Genome-Wide Identification and Expression Patterns of Cucumber Invertases and Their Inhibitor Genes.

Invertases and their inhibitors play important roles in sucrose metabolism, growth and development, signal transduction, and biotic and abiotic stress tolerance in many plant species. However, in cucumber, both the gene members and functions of invertase and its inhibitor families remain largely unclear. In this study, in comparison with the orthologues of Citrullus lanatus (watermelon), Cucumis melo (melon), and Arabidopsis thaliana (Arabidopsis), 12 invertase genes and 12 invertase inhibitor genes were identified from the genome of Cucumis sativus (cucumber). Among them, the 12 invertase genes were classified as 4 cell wall invertases, 6 cytoplasmic invertases, and 2 vacuolar invertases. Most invertase genes were conserved in cucumber, melon, and watermelon, with several duplicate genes in melon and watermelon. Transcriptome analysis distinguished these genes into various expression patterns, which included genes CsaV3_2G025540 and CsaV3_2G007220, which were significantly expressed in different tissues, organs, and development stages, and genes CsaV3_7G034730 and CsaV3_5G005910, which might be involved in biotic and abiotic stress. Six genes were further validated in cucumber based on quantitative real-time PCR (qRT-PCR), and three of them showed consistent expression patterns as revealed in the transcriptome. These results provide important information for further studies on the physiological functions of cucumber invertases (CSINVs) and their inhibitors (CSINHs).

Formation of n-Hexane-in-DMF Nonaqueous Pickering Emulsions: ABC Triblock Worms versus AB Diblock Worms.

Nonaqueous Pickering emulsions exhibit promising applications in many industrial areas but have been relatively less studied in the past. In this study, n-hexane-in-DMF nonaqueous Pickering emulsions stabilized by core cross-linked copolymer worms with mixed shells are demonstrated for the first time. Core cross-linked copolymer worms with mixed shells were prepared by seeded reversible addition-fragmentation chain transfer (RAFT) quasi-solution polymerization. Specifically, polystyrene-poly(4-vinylpyridine) (PS-P4VP) diblock copolymer worms were first prepared via RAFT-mediated dispersion polymerization in toluene under the given conditions using PS as both the macro-CTA and the stabilizer block. After the chemical cross-linking of P4VP cores, PS-P4VP diblock copolymer worms were chain-extended with LMA in DMF/toluene (1:9, weight ratio) mixed solvents, producing core cross-linked PS-P4VP-PLMA worms with PS/PLMA mixed shells. The as-prepared core cross-linked PS-P4VP-PLMA worms with mixed PS/PLMA shells were further utilized as Pickering emulsifiers for the generation of nonaqueous n-hexane-in-DMF Pickering emulsions. The emulsifying performances of mixed-shell copolymer worms were compared with those of their spherical and linear analogues with entirely identical chemical compositions as well as PS-P4VP diblock copolymer worm precursors, respectively.

CuCl2·2H2O/TBHP mediated synthesis of ß-enaminones via coupling reaction of vinyl azides with aldehydes.

A facile and efficient oxidative functionalization of vinyl azides with aldehydes furnishing a diverse array of ß-acylated enaminones was developed. The cross coupling was accomplished in the presence of CuCl2·2H2O/TBHP and produced the desired ß-acylated enaminones in a (Z)-stereo-selective and atom-economic manner, which make this protocol particularly attractive. In the transformation, the new C-C and C-N bonds were formed via a one-pot strategy including the process of radical addition and recombination.

H2O2-mediated room temperature synthesis of 2-arylacetophenones from arylhydrazines and vinyl azides in water.

An environmentally benign, cost-efficient and practical methodology for the room temperature synthesis of 2-arylacetophenones in water has been discovered. The facile and efficient transformation involves the oxidative radical addition of arylhydrazines with α-aryl vinyl azides in the presence of H2O2 (as a radical initiator) and PEG-800 (as a phase-transfer catalyst). From the viewpoint of green chemistry and organic synthesis, the present protocol is of great significance because of using cheap, non-toxic and readily available starting materials and reagents as well as amenability to gram-scale synthesis, which provides an attractive strategy to access 2-arylacetophenones.

An efficient domino strategy for synthesis of 3-substituted 4-oxo-4,5-dihydro-1H-pyrrolo[3,2-c]pyridine derivatives in water.

A strategy for catalyst-free domino reaction of 4-aminopyridin-2(1H)-ones, arylglyoxal hydrates and different 1,3-dicarbonyl compounds in water has been established. The mild and efficient procedure afforded pyrrolo[3,2-c]pyridine derivatives with 76-94% yields after simple crystallization. The present procedure shows promising characteristics, such as readily available starting materials, the use of water as reaction media, simple and efficient one-pot operation, and avoiding the need for any hazardous or expensive catalysts.

Amphiphilic Double-Brush Copolymers with a Polyurethane Backbone: A Bespoke Macromolecular Emulsifier for Ionic Liquid-in-Oil Emulsion.

The study on ionic liquid (IL)-based emulsions is very interesting due to the "green" quality and potential wide applications of ILs, whereas the emulsifiers for the formation of IL-based emulsions are extremely limited and mainly centered on low molecular weight surfactants. In this work, synthesis of amphiphilic double-brush copolymers (DBCs) and their application as bespoke macromolecular emulsifiers for the formation of IL-containing non-aqueous emulsions are described. DBCs consisted of a polyurethane (PU) backbone and poly(N,N-dimethyl acrylamide) (PDMA) and poly(methyl methacrylate) (PMMA) chains that were grafted simultaneously at the same reactive site along the PU backbone (PU-g-PDMA/PMMA), which were synthesized through the combination of polyaddition and the reversible-deactivation radical polymerization reactions. Highly stable [Bmim][PF6]-in-benzene emulsions could be gained by adopting PU-g-PDMA/PMMA DBCs as macromolecular emulsifiers at a low content, such as 0.025 wt %. On the basis of the stability and the size of emulsion droplets, PU-g-PDMA/PMMA DBCs exhibited much better emulsifying performances than their analogues, including PU-g-PDMA, PU-g-PMMA, and PDMA-b-PMMA copolymers. Such excellent emulsifying performances of PU-g-PDMA/PMMA DBCs were due to high interfacial activities. PU-g-PDMA/PMMA DBCs exhibited higher capabilities in lowering the interfacial tension of the [Bmim][PF6]-benzene interface than their analogues. A large energy barrier to desorption of adsorbed PU-g-PDMA/PMMA DBCs from the interface contributed to high stability of the [Bmim][PF6]-in-benzene emulsion.

Pickering Emulsions Stabilized by Diblock Copolymer Worms Prepared via Reversible Addition-Fragmentation Chain Transfer Aqueous Dispersion Polymerization: How Does the Stimulus Sensitivity Affect the Rate of Demulsification?

Responsive Pickering emulsions exhibit promising application in industry owing to the integration of the high storage stability with on-demand demulsification. In this study, stimuli-responsive Pickering emulsions stabilized by poly[oligo(ethylene glycol) methyl ether methacrylate]15-b-poly(diacetone acrylamide)120 (E15D120) worms were indicated, in which E15D120 worms were prepared via reversible addition-fragmentation chain transfer-based aqueous dispersion polymerization using thermo-sensitive POEGMA15 as both the stabilizer block and macro-chain transfer agent. The factors influencing the morphologies of copolymers during polymerization-induced self assembly have been investigated. A series of different morphological polymer nanoparticles including spheres, worms, and vesicles could be produced through rational synthesis. E15D120 worms demonstrated excellent emulsifying performances and could be used as emulsifiers to form n-dodecane-in-water Pickering emulsions at a low content. The formed n-dodecane-in-water Pickering emulsions revealed a slow demulsification at pH 10 or 70 °C or pH 10/70 °C combinations, and several hours were needed for the demulsification of Pickering emulsions. However, n-dodecane-in-water Pickering emulsions displayed a rapid demulsification (∼10 min) at an elevated temperature, such as 90 °C. The different demulsification rates were attributed to different sensitivities of E15D120 worms to external stimuli. Pickering emulsions integrating a rapid responsive demulsification with a slow one would be well satisfactory on different occasions.

Simple and efficient one-pot multi-step strategy for the synthesis of 2-substituted (1,2,5-triarylpyrrolo[3,2-c]pyridin-3-yl)-N-arylacetamide derivatives in water.

A novel one-pot multi-step domino strategy for the synthesis of functionalized 2-substituted acetic acids, 2-substituted (1,2,5-triarylpyrrolo[3,2-c]pyridin-3-yl)acetates and 2-substituted-(1,2,5-triarylpyrrolo[3,2-c]pyridin-3-yl)-N-arylacetamides has been established from inexpensive and readily available starting materials. The reaction can be easily performed by employing different substrates via a one-pot multi-step domino reaction. The target products can be easily obtained with satisfactory yields by only simple recrystallization from a mixture of hot 95% ethanol and N,N-dimethylformamide. The reaction features of readily available starting materials, broad substrate scope, bond-forming efficiency, simple one-pot multi-step synthesis as well as green reaction media, make the procedure highly useful for the construction of potential pharmacological heterocyclic molecules.

Metallic C5N monolayer as an efficient catalyst for accelerating redox kinetics of sulfur in lithium-sulfur batteries.

Lithium-sulfur battery is one of the most promising applicants for the next generation of energy storage devices whose commercial applications are impeded by the key issue of the shuttle effect. To overcome this obstacle, various two-dimensional (2D) carbon-based metal-free compounds have been proposed to serve as anchoring materials for immobilizing soluble lithium polysulfides (LiPs), which however suffer from low electronic conductivity implying unsatisfactory performance for catalyzing sulfur redox. Therefore, we have predicted metallic C5N monolayers, possessing hexagonal (H) and orthorhombic (O) phases, exhibiting excellent performance for suppressing the shuttle effect. First-principles simulations demonstrate that O-C5N could serve as a bifunctional anchoring material due to its strong adsorption capability to LiPs and excellent catalytic performance for sulfur redox with active sites from both basal plane and zigzag edges. Furthermore, the rate of Li2S oxidation over O-C5N is fast due to the low energy barrier of 0.93 eV for Li2S decomposition. While for H-C5N, only N atoms located at the armchair edges can efficiently trap LiPs and boost the formation and dissociation of Li2S during discharge and charge processes, respectively. The current work opens an avenue of designing 2D metallic carbon-based anchoring materials for lithium-sulfur batteries, which deserves further experimental research efforts.

Janus-Like Single-Chain Polymer Nanoparticles as Two-in-One Emulsifiers for Aqueous and Nonaqueous Pickering Emulsions.

The exploration of Pickering emulsions is very significant owing to their versatile and important applications in many scopes. In this study, synthesis of a novel kind of single-chain polymer nanoparticle (SCPN) and its stabilized Pickering emulsions were demonstrated. To this end, linear-dendritic diblock copolymers consisting of poly((2-dimethylamino) ethyl methacrylate) (PDMAEMA) blocks and four-generation dendritic aliphatic polyester blocks (G4) have been first synthesized by the combination of click chemistry and reversible addition-fragmentation chain transfer (RAFT) polymerization reaction. The subsequent intramolecular cross-linking of the PDMAEMA block of PDMAEMA-b-G4 copolymers in DMF using 1,4-diiodobutane as cross-linkers afforded Janus-like SCPNs that exhibited a cross-linked PDMAEMA head tethered by a short dendritic tail. The molecular weight and distribution together with the structure of polymers were carefully characterized by GPC and NMR spectroscopy. By the employment of the as-synthesized Janus-like SCPNs as Pickering emulsifiers, aqueous and nonaqueous Pickering emulsions including water-in-oil and oil-in-oil as well as ionic liquid-in-oil were generated. Under the same conditions, it was found that the long-term stabilities of Pickering emulsions stabilized by Janus-like SCPNs were superior to those of Pickering emulsions stabilized by their linear quaternized PDMAEMA-b-G4 by CH3I analogous.

Triple-Responsive Pickering Emulsion Stabilized by Core Cross-linked Supramolecular Polymer Particles.

It is significant to explore multiresponsive Pickering emulsions because of their flexibility in terms of demulsification in comparison with the single stimuli-responsive systems. In this study, we described a triple-responsive oil-in-water Pickering emulsion that was stabilized by amphiphilic core cross-linked supramolecular polymer particles (CCSPs). For this purpose, ß-cyclodextrin-terminated poly(N-isopropylacrylamide) (PNIPAM-ß-CD) and azobenzene-capped poly(4-vinylpyridine) (P4VP-azo) were separately synthesized by reversible addition-fragmentation chain transfer polymerization. By virtue of the inclusion interaction between the ß-CD host and the azobenzene guest in dimethyl sulfoxide, the amphiphilic supramolecular block copolymer, poly(4-vinylpyridine)-b-poly(N-isopropylacrylamide) (P4VP-b-PNIPAM), was formed. CCSPs were prepared through the combination of the self-assembly of P4VP-b-PNIPAM in the selective solvent, water, and the cross-linking of the P4VP core with 1,4-dibromobutane. Due to thermoresponsiveness of PNIPAM shells and the supramolecular linkages between the cross-linked hydrophobic P4VP core and hydrophilic PNIPAM shells, the as-prepared CCSPs exhibited temperature-, light-, and amantadine hydrochloride guest-triggered morphological transitions. Such triple-responsive morphological transitions gifted CCSPs stabilized oil-in-water Pickering emulsion with flexible demulsification in response to various factors, such as thermo, light, and amantadine hydrochloride or their combinations. Such triple-responsive oil-in-water Pickering emulsion also provided an ideal platform for heterogeneous reactions conducted at the oil-water interface. A large interfacial area and responsive demulsification allowed the reaction to be performed with an efficient and sustainable pattern.

Six-Step Total Synthesis of (±)-Conolidine.

A concise total synthesis of (±)-conolidine, a potent nonopioid analgesic, in 19% overall yield is described here. A gold(I)-catalyzed Conia-ene reaction (Toste cyclization) and a Pictet-Spengler reaction served as key transformations for assembling the 1-azabicyclo[4.2.2]decane core and defining the geometry of the exocyclic double bond. The activation energies of formation of the vinyl-gold intermediates were calculated and revealed a silyl enol ether with an unprotected indole moiety as a suitable precursor for the Toste cyclization. This six-step synthesis did not involve any nonstrategic redox manipulations.

Pd(II)-Catalyzed Denitrogenative and Desulfinative Addition of Arylsulfonyl Hydrazides with Nitriles.

A Pd(II)-catalyzed denitrogenative and desulfinative addition of arylsulfonyl hydrazides with nitriles has been successfully achieved under mild conditions. This transformation is a new method for the addition reaction to nitriles with arylsulfonyl hydrazides as arylating agent, thus providing an alternative synthesis of aryl ketones. The reported addition reaction is tolerant to many common functional groups, and works well in the presence of electron-donating and electron-withdrawing substituents. Notably, the reported denitrogenative and desulfinative addition was also appropriate for alkyl nitriles, making this newly developed transformation attractive.

Facile, eco-friendly, catalyst-free synthesis of polyfunctionalized quinoxalines.

A novel, facile and eco-friendly synthesis of quinoxalines from [Formula: see text] and 1,2-diamines was developed. An attractive feature of this protocol is that the desired products could be generated efficiently in water and without any catalyst, which is in accordance with the aim of green chemistry. A plausible mechanism has been proposed.

A novel quinazoline-based analog induces G2/M cell cycle arrest and apoptosis in human A549 lung cancer cells via a ROS-dependent mechanism.

6-amino-4-(4-phenoxyphenylethylamino)quinazoline (QNZ) is an excellent quinazoline-containing NF-κB inhibitor also acting as a novel anticancer agent. Considering both the medicinal significance of quinazoline scaffold and the tunable functionality of Michael acceptor-centric pharmacophores in the electrophilicity-based prooxidant strategy, we designed a novel QNZ-inspired electrophilic molecule QNZ-A by introducing a Michael acceptor unit at position-6 of quinazoline ring in QNZ. Our results identified QNZ-A as a promising selective cytotoxic agent against A549 cells. QNZ-A, by virtue of its Michael acceptor unit, induced reactive oxygen species (ROS) accumulation associated with collapse of the redox buffering system in A549 cells. This caused up-regulation of p53-inducible p21 and down-regulation of redox sensitive Cdc25C along with Cyclin B1/Cdk1, leading to a G2/M cell cycle arrest and final cell apoptosis. By contrast, QNZ-B, a reduction product of QNZ-A lacking the Michael acceptor unit failed to induce ROS generation and all these cell cycle-related events. In conclusion, this work provided a successful example of designing QNZ-directed anticancer agent by a ROS-promoting strategy and identified QNZ-A as a selective anticancer agent against A549 cells through G2/M cell cycle arrest and apoptosis via a ROS-dependent mechanism.

Mechanism and Origin of Chemical Selectivity in Oxaziridine-Based Methionine Modification: A Computational Study.

Oxaziridine-based redox sulfur imidation provides a breakthrough strategy for selective modification at methionine in proteins. The chemoselectivity of imidization (N-transfer) over oxidation (O-transfer) of the thioether functionality of methionine, and the modification selectivity of methionine over other amino acids, are the key features of this strategy. To elucidate the detailed reaction mechanism and the origin of the reported chemoselectivity, a theoretical investigation on the oxaziridine-based methionine modification reaction is reported. It is found that both the N-transfer and O-transfer pathways occur in a concerted mechanism. Distortion/interaction-activation strain model analysis indicates that the N-transfer chemoselectivity is mainly controlled by the interaction energy. Orbital and charge analysis further supports that the interaction energy resulting from the orbital interaction favors the N-transfer pathway at the early stage of the reaction. The calculated reactivity of eight potential amino acid competitors with the oxaziridine shows excellent selectivity for methionine modification, consistent with the experimental observations. The scarcity of active species in neutral aqueous solution leads to the weak reactivity of tyrosine, lysine, and arginine. The stronger charge-transfer interactions between methionine and the oxaziridine compared with that for the other amino acids also play vital roles in the modification selectivity.

Selective Synthesis of Alkynylated Isoquinolines and Biisoquinolines via RhIII Catalyzed C-H Activation/1,3-Diyne Strategy.

Described herein is a convenient and highly selective synthesis of alkynylated isoquinolines and biisoquinolines from various aryl ketone O-pivaloyloxime derivatives and 1,3-diynes via rhodium-catalyzed C-H bond activation. In this transformations, alkynylated isoquinolines, 3,4'- and 3,3'-biisoquinolines could be obtained respectively through changing the reaction conditions. Mechanistic investigation revealed that the C-H activation of aryl ketone O-pivaloyloxime was the key step to this reaction.

Mechanistic Study on Gold-Catalyzed Highly Selective Hydroamination of Alkylidenecyclopropanes.

Density functional theory calculations have been carried out to study the mechanism of the gold-catalyzed highly selective hydroamination of alkylidenecyclopropanes. Two main mechanisms (i.e., double-bond activation-first and three-membered-ring activation-first mechanisms) have been examined. The double-bond activation-first mechanism results in the alkene hydroamination product, and it mainly consists of three steps: C-N bond formation, C-C bond rotation, and protodeauration (rate-determining step). Meanwhile, the three-membered-ring activation-first mechanism finally produces allylic amines, and it occurs via the ring-opening (rate-determining step), C-N bond formation, and protodeauration steps. The calculation results show good agreement with the experimental outcomes on the chemo-, regio-, and diastereoselectivity. On this basis, we found that the regioselectivity is caused by the C-C bond rotation step, while the diastereoselectivity is determined by both the C-C bond rotation and the protodeauration steps in the double-bond activation-first mechanism.

Facile synthesis of benzoindoles and naphthofurans through carbonaceous material-catalyzed cyclization of naphthylamines/naphthols with nitroolefins in water.

A facile and efficient approach has been established for the synthesis of benzoindole and naphthofuran derivatives via the metal-free cyclization reaction of nitroolefins with naphthylamines/naphthols. Various substituted benzoindoles and naphthofurans are obtained in good to excellent yields. Moreover, the ability to recycle the carbonaceous material makes this method quite cost-effective and environmentally benign compared to traditional acid-catalyzed methods. Theoretical studies indicated that the reaction between naphthylamine and nitroolefin catalyzed by this solid acid was thermodynamically controlled at 60 °C, resulting in the formation of the benzoindoles.

Solvothermal synthesis of stable nanoporous polymeric bases-crystalline TiO2 nanocomposites: visible light active and efficient photocatalysts for water treatment.

Visible light active and stable nanoporous polymeric base-crystalline TiO2 nanocomposites were solvothermally synthesized from in situ copolymerization of divinylbenzene (DVB) with 1-vinylimidazolate (VI) or 4-vinylpyridine (Py) in the presence of tetrabutyl titanate without the use of any other additives (PDVB-VI-TiO2-x, PDVB-Py-TiO2-x, where x stands for the molar ratio of TiO2 to VI or Py), which showed excellent activity with respect to catalyzing the degradation of organic pollutants of p-nitrophenol (PNP) and rhodamine-B (RhB). TEM and SEM images show that PDVB-VI-TiO2-x and PDVB-Py-TiO2-x have abundant nanopores, and TiO2 nanocrystals with a high degree of crystallinity were homogeneously embedded in the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x, forming a stable 'brick-and-mortar' nanostructure. PDVB-VI and PDVB-Py supports act as the glue linking TiO2 nanocrystals to form nanopores and constraining the agglomeration of TiO2 nanocrystals. XPS spectra show evidence of unique interactions between TiO2 and basic sites in these samples. UV diffuse reflectance shows that PDVB-VI-TiO2-x and PDVB-Py-TiO2-x exhibit a unique response to visible light. Catalytic tests show that the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x were active in catalyzing the degradation of PNP and RhB organic pollutants under visible light irradiation. The enhanced activities of the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x were ascribed to synergistic effects between abundant nanopores and the unique optical adsorption of visible light in the samples.