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Hepatic ischemia-reperfusion injury (IRI) is a common pathological process during hepatectomy and liver transplantation and the two primary reasons for hepatic IRI are reactive oxygen species (ROS)-mediated oxidative stress and excessive inflammatory responses. Herein, a novel antioxidant nanodrug (A-MPDA@Fe3O4@PVP) is prepared by employing L -arginine-doped mesoporous polydopamine (A-MPDA) nanoparticles as the carrier for deposition of ultra-small ferric oxide (Fe3O4) nanoparticles and further surface modification with polyvinylpyrrolidone (PVP). A-MPDA@Fe3O4@PVP not only effectively reduces the aggregation of ultra-small Fe3O4, but also simultaneously replicates the catalytic activity of catalase (CAT) and superoxide dismutase (SOD). A-MPDA@Fe3O4@PVP with good antioxidant activity can rapidly remove various toxic reactive oxygen species (ROS) and effectively regulate macrophage polarization in vitro. In the treatment of hepatic IRI, A-MPDA@Fe3O4@PVP effectively alleviates ROS-induced oxidative stress, reduces the expression of inflammatory factors, and prevents apoptosis of hepatocytes through immune regulation. A-MPDA@Fe3O4@PVP can further protect liver tissue by activating the PPARγ/NF-κB pathway. This multiplex antioxidant enzyme therapy can provide new references for the treatment of IRI in organ transplantation and other ROS-related injuries such as fibrosis, cirrhosis, and bacterial and hepatic viral infection. [ABSTRACT FROM AUTHOR]

A base-catalyzed and DMSO-promoted atom economic intramolecular hydroalkoxylation was developed to prepare a variety of pentacyclic chromeno[4,3-b]indolines in good yields with high regioselectivity and diastereoselectivity. Mechanistic studies revealed that DMSO played important roles as a green solvent and an activator of unactivated alkenes via hydrogen-bonding and ion pairing to facilitate a 5-exo-trig cyclization. The present method highlights mild reaction conditions, short reaction time, broad substrate scope, a new application of DMSO, and gram-scalable preparation without column chromatography. [ABSTRACT FROM AUTHOR]

We report a green cascade approach to prepare a variety of 3-aminoindole derivatives in good to excellent yields through an iron(III)-catalyzed dehydrogenative cross-coupling reaction of 2-arylindoles and primary benzylamines under mild reaction conditions. Mechanistic studies show that a cascade reaction involves a tert-butyl nitrite (TBN)-mediated nitrosation of 2-substituted indoles and a 1,5-hydrogen shift to afford indolenine oximes, sequential iron(III)-catalyzed condensation and a 1,5-hydrogen shift over four steps in a one-pot reaction. The reaction shows a broad substrate scope of indoles and benzylamines and tolerates a wide range of functional groups. Moreover, the reaction is easily performed at the gram scale without producing waste after the reaction is completed. The 3-aminoindole product is purified by simple extraction, washing, and recrystallization without flash column chromatography. A double imine ligand containing the 3-aminoindole unit is facile to obtain in a 52% yield in one step. The present method highlights readily available starting materials, a simple purification procedure, and the usage of cheap, nontoxic, and environmentally benign iron(III) catalysts. [ABSTRACT FROM AUTHOR]

We describe a cascade strategy for tri- or tetrafunctionalization of alkenylboronic acids to prepare diverse tetrahydrocarbazol-1-ones and indolo[2,3-a]carbazoles in good yields with N-hydroxybenzotriazin-4-one (HOOBT) and arylhydrazines as oxygen and nitrogen sources, respectively. Mechanistic studies reveal that the domino reaction undergoes the copper-catalyzed Chan–Lam reaction, [2,3]-rearrangement, nucleophilic substitution, oxidation and sequential [3,3]-rearrangement over five steps in a one-pot reaction. The reaction shows a broad substrate scope and tolerates a wide range of functional groups. More importantly, the reaction is easily performed at gram scales and the product is purified by simple extraction, washing, and recrystallization without flash column chromatography. The present protocol features easily available starting materials, high site-marked functionalization, five-step cascade in one pot, multiple C–C/C–O/C–N bond formation, and diversity of indole motifs. [ABSTRACT FROM AUTHOR]

The photoluminescence stability of lanthanide complexes (Lnx) in biological media is of the utmost significance for the construction of optically encoded nano-on-microbeads in multiplex bioassays. Herein, we propose a new type of encoding guest consisting of MOF@MOF nanohybrids, where isomorphic ZIF-8 and ZIF-90 were employed as the core and shell domain, respectively, to separately modulate the hosting and the protection of the inner Lnx guests. Especially, the thin ZIF-90 shell epitaxially grown on the ZIF-8 core was employed as an intermediate layer to facilitate surface covalent fluorination via an aldehyde ligand. Thereby, a superhydrophobic surface was obtained, which led to strong water-resistance of the hybrid nanoparticles, stable host–guest structure, and high quantum yields (19.1%) in biological media. A coating layer of a surface active polymer (polydopamine, PDA) was utilized to conjugate the MOF nanoparticles on polystyrene microspheres for building the second-level host–guest architecture of 3D core–satellite pluralistic hybrids. Finally, single/dual-color encoded beads (EBs) were obtained by altering the ratios of the hybrid MOF guests emitting at different wavelengths. As a proof of concept, the detection of a model tumor marker (alpha-fetoprotein, AFP) was successfully performed using the encoded beads. These findings can pave the way for the rational design of core–shell MOFs and hierarchical structures with high synergy and excellent flexibility toward stable photoluminescence of lanthanide complexes in bioassays. [ABSTRACT FROM AUTHOR]

Twenty-seven 3-(benzo[d]thiazol-2-yl)-4-aminoquinoline derivatives have been designed and synthesized as topoisomerase I inhibitors. The in vitro anti-proliferation evaluation against four human cancer cell lines (MGC-803, HepG-2, T24, and NCI-H460) and one normal cell line (HL-7702) indicated that most of them exhibited potent cytotoxicity. Among them, 5a was identified as the most promising candidate with a low IC50 value of about 2.20 ± 0.14 and was selected for further exploration. Spectroscopic analyses and agarose-gel electrophoresis assays indicated that 5a could interact with DNA and strongly inhibit topoisomerase I (Topo I). Further screening of the Topo I activity of compounds 5b, 5c, 5e, 5f, 5h, 5i, 5j, 5l, and 5n suggested that some of the compounds might exert quite a different cytotoxicity profile to that of 5a. Molecular modeling studies confirmed that 5a adopts a unique mode to interact with DNA and Topo I. Other molecular mechanistic studies suggested that the treatment of MGC-803 cells with 5a induces S phase arrest, up-regulates the pro-apoptotic protein, down-regulates the anti-apoptotic protein, activates caspase-3, and subsequently induces mitochondrial dysfunction so as to induce cell apoptosis. The in vivo efficiency of 5a was also evaluated on MGC-803 xenograft nude mice and the relative tumor growth inhibition was 42.4% at 12 mg kg−1 without an obvious loss in the body weight. [ABSTRACT FROM AUTHOR]

We report a relay catalysis for the highly stereoselective synthesis of densely substituted oxazonine-fused endoperoxides in good yields. This domino reaction is based on an Yb(OTf)3 and visible light promoted [3 + 2] cycloaddition/[3,3]-rearrangement, and in situ [4 + 2] cycloaddition with air in one pot under mild reaction conditions from N-vinyl-α,β-unsaturated nitrones and methylenecyclopropanes, leading to a practical assembly of densely substituted oxazonine-fused endoperoxides containing five stereocenters with a wide substrate scope and excellent diastereoselectivity. Mechanistic studies reveal that the O–O bond of the endoperoxide ring is derived from singlet oxygen (1O2) generated by air under a white LED. Moreover, such an asymmetric relay catalyst has also been realized to afford chiral endoperoxides in good enantioselectivity. Biological tests show that the designed oxazonine-fused endoperoxides significantly inhibited nitric oxide (NO) generation in LPS-stimulated RAW264.7 cells and exhibited their bioactivity as good anti-inflammatory agents. [ABSTRACT FROM AUTHOR]

We report a metal-free, heterogeneous, inexpensive, and environmentally friendly graphene oxide-catalyzed aza-semipinacol rearrangement of 2-(3-methyleneindolin-2-yl)phenols to prepare 2-(indol-2-yl)phenols and benzofuro[3,2-b]indolines containing quaternary carbon centers in good to excellent yields under mild conditions. The detailed studies demonstrate that graphene oxide can function as a heterogeneous catalyst and provide hydrogen bonding and ion pair interactions on the surface to promote the rearrangement process. The substituent effect on the C2-position of indoline is two-fold, affording 2-(indol-2-yl)phenols by aza-semipinacol rearrangement and benzofuro[3,2-b]indolines by 5-exo-trig cyclization. The stereochemistry of the C3-quaternary carbon center generated from the C2-quaternary carbon center of indoline is retained during the rearrangement. More importantly, the graphene oxide can be easily recovered by washing and recycled seven times without loss of catalytic activity. [ABSTRACT FROM AUTHOR]

A general protocol for the construction of novel densely functionalized γ-lactones was developed in good to excellent yields with high diastereoselectivity from easily available N-vinyl-α,β-unsaturated nitrones and ketenes. The reaction involves copper-catalyzed [5 + 2] cycloaddition, N–O bond cleavage, 6π electron cyclization, and aromatization to afford various γ-(pyridin-2-yl)lactones over four step transformations in a single flask. The present method features mild reaction conditions, high atom economy, high regio- and diastereoselectivity, diversity of γ-lactones, and a new application of the O-transfer reaction. [ABSTRACT FROM AUTHOR]

In recent years, another two-dimensional (2D) family, monolayer metal monochalcogenides (group IIIA–VIA), has attracted extensive attention. In this work, we adopt density functional theory (DFT) and the non-equilibrium Green's function (NEGF) method to systematically investigate the ballistic thermoelectric properties of the IIIA–VIA family, including GaS, GaSe, GaTe, InS, InSe, and InTe. Among others, the InTe monolayer possesses the highest figure of merit, ZT = 2.03 at 300 K, due to its ultra-low thermal conductance. Biaxial strain in the range of −10% (compressive) to 10% (tensile) is applied to the InTe monolayer and the strain-induced electronic and thermal transport properties are discussed. The maximum ZT (up to 2.7) for the InTe monolayer at 300 K is achieved under an 8% tensile strain. [ABSTRACT FROM AUTHOR]

An iron(iii)-catalyst controlled cyclization and selective N–O bond cleavage of N-vinyl-α,β-unsaturated nitrones has been achieved under mild conditions to access tetrasubstituted pyridines and 3,5-disubstituted isoxazolines in moderate to good yields. The tetrasubstituted pyridines were afforded with FeCl3 as a catalyst while using FeCl3·6H2O combined with 1,10-phenanthroline delivered isoxazolines. The regioselectivity for cyclization of styrenyl groups in N-vinyl-α,β-unsaturated nitrones was completely different during the formation of pyridines and isoxazolines. A rational mechanism for the formation of pyridines and isoxazolines was proposed based on the further control experimental studies. The isoxazolines can be converted to a novel bidentate N-ligand over four steps and an epoxypyridine scaffold was obtained from N-vinyl nitrone when copper(ii) acetate in combination with the prepared bidentate N-ligand was used. [ABSTRACT FROM AUTHOR]

A variety of 2,3-quaternary fused indolines could be prepared in good yields with high diastereoselectivity from alkynyl tethered oximes and diaryliodonium salts under mild metal-free conditions. The reaction initially goes through a selective N-arylation to provide alkynyl tethered nitrones and regioselectively undergoes an intramolecular (3 + 2) cycloaddition followed by a [3,3]-sigmatropic rearrangement to afford 2,3-quaternary fused indolines in a one-pot fashion. The method features easily available cheap materials, multiple bond formation, gram scalable preparation and diversity of fused indoline scaffolds. [ABSTRACT FROM AUTHOR]

A new family of two-dimensional topological insulator, hydrogenated monolayer Pb2XY (X = Ga/In, Y = Sb/Bi), has been predicted using first-principles density functional theory. The electronic bulk band gap of the proposed systems can be induced in the presence of a spin–orbit coupling effect and its highest value (0.25 eV) was observed in the hydrogenated monolayer Pb2GaBi, which is suitable for practical application. Our simulation study points out that the nanoribbons derived from this new family harbor gapless edge channels. The non-trivial topological nature was further confirmed by calculating the Z2 topological invariant. These novel systems provide a new platform for topological phenomena observation and spintronic applications. [ABSTRACT FROM AUTHOR]

H-Titanate nanotubes (H-TiNTs) were prepared and used as catalysts for the oxidation of dibenzothiophene (DBT), which is typically found in diesel. The catalyst was synthesized through a hydrothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption–desorption. The effects of typical diesel components on sulfur removal from the model oil were also evaluated by adding various amounts of 1-octylene, xylene or cyclohexane to the oxidation system. The H-TiNTs exhibited superior catalytic selectivity in oxidative desulfurization (ODS) without an obvious decrease in activity in the presence of the various diesel compounds. Both UV and Raman spectroscopy analyses revealed that the Ti-hydroperoxide generated from H-TiNTs in the presence of hydrogen peroxide played a crucial role in the selective oxidation process. The oxidation mechanism was also explored. [ABSTRACT FROM AUTHOR]

In this work, for the first time, we systematically investigate the ballistic transport properties of WSe2 nanoribbons using first-principles methods. Armchair nanoribbons with narrow ribbon width are mostly semiconductive but the zigzag nanoribbons are metallic. Surprisingly, an enhancement in thermoelectric performance is discovered moving from monolayers to nanoribbons, especially armchair ones. The maximum room-temperature thermoelectric figure of merit of 2.2 for an armchair nanoribbon is discovered. This may be contributed to by the effects of the disordered edges, owing to the existence of dangling bonds at the ribbon edge. H-passivation has turned out to be an effective way to stabilize the edge atoms, which enhances the thermodynamic stability of the nanoribbons. In addition, after H-passivation, all of the armchair nanoribbons exhibit semiconductive properties with similar band gaps (∼1.3 eV). Our work provides instructional theoretical evidence for the application of armchair WSe2 nanoribbons as promising thermoelectric materials. The enhancement mechanism of the disordered edge effect can also encourage further exploration to achieve outstanding thermoelectric materials. [ABSTRACT FROM AUTHOR]

A novel and efficient approach to the synthesis of 2,5-disubstituted oxazoles is developed via a 1,3-dipolar cycloaddition/ring cleavage/1,2-H migration/denitrogenation/copper-catalyzed aerobic oxidative dehydrogenative cyclization cascade. The desired products can be obtained from readily available aromatic terminal alkenes and azides employing air as the oxidant under mild conditions, and it offers an attractive alternative method for the synthesis of oxazole derivatives. [ABSTRACT FROM AUTHOR]

Hepatic ischemia-reperfusion injury (IRI) is a common pathological process during hepatectomy and liver transplantation and the two primary reasons for hepatic IRI are reactive oxygen species (ROS)-mediated oxidative stress and excessive inflammatory responses. Herein, a novel antioxidant nanodrug (A-MPDA@Fe 3 O 4 @PVP) is prepared by employing L-arginine-doped mesoporous polydopamine (A-MPDA) nanoparticles as the carrier for deposition of ultra-small ferric oxide (Fe 3 O 4 ) nanoparticles and further surface modification with polyvinylpyrrolidone (PVP). A-MPDA@Fe 3 O 4 @PVP not only effectively reduces the aggregation of ultra-small Fe 3 O 4 , but also simultaneously replicates the catalytic activity of catalase (CAT) and superoxide dismutase (SOD). A-MPDA@Fe 3 O 4 @PVP with good antioxidant activity can rapidly remove various toxic reactive oxygen species (ROS) and effectively regulate macrophage polarization in vitro . In the treatment of hepatic IRI, A-MPDA@Fe 3 O 4 @PVP effectively alleviates ROS-induced oxidative stress, reduces the expression of inflammatory factors, and prevents apoptosis of hepatocytes through immune regulation. A-MPDA@Fe 3 O 4 @PVP can further protect liver tissue by activating the PPARγ/NF-κB pathway. This multiplex antioxidant enzyme therapy can provide new references for the treatment of IRI in organ transplantation and other ROS-related injuries such as fibrosis, cirrhosis, and bacterial and hepatic viral infection.

A variety of 4-(trichloromethyl)pyrido[2',1':3,4]pyrazino[2,1- b ]quinazolinones were prepared in moderate to good yields with high regioselectivity through intramolecular 6- endo-dig cyclization and trichloromethylation of N 3-alkynyl-2-pyridinyl-tethered quinazolinones in chloroform. Mechanistic studies revealed that chloroform might serve as a trichloromethyl anion precursor. Furthermore, the reaction could be easily performed on gram scales and an estrone-derived 4-(trichloromethyl)pyrido[2',1':3,4]pyrazino[2,1- b ]quinazolinone was prepared over five steps. The present method features broad substrate scope, good functional group tolerance, new dearomatization of pyridine rings, and chloroform as the trichloromethylation reagent.

A variety of functionalized spiroindolenine-3,3'-pyrrolo[2,1- b ]quinazolinones were prepared in good to excellent yields through a gold(I)-catalyzed dearomative cyclization of N -alkynyl quinazolinone-tethered C2-substituted indoles. This reaction features a broad substrate scope, good functional group tolerance, and easy gram-scale preparation and transformations. Furthermore, biological activity studies showed that most of the obtained spiroindolenine-3,3'-pyrrolo[2,1- b ]quinazolinone scaffolds showed potential as good anti-inflammatory agents.

A variety of functionalized sulfonium ylides were prepared in good yields through MnSO 4 -promoted S-O bond cleavage from activated alkynes and sulfoxides. Experimental results showed that the MnSO 4 catalyst played important roles in accelerating the reaction and promoting the [1,3]-rearrangement of the S-O bond. Furthermore, the product was easily obtained on a gram scale by simple recrystallization without column chromatography. The obtained product can be converted to new sulfonium ylides and undergo cycloaddition with an alkyne to afford a trisubstituted furan scaffold.

The research on graphene-based anode materials for high-performance lithium-ion batteries (LIBs) has been prevalent in recent years. In the present work, carbon-coated SnO 2 riveted on a reduced graphene oxide sheet composite (C@SnO 2 /RGO) was fabricated using GO solution, SnCl 4 , and glucose via a hydrothermal method after heat treatment. When the composite was exploited as an anode material for LIBs, the electrodes were found to exhibit a stable reversible discharge capacity of 843 mA h g -1 at 100 mA g -1 after 100 cycles with 99.5% coulombic efficiency (CE), and a specific capacity of 485 mA h g -1 at 1000 mA g -1 after 200 cycles; these values were higher than those for a sample without glucose (SnO 2 /RGO) and a pure SnO 2 sample. The favourable electrochemical performances of the C@SnO 2 /RGO electrodes may be attributed to the special double-carbon structure of the composite, which can effectively suppress the volume expansion of SnO 2 nanoparticles and facilitate the transfer rates of Li + and electrons during the charge/discharge process., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Various α-aminooxy amides bearing a quaternary carbon at the α-position were prepared in good to excellent yields under mild reaction conditions from N-vinyl nitrones and α-bromohydroxamates. The N-vinyl nitrones tolerate a wide range of N-vinyl fluorenone nitrones and N-vinyl isatin nitrones. Mechanistic studies show that the reaction initially proceeds through [3 + 3] cycloaddition between N-vinyl nitrones and aza-oxyallyl cations generated from α-bromohydroxamates to afford six-membered N,O-heterocycles, followed by double C-N bond cleavage in the presence of the Sc(OTf)3 catalyst. A selective N-O bond cleavage of the obtained α-aminooxy amides is also realized under Fe/NH4Cl conditions. Furthermore, gram-scalable preparations of α-aminooxy amides are easily achieved.

Nanocarriers with high local curvatures hold a great potential of inducing effective penetration of intracellular barriers and cytosolic delivery of membrane-impermeable drugs. However, the fine control of the sharp edges and their morphological effects inside cells remains largely unexplored. Herein, a nanocarrier system of hybrid mesoporous nanorods with six-arm star-shaped end faces and groove-patterned lateral faces was developed to maximize surface regions with high local curvatures for enhancing membrane destabilization. Specifically, twisted (right-handed) nanorods (TNR, diameter ∼120, aspect ratio 4-5) with a hexagon cross-section from a templated synthesis were modified by amino groups to promote surface coating of a wet-adhesive polymer, i.e. polydopamine (PDA). An edge-preferential deposition of PDA by local curvature effects led to the protective etching of silica, and in turn, the formation of nanorods with varying groove depths at different volumes of the aqueous coating solution. Finally, branched polyethylene imine (PEI) was grafted on the exterior surface of the nanorods for enhancing the dispersity and cellular uptake rate. As verified by elaborate in vitro investigations, the configuration of nanorods with the sharpest edges/deepest grooves can be rotated to a lying-down/upright mode in order to minimize/maximize the membrane tension during the interaction with membranes, which consequently resulted in highly efficient lysosomal escape despite the relatively lower uptake degree. The successful delivery of vorinostat (SAHA, a FDA-approved histone deacetylase inhibitor) and inhibition of cancer cells demonstrated the attractive ability of the nanocarriers in drug delivery.

β-Acetoxy alcohols can be synthesized in good yields with excellent diastereoselectivity from tertiary alcohols through PhI(OAc)2-mediated metal-free β-acetoxylation. Mechanistic studies showed that the β-acetoxylation process might undergo dehydration and sequential highly regioselective and diastereoseletive dioxygenation. Gram scale and diverse useful scaffolds could be prepared via this β-acetoxylation process.

In this work, for the first time, we systematically investigate the ballistic transport properties of WSe2 nanoribbons using first-principles methods. Armchair nanoribbons with narrow ribbon width are mostly semiconductive but the zigzag nanoribbons are metallic. Surprisingly, an enhancement in thermoelectric performance is discovered moving from monolayers to nanoribbons, especially armchair ones. The maximum room-temperature thermoelectric figure of merit of 2.2 for an armchair nanoribbon is discovered. This may be contributed to by the effects of the disordered edges, owing to the existence of dangling bonds at the ribbon edge. H-passivation has turned out to be an effective way to stabilize the edge atoms, which enhances the thermodynamic stability of the nanoribbons. In addition, after H-passivation, all of the armchair nanoribbons exhibit semiconductive properties with similar band gaps (∼1.3 eV). Our work provides instructional theoretical evidence for the application of armchair WSe2 nanoribbons as promising thermoelectric materials. The enhancement mechanism of the disordered edge effect can also encourage further exploration to achieve outstanding thermoelectric materials.