High-Performance MnO2 Nanowire/MoS2 Nanosheet Composite for a Symmetrical Solid-State Supercapacitor.

To improve the production rate of MoS2 nanosheets as an excellent supercapacitor (SC) material and enhance the performance of the MoS2-based solid-state SC, a liquid phase exfoliation method is used to prepare MoS2 nanosheets on a large scale. Then, the MnO2 nanowire sample is synthesized by a one-step hydrothermal method to make a composite with the as-synthesized MoS2 nanosheets to achieve a better performance of the solid-state SC. The interaction between the MoS2 nanosheets and MnO2 nanowires produces a synergistic effect, resulting in a decent energy storage performance. For practical applications, all-solid-state SC devices are fabricated with different molar ratios of MoS2 nanosheets and MnO2 nanowires. From the experimental results, it can be seen that the synthesized nanocomposite with a 1:4 M ratio of MoS2 nanosheets and MnO2 nanowires exhibits a high Brunauer-Emmett-Teller surface area (∼118 m2/g), optimum pore size distribution, a specific capacitance value of 212 F/g at 0.8 A/g, an energy density of 29.5 W h/kg, and a power density of 1316 W/kg. Besides, cyclic charging-discharging and retention tests manifest significant cycling stability with 84.1% capacitive retention after completing 5000 rapid charge-discharge cycles. It is believed that this unique, symmetric, lightweight, solid-state SC device may help accomplish a scalable approach toward powering forthcoming portable energy storage applications.

Exploiting the umpolung reactivity of diazo groups: direct access to triazolyl-azaarenes from azaarenes.

The present work documents electrophilic substitution of azaarenes, mainly isoquinolines, with hypervalent iodine diazo reagents (HIDR) followed by formal [3+2]-dipolar cycloaddition in a tandem fashion. Other azaarenes viz. pyridines and phenanthridines too could be successfully used in the reaction. The methodology capitalizes on the umpolung nature of α-aryliodonio diazo compounds for installing a nucleophile, i.e. azaarene, at their α-position. Subsequent ylide formation and intramolecular 1,5-cyclization furnished 4,3-fused 1,2,4-triazolyl-azaarenes in good yields. The reaction is notable for its mild conditions, operational simplicity and fairly general scope.

Regioselective synthesis of functionalized pyrazole-chalcones via a base mediated reaction of diazo compounds with pyrylium salts.

A base-mediated reaction of triaryl/alkyl pyrylium tetrafluoroborate salts with α-diazo-phosphonates, sulfones and trifluoromethyl compounds affords the corresponding functionalized pyrazole-chalcones as 5-P-5 and 3-P-3 tautomeric mixture. The reaction proceeds through an initial nucleophilic addition of diazo substrates to pyrylium salts followed by a base-mediated pyrylium ring-opening and intramolecular 1,5-cyclization to afford formal 1,3-dipolar cycloaddition products. The products underwent a Nazarov-type cyclization upon hydride reduction followed by acidic-workup, furnishing the corresponding indenyl-pyrazoles in high yields.

Visible Light-Induced, Metal-Free Denitrative [3+2] Cycloaddition for Trisubstituted Pyrrole Synthesis.

A metal-free, regioselective synthesis of trisubstituted pyrroles has been developed through a formal [3+2] cycloaddition reaction between 2H-azirines and nitroalkenes under visible light/photoredox-catalyzed conditions. The reaction proceeds through 2H-azaallenyl radical addition on ß-nitrostyrenes in a Michael fashion followed by a base-mediated denitration reaction. The directive group influence of the nitro group controls the regiochemistry of the reaction.

Intramolecular trapping of ammonium ylides with N-benzoylbenzotriazoles in aqueous medium: direct access to the pseudoindoxyl scaffold.

The present work documents an operationally simple, clean and practical method for accessing the 2,2-disubstituted indolin-3-one (pseudoindoxyl) scaffold. The rhodium carbenoid mediated reaction between N-o-alkylamino benzoylbenzotriazoles and aryl diazoacetates occurs smoothly in water and exploits the leaving group ability of the benzotriazole moiety to install the carbonyl function in the product. Other highlights of the methodology are a wide substrate scope and experimental practicality given the re-use of the benzotriazole byproduct for starting material preparation.