From VIB‑to VB‑Group Transition Metal Disulfides:Structure Engineering Modulation for Superior Electromagnetic Wave Absorption

The laminated transition metal disulfides(TMDs),which are well known as typical two-dimensional(2D)semiconductive materials,possess a unique layered structure,leading to their wide-spread applications in various fields,such as catalysis,energy storage,sensing,etc.In recent years,a lot of research work on TMDs based functional materials in the fields of electromagnetic wave absorption(EMA)has been carried out.Therefore,it is of great significance to elaborate the influence of TMDs on EMA in time to speed up the application.In this review,recent advances in the development of electromagnetic wave(EMW)absorbers based on TMDs,ranging from the VIB group to the VB group are summarized.Their compositions,microstructures,electronic properties,and synthesis methods are presented in detail.Particularly,the modulation of structure engineering from the aspects of heterostructures,defects,morphologies and phases are systematically summarized,focusing on optimizing impedance matching and increasing dielectric and magnetic losses in the EMA materials with tunable EMW absorption performance.Milestones as well as the challenges are also identified to guide the design of new TMDs based dielectric EMA materials with high performance.

Novel Reduction of Sodium Alkyl Thiosulfates to Disulfides with TiCl_4/Sm System

Sodium alkyl thiosulfates(Bunte salts) can be readily reduced to the corresponding disulfides with TiCl4/Sm system in good to excellent yields under mild conditions

A Novel Method of Preparing Unsymmetrical Thioether from Disulfides

The disulfides reacted with zinc in DMF, followed by alkyl halides, giving unsymmetrical thioether in excellent yields. This reaction takes place under mild and neutral conditions.

STUDIES ON THE REACTION OF SULFUR,SELENIUM AND TELLURIUM WITH SODIUM HYDROXIDE UNDER PHASE TRANSFER CATALYSIS(Ⅱ).A CONVENIENT METHOD FOR THE SYNTHESIS OF BI(ACYL)DISULFIDES

A simple and general method for the synthesis of bi(acyl)disulfides is reported.Sulfur is allowed to react with sodium hydroxide to give sodium disulfide at 65℃ under PTC,which can react with acyl halides to afford bi(acyl)disulfides in good to excellent isolated yields.The effects of solvents and phase transfer catalysts are discussed.

Quantification of Global Protein Disulfides and Thiol-Protein Mixed Disulfides to Study the Protein Dethiolation Mechanisms

The redox state of cellular thiols is widely studied because it was recently linked to many different diseases and pathologies. In this work we quantified the concentrations of protein disulfides (PSSP) and thiol-protein mixed disulfides (XSSP) in rat tissues (liver, kidney and heart) and cells (Raw 264.7) by an improved method of XSSP and PSSP determination after oxidative stress induced by diamide. Under native and denaturing conditions, a thiol block by N-ethymaleimide was introduced to avoid thiol exchange reaction activations by protein SH groups (PSH) (PSH + XSSP ←→ PSSP + XSH) and alterations of original XSSP/PSSP levels. Low molecular weight thiols (XSH) and PSH were respectively measured by HPLC on supernatants and on corresponding pellets by DTNB (Ellman’s reagent) after dithiothreitol reduction. PSSP concentrations of liver, heart and kidney were respectively 0.304, 0.605 and 0.785 μmoles/g and after diamide exposure they were significantly augmented of about 65%-70% in liver and heart, but not in the kidney. Normal XSSP, that were -20 times lower than normal PSSP were induced by diamide in liver and heart of about 40 times, but not in kidney. Thermodynamic criteria regarding the pKa values of thiols engaged as PSSP and GSSP were used to interpret dethiolation mechanisms via thiol exchange reactions.

Novel Reduction of Arylsulfonyl Chlorides and Sodium Alkyl Thiosulfates to Disulfides with TiCl_4/Zn System

T1Cl4/Zn system reduces arylsulfonyl chlorides and sedium aldyl thiosulfates to corresponding disulfides in moderate to good yields

Visible-light photocatalytic selective aerobic oxidation of thiols to disulfides on anatase TiO2

This work presents the visible-light photocatalytic selective oxidation of thiols to disulfides with molecular oxygen(O2) on anatase TiO2. The high specific surface area of anatase TiO2 proved to be especially critical in conferring high photocatalytic activity. Herein, surface complexation between thiol and TiO2 gives rise to photocatalytic activity under irradiation with 520 nm green light-emitting diodes(LEDs), resulting in excellent reaction activity, substrate scope, and functional group tolerance. The transformation was extremely efficient for the selective oxidation of various thiols, particularly with substrates bearing electron-withdrawing groups(reaction times of less than 10 min). To date, the longest wavelength of visible light that this system can utilize is 520 nm by the surface complex of substrate-TiO2. Importantly, O2 was found to act as the electron and proton acceptor, rather than to incorporate into the substrates. Our findings regarding this surface complex-based photocatalytic system can allow one to understand the interaction between the conduction band electrons and O2.

Simultaneous Reduction of Nitro Group and S-S Bond in Nitrodisulfides by Samarium Diiodide: A New Approach to Benzothiazolines

Nitrodisulfides were reduced by SmI2/HMPA in anhydrous THF at room temperature to produce active intermediates (samarium thiolates and amides), which were 'living' double-anions and reacted smoothly with aldehydes or ketones to afford benzothiazolines in good yields under mild and neutral conditions.

Immobilizing Triphenylamine with Photoredox Inert Sr^(2+)Forming Sr-MOF with Controlled Electron Migration for Photocatalytic Oxidation of Thiols to Disulfides

The photocatalytic oxidative coupling of thiols is one of the most popular methods to synthesize the disulfides.Triphenylamine and its derivatives(TPAs)are promising for the above reaction,but suffer from the easy polymerization and difficult separation.To overcome these obstacles while controlling the photogenerated electrons transfer directly to target substrates,herein,we constructed one TPA-based metal-organic framework(MOF),(Me_(2)NH_(2))[Sr(TCBPA)]·DMA·3H_(2)O(1),by direct self-assembly of tris(4′-carboxybiphenyl)amine(H_(3)TCBPA)and photoredox inert strontium ion(Sr^(2+)).DFT calculations revealed that the valence band maximum(VBM)and the conduction band minimum(CBM)are mainly located on TCBPA^(3-),successfully inhibiting the undesirable electron migration to metal nodes.Experimental results indicated that 1 displays superior performance than homogeneous H_(3)TCBPA,which may result from the abundant π…π and C—H…π interactions between the well-arranged TCBPA^(3-)and the build-in electric field between the anionic framework and the Me_(2)NH^(2+).This work highlights that immobilizing TPAs into MOFs is one promising approach to designing heterogeneous photocatalysts for the synthesis of disulfides by oxidative coupling of thiols.

Visible-light-induced C–H sulfenylation of quinoxalin-2(1H)-ones with disulfides by sustainable cerium catalysis

Using visible light as energy to form free radicals has important synthetic value.A novel and efficient visible-lightmediated strategy has been developed for the generation of thiobenzene radicals through cerium-catalyzed activation of the disulfides.Through this photochemical reaction,various 3-sulfenylated quinoxalin-2(1H)-ones can be conveniently obtained in good yields with good functional group tolerance.Our transformation provides an alternative that allows rapid access to various C3 sulfenylated quinoxalin-2(1H)-ones in a sustainable and practical manner.

Active MoS_(2)-based electrode for green ammonia synthesis

Nitrogen electro-reduction under mild conditions is one promising alternative approach of the energyconsuming Haber-Bosch process for the artificial ammonia synthesis.One critical aspect to unlocking this technology is to discover the catalysts with high selectivity and efficiency.In this work,the N_(2)-to-NH_(3)conversion on the functional MoS_(2)is fully investigated by density functional theory calculations since the layered MoS_(2)provides the ideal platform for the elaborating copies of the nitrogenase found in nature,wherein the functionalization is achieved via basal-adsorption,basal-substitution or edge-substitution of transition metal elements.Our results reveal that the edge-functionalization is a feasible strategy for the activity promotion;however,the basal-adsorption and basal-substitution separately suffer from the electrochemical instability and the NRR inefficiency.Specifically,MoS_(2)functionalized via edge W-substitution exhibits an exceptional activity.The energetically favored reaction pathway is through the distal pathway and a limiting potential is less than 0.20 V.Overall,this work escalates the rational design of the high-effective catalysts for nitrogen fixation and provides the explanation why the predicated catalyst have a good performance,paving the guidance for the experiments.

Computational investigation of the lubrication behaviors of dioxides and disulfides of molybdenum and tungsten in vacuum

Lamellar compounds such as the disulfides of molybdenum and tungsten are widely used as additives in lubricant oils or as solid lubricants in aerospace industries.The dioxides of these two transition metals have identical microstructures with those of the disulfides.The differences in the lubrication behaviors of disulfide and dioxides were investigated theoretically.Tungsten dioxide and molybdenum dioxide exhibit higher bond strengths at the interface and lower interlayer interactions than those of the disulfides which indicates their superlubricity.Furthermore,the topography of the electron density of the single layer nanostructure determined their sliding potential barrier;the dioxides showed a weaker electronic cloud distribution between the two neighboring oxygen atoms,which facilitated the oxygen atoms of the counterpart to go through.For commensurate friction,the dioxides exhibited nearly the same value of friction work,and same was the case for the disulfides.The lower positive value of friction work for the dioxides confirmed their improved lubricity than the disulfides and the higher mechanical strength of the bulk dioxides demonstrated that they are excellent solid lubricants in vacuum.

An efficient and convenient method for preparation of disulfides from thiols using air as oxidant catalyzed by Co-Salophen

Disulfides have been synthesized by oxidation of thiols using air as oxidant catalyzed by Co-Salophen with high yields,mild and neutral conditions,and easy procedures of the catalyst.The products were confirmed by ~1H NMR and IR.

An efficient and convenient method for the preparation of disulfides from thiols using oxygen as oxidant catalyzed by tert-butyl nitrite

An efficient and convenient tert-butyl nitrite-catalyzed selective aerobic oxidation of thiols has been developed. Under the optimal reaction conditions, a number of thiol derivatives including aromatic thiols, heteroaromatic thiols and aliphatic thiols can be converted into their corresponding disulfides in good to excellent yields.

Effect of Vacancy Defects on the Properties of CoS_(2) and FeS_(2)

In order to explore the effect of vacancy defects on the structural,electronic,magnetic and optical properties of CoS_(2) and FeS_(2),first-principles calculation method was used to investigate the alloys.The calculated results of materials without vacancy are consistent with those reported in the literatures,while the results of materials with vacancy defect were different from those of literatures due to the difference vacancy concentration.The Co vacancy defect hardly changes the half-metallic characteristic of CoS_(2).The Fe vacancy defect changes FeS_(2) from semiconductor to half-metal,and the bottom of the spin-down conduction band changes from the p orbital state of S to the d(t_(2g))orbital state of Fe,while the top of the valence band remains the d orbital d(eg)state of Fe.The half-metallic Co vacancy defects of CoS_(2) and Fe vacancy defects of FeS_(2) are expected to be used in spintronic devices.S vacancy defects make both CoS_(2) and FeS_(2) metallic.Both the Co and S vacancy defects lead to the decrease of the magnetic moment of CoS_(2),while both the Fe and S vacancy defects lead to the obvious magnetic property of FeS_(2).Vacancy defects enhance the absorption coefficient of infrared band and long band of visible light obviously,and produce obvious red shift phenomenon,which is expected to be used in photoelectric devices.

Film Flow of Nano-Micropolar Fluid with Dissipation Effect

The physical problem of the thin film flow of a micropolar fluid over a dynamic and inclined substrate under the influence of gravitational and thermal forces in the presence of nanoparticles is formulated.Five different types of nanoparticle samples are accounted for in this current study,namely gold Au,silver Ag,molybdenum disulfide MoS_(2),aluminum oxide Al_(2)O_(3),and silicon dioxide SiO_(2).Blood,a micropolar fluid,serves as the common base fluid.An exact closed-form solution for this problem is derived for the first time in the literature.The results are particularly validated against those for the Newtonian fluid and show excellent agreement.It was found that increasing values of the spin boundary condition and micropolarity lead to a reduction in both the thermal and momentum boundary layers.A quantitative decay in the Nusselt number for a micropolar fluid,as compared to a Newtonian one for all the tested nanoparticles,is anticipated.Gold and silver nanoparticles(i)intensify in the flow parameter as the concentration of nanoparticles increases(ii)yield a higher thermal transfer rate,whereas molybdenum disulfide,aluminum oxide,and silicon dioxide exhibit a converse attitude for both Newtonian and micropolar fluids.The reduction in film thickness for fluid comprising gold particles,as compared to the rest of the nanoparticles,is remarkable.

Unraveling high efficiency multi-step sodium storage and bidirectional redox kinetics synergy mechanism of cobalt-doping vanadium disulfide anode

Sodium-based storage devices based on conversion-type metal sulfide anodes have attracted great atten-tion due to their multivalent ion redox reaction ability.However,they also suffer from sodium polysul-fides(NaPSs)shuttling problems during the sluggish Na^(+) redox process,leading to"voltage failure"and rapid capacity decay.Herein,a metal cobalt-doping vanadium disulfide(Co-VS_(2))is proposed to simulta-neously accelerate the electrochemical reaction of VS_(2) and enhance the bidirectional redox of soluble NaPSs.It is found that the strong adsorption of NaPSs by V-Co alloy nanoparticles formed in situ during the conversion reaction of Co-VS_(2) can effectively inhibit the dissolution and shuttle of NaPSs,and ther-modynamically reduce the formation energy barrier of the reaction path to effectively drive the complete conversion reaction,while the metal transition of Co elements enhances reconversion kinetics to achieve high reversibility.Moreover,Co-VS_(2) also produce abundant sulfur vacancies and unsaturated sulfur edge defects,significantly improve ionic/electron diffusion kinetics.Therefore,the Co-VS_(2) anode exhibits ultrahigh rate capability(562 mA h g^(-1) at 5 A g^(-1)),high initial coulombic efficiency(~90%)and 12,000 ultralong cycle life with capacity retention of 90%in sodium-ion batteries(SIBs),as well as impressive energy/power density(118 Wh kg^(-1)/31,250 W kg^(-1))and over 10.000 stable cycles in sodium-ion hybrid capacitors(SIHCs).Moreover,the pouch cell-type SIHC displays a high-energy density of 102 Wh kg^(-1) and exceed 600 stable cycles.This work deepens the understanding of the electrochemical reaction mechanism of conversion-type metal sulfide anodes and provides a valuable solution to the shuttlingofNaPSs inSIBsandSIHCs.

High-throughput calculation-based rational design of Fe-doped MoS_(2) nanosheets for electrocatalytic p H-universal overall water splitting

Electrocatalytic water splitting is crucial for H2generation via hydrogen evolution reaction(HER)but subject to the sluggish dynamics of oxygen evolution reaction(OER).In this work,single Fe atomdoped MoS_(2)nanosheets(SFe-DMNs)were prepared based on the high-throughput density functional theory(DFT)calculation screening.Due to the synergistic effect between Fe atom and MoS_(2)and optimized intermediate binding energy,the SFe-DMNs could deliver outstanding activity for both HER and OER.When assembled into a two-electrode electrolytic cell,the SFe-DMNs could achieve the current density of 50 mA cm^(-2)at a low cell voltage of 1.55 V under neutral condition.These results not only confirmed the effectiveness of high-throughput screening,but also revealed the excellent activity and thus the potential applications in fuel cells of SFe-DMNs.

Heterostructural NiFeW disulfide and hydroxide dual‐trimetallic core‐shell nanosheets for synergistically effective water oxidatio

A stable and highly active core‐shell heterostructure electrocatalyst is essential for catalyzing oxygen evolution reaction(OER).Here,a dual‐trimetallic core‐shell heterostructure OER electrocatalyst that consists of a NiFeWS_(2)inner core and an amorphous NiFeW(OH)_(z)outer shell is designed and synthesized using in situ electrochemical tuning.The electrochemical measurements of different as‐synthesized catalysts with a similar mass loading suggest that the core‐shell Ni_(0.66)Fe_(0.17)W_(0.17)S_(2)@amorphous NiFeW(OH)_(z)nanosheets exhibit the highest overall performance compared with that of other bimetallic reference catalysts for the OER.Additionally,the nanosheet arrays were in situ grown on hydrophilic‐treated carbon paper to fabricate an integrated three‐dimensional electrode that affords a current density of 10 mA cm^(−2)at a small overpotential of 182 mV and a low Tafel slope of 35 mV decade^(−1)in basic media.The Faradaic efficiency of core‐shell Ni_(0.66)Fe_(0.17)W_(0.17)S_(2)@amorphous NiFeW(OH)_(z)is as high as 99.5%for OER.The scanning electron microscope,transmission electron microscope,and X‐ray photoelectron spectroscopy analyses confirm that this electrode has excellent stability in morphology and elementary composition after long‐term electrochemical measurements.Importantly,density functional theory calculations further indicate that the core‐shell heterojunction increased the conductivity of the catalyst,optimized the adsorption energy of the OER intermediates,and improved the OER activity.This study provides a universal strategy for designing more active core‐shell structure electrocatalysts based on the rule of coordinated regulation between electronic transport and active sites.

Fine-tuning the activation behaviors of ternary modular cabazitaxel prodrugs for efficient and on-target oral anti-cancer therapy

The disulfide bond plays a crucial role in the design of anti-tumor prodrugs due to its exceptional tumor-specific redox responsiveness. However, premature breaking of disulfide bonds is triggered by small amounts of reducing substances (e.g., ascorbic acid, glutathione, uric acid and tea polyphenols) in the systemic circulation. This may lead to toxicity, particularly in oral prodrugs that require more frequent and high-dose treatments. Fine-tuning the activation kinetics of these prodrugs is a promising prospect for more efficient on-target cancer therapies. In this study, disulfide, steric disulfide, and ester bonds were used to bridge cabazitaxel (CTX) to an intestinal lymph vessel-directed triglyceride (TG) module. Then, synthetic prodrugs were efficiently incorporated into self-nanoemulsifying drug delivery system (corn oil and Maisine CC were used as the oil phase and Cremophor EL as the surfactant). All three prodrugs had excellent gastric stability and intestinal permeability. The oral bioavailability of the disulfide bond-based prodrugs (CTX-(C)S-(C)S-TG and CTX-S-S-TG) was 11.5- and 19.1-fold higher than that of the CTX solution, respectively, demonstrating good oral delivery efficiency. However, the excessive reduction sensitivity of the disulfide bond resulted in lower plasma stability and safety of CTX-S-S-TG than that of CTX-(C)S-(C)S-TG. Moreover, introducing steric hindrance into disulfide bonds could also modulate drug release and cytotoxicity, significantly improving the anti-tumor activity even compared to that of intravenous CTX solution at half dosage while minimizing off-target adverse effects. Our findings provide insights into the design and fine-tuning of different disulfide bond-based linkers, which may help identify oral prodrugs with more potent therapeutic efficacy and safety for cancer therapy.