Step-growth Polymerization of Aziridines with Elemental Sulfur: Easy Access to Linear Polysulfides and Their Use as Recyclable Adhesives.

The bulk radical polymerization of bis(aziridine) with molten elemental sulfur resulted in brittle, cross-linked polymers. However, when the bis(aziridine) was treated with elemental sulfur in the presence of an organobase, the ring-opening reaction of aziridine with oligosulfide anions occurred, leading to the formation of linear polymers by step-growth polymerization. These newly synthesized polymers possess repeating units containing a sulfonamide or amide functional moiety and oligosulfide bonds with an average sulfur segment of about two. A small molecular model reaction confirmed the nucleophilic addition reaction of elemental sulfur to aziridine. It was verified that S-S dynamic bond exchange takes place in the presence of an organic base within the linear chains. The mixture of the synthesized polysulfides with pyridine exhibits exceptional adhesive properties when applied to steel, and aluminum substrates. Notably, these prepared adhesives displayed good reusability due to the dynamic S-S exchange and complete recyclability due to their solution processability. This elemental sulfur-involved polymerization approach represents an innovative method for the synthesis of advanced sulfur-containing polymers, demonstrating the potential for various applications in adhesives and beyond.

Generation of bioluminescent enzyme immunoassay for ferritin by single-chain variable fragment and its NanoLuc luciferase fusion.

Ferritin, widely present in liver and spleen tissue, is considered as a serological biomarker for liver diseases and cancers. The detection of ferritin may be an important tool in health diagnosis. In this study, 14 non-immunized chicken spleens were utilized to construct a single-chain fragment (scFv) phage library. After 4 rounds of panning, 7 unique clones were obtained. The optimal clone was further screened and combined with NanoLuc luciferase (Nluc) as a dual functional immunoprobe to bioluminescent enzyme immunoassay (BLEIA), which was twice as sensitive as its parental scFv-based double-sandwich enzyme-linked immunoassay (ds-ELISA). The cross-reactivity analysis revealed that the proposed methods were highly selective and suitable for clinical detection. To further verify the performance of the immunoassays, serum samples were tested by the proposed methods and a commercial ELISA kit, and there was a good correlation between the results. These results suggested that scFv fused with Nluc might be a powerful dual functional tool for rapid, practically reliable, and highly sensitive ferritin detection.

Electroinduced Reconfiguration of Complex Emulsions for Fabrication of Polymer Particles with Tunable Morphology.

Continuous morphological control of anisotropic particles is always an important challenge in the field of materials. In this study, a new strategy for continuous fabrication of polymer particles with various morphologies induced by electricity is reported using complex emulsions as template. A synthetic electro-responsive surfactant containing ferrocene group is used to prepare complex emulsions, which contain a polymerizable monomer as inner phase. With the increasing time of electrical stimulation on the complex emulsions, hollow, hemispherical, mushroom-like, and spherical particles are constructed successively after photopolymerization. The Marangoni effect caused by the heterogeneity in the interfacial tension at the droplet surface is the reason for the reconfigurable morphology of the complex emulsion. The controllable complex emulsions by electricity present a versatile platform for constructing fine control of the microstructure and shape anisotropy of particles having customized shapes and functionalities, opening a new possibility for designing sophisticated architectures.

Three-Dimensional Graphene/Ag Aerogel for Durable and Stable Li Metal Anodes in Carbonate-Based Electrolytes.

The use of Li metal as the anode for Li-based batteries has attracted considerable attention due to its ultrahigh energy density. However, the formation of Li dendrites, uneven deposition, and huge volume changes hinder its reliable implementation. These issues become much more severe in commercial carbonate-based electrolytes than in ether-based electrolytes. Herein, a rationally designed three-dimensional graphene/Ag aerogel (3D G-Ag aerogel) is proposed for Li metal anodes with long cycle life in carbonate-based electrolytes. The modified lithiophilic nature of G-Ag aerogel, realized through decoration with Ag NPs, effectively decreases the energy barrier for Li nucleation, regulating uniform Li deposition behavior. Moreover, the highly flexible, conductive 3D porous architecture with hierarchical mesopores and macropores can readily accommodate deposited Li and ensures the integrity of the conductive network during cycling. Consequently, high coulombic efficiency (over 93.5 %) and a significantly long cycle life (1589 h) over 200 cycles, with a relatively high cycling capacity of 2.0 mAh cm-2 , can easily be achieved, even in a carbonate-based electrolyte. Considering the intrinsic high voltage windows of carbonate-based electrolytes, matching the G-Ag aerogel Li metal anode with a high-voltage cathode can be envisaged for the fabrication of high-energy-density Li secondary batteries.

Variation in Essential Oil and Bioactive Compounds of Curcuma kwangsiensis Collected from Natural Habitats.

The chemical compositions of essential oils (EOs) extracted from Curcuma kwangsiensis rhizomes collected from six natural habitats in P. R. China were evaluated using gas chromatography/mass spectrometry (GC/MS). Fifty-seven components were identified from the six EOs, and their main constituents were 8,9-dehydro-9-formyl-cycloisolongifolene (2.37 - 42.59%), germacrone (6.53 - 22.20%), and l-camphor (0.19 - 6.12%). The six EOs exhibited different DPPH radical-scavenging activities (IC50 , 2.24 - 31.03 µg/ml), with the activity of most of EOs being much higher than that of Trolox C (IC50 , 10.49 µg/ml) and BHT (IC50 , 54.13 µg/ml). Most EOs had potent antimicrobial effects against the tested bacteria and fungus. They also exhibited cytotoxicity against B16 (IC50 , 4.44 - 147.4 µg/ml) and LNCaP cells (IC50 , 73.94 - 429.25 µg/ml). The EOs showed excellent anti-inflammatory action by significantly downregulating expression of pro-inflammatory cytokines, cyclooxygenase-2, and tumor necrosis factor-α. This study provides insight into the interrelation among growth location, phytoconstituents, and bioactivities, and the results indicate the potential of C. kwangsiensis as natural nutrients, medicines, and others additives.

Sensitive and selective detection of uracil-DNA glycosylase activity with a new pyridinium luminescent switch-on molecular probe.

Uracil-deoxyribonucleic acid glycosylase (UDG) is known to function as an important base-excision repair enzyme and eliminate uracil from DNA molecules to maintain genomic integrity. A new small organic molecule (DID-VP) with interesting structural properties was synthesized as a G-quadruplex selective ligand and was demonstrated to be a sensitive luminescent switch-on probe in a convenient luminescent assay specifically for UDG detection in fetal bovine serum samples under rapid and simple conditions. This newly developed analytical method is based on the UDG enzymatic activity to unwind a duplex DNA substrate, and comprises a G-quadruplex-forming sequence (ON1) and uracil-containing DNA strand (ON2) to generate a remarkable fluorescence signal through the specific interaction of DID-VP with ON1. This luminescent switch-on assay is able to achieve high sensitivity and specificity for UDG over other enzymes. The application range of the present analytical system is found to be 0.05 to 1.00 U mL(-1) UDG with a very low detection limit of 0.005 U mL(-1). The recovery study of UDG in real samples gave a very good performance with 75.05%-102.7% recovery. In addition, an extended application of the assay in screening of UDG inhibitors is demonstrated. A good dose-dependence of the luminescence response with respect to the concentration of UDG inhibitors in samples was observed.

Bifunctional CdS-MoO2 catalysts for selective oxidation of lactic acid coupled with photocatalytic H2 production.

The persistent hurdles of charge rapid recombination, inefficient use of light and utilization of sacrificial reagents have plagued the field of photocatalytic hydrogen evolution (PHE). In this research, tiny MoO2 nanoparticles of 10 nm in diameter were prepared through a straightforward solvothermal approach with a specific ratio of oleylamine and oleic acid as stabilizers. The critical factor in the synthesis process was found to be the ratio of oleylamine to oleic acid. Moreover, a two-phase interface assembly method facilitated the uniform deposition of MoO2 onto CdS nanorods. Due to the localized plasmonic-thermoelectric effect on the surface of MoO2 along with its abundant oxygen vacancies, the composite catalyst exhibited outstanding photo-utilization efficiency and an abundance of active sites. The CdS-MoO2 composite displayed a unique photochemical property in transforming lactic acid into pyruvic acid and generating hydrogen simultaneously. After exposure to artificial sunlight for 4 h, significant values of 4.7 and 3.7 mmol⋅g-1⋅h-1 were achieved for hydrogen production and pyruvic acid formation, respectively, exceeding CdS alone by 3.29 and 4.02-fold, while the selectivity of pyruvic acid was 95.68 %. Furthermore, the S-Scheme electron transport mechanism in the composites was elucidated using Electron Paramagnetic Resonance (EPR) spectroscopy, radical trapping experiments, energy band structure analysis, and the identification of critical intermediates in the process of selective oxidation. This work sheds light on the design and preparation of high-performance photocatalysts for biorefining coupled with efficient hydrogen evolution.

Outstanding photo-thermo synergy in aerobic oxidation of cyclohexane by bismuth tungstate-bismuth oxychloride high-low heterojunction.

The difficulty of achieving both high conversion rate and high selectivity is a huge challenge in the catalytic aerobic oxidation of cyclohexane. In this paper, bismuth tungstate-bismuth oxychloride (Bi2WO6-BiOCl) nanoflower heterojunctions prepared via a one-step solvothermal process were applied in the photo-thermo synergetic catalytic oxidation of cyclohexane in the dried air. With the addition of little water at different reaction temperature, the ratio of bismuth to tungsten and the mass ratio of Bi2WO6 to BiOCl can be precisely tailored in the nanoflower sphere composites with thin nanosheets. Their microscopic morphology, elemental composition, crystal structure, and photoelectrochemical characteristics were explored by different characterization methods. The Bi2WO6-BiOCl composites possessed poor photocatalytic and thermal performances with the low conversion rates of 1.43% and 2.68%, respectively. However, through the photo-thermo catalytic oxidation process, an exceptional conversion rate of 13.32% was achieved with excellent selectivity of 99.22% for cyclohexanone and cyclohexanol (KA oil) using the same Bi2WO6-BiOCl composites. This superior performance outstrips Bi2WO6 flowers, BiOCl nanosheets and Bi2WO6-BiOCl composites with other compounding ratios. The creation of a high-low heterojunction in the Bi2WO6-BiOCl composite was confirmed by band energy analysis. The opto-electronic analysis, band energy analysis, sacrifice experiments, and active radical analysis were employed to elucidate the mechanism for the exceptional photo-thermo catalytic performance in detail. This work offers an exploratory solution to the challenges of high energy consumption and the difficulty in simultaneously achieving high selectivity and high conversion rates in cyclohexane oxidation, thus holding significant value.

1,4-Bis[4-(meth-oxy-carbon-yl)benz-yl]-1H-1,2,4-triazol-4-ium bromide.

In the title salt, C(20)H(20)N(3)O(4) (+)·Br(-), the dihedral angle between the benzene rings is 8.69 (16)°, and those between the benzene rings and the triazole ring are 69.98 (18) and 72.17 (18)°. In the crystal, C-H⋯Br hydrogen bonds link the cations and anions into chains along the c axis.

Manganese phosphorous trifulfide nanosheets and nitrogen doped carbon dot composites with manganese vacancies for a greatly enhanced hydrogen evolution.

As a novel chalcogenide photocatalyst, MnPS3 suffered from limited visible light absorption, high photogenerated electron-hole recombination, and low hole oxidation capability due to its high valence band (VB) potential. In this work, the novel MnPS3 nanosheets-Nitrogen-doped carbon dots (NCDs) composites were fabricated by immobilizing NCDs with terminal amine groups on Na+ intercalated MnPS3 nanosheets for a greatly enhanced photocatalytic hydrogen production activity. MnPS3 nanosheets of 400 nm with Mn2+ vacancies are produced in high yield by NaCl intercalation and subsequent exfoliation in N-methylpyrrolidone (NMP). NCDs with 5 nm are evenly loaded on the surface of MnPS3 nanosheets of 400 nm via strong chemical interactions of ammonium sulfate salts formed at the interface. The MnPS3-NCDs composites exhibit enhanced light absorption at 500-600 nm, reduced charge recombination and notably promoted photocatalytic activity in relative to neat MnPS3 nanosheets. MnPS3-NCDs composite with the NCDs content of 16.5% possessed the highest photocatalytic hydrogen evolution rate of 339.63 µmol·g-1·h-1 with good cycling stability, which is 9.17 times that of exfoliated MnPS3 nanosheets. The type-II MnPS3-NCDs heterojunction is conducive to the efficient interfacial carrier transport and the significantly improved photocatalytic hydrogen generation activity. Our work confirmed that the non-toxic MnPS3 could possess photocatalytic performance comparable to CdS, which will be promising to become an attractive visible-light driven photocatalyst in environmental purification and energy applications.

Mechanism-Dependent Selectivity: Fluorocyclization of Unsaturated Carboxylic Acids or Alcohols by Hypervalent Iodine.

To understand the unprecedented difference between 6-endo and 5-exo selectivity in hypervalent iodine (III) promoted fluorocyclization of unsaturated carboxylic acids or alcohols by difluoroiodotoluene, density functional theory (DFT) studies have been performed to systematically compare both the previous proposed "fluorination first and cyclization later" mechanism and the alternative "cyclization first and fluorination later" mechanism. Our results revealed that the selectivity is mechanism-dependent. The unsaturated alcohol prefers the fluorination first and the 6-endo-tet cyclization later pathway, leading to the experimentally observed 6-endo ether product. In contrast, the unsaturated carboxylic acid plausibly undergoes the 5-exo-trig cyclization first and the fluorination later to the experimentally observed 5-exo lactone product. The pK a property of the functional group of the substrate is found to play a key role in determining the reaction mechanism. The provided insights into the mechanism-dependent selectivity should help advance the development of fluorocyclization reactions with hypervalent iodine reagents.

Photo-thermo catalytic selective oxidation of cyclohexane by In-situ prepared nonstoichiometric Molybdenum oxide and Silver-palladium alloy composite.

The highly selective oxidation of cyclohexane to cyclohexanone and cyclohexanol (KA oil) is one of the most challenging issues in the chemical industry. However, the difficulty in attaining high selectivity and high conversion rate in parallel for the existing catalysts limits its practical application. In this paper, a novel photo-thermo synergistic catalyst was reported for the aerobic oxidation of cyclohexane. The uniform blue MoO3-x nanowires with small diameter stabilized by polyvinyl pyrrolidone (PVP) were synthesized by a hydrothermal method, and a series of MoO3-x-AgPd composite materials of different proportions were prepared by an in-situ reduction process. The morphology, crystalline structure, surface chemical bonding, photoelectrochemical properties of MoO3-x-AgPd composites are thoroughly characterized. The MoO3-x-AgPd composites present significantly increased catalytic performance than MoO3-x nanowires in the photo-thermo synergistic catalytic oxidation of cyclohexane under dry air. The high conversion rate of 11.3% with the KA oil selectivity of 99.0% was achieved by the MoO3-x-Ag20Pd20 composites under photo-thermo catalytic process at 120 ℃, which is 1.5 times of that by MoO3-x nanowires. Under photo-thermo catalytic process, a high cyclohexane conversion rate similar to that of higher temperature thermal catalysis can be obtained at lower reaction temperature, and more cyclohexanol can be produced with a ketone to alcohol (K/A) ratio of 0.254. The significantly enhanced catalytic activity can be attributed to the effective charge transfer in the AgPd alloy nanoparticles, the optimized band gap structure, the suppressed charge recombination, and the promoted photo-thermo synergetic catalytic effect. This work provides a new reference scheme for the design and preparation of high-efficiency photo-thermo catalysts for the selective oxidation of cyclohexane.

Fabrication of graphitic carbon Nitride/Nonstoichiometric molybdenum oxide nanorod composite with the nonmetal plasma enhanced photocatalytic hydrogen evolution activity.

The extended light absorption and the prevented charge recombination are crucial for the graphitic carbon nitride (g-C3N4) based photocatalytic materials. Herein, nonstoichiometric molybdenum oxide (MoO3-x) nanorods with oxygen vacancies were synthesized by a hydrothermal method with trace amount of oleylamine, and the Z-scheme two-dimentional (2D)/one-dimentional (1D) g-C3N4/MoO3-x composites were prepared by a facile electrostatic assembling approach. The blue MoO3-x nanorods with oxygen vacancies are loaded uniformly on the g-C3N4 nanosheets. The g-C3N4/MoO3-x composite materials exhibit strong absorption in the visible and near-infrared light regions, and the improved charge separation efficiency through the Z-scheme charge transfer mechanism. The g-C3N4/MoO3-x composite presents a significantly improved photocatalytic hydrogen generation activity with good cycling stability compared with sonicated g-C3N4 nanosheets. The best hydrogen generation activity of 209.2 µmol·h-1 under solar light irradiation and the highest apparent quantum efficiency of 4.4% irradiated at 365 nm are obtained by the g-C3N4/MoO3-x composite with a mass percent of 27.5%, which is 2.63 times of g-C3N4. The weight ratios and the content of oxygen vacancies in the small-size MoO3-x nanorods have a significant influence on the photocatalytic hydrogen performance. Moreover, effective photocatalytic overall water splitting can be achieved with the H2 and O2 evolution rates of 0.755 and 0.368 µmol∙h-1 by the g-C3N4/MoO3-x composite. The novel g-C3N4/MoO3-x composite will have broad prospects in the field of photocatalytic applications.

New 3',8''-linked biflavonoids from Selaginella uncinata displaying protective effect against anoxia.

Seven 3',8''-linked bioflavonoids, including one new compound, (2''S)-2'', 3''-dihydroamentoflavone-4'-methyl ether and six known compounds: (2S)-2,3- dihydroamentoflavone-4'-methyl ether, (2S,2''S)-2,3,2'',3''-tetrahydroamento- flavone-4'-methyl ether, (2S,2''S)-tetrahydroamentoflavone, (2S)-2,3-dihydro- amentoflavone and (2''S)-2'',3''-dihydroamentoflavone (6) and amentoflavone, were isolated from the 60% ethanolic extract of Selaginella uncinata (Desv.) Spring. The structures of these compounds were elucidated mainly by analysis of their 1D and 2D NMR spectroscopic data, and their absolute configurations were determined by circular-dichroism (CD) spectroscopy. All the seven compounds showed protective effect against anoxia in the anoxic PC12 cells assay, in which compound 6 displayed particularly potent activity.

Enhanced performance of a surface plasmon resonance-based immunosensor for the detection of glycocholic acid.

The concentration of glycocholic acid (GCA) in urine and blood is an important biomarker for liver cancer. Monitoring of GCA depends to a large extent on the availability of appropriate analytical techniques. In this work, based on the immobilization of GCA-OVA onto the sensor chip surface, a label-free competitive inhibition immunoassay for the determination of GCA with the surface plasmon resonance (SPR) technique was developed. The proposed SPR immunosensor is simple to prepare, recyclable and exhibits excellent sensitivity to GCA (a linear range of 13.3-119.4 ng mL-1 and a limit of detection (LOD) of 2.5 ng mL-1), which was 14 times lower than that of the traditional immunoassay. Excellent recoveries and correlation between these two methods were observed (R2 = 0.995). Hence, it can be proved that the SPR immunosensor could be used to achieve rapid and sensitive quantitative detection of GCA in real urine samples and meet clinical needs.

Methyl 4-bromo-3-hy-droxy-benzoate.

In the title compound, C(8)H(7)BrO(3), the meth-oxy-carbonyl group is twisted at a dihedral angle of 8.06 (4)° with respect to the benzene ring. In the crystal, mol-ecules are connected by O-H⋯O hydrogen bonds into helical chains running along the b axis.

(3E,5E)-3,5-Bis(4-hy-droxy-benzyl-idene)oxan-4-one.

In the title compound, C(19)H(16)O(4), there are two 4-hy-droxy-benzyl substituents on the oxan-4-one (tetra-hydro-pyran-4-one) ring, which exhibits an envelope conformation. The dihedral angles between pyran-one ring and the two benzene rings are 26.69 (9) and 36.01 (9)° while the benzene rings make a dihedral angle of 20.88 (10)°. In the crystal, mol-ecules are linked by inter-molecular O-H⋯O hydrogen bonds into a supra-molecular three-dimensional twofold inter-penetrating hydrogen-bonded network.

1,3-Bis[4-(meth-oxy-carbon-yl)benz-yl]benzimidazolium bromide monohydrate.

In the title compound, C(25)H(23)N(2)O(4) (+)·Br(-)·H(2)O, the dihedral angles between the benzimidazole ring system and the two benzene rings are 87.77 (11) and 63.05 (11)°; the dihedral angle between the two benzene rings is 66.25 (13)°. The crystal structure exhibits C-H⋯O and O-H⋯Br inter-actions; it is also stabilized by π-π stacking inter-actions, with a face-to-face separation of 3.456 Šbetween parallel benzimidazole ring systems.

(3E,5E)-3,5-Bis(4-hy-droxy-3,5-di-methoxy-benzyl-idene)oxan-4-one monohydrate.

In the title compound, C(23)H(24)O(8)·H(2)O, the six-membered ring of the oxan-4-one (tetra-hydro-pyran-4-one) ring displays an envelope conformation with the heterocyclic O atom at the flap position. The dihedral angles between the terminal benzene rings is 37.23 (10)°. Classical intermolecular O-H⋯O and weak C-H⋯O hydrogen bonds are present in the crystal structure.

Recent Advances on Imidazolium-Functionalized Organic Cationic Polymers for CO2 Adsorption and Simultaneous Conversion into Cyclic Carbonates.

The cycloaddition reaction of CO2 with various epoxides to generate cyclic carbonates is one of the most promising and efficient approaches for CO2 fixation. Typical imidazolium-based ionic liquids possessing electrophilic cations and nucleophilic halogen anions have been identified as excellent and environmentally friendly candidates for synergistically activating epoxides to convert CO2 . Therefore, the feasible construction of a series of imidazolium-functionalized organic cationic polymers can bridge the gap between homogeneous and heterogeneous catalysis, thereby obtaining highly selective CO2 adsorption and simultaneous conversion ability. This Review describes the recent advancements made with regard to the design and synthesis of this type of polymeric networks having imidazolium functionality. They are considered as an outstanding heterogeneous catalyst for the cycloaddition of CO2 to epoxides. Based on the perspective from the design of building blocks to the synthesis of cationic polymers, the focus mainly lies on how to introduce imidazole units into the material backbone via a covalent linking approach and how to incorporate other active sites capable of activating CO2 and/or epoxides into such polymeric materials.