Chemoselective transfer hydrogenation to nitroarenes mediated by oxygen-implanted MoS2

In Situ Molecular Engineering Strategy to Construct Hierarchical MoS2 Double-Layer Nanotubes for Ultralong Lifespan "Rocking-Chair" Aqueous Zinc-Ion Batteries

Rechargeable aqueous zinc ion batteries (AZIBs) have gained considerable attention owing to their low cost and high safety, but dendrite growth, low plating/stripping efficiency, surface passivation, and self-erosion of the Zn metal anode are hindering their application. Herein, a one-step in situ molecular engineering strategy for the simultaneous construction of hierarchical MoS2 double-layer nanotubes (MoS2-DLTs) with expanded layer-spacing, oxygen doping, structural defects, and an abundant 1T-phase is proposed, which are designed as an intercalation-type anode for "rocking-chair" AZIBs, avoiding the Zn anode issues and therefore displaying a long cycling life. Benefiting from the structural optimization and molecular engineering, the Zn2+ diffusion efficiency and interface reaction kinetics of MoS2-DLTs are enhanced. When coupled with a homemade ZnMn2O4 cathode, the assembled MoS2-DLTs//ZnMn2O4 full battery exhibited impressive cycling stability with a capacity retention of 86.6% over 10 000 cycles under 1 A g-1anode, outperforming most of the reported "rocking-chair" AZIBs. The Zn2+/H+ cointercalation mechanism of MoS2-DLTs is investigated by synchrotron in situ powder X-ray diffraction and multiple ex situ characterizations. This research demonstrates the feasibility of MoS2 for Zn-storage anodes that can be used to construct reliable aqueous full batteries.

Molecularly Engineering Defective Basal Planes in Molybdenum Sulfide for the Direct Synthesis of Benzimidazoles by Reductive Coupling of Dinitroarenes with Aldehydes

Developing more sustainable catalytic processes for preparing N-heterocyclic compounds in a less costly, compact, and greener manner from cheap and readily available reagents is highly desirable in modern synthetic chemistry. Herein, we report a straightforward synthesis of benzimidazoles by reductive coupling of o-dinitroarenes with aldehydes in the presence of molecular hydrogen. An innovative molecular cluster-based synthetic strategy that employs Mo₃S₄ complexes as precursors have been used to engineer a sulfur-deficient molybdenum disulfide (MoS₂)-type material displaying structural defects on both the naturally occurring edge positions and along the typically inactive basal planes. By applying this catalyst, a broad range of functionalized 2-substituted benzimidazoles, including bioactive compounds, can be selectively synthesized by such a direct hydrogenative coupling protocol even in the presence of hydrogenation-sensitive functional groups, such as double and triple carbon-carbon bonds, nitrile and ester groups, and halogens as well as diverse types of heteroarenes.

Molybdenum disulfide (MoS2): A novel activator of peracetic acid for the degradation of sulfonamide antibiotics

Sulfonamide antibiotics (SAs) are typical antibiotics and have attracted increasing concerns about their wide occurrence in environment as well as potential risk for human health. In this study, we applied a novel advanced oxidation process in SAs degradation by combining molybdenum sulfide and peracetic acid (MoS₂/PAA). Reactive oxygen species (ROS) including HO^●, CH₃C(O)O^●, CH₃C(O)OO^●, and ¹O₂ were generated from PAA by MoS₂ activation and contributed to SAs degradation. The effects of initial pH, the dosages of PAA and MoS₂, and humic acid for SAs degradation were further evaluated by selecting sulfamethoxazole (SMX) as a target SA in the MoS₂/PAA process. Results suggested that the optimum pH for SMX removal was 3, where the degradation efficiency of SMX was higher than 80% after reaction for 15 min. Increasing PAA (0.075-0.45 mM) or MoS₂ (0.1-0.4 g/L) dosages facilitated the SMX degradation, while the presence of humic acids retarded the SMX removal. This MoS₂/PAA process also showed good efficiencies in removing other SAs including sulfaguanidine, sulfamonomethoxine and sulfamerazine. Their possible degradation pathways were proposed based on the products identification and DFT calculation, showing that apart from the oxidation of amine groups to nitro groups in SAs, MoS₂/PAA induced SO₂ extrusion reaction for SAs that contained six-membered heterocyclic moieties.

Effect of Fe, Co and Ni promoters on MoS2 based catalysts for chemoselective hydrogenation of nitroarenes

The effect of Fe, Co and Ni promoters on supported MoS₂ catalysts for hydrogenation of nitroarenes were systematically investigated via experiment, characterization and DFT calculation. It was found that the addition of promoters remarkably improved the reaction activity in a sequence of Ni > Co > Fe > Mo. Meanwhile Ni promoted catalyst with the best performance showed good recyclability and chemoselectivity for a wide substrate scope. The characterization results revealed that the addition of promoters decreased the interaction between Mo and support and facilitated the reductive sulfidation of Mo species to produce more coordinated unsaturated sites (CUS). DFT calculations showed that the addition of promoters increased the formation of CUS, and enhanced the adsorption of hydrogen. The influence degree of promoters followed the sequence Ni > Co > Fe > Mo, which was consistent with those of the activities. Nitrobenzene hydrogenation and hydrogen activation occurred at the S and Mo edge, respectively. The adsorbed hydrogen diffused from the Mo edge to the S edge to participate in the hydrogenation reaction. Mechanism investigation showed that the main reason for increased activity by the addition of promoters was the increase of amounts of CUS and the secondary reason was the augmentation of intrinsic activity of CUS. The present studies give a new understanding for promoter modified MoS₂ catalysts applied for hydrogenation of nitroarenes.

The addition of promoters remarkably improved the activity for hydrogenation of nitroarenes in a sequence of Ni > Co > Fe > Mo and the amount of CUS active center was supposed to be the main reason to influence the reaction activity.

On the catalytic transfer hydrogenation of nitroarenes by a cubane-type Mo3S4 cluster hydride: disentangling the nature of the reaction mechanism

Cubane-type Mo₃S₄ cluster hydrides decorated with phosphine ligands are active catalysts for the transfer hydrogenation of nitroarenes to aniline derivatives in the presence of formic acid (HCOOH) and triethylamine (Et₃N). The process is highly selective and most of the cluster species involved in the catalytic cycle have been identified through reaction monitoring. Formation of a dihydrogen cluster intermediate has also been postulated based on previous kinetic and theoretical studies. However, the different steps involved in the transfer hydrogenation from the cluster to the nitroarene to finally produce aniline remain unclear. Herein, we report an in-depth computational investigation into this mechanism. Et₃N reduces the activation barrier associated with the formation of Mo-HHOOCH dihydrogen species. The global catalytic process is highly exergonic and occurs in three consecutive steps with nitrosobenzene and N-phenylhydroxylamine as reaction intermediates. Our computational findings explain how hydrogen is transferred from these Mo-HHOOCH dihydrogen adducts to nitrobenzene with the concomitant formation of nitrosobenzene and the formate substituted cluster. Then, a β-hydride elimination reaction accompanied by CO₂ release regenerates the cluster hydride. Two additional steps are needed for hydrogen transfer from the dihydrogen cluster to nitrosobenzene and N-phenylhydroxylamine to finally produce aniline. Our results show that the three metal centres in the Mo₃S₄ unit act independently, so the cluster can exist in up to ten different forms that are capable of opening a wide range of reaction paths. This behaviour reveals the outstanding catalytic possibilities of this kind of cluster complexes, which work as highly efficient catalytic machines.

Ionic liquid assisted hydrothermal synthesis of MoS2 double-shell polyhedral cages with enhanced catalytic hydrogenation activities

MoS₂ double-shell polyhedral cages are synthesized via an ionic liquid assisted hydrothermal route and exhibit enhanced catalytic hydrogenation properties.