEP) surface studies were used to map hydrogen bond interactions and the electron distribution in the highly active compounds. In addition, the preliminary exploration of the antibacterial mechanism revealed that the active molecule 4 a could infiltrate the membrane of MRSA and insert into MRSA DNA to prevent its replication, thus activating strong inhibition of the bacteria. Furthermore, highly active derivative 4 a could better respond to inflammatory factors (IL-6, IL-10, TNF-α and PGE-2), and it is less likely to cause inflammatory complications, hence diversifying the functions of antibacterial candidate molecules. These findings effectively indicate the potential of the bioactive hybrid 4 a as a multifunctional anti-MRSA agent. Further exploration of the development of antimicrobials combining these kinds of 2-hydroxypropyl group linked indole derivatives is of great value.

Molten salt synthesis of NiCo-NiCo2O4@C nanotubes as anode materials for Li-ion batteries.

The construction of carbon-encapsulated transition metal nanotube structures is a preferred method that can effectively slow down volume expansion, improve cycling stability and enhance the electrical conductivity of the reactive sites of lithium-ion batteries. In this study, nanotubes of carbon-coated NiCo-NiCo2O4 nanoparticles (NC-NCO@C) were prepared by a one-step molten salt method at high temperature using Ni and Co as catalytic centers and sodium acetate as carbon source. We used NC-NCO@C-2 nanotubes as anode materials for lithium-ion batteries(LIBs), which exhibited excellent lithium storage performance and good stability, with a specific capacity of 616.26 mAh g-1 after 1000 cycles at a high current density of 1 A g-1. In addition, NC-NCO@C-2 were used as anodes in lithium-ion full cells and LiFePO4 (LFP) was used as the cathode. The NC-NCO@C-2//LFP full-cell exhibits high capacity and good cycling stability, with a capacity of 100.7 mAh g-1 after 100 cycles and a capacity retention rate of 92%. The construction of NC, NCO, and carbon ternary complexes was found to activate and promote the reversible conversion of certain inorganic components at the solid electrolyte interfaces (SEI), which effectively reduced the volume change during cycling, increased the electrical conductivity, and improved the cycling stability of the electrode. The proposed one-step molten salt synthesis of Carbon-coated metals complexes with excellent compatibility characteristics, is expected to solve the problem of volume change in transition metals, which is encountered in LIBs applications.

Discovery of a Thioxanthone-TfOH Complex as a Photoredox Catalyst for Hydrogenation of Alkenes Using p-Xylene as both Electron and Hydrogen Sources.

Hydrogenation of alkenes is one of the most fundamental transformations in organic synthesis, and widely used in the petrochemical, pharmaceutical, and food industries. Although numerous hydrogenation methods have been developed, novel types of catalysis with new mechanisms and new hydrogen sources are still desirable. Thioxanthone (TX) is widely used in energy-transfer photoreactions, but rarely in photoredox processes. Herein we show that a catalytic amount of TfOH as a co-catalyst can tune the properties of TX to make it a photoredox catalyst with highly enhanced oxidative capability in the hydrogenation of carbonylated alkenes with the cheap petroleum industrial product p-xylene serving as the hydrogen source. Deuterium can also be introduced by this method by using D2 O as the D source. To the best of our knowledge, this is the first example of using p-xylene as a hydrogen source.

Potential antibacterial ethanol-bridged purine azole hybrids as dual-targeting inhibitors of MRSA.

A new class of antibacterial ethanol-bridged purine azole hybrids as potential dual-targeting inhibitors was developed. Bioactivity evaluation showed that some of the target compounds had prominent antibacterial activity against the tested bacteria, notably, metronidazole hybrid 3a displayed significant inhibitory activity against MRSA (MIC = 6 µM), and had no obvious toxicity on normal mammalian cells (RAW 264.7). In addition, compound 3a also did not induce drug resistance of MRSA obviously, even after fifteen passages. Molecular modeling studies showed that the highly active molecule 3a could insert into the base pairs of topoisomerase IA-DNA as well as topoisomerase IV-DNA through hydrogen bonding. Furthermore, a preliminary study on the antibacterial mechanism revealed that the active molecule 3a could rupture the bacterial membrane of MRSA and insert into MRSA DNA to block its replication, thus possibly exhibiting strong antibacterial activity. These results strongly indicated that the highly active hybrid 3a could be used as a potential dual-targeting inhibitor of MRSA for further development of valuable antimicrobials.

Novel chalcone-conjugated, multi-flexible end-group coumarin thiazole hybrids as potential antibacterial repressors against methicillin-resistant Staphylococcus aureus.

The increasing resistance of methicillin-resistant Staphylococcus aureus (MRSA) to antibiotics has led to a growing effort to design and synthesize novel structural candidates of chalcone-conjugated, multi-flexible end-group coumarin thiazole hybrids with outstanding bacteriostatic potential. Bioactivity screening showed that hybrid 5i, which was modified with methoxybenzene, exerted a significant inhibitory activity against MRSA (MIC = 0.004 mM), which was 6 times better than the anti-MRSA activity of the reference drug norfloxacin (MIC = 0.025 mM). Compound 5i neither conferred apparent resistance onto MRSA strains even after multiple passages nor triggered evident toxicity to human hepatocyte LO2 cells and normal mammalian cells (RAW 264.7). Molecular docking showed that highly active molecule 5i might bind to DNA gyrase by forming stable hydrogen bonds. In addition, molecular electrostatic potential surfaces were developed to explain the high antibacterial activity of the target compounds. Furthermore, preliminary mechanism studies suggested that hybrid 5i could disrupt the bacterial membrane of MRSA and insert itself into MRSA DNA to impede its replication, thus possibly becoming a potential antibacterial repressor against MRSA.

Visible Light-Induced Pericyclic Cascade Reaction for the Synthesis of Quinolinone Derivatives with an Oxabicyclo[4.2.0]octene Skeleton.

A photoinduced pericyclic cascade reaction has been developed to afford oxabicyclo[4.2.0]octenes. Mechanistic studies show that this reaction undergoes [2 + 2]-photocycloaddition, base-promoted elimination, retro-4π-electrocyclization, [1,5]-H shift, and 4π-electrocyclization procedures. This reaction features wide substrate scope, good functional group tolerance, and excellent diastereoselectivity.

Novel Schiff base-bridged multi-component sulfonamide imidazole hybrids as potentially highly selective DNA-targeting membrane active repressors against methicillin-resistant Staphylococcus aureus.

A new type of Schiff base-bridged multi-component sulfonamide imidazole hybrids with antimicrobial potential was developed. Some target compounds showed significant antibacterial potency. Observably, butylene hybrids 4h exhibited remarkable inhibitory efficacy against clinical MRSA (MIC = 1 µg/mL), but had no significant toxic effect on normal mammalian cells (RAW 264.7). The highly active molecule 4h was revealed by molecular modeling study that it could insert into the base-pairs of DNA hexamer duplex and bind with the ASN-62 residue of human carbonic anhydrase isozyme II through hydrogen bonding. Furthermore, further preliminary antibacterial mechanism experiments confirmed that compound 4h could effectively interfere with MRSA membrane and insert into bacterial DNA isolated from clinical MRSA strains through non-covalent bonding to produce a supramolecular complex, thus exerting its strong antibacterial efficacy by impeding DNA replication. These findings strongly implied that the highly active hybrid 4h could be used as a potential DNA-targeting template for the development of valuable antimicrobial agent.

Light-enabled, AlCl3-catalyzed regioselective intramolecular nucleophilic addition of non-nucleophilic alkyls to alkynes.

Light-enabled, AlCl3-catalyzed regioselective intramolecular nucleophilic cyclization of alkynes using non-nucleophilic alkyls as the nucleophile is reported. Upon photoexcitation, o-alkylphenyl alkynyl ketones can be transferred into (E)-photoenols. Thus, a nucleophilic methylene is formed from the non-nucleophilic alkyl. An AlCl3 catalyst can stabilize the (E)-photoenol intermediate and facilitate further intramolecular nucleophilic cyclization. DFT calculations indicated that the AlCl3-catalyzed cyclization is the regioselectivity determining step.

Visible-Light-Induced Dehydrohalogenative Coupling for Intramolecular α-Alkenylation: A Way to Build Seven- and Eight-Membered Rings.

A visible-light-induced intramolecular α-alkenylation has been developed via metal-free dehydrohalogenative C(sp2)-C(sp2) coupling reaction to afford seven- and eight-membered rings. Extensive mechanistic studies prove that this reaction proceeds through a [2 + 2]-photocycloaddition, elimination, and retro-[2 + 2]-photocycloaddition process, with cyclobutane and cyclobutene being involved as key intermediates. This transformation is broadly applicable and highly stereoselective, yielding exclusively cyclic (1Z,3Z)-1,3-diene via photochemically allowed disrotation. This protocol excavates new applications of [2 + 2]-photocycloadditions, which may find their way in future olefin-olefin coupling reactions and medium-sized ring synthesis.

An intrinsically stretchable and compressible Zn-air battery.

An intrinsically highly stretchable and compressible Zn-air rechargeable battery with good electrochemical performance was fabricated for the first time. It exhibits the merits of 300% intrinsic stretchability and 85% intrinsic compressibility with excellently retained electrochemical performance, a decrease in catalyst cost of 40 times, the fewest number of components and facile fabrication.

Sensitive Detection of Caffeic Acid and Rutin via the Enhanced Anodic Electrochemiluminescence Signal of Luminol.

The electrooxidation of phenolic groups of caffeic acid and rutin promote anodic electrochemiluminescence (ECL) luminol substantially. A sensitive, and cost-effective ECL method has thus been developed to detect caffeic acid, ranging from 0.1 to 5.0 µM, with a detection limit of 0.1 µM and rutin ranging from 0.2 to 25 µM with a detection limit of 0.12 µM. Contrarily, phenolic compounds quench the weak cathodic ECL of luminol. Both of anodic and cathodic ECL mechanisms of luminol in the presence of phenolic compounds are analyzed. The method based on the boomed anodic ECL of luminol is comparable to those based on Ru(bpy)32+ and S2O82-/O2 systems. A lower onset potential and price than the other ECL reagents would realize its widely applications in the detection of phenolic compounds in food and medicine.

Synthesis and Properties of Azide-Functionalized Ionic Liquids as Attractive Hypergolic Fuels.

Hypergolic ionic liquids (ILs) have shown a great promise as viable replacements for toxic and volatile hydrazine derivatives used as propellant fuels, and hence, have attracted increasing interest over the last decade. To take advantage of the reactivity and high energy density of the azido group, a family of low-cost and easily prepared azide-functionalized cation-based ILs, including fuel-rich anions, such as nitrate, dicyanamide, and nitrocyanamide anions, were synthesized and characterized. All the dicyanamide- and nitrocyanamide-based ILs exhibited spontaneous combustion upon contact with 100 % HNO3 . The densities of these hypergolic ILs varied in the range 1.11-1.29 g cm-3 , and the density-specific impulse, predicted based on Gaussian 09 calculations, was between 289.9 and 344.9 s g cm-3 . The values of these two key physical properties are much higher than those of unsymmetrical dimethylhydrazine (UDMH). Among the studied compounds, compound IL-3b, that is, 1-(2-azidoethyl)-1-methylpyrrolidin-1-ium dicyanamide, shows excellent integrated properties including the lowest viscosity (30.9 M Pa s), wide liquid operating range (-70 to 205 °C), shortest ignition-delay time (7 ms) with 100 % HNO3 , and superior density specific impulse (302.5 s g cm-3 ), suggesting promising applications with potential as bipropellant formulations.

Facile in situ growth of ZnO nanosheets standing on Ni foam as binder-free anodes for lithium ion batteries.

ZnO has attracted increasing attention as an anode for lithium ion batteries. However, the application of such anode materials remains restricted by their poor conductivity and large volume changes during the charge/discharge process. Herein, we report a simple hydrothermal method to synthesize ZnO nanosheets with a large surface area standing on a Ni foam framework, which is applied as a binder-free anode for lithium ion batteries. ZnO nanosheets were grown in situ on Ni foam, resulting in enhanced conductivity and enough space to buffer the volume changes of the battery. The ZnO nanosheets@Ni foam anode showed a high specific capacity (1507 mA h g-1 at 0.2 A g-1), good capacity retention (1292 mA h g-1 after 45 cycles), and superior rate capacity, which are better than those of ZnO nanomaterial-based anodes reported previously. Moreover, other transition metal oxides, such as Fe2O3 and NiO were also formed in situ on Ni foam with perfect standing nanosheets structures by this hydrothermal method, confirming the universality and efficiency of this synthetic route.