Effects of Stephania hainanensis alkaloids on MSU-induced acute gouty arthritis in mice.

BACKGROUND: Gout is initiated by the precipitation of monosodium urate (MSU) crystals within the joints and soft tissues, and it can eventually cause acute or chronic arthritis. MSU crystals trigger, amplify, and maintain a strong inflammatory response through promoting proinflammatory activity. In this study, the therapeutic effects of Stephania hainanensis (S. hainanensis) total alkaloid (SHA) were tested and evaluated on MSU-induced acute gouty arthritis in a mouse model. METHODS: After oral administration of SHA (10 or 20 mg/kg) or the antigout medicine colchicine (0.5 mg/kg) once daily for 3 consecutive days, MSU crystals suspended in saline (2.5 mg/50 µl) were intradermally injected into the right paw of the mice. Then, SHA and colchicine were administered for another 2 days. During this period, swelling of the ankle and clinical scores were measured at 12, 24, and 48 h postinjection. After the mice were euthanized, inflammatory cytokine expression and paw tissue inflammation-related gene and protein expression, and a histopathological analysis was performed. RESULTS: SHA had obvious therapeutic effects on MSU-induced acute gouty arthritis in mice. SHA alleviated ankle swelling and inhibited the production of cytokines, such as IL-1ß and TNF-α. In addition, NLRP3, Caspase-1 and IL-1ß, which are activated by MSU were also suppressed by SHA. The histological evaluation showed that SHA relieved the infiltration of inflammation around the ankle. CONCLUSIONS: These results suggest that SHA is capable of anti-inflammatory activities and may be useful for treating gouty arthritis.

Bioinspired metal complexes for energy-related photocatalytic small molecule transformation.

Bioinspired transformation of small-molecules to energy-related feedstocks is an attractive research area to overcome both the environmental issues and the depletion of fossil fuels. The highly effective metalloenzymes in nature provide blueprints for the utilization of bioinspired metal complexes for artificial photosynthesis. Through simpler structural and functional mimics, the representative herein is the pivotal development of several critical small molecule conversions catalyzed by metal complexes, e.g., water oxidation, proton and CO2 reduction and organic chemical transformation of small molecules. Of great achievement is the establishment of bioinspired metal complexes as catalysts with high stability, specific selectivity and satisfactory efficiency to drive the multiple-electron and multiple-proton processes related to small molecule transformation. Also, potential opportunities and challenges for future development in these appealing areas are highlighted.

Thiol Activation toward Selective Thiolation of Aromatic C-H Bond.

Direct C-S bond coupling is an attractive way to construct aryl sulfur ether, a building block for a variety of biological active molecules. Herein, we disclose an effective model for regioselective thiolation of the aromatic C-H bond by thiol activation instead of arene activation. Strikingly, this method has been applied into anisole derivatives that are not available in the arene activation approach to forge a single thioether isomer with high reactivity.

Photoelectrochemical cell for P-H/C-H cross-coupling with hydrogen evolution.

Photoelectrochemistry enables the formation of a variety of active intermediates for organic synthesis in an environmentally friendly manner. Herein, a photoelectrochemical cell is fabricated to realize activation of P-H/C-H bonds for cross-coupling hydrogen evolution. As compared with an electrochemical cell, nearly 90% external bias input is saved to drive the C-P bond construction with good to excellent yields.

Semiconductor Quantum Dots: An Emerging Candidate for CO2 Photoreduction.

As one of the most critical approaches to resolve the energy crisis and environmental concerns, carbon dioxide (CO2 ) photoreduction into value-added chemicals and solar fuels (for example, CO, HCOOH, CH3 OH, CH4 ) has attracted more and more attention. In nature, photosynthetic organisms effectively convert CO2 and H2 O to carbohydrates and oxygen (O2 ) using sunlight, which has inspired the development of low-cost, stable, and effective artificial photocatalysts for CO2 photoreduction. Due to their low cost, facile synthesis, excellent light harvesting, multiple exciton generation, feasible charge-carrier regulation, and abundant surface sites, semiconductor quantum dots (QDs) have recently been identified as one of the most promising materials for establishing highly efficient artificial photosystems. Recent advances in CO2 photoreduction using semiconductor QDs are highlighted. First, the unique photophysical and structural properties of semiconductor QDs, which enable their versatile applications in solar energy conversion, are analyzed. Recent applications of QDs in photocatalytic CO2 reduction are then introduced in three categories: binary II-VI semiconductor QDs (e.g., CdSe, CdS, and ZnSe), ternary I-III-VI semiconductor QDs (e.g., CuInS2 and CuAlS2 ), and perovskite-type QDs (e.g., CsPbBr3 , CH3 NH3 PbBr3 , and Cs2 AgBiBr6 ). Finally, the challenges and prospects in solar CO2 reduction with QDs in the future are discussed.

Regioselective Ortho Amination of an Aromatic C-H Bond by Trifluoroacetic Acid via Electrochemistry.

A trifluoroacetic acid-facilitated ortho amination of alkoxyl arene has been established via anodic oxidation in an undivided cell. In the absence of any additional metal or oxidant reagents, a series of aromatic and heteroaromatic amine derivatives have been synthesized in good to excellent yields. Our findings reveal the possibility of achieving complete ortho-selective amination of a simple arene, which emerges as an efficient route for facile and large-scale organic synthesis.

Eosin†Y as a Direct Hydrogen-Atom Transfer Photocatalyst for the Functionalization of C-H Bonds.

Eosin Y, a well-known economical alternative to metal catalysts in visible-light-driven single-electron transfer-based organic transformations, can behave as an effective direct hydrogen-atom transfer catalyst for C-H activation. Using the alkylation of C-H bonds with electron-deficient alkenes as a model study revealed an extremely broad substrate scope, enabling easy access to a variety of important synthons. This eosin Y-based photocatalytic hydrogen-atom transfer strategy is promising for diverse functionalization of a wide range of native C-H bonds in a green and sustainable manner.

Recent Advances in Sensitized Photocathodes: From Molecular Dyes to Semiconducting Quantum Dots.

The increasing demand for sustainable and environmentally benign energy has stimulated intense research to establish highly efficient photo-electrochemical (PEC) cells for direct solar-to-fuel conversion via water splitting. Light absorption, as the initial step of the catalytic process, is regarded as the foundation of establishing highly efficient PEC systems. To make full use of visible light, sensitization on photoelectrodes using either molecular dyes or semiconducting quantum dots provides a promising method. In this field, however, there remain many fundamental issues to be solved, which need in-depth study. Here, fundamental knowledge of PEC systems is introduced to enable readers a better understanding of this field. Then, the development history and current state in both molecular dye- and quantum dot-sensitized photocathodes for PEC water splitting are discussed. A systematical comparison between the two systems has been made. Special emphasis is placed on the research of quantum dot-sensitized photocathodes, which have shown superiority in both efficiency and durability towards PEC water splitting at the present stage. Finally, the opportunities and challenges in the future for sensitized PEC water-splitting systems are proposed.

Self-assembled inorganic clusters of semiconducting quantum dots for effective solar hydrogen evolution.

Owing to promoted electron-hole separation, the catalytic activity of semiconducting quantum dots (QDs) towards solar hydrogen (H2) production has been significantly enhanced by forming self-assembled clusters with ZnSe QDs made ex situ. Taking advantage of the favored interparticle hole transfer to ZnSe QDs, the rate of solar H2 evolution of CdSe QDs can be increased to ∼30 000 µmol h-1 g-1 with ascorbic acid as the sacrificial reagent, ∼150-fold higher than that of bare CdSe QDs clusters under the same conditions.

Enhanced Charge Separation Efficiency Accelerates Hydrogen Evolution from Water of Carbon Nitride and 3,4,9,10-Perylene-tetracarboxylic Dianhydride Composite Photocatalyst.

The catalytic ability of graphitic carbon nitride is greatly affected by its intrinsic electronic properties. Although combination with chromophore has been demonstrated to be one of the promising approaches to improve the catalytic performance of carbon nitride, it is imperative to understand the key factors governing the whole process. Here, we report a composite photocatalyst CN-P by embedding perylene unit into the matrix of carbon nitride. The composite photocatalyst could catalyze hydrogen evolution with a high rate of 17.7 mmol h-1 g-1, which is 2.8 times faster than pure carbon nitride. The apparent quantum efficiency is high up to be 5.8% at 450 nm. Detailed studies reveal that the light absorption ability and charge separation efficiency are greatly enhanced in the synthesized catalyst. These are the key factors for the improved hydrogen evolution ability of CN-P than that of pure carbon nitride.

Three-Dimensional Graphene Networks with Abundant Sharp Edge Sites for Efficient Electrocatalytic Hydrogen Evolution.

To achieve sustainable production of hydrogen (H2 ) through water splitting, establishing efficient and earth-abundant electrocatalysts is of great necessity. Morphology engineering of graphene is now shown to modulate the electronic structure of carbon skeleton and in turn endow it with excellent ability of proton reduction. Three-dimensional (3D) graphene networks with a high density of sharp edge sites are synthesized. Electrocatalytic measurements indicate that the obtained 3D graphene networks can electrocatalyze H2 evolution with an extremely low onset potential of about 18 mV in 0.5 m H2 SO4 solution, together with good stability. A combination of control experiments and density functional theory (DFT) investigations indicates that the exceptional H2 evolution performance is attributed to the abundant sharp edge sites of the advanced frameworks, which are responsible for promoting the adsorption and reduction of protons.

Assembling metallic 1T-MoS2 nanosheets with inorganic-ligand stabilized quantum dots for exceptional solar hydrogen evolution.

Due to their enhanced light harvesting, favored interfacial charge transfer and excellent proton reduction activity, hybrid photocatalysts of metallic 1T-MoS2 nanosheets and inorganic-ligand stabilized CdSe/ZnS QDs obtained via a self-assembly approach can produce H2 gas with a rate of ∼155 ± 3.5 µmol h-1 mg-1 under visible-light irradiation (λ = 410 nm), the most exceptional performance of solar H2 evolution using MoS2 as a cocatalyst known to date.

Self-Assembled Framework Enhances Electronic Communication of Ultrasmall-Sized Nanoparticles for Exceptional Solar Hydrogen Evolution.

Colloidal quantum dots (QDs) have demonstrated great promise in artificial photosynthesis. However, the ultrasmall size hinders its controllable and effective interaction with cocatalysts. To improve the poor interparticle electronic communication between free QD and cocatalyst, we design here a self-assembled architecture of nanoparticles, QDs and Pt nanoparticles, simply jointed together by molecular polyacrylate to greatly enhance the rate and efficiency of interfacial electron transfer (ET). The enhanced interparticle electronic communication is confirmed by femtosecond transient absorption spectroscopy and X-ray transient absorption. Taking advantage of the enhanced interparticle ET with a time scale of ∼65 ps, 5.0 mL of assembled CdSe/CdS QDs/cocatalysts solution produces 94 ± 1.5 mL (4183 ± 67 µmol) of molecular H2 in 8 h, giving rise to an internal quantum yield of ∼65% in the first 30 min and a total turnover number of >1.64â€¯× 107 per Pt nanoparticle. This study demonstrates that self-assembly is a promising way to improve the sluggish kinetics of the interparticle ET process, which is the key step for advanced H2 photosynthesis.

Hole-Accepting-Ligand-Modified CdSe QDs for Dramatic Enhancement of Photocatalytic and Photoelectrochemical Hydrogen Evolution by Solar Energy.

Solar H2 evolution of CdSe QDs can be significantly enhanced simply by introducing a suitable hole-accepting-ligand for achieving efficient hole extraction and transfer at the nanoscale interfaces, which opens an effective pathway for dissociation of excitons to generate long-lived charge separation, thus improving the solar-to-fuel conversion efficiency.

Secondary coordination sphere accelerates hole transfer for enhanced hydrogen photogeneration from [FeFe]-hydrogenase mimic and CdSe QDs in water.

Achieving highly efficient hydrogen (H2) evolution via artificial photosynthesis is a great ambition pursued by scientists in recent decades because H2 has high specific enthalpy of combustion and benign combustion product. [FeFe]-Hydrogenase ([FeFe]-H2ase) mimics have been demonstrated to be promising catalysts for H2 photoproduction. However, the efficient photocatalytic H2 generation system, consisting of PAA-g-Fe2S2, CdSe QDs and H2A, suffered from low stability, probably due to the hole accumulation induced photooxidation of CdSe QDs and the subsequent crash of [FeFe]-H2ase mimics. In this work, we take advantage of supramolecular interaction for the first time to construct the secondary coordination sphere of electron donors (HA(-)) to CdSe QDs. The generated secondary coordination sphere helps realize much faster hole removal with a ~30-fold increase, thus leading to higher stability and activity for H2 evolution. The unique photocatalytic H2 evolution system features a great increase of turnover number to 83600, which is the highest one obtained so far for photocatalytic H2 production by using [FeFe]-H2ase mimics as catalysts.

Improved Photoelectrocatalytic Performance for Water Oxidation by Earth-Abundant Cobalt Molecular Porphyrin Complex-Integrated BiVO4 Photoanode.

An earth-abundant, low-cost cobalt porphyrin complex (CoTCPP) is designed as a molecular catalyst to work on three-dimensional BiVO4 film electrode for water oxidation for the first time. Under illumination of a 100 mW cm(-2) Xe lamp, the CoTCPP-functionalized BiVO4 photoanode exhibits a 2-fold enhancement in photocurrent density at 1.23 V vs RHE and nearly a 450 mV cathodic shift at 0.5 mA cm(-2) photocurrent density relative to bare BiVO4 in 0.1 M Na2SO4 (pH = 6.8). Simultaneously, stoichiometric oxygen and hydrogen are generated with a faradic efficiency of 80% over 4 h. The activity and stability of the BiVO4 photoanode are dramatically increased by molecular CoTCPP, giving rise to higher performance than previously reported noble metal ruthenium complex-modified BiVO4 photoanode. By using hydrogen peroxide as the hole scavenger, we demonstrate that molecular CoTCPP catalyst greatly suppresses the hole-electron recombination on the surface of BiVO4 semiconductor, which offers a promising route toward high efficiency, low cost, practical solar fuel generation device.