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Tropospheric ozone pollution has been a major environmental issue, and mitigation of this persistent problem requires a comprehensive understanding of the sensitivity of ozone to its precursors, i.e., nitrogen oxides (NOx) and volatile organic compounds (VOCs). Recent studies have proposed several "new" reactive nitrogen chemical processes, including additional sources of nitrous acid, heterogeneous uptake of dinitrogen pentoxide, and production of nitryl chloride. These processes significantly affect the budgets of radicals and NOx and hence the formation of ozone. In present study, we aim to investigate to what extent these processes alter the relationships between ozone and its precursors. A revised Weather Research and Forecasting model coupled with Chemistry incorporating the "new" nitrogen chemistry was adopted to simulate the ozone sensitivity regime in China in summer. The results showed that nitrogen chemistry changed the ozone sensitivity regime for approximately 40% of the simulated area with human influence, mostly from VOC-sensitive or NOx-sensitive regimes to mixed-sensitive regime. The nitrogen chemistry changed the isopleth plots of the ozone peak values for major cities, suggesting a different strategy for controlling ozone pollution. This study underscores the need to consider unconventional nitrogen chemistry in air quality models used in the design of ozone control strategies. [ABSTRACT FROM AUTHOR]

Polymeric nanoparticles have been widely investigated as insulin delivery systems for oral administration. However, the toxic nature of many artificial polymers hampers their effective application, creating a demand for the further exploration of alternative natural polymers. In addition, ethnobotanical research has reported that over 800 plant species have a hypoglycemic function, some of which are polymers. For the advantages of both areas to be combined, the aim of this work was to choose an organic hypoglycemic polymer and prepare it into an insulin carrier to build a dual-functional oral insulin delivery system. We found that the insulin loading rate, release mode, thermostability, and both in vitro and in vivo absorption and efficacy varied with the different modifications of polygalacturonic acid (PGLA) nanoparticulate backbones. By in vivo pharmaceutical testing and constantly monitoring the symptoms of type 1 diabetic (T1D) rats, we ascertained the hypoglycemic function of the nanoparticles and showed that overall diabetic symptoms were ameliorated after the long-term daily administration of nanoparticles with no significant damage to organ structure or cell viability. [ABSTRACT FROM AUTHOR]

A dramatic improvement of the toughness of polydicyclopentadiene (PDCPD) composite containing low amounts of vinyl-functionalized SiO2 was achieved, and the toughening mechanism was investigated. Considering the nonpolarity of the DCPD monomer and the probability of covalent bonding between SiO2 and DCPD, vinyl-functionalized SiO2 (V-SiO2) with a high content of vinyl groups was prepared by a facile, reproducible, one-step, remodeled synthetic sol-gel process. The V-SiO2 was characterized with respect to the content of vinyl groups, particle size, and morphology by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), dynamic light scattering (DLS), and field-emission scanning electron microscopy (FE-SEM). PDCPD/V-SiO2 composites were prepared by in situ polymerization. The mechanical properties of the PDCPD/V-SiO2 composites were investigated by universal testing machine (UTM) and dynamic mechanical analysis (DMA). A slight decrease in the yield strength was observed with increasing loading of V-SiO2, whereas the elongation at break increased substantially from 9.0% to 143.4% and the tensile toughness increased by a factor of 14 compared to that of neat PDCPD when just 0.2 wt % V-SiO2 had been added. The dramatic toughness enhancement is attributed to the formation of microvoids and microcracks during the process of stretching, which can absorb a great deal of energy. [ABSTRACT FROM AUTHOR]

Ultrasensitive and specific in situ imaging of gene expression is essential for molecular medicine and clinical theranostics. We develop a novel fluorescence in situ hybridization (FISH) strategy based on a new branched hybridization chain reaction (bHCR) for efficient signal amplification in the FISH assay and a ligase-mediated discrimination for specific mutation detection. To our knowledge, this is the first time that HCR has been realized for mutation detection in the FISH assay. In vitro assay shows that the ligation-bHCR strategy affords high specificity in discriminating single-nucleotide variation in mRNA, and it generates a highly branched polymeric product that confers more efficient amplification or better sensitivity than HCR. Imaging analysis reveals that ligation-bHCR generates highly bright spot-like signals for localization of individual mRNA molecules, and spot signals of different colors are highly specific in genotyping point mutation of individual mRNA. Moreover, this strategy is shown to have the potential for quantitative imaging of the expression of mRNA at the single-cell level. Therefore, this strategy may provide a new promising paradigm in developing highly sensitive and specific FISH methods for various diagnostic and research applications. [ABSTRACT FROM AUTHOR]

Four novel matrine-based alkaloids (1-4) were isolated from the seeds of Sophora alopecuroides. Compounds 1 and 2 possess unprecedented 6/6/6/4 and 6/5/6/6 ring systems, respectively, while 3 and 4 are a pair of stereoisomeric matrine-acetophenone alkaloids with an unusual skeleton. Their structures were elucidated by means of spectroscopic methods and single-crystal X-ray diffraction. Hypothetical biogenetic pathways for 1-4 are proposed, and their antiviral activities are also discussed. [ABSTRACT FROM AUTHOR]

A series of 2,5,8,11-tetraalkenyl perylene bisimide (PBI) derivatives were synthesized through Ru(II)- or Rh(III)-catalyzed regio- and steroselective oxidative C-H olefination in one step. The optical electronic and self-assembly of the 2,5,8,11-substituted PBIs were investigated, which showed great potential in optoelectronic applications. [ABSTRACT FROM AUTHOR]

A (ONSO)CrCl complex-based binary catalyst for efficient ring-opening copolymerization (ROCOP) of epoxide and norbornene anhydride (NA) in a stereoselective manner to afford polymers with variable stereoisomerism is reported. The role of (ONSO)CrCl complex on the cis/trans selectivity of resulting polyester as well as enhancement of the reaction rate has been revealed. The formation of chelates between the endo-diester unit of the polyester chain and the metal center plays a determinate role in the stereoselectivity of the cis-(endo, endo)-polyester in solution copolymerization of endo-NA with epoxides in the presence of metal complex. Additionally, the stereostructure of resulting polyester is also dependent on the polymerization method, NA type, and the bulkiness of the substituent of the formed ester units in the polyester chain. Accordingly, a proposed mechanistic pathway for the stereostructure formation of polyesters is provided. [ABSTRACT FROM AUTHOR]

Two micromesoporous composites of MCM-41/13X are synthesized through a two-step crystallization process and a one-step crystallization process, respectively. The results of X-ray diffraction, nitrogen adsorption-desorption isotherms, Fourier transform infrared spectroscopy, and transmission electron microscopy results show that the as-prepared samples possessed both micropores and mesopores. The materials take advantage of not only the large adsorption capacity and thermal stability of the microporous material, but also the rapid diffusion and mass transfer of mesoporous materials, which lead to improve CO2 adsorption capacities compared to the pure microporous or mesoporous materials. [ABSTRACT FROM AUTHOR]

The metastable semiconductor phase allows for the exploration of unusual properties and functionalities of abnormal structures, although it is often difficult to prevent thermodynamic transformations to lower energy structures from higher, unfavored energy states. Here, we show for the first time the preparation of high-quality ultralong metastable zincblende (ZB)-MnSe nanowires with a four-coordinate structure via solution-solid-solid (SSS) growth in a mild solution-phase synthetic environment (120-220 °C) in the presence of a trace amount of Ag(I). The metastable ZB-MnSe nanowires are stabilized kinetically due to the catalysis of early formed body-centered cubic (bcc) fast-ionic (superionic) Ag2Se nanocrystals from the Ag(I) source, and the ZB-MnSe nanowires grow epitaxially along the ⟨110⟩ axis rather than the ⟨111⟩ axis, as commonly observed for typical four-coordinate Grimm-Sommerfeld bonding solids. Our method provides a new route for the growth of metastable nanostructures. [ABSTRACT FROM AUTHOR]

A convenient and highly α-regioselective strategy for the synthesis of 3-prenyl-3-hydroxy-2-oxindoles has been developed starting from isatins and prenylzinc with good to excellent yields. This protocol provides a straightforward and practical way to introduce an α-prenyl moiety into the C-3 position of isatins. The advantages of this reaction are use of the cheap and readily available reagents, operational simplicity, and wide substrate scope. Furthermore, this transformation was applied to the synthesis of several oxindole-containing natural products, which further demonstrated the synthetic utility of this methodology. [ABSTRACT FROM AUTHOR]

Pd-catalyzed regioselective coupling of β-C(sp²)-H bonds in aromatic amines protected by oxalyl amide with carbon monoxide is reported. The reaction could tolerate various functional groups and could afford good to excellent yields of the corresponding 3,4-dihydroisoquinolinone derivatives. Remarkably, it could also tolerate β-arylethylamino acid and thiopheneethylamine derivatives, thus showing their potential for producing several important units for bioactive compound synthesis. [ABSTRACT FROM AUTHOR]

Radical chain reactions leading to C-C bond formation are widely used in organic synthesis, and initiation of the radical chain process usually requires thermolabile radical initiators. Recent studies on transition-metal-free cross-coupling reactions between aryl halides and arenes have demonstrated an unprecedented initiation system for radical chain reactions, where the combination of simple organic additives and a base was used in place of conventional radical initiators. Among them, the combination of N,N'-dimethylethylenediamine (DMEDA) and t-BuOK is one of the most efficient and representative reaction systems, and the radical initiation mechanism of this system has attracted considerable research interest. In this study, through the combination of kinetic studies, deuterium labeling experiments, and DFT calculations, the radical initiation mechanism of the diamine-promoted cross-coupling reaction was carefully reinvestigated. In light of the present study, a mechanistic network of radical initiation in the DMEDA/t-BuOK system was revealed, which differs dramatically from the previously realized single radical initiation pathway. In this mechanism, the diamine acts as a hydrogen atom donor and plays a dual role as both "radical amplifier" and "radical regulator" to initiate the radical chain process as well as to control the concentration of reactive radical species. This represents a rare example of a structurally simple molecule playing such a subtle role in the radical chain reaction system. The present study sheds some light on the novel radical initiation mode in transition-metal-free cross-coupling reactions following a base-promoted homolytic aromatic substitution (BHAS) mechanism, and may also help to understand the mechanism of relevant reactions. [ABSTRACT FROM AUTHOR]

A thorough understanding of the antimicrobial mechanisms of graphene materials (GMs) is critical to the manipulation of highly efficient antimicrobial nanomaterials for future biomedical applications. Here we review the most recent studies of GM-mediated antimicrobial properties. This review covers the physicochemical properties of GMs, experimental surroundings, and selected microorganisms as well as the interaction between GMs and selected microorganisms to explore controversial antimicrobial activities. Finally, we rationally analyze the strengths and weaknesses of the proposed mechanisms and provide new insights into the remaining challenges and perspectives for future studies. [ABSTRACT FROM AUTHOR]

The self-assembly of Ln(ClO4)3·6H2O and Zn(OAc)2·2H2O with pyrazine-2-carboxylic acid (HL) results in the formation of three novel nanosized {LnIII24ZnII6} triangular metallorings, [Gd24Zn6L24(OAc)22(µ3-OH)30(H2O)14](ClO4)7(OAc)·2CH3OH·26H2O (1), [Tb24Zn6L24(OAc)22(μ3-OH)30(CH3O)2(CH3OH)2(H2O)10](ClO4)5(OH)·6CH3OH·12H2O (2), and (H3O)[Dy24Zn6L24(OAc)22(μ3-OH)30(H2O)14](ClO4)7(OAc)2·4CH3OH·22H2O (3), having the largest nuclearity among any known Ln/Zn clusters. Magnetic and luminescent studies reveal the special prowess for each lanthanide complex. Magnetic studies reveal that 1 exhibits a significant cryogenic magnetocaloric effect with a maximum -ΔSm (isothermal magnetic entropy change) value of 30.0 J kg-1 K-1 at 2.5 K and 7 T and that a slow magnetization relaxation is observed for the dysprosium analogue. In addition, the solid-state photophysical properties of 2 display strong characteristic TbIII photoluminescent emission in the visible region, suggesting that TbIII-based luminescence is sensitized by the effective energy transfer from the ligand HL to the metal centers. [ABSTRACT FROM AUTHOR]

In order to evaluate the impact of bridge conformation on electronic coupling in donor-bridge-acceptor triad systems, two Mo2 dimers, [Mo2(DAniF)3]2[μ-1,4-{C(O)NH}2-Naph] (1, DAniF = N,N'-di(p-anisyl)formamidinate and Naph = naphthalenyl) and [Mo2(DAniF)3]2[μ-1,4-(CS2)2-2,5-Me2C6H2] (2), have been synthesized and structurally characterized. These two compounds feature a large dihedral angle (>60°) between the central aromatic ring and the plane defined by the Mo-Mo bond vectors, which is distinct from the previously reported phenylene bridged analogues [Mo2(DAniF)3]2[μ-1,4-{C(O)NH}2-ph] (I) and [Mo2(DAniF)3]2[μ-1,4-(CS2)2-C6H4] (II), respectively. Unusual optical behaviors are observed for the mixed-valence (MV) species (1+ and 2+), generated by single-electron oxidation. While 2+ exhibits a weak intervalence charge transfer (IVCT) absorption band in the near-IR region, the IVCT band is absent in the spectrum of 1+, which is quite different from what observed for I+ and II+. Optical analyses, based on superexchange formalism and Hush model, indicate that, in terms of Robin-Day classification, mixed-valence species 1+ belongs to the electronically uncoupled Class I and complex 2+, with Hab = 220 cm-1, is assigned to the weakly coupled Class II. Together with I+ and II+, the four MV complexes complete a transition from Class I to Class II-III borderline as a result of manipulating the geometric topology of the bridge. Given the structural and electronic features for the molecular systems, the impacts of electrostatic interaction (through-space) and electron resonance (through-bond) on electronic coupling are discussed. [ABSTRACT FROM AUTHOR]

Small molecules or metal ions can be employed as catalysts to accelerate metalloporphyrin formation. Herein, we for the first time report the coordination reaction between cadmium(II) and 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin can be accelerated by nitrogen-doped graphene quantum dots (NGQDs). This catalytic reaction results in the change of the absorption of porphyrins and the fluorescence of NGQDs as a result of the inner filter effect (IFE) of the porphyrins on the assembled NGQDs. Both signals can be used for rapid and sensitive determination of metal ions. The present work promises a novel strategy for constructing sensors for metal ions. [ABSTRACT FROM AUTHOR]

Exposureto polycyclic aromatic hydrocarbons (PAHs) in the foodchain is the major human health hazard associated with the DeepwaterHorizon oil spill. C1-chrysenes are representative PAHs present inthe crude oil and have been detected in contaminated sea food in amountsthat exceed their permissible safety thresholds. We describe the metabolismof the most carcinogenic C1-chrysene regioisomer, 5-methylchrysene(5-MC), in human HepG2 cells. The structures of the metabolites wereidentified by HPLC-UV-fluorescence detection and LC-MS/MS. 5-MC-tetraol,a signature metabolite of the diol-epoxide pathway, was identifiedas reported previously. Novel O-monosulfonated-5-MC-catechol isomersand O-monomethyl-O-monosulfonated-5-MC-catechol were discovered, andevidence for their precursor ortho-quinones was obtained. The identitiesof O-monosulfonated-5-MC-1,2-catechol, O-monomethyl-O-monosulfonated-5-MC-1,2-catechol,and 5-MC-1,2-dione were validated by comparison to authentic synthesizedstandards. Dual metabolic activation of 5-MC involving the formationof bis-electrophiles, i.e., a mono-diol-epoxide and a mono-ortho-quinonewithin the same structure, bis-diol-epoxides, and bis-ortho-quinonesis reported for the first time. Evidence was also obtained for minormetabolic conversion of 5-MC to form monohydroxylated-quinones andbis-phenols. The identification of 5-MC-tetraol, O-monosulfonated-5-MC-1,2-catechol,O-monomethyl-O-monosulfonated-5-MC-1,2-catechol, and 5-MC-1,2-dionesupports metabolic activation of 5-MC by P450 and AKR isozymes followedby metabolic detoxification of the ortho-quinone through interceptionof redox cycling by COMT and SULT isozymes. The major metabolites,O-monosulfonated-catechols and tetraols, could be used as biomarkersof human exposure to 5-MC resulting from oil spills. [ABSTRACT FROM AUTHOR]

An intramolecular [4 + 2] cycloaddition reaction of o-quinonemethides generated from salicylaldehydes and α-prenylated alcohols is described. In the presence of a catalytic amount of benzenesulfonic acid (BSA), the reaction proceeded smoothly in EtOH to afford furo[3,2-c]benzopyrans through a three-bond forming process in moderate to excellent yields with high diastereoselectivity. This reaction provides a simple and straightforward protocol to efficiently construct furo[3,2-c]benzopyran skeletons. A possible mechanism involving hemiacetal formation/hetero-Diels–Alder reaction is proposed to rationalize the observed results. [ABSTRACT FROM AUTHOR]

The article talks about supramolecular chirality in self-assembled systems. Topics include features of supramolecular chirality such as photoirradiation, chemical additives and sonication; helicity or helical chirality; and applications of supramolecular chirality including supramolecular chiroptical switches, supramolecular chiral catalysis and circularly polarized luminescence.

A facilestrategy has been demonstrated for the selective synthesisof highly stereoregular polyesters with cis-2,3-(exo,exo) or trans-2,3-(exo,endo) repeating units by the organocatalystsmediated alternating copolymerization of cyclohexene oxide and norborneneanhydride (NA) stereoisomers. The geometrical structure of polyestercan be tuned simply by modulating the type of NA isomers (endo- or exo-NA), monomer feed ratio, andreaction temperature. The cis- (>99%) and trans-polyesters (>99%) exhibit high glass transitiontemperatureup to 129.8 and 115.9 °C, respectively. The resulting polyestersprovide a versatile platform to incorporate various functional groupsthrough the robust thiol–ene reaction of the pendant norbornenylgroups. [ABSTRACT FROM AUTHOR]

A family of four Dy3 triangular circular helicates, namely, [Dy3(HL)3(μ3-OH)(CH3OH)2(H2O)4]Cl1.5(OH)0.5·0.5H2O (1), [Dy3(HL)3(μ3-OH)(CH3OH)3(H2O)2Cl]Cl·CH3OH (2), [Dy3(HL)3(μ3-OH)(CH3OH)3(H2O)2(NO3)](NO3) (3), and [Dy3(HL)3(μ3-OH)(CH3OH)4(ClO4)](ClO4) (4), were assembled by the reaction of a new acylhydrazone ligand H3L [(3-hydroxy)-N'-((8-hydroxyquinolin-2-yl)methylene)picolinohydrazide] with different dysprosium(III) salts. These compounds represent the first examples of μ-Oacylhydrazone-bridged triangular Dy3 SMMs reported to date. Alternating-current magnetic susceptibility measurements revealed that compounds 1 and 2 show typical SMM behavior with the occurrence of multiple relaxation processes, whereas frequency-dependent relaxation signals without χ" peaks were observed in 3 and 4 under zero dc field. Such distinct dynamic behaviors are attributed to the different sizes of the terminal coordination solvent/anions (H2O, Cl-, NO3-, and ClO4- for 1-4, respectively) at the Dy3 site. Here, similar deviations from the ideal monocapped square-antiprismatic (C4v) geometry defined by SHAPE software were observed around local Dy centers in 1 and 2, whereas the situation was completely different in 3 and 4 as a result of the presence of relatively large anions in the limited space defined by three intercrossing rigid hydrazone ligands. [ABSTRACT FROM AUTHOR]

This paper reports the influence of emulsification process on the packing of layered double hydroxide (LDH) particles at the aqueous/oil phase interface and the properties of the resulting Pickering emulsions. Emulsions prepared by ultrasonication display superior long-term stability and gel-like characteristics at the dispersed phase volume fraction well below the random close packing limit, whereas emulsions with same compositions prepared by vortex mixing show some extent of sedimentation and liquid-like behaviors. Rheological measurements demonstrate that the zero-shear elastic modulus and yield stress of gel-like emulsions exhibit power-law dependences on particle concentration and independence on aqueous/oil phase ratio. The microstructural origin of this behavior is investigated by optical microscopy, revealing the droplets become strongly adhesive and a heterogeneous percolating network is formed among neighboring droplets. Fluorescent confocal microscopy measurements further confirm that the droplet adhesion is due to particle layers bridging opposite interfaces. In contrast, homogeneous, isolated, and densely packed droplets are present in emulsions prepared by vortex mixing, which results in these systems being dominantly viscous like the suspending fluid. This study shows that the emulsification process can be used as a trigger to modify long-term stability and rheology of solid-stabilized multiphase mixtures, which greatly expands their potential technological applications. [ABSTRACT FROM AUTHOR]

Freestanding nanoparticle membranes over circular wells are prepared by utilizing surface engineering. The crucial step of this method is the hydrophobic treatment of the substrate surface, which causes the water droplet to be suspended over wells during drying. Consequently, the nanoparticle monolayer self-assembled at the surface of the water droplet would drape itself over wells instead of being dragged into wells and ruptured into patches after the evaporation of water. This scenario was confirmed by the results of control experiments with changes in the hydrophobicity of the surface and the depth of wells. Moreover, the NaCl crystallization experiment provides additional evidence for the dynamic process of drying. Freestanding nanoparticle membranes with different nanoparticle core sizes and different lengths of ligands have been successfully prepared using the same route. The Young's modulus of one typical kind of prepared freestanding nanoparticle membrane was measured with force microscopy. [ABSTRACT FROM AUTHOR]

Ithas been demonstrated for the first time that α-phosphonovinyltosylates could efficiently couple with a range of arylboronic acidsto access α-arylethenylphosphonates. The unprecedented procedureexhibits excellent functional group tolerance, giving the terminalvinylphosphonates in good to excellent isolated yields (60–99%)under mild reaction conditions. [ABSTRACT FROM AUTHOR]

This study demonstrates a rapid visualization assay for on-spot sensing of alcohol content as well as for discriminating methanol-containing beverages with solvent stimuli-responsive supramolecular ionic material (SIM). The SIM is synthesized by ionic self-assembling of imidazolium-based dication C10(mim)2 and dianionic 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) in water and shows water stability, a solvent stimuli-responsive property, and adaptive encapsulation capability. The rationale for the visualization assay demonstrated here is based on the combined utilization of the unique properties of SIM, including its water stability, ethanol stimuli-responsive feature, and adaptive encapsulation capability toward optically active rhodamine 6G (Rh6G); the addition of ethanol into a stable aqueous dispersion of Rh6G-encapsulated SIM (Rh6G-SIM) destructs the Rh6G-SIM structure, resulting in the release of Rh6G from SIM into the solvent. Alcohol content can thus be visualized with the naked eyes through the color change of the dispersion caused by the addition of ethanol. Alcohol content can also be quantified by measuring the fluorescence line of Rh6G released from Rh6G-SIM on a thin-layer chromatography (TLC) plate in response to alcoholic beverages. By fixing the diffusion distance of the mobile phase, the fluorescence line of Rh6G shows a linear relationship with alcohol content (vol %) within a concentration range from 15% to 40%. We utilized this visualization assay for on-spot visualizing of the alcohol contents of three Chinese commercial spirits and discriminating methanol-containing counterfeit beverages. We found that addition of a trace amount of methanol leads to a large increase of the length of Rh6G on TLC plates, which provides a method to identify methanol adulterated beverages with labeled ethanol content. This study provides a simple yet effective assay for alcohol content sensing and methanol differentiation. [ABSTRACT FROM AUTHOR]

A hydrothermal approach for the cutting of boron-doped graphene (BG) into boron-doped graphene quantum dots (BGQDs) has been proposed. Various characterizations reveal that the boron atoms have been successfully doped into graphene structures with the atomic percentage of 3.45%. The generation of boronic acid groups on the BGQDs surfaces facilitates their application as a new photoluminescence (PL) probe for label free glucose sensing. It is postulated that the reaction of the two cis-diol units in glucose with the two boronic acid groups on the BGQDs surfaces creates structurally rigid BGQDs-glucose aggregates, restricting the intramolecular rotations and thus resulting in a great boost in the PL intensity. The present unusual "aggregation-induced PL increasing" sensing process excludes any saccharide with only one a"5-diol unit, as manifested by the high specificity of BGQDs for glucose over its close isomeric cousins fructose, galactose, and mannose. It is believed that the doping of boron can introduce the GQDs to a new kind of surface state and offer great scientific insights to the PL enhancement mechanism with treatment of glucose. [ABSTRACT FROM AUTHOR]

The magnetic relaxation dynamics of low-coordinate DyIII and ErIII complexes, namely three-coordinate ones with an equatorially coordinated triangle geometry and five-coordinate ones with a trigonal bipyramidal geometry, have been exploited for the first time. The three-coordinate Er-based complex is the first equatorially coordinated mononuclear Er-based single-molecule magnet (SMM) corroborating that simple models can effectively direct the design of target SMMs incorporating 4f-elements. [ABSTRACT FROM AUTHOR]

In this work, we designed a novel detection strategy to realize simultaneous determination of multiplex lectin by labeling glucosamine (G1) and galactosamine (G2) with different-colored semiconductor quantum dots (QDs). On the basis of the agglutination of the aminosugar-labeled QDs induced by the exclusive binding between the lectin and sugar on the QDs surfaces, the fluorescence emission of the QDs supernatant after centrifugation decreased with relevant lectin concentration [i.e., when concanavalin A (Con A) exists alone], only green color fluorescence emission from QDs-G1 supernatant decreased, so it is peanut agglutinin (PNA) and red color fluorescence emission from QDs-G2. Moreover, since QDs can be simultaneously excited with multiple fluorescence colors and have a larger Stokes shift than organic fluorophores, when both Con A and PNA are present in the sample, both of the green and red color fluorescence emission from QDs-G1 and QDs-G2 supernatant would decrease, thus realizing the simultaneous determination of Con A and PNA. The detection limits of Con A and PNA are 0.30 and 0.18 nM (3σ), respectively. Furthermore, the present detection method not only can determine the protein/lectins by fluorescence spectral method but also can realize visualization detection by UV lamp illumination. To the best of our knowledge, this is the first report of such analytical method in multiple and simultaneous lectin detection. [ABSTRACT FROM AUTHOR]

A simple and sensitive photoluminescence (PL) assay for the activity of a protein kinase based on the selective aggregation of phosphorylated peptide-graphene quantum dot (GQD) conjugates triggered by Zr4+ ion coordination has been established. With more sophisticated design of the peptide substrate sequences, detecting other enzymes could also be possible. Under optimal conditions, a linear relationship between the decreased PL intensity of peptide-GQD conjugates and the concentration of casein kinase II (CK2) in the range from 0.1 to 1.0 unit mL-1 with a detection limit of 0.03 unit mL-1 (3σ) was obtained. The EC50 value (i.e., the enzyme concentration producing 50% substrate conversion) for CK2 was evaluated to be 0.34 unit mL-1. The proposed method showed potential applications in kinase inhibitor screening. To demonstrate the potential of this GQD-based platform for screening of kinase inhibitors in real biological systems, the inhibition of CK2 phosphorylation activity by four different inhibitors (ellagic acid, 5,6-dichlorobenzimidazole-l-β-D-ribofuranoside, emodin, and quercetin) was tested in human serum by comparing signals from samples incubated with the inhibitors against that without any inhibitor. As expected, in the presence of inhibitors, the PL intensity increased with increasing inhibitor efficiency. The IC50 value (inhibitor concentration producing 50% inhibition) for ellagic acid was estimated to be 0.041 μM. The developed protocol provides a new and promising tool for the analysis of both the enzyme and its inhibitors with low cost and excellent performance. [ABSTRACT FROM AUTHOR]

The reactions between a salen ligand N,N′-bis(3-methoxysalicylidene)-1,2-cyclohexanediamine (H2L) and different metal salts lead to the formation of four 3d-4f [MDy] and [MDy]2 (M = Zn/Cu) compounds, where the [MDy]2 can be considered as resulting from the assembly of two [MDy] building blocks. Field-induced single molecule magnet (SMM) behavior was observed in [ZnDy] and [CuDy] compounds with the effective suppression of fast quantum tunneling under a dc field. Moreover, the [ZnDy]2 compound demonstrates typical SMM behavior, which may originate from the high axial anisotropy of Dy ions correlating to the change of coordination geometry and enhanced ferromagnetic interactions between Dy ions via the coupling of two [DyZn] units. The result suggests the positive effects of coupling blocking units to enhance their SMM behavior, presenting a promising strategy for constructing efficient heterometallic SMMs. [ABSTRACT FROM AUTHOR]

A one-pot synthetic strategy for diarylamines using only aromatic amines as starting materials has been developed. This method involved a PhI(OAc)2-induced oxidative dearomatization of N-sulfonyl protected para-substituted anilines, a Bi(OTf)3-catalyzed imino exchange reaction between N-sulfonyl cyclohexadienimines and aromatic amines, and a CF3COOH/Zn mediated reductive aromatization of the resulting N-aryl cyclohexadienimines. [ABSTRACT FROM AUTHOR]

Two new dinuclear dysprosium compounds, [Dy2(HL1)2(PhCOO)2(CH3OH)2] (l) and [Dy2(L2)2(NO3)2-(CH3OH)2]-2CH3OH-4H2O(2), have been assembled through applying two ligands with different coordination pockets. The different features of ligands H3L1 and H2L2 result in the distinct coordination geometry of the metal ions in their respective structures. The Dy ions of complexes 1 and 2 were linked by the alkoxide- and hydrazone-O, and display the hula hoop-like and the broken hula hoop-like coordination geometry, respectively. Consequendy, these two compounds show distinct magnetic properties. Complex 1 behaves as a single molecule magnet (SMM) with rather slow quantum tunneling rate (... > 274 ms), while no SMM behavior was observed for complex 2. In addition, the comparison of the structural parameters among the similar Dy2 SMMs with hula hoop-like geometry reveals the significant role played by coordination geometry and magnetic interaction in modulating the relaxation dynamics of SMMs. [ABSTRACT FROM AUTHOR]

This study demonstrates a facile yet effective strategy for amperometric assay of electrochemically inactive heparin based on an anion-exchange mechanism with polyimidazolium (Pim) as the synthetic receptor. The rationale for the amperometric heparin assay is essentially based on the different binding affinity of the synthetic Pim receptor toward electrochemically active ferricyanide (Fe(CN)63-) and electrochemically inactive heparin. To accomplish the amperometric assay, Pim is first synthesized and used as the artificial receptor to recognize the anions (i.e., Fe(CN)63- and heparin). The stronger binding affinity of the synthetic Pim receptor toward heparin than toward Fe(CN)63- essentially validates the amperometric heparin assay through an anion-exchange mechanism with the decrease in the redox peak current of Fe(CN)63- adsorbed onto the Pim film as the signal readout. The anion exchange between Fe(CN)63- and heparin on the Pim receptor is verified by cyclic voltammetry and Fourier transform IR and UV-visible spectroscopies. The ratio of the current decrease shows a linear relationship with heparin concentration with a concentration range from 0.5 to 10 µM. With animal experiments by dosing intraperitoneally and collecting the serum sample, the method is demonstrated to be potentially useful for investigating heparin metabolism in the biological system. This study not only provides a simple yet effective route to a heparin assay but also opens a new way to developing amperometric methods for electrochemically inert species by fully utilizing the supramolecular principles. [ABSTRACT FROM AUTHOR]

It is remarkable that Brønsted acidic ionic liquids(BAILs)have several unique advantages in the acid-catalysis reaction, whichavoids the technical issues raised from mineral acids. The kineticsfor the ketalization of cyclohexanone with glycol using BAILs as catalystswas therefore studied for the first time. The effects of various parameterssuch as kind of BAILs, temperature, catalyst loading, and molar ratioof the reactants on the conversion of cyclohexanone were examinedin detail, and a pseudohomogeneous (PH) kinetic model was used successfullyto correlate the experimental data in the temperature range from 313.15to 343.15 K. The kinetic parameters such as reaction rate constant,activation energy, and chemical equilibrium constant then were proposedand utilized to interpret the catalytic activities of the BAILs catalysts.It was also validated from the comparison of catalytic performanceamong the BAILs, H2SO4, and solid resin thatthe BAILs were considered to be environmentally friendly and highefficient catalysts, and were suggested to replace mineral and solidacids in the synthesis of ketal. [ABSTRACT FROM AUTHOR]

3-Alkenylation or 3-alkylation of indole with propargylic alcohols could be efficiently controlled by the catalyst. In the presence of triflic acid, 3-alkenylation of indole occurred and a 3,4-dihydrocyclopenta[b] indole skeleton was effectively constructed in moderate to excellent yields via a cascade process. In the presence of Cu(OTf)2, 3-alkylation of indole resulted in the formation of 3-propargylic indole, which could be further converted into 2-iodo-1,4-dihydrocyclopenta[b]indoles in the presence of N-iodosuccinimide and boron trifluoride etherate. Possible mechanisms related to the 3-alkenylation or 3-alkylation of indole and their extension to the formation of 3,4-dihydrocyclopenta[b]indoles or 1,4-dihydrocyclopenta[b]indoles are postulated and discussed. [ABSTRACT FROM AUTHOR]

Crystallization and coarsening kinetics of nonisothermalprecipitationprocess of rutile in modified Ti-bearing blast furnace slag were discussed.The modified slag was analyzed by X-ray diffraction (XRD) and scanningelectron microscope (SEM) and EDX. The experimental results showedthat the cooling rate has an important effect on precipitation ofthe rutile phase. Low cooling rate is in favor of the increase inthe volume fraction of rutile phase in Ti-bearing blast furnace slagand the growth of rutile phase. The volume fraction of rutile phasewas approximately described by JMAK equation. The experiential expressionof average crystal radius for rutile phase was also obtained. [ABSTRACT FROM AUTHOR]

The oligopeptide transporter PEPT1 is considered-as a valuable target (or prodrug design, but its 3D structure and substrate speificity of PEPT1 are not fully understood. In tins study, we designed, a focused dipeptide conjugated azidothymidine (AZT) library and described a convenient and efficient solid phase synthesis scheme based on click chemistry. Over 60 candidate structures containing various dipeptide sequences were obtained with high purity, and screened in a PEPT1 overerxpressing cell model for their abilities to compete with the known ligand cephalexin. Some of the compounds selected to have medium or high affinity were tested for tbeir in vivo transport in a single-pass intestinal perfusion experiment. Results showed that the designed library contained some new structure features that have high affinities toward PEPT1 and could be further explored for their application in prodrug design and development. [ABSTRACT FROM AUTHOR]

Controlled manipulation of individual micro- and nanoscaleobjectsrequires the use of trapping forces that can be focused and translatedwith high spatial and time resolution. We report a new strategy thatuses the flow of mobile microvortices to trap and manipulate singleobjects in fluid with essentially no restrictions on their materialproperties. Fluidic trapping forces are generated toward the centerof microvortices formed by magnetic microactuators, that is, rotatingnanowire or self-assembled microbeads, actuated by a weak rotatingmagnetic field (|B|< 5 mT). We demonstrate precisemanipulation of single microspheres and microorganisms near a solidsurface in water. [ABSTRACT FROM AUTHOR]

Self-assembly of several low-molecular-weight l-glutamic acid-based gelators, which individually formed helical nanotube or nanofiber structures, was investigated in the presence of Cu2誉. It was found that, when Cu2솫 added into the system, the self-assembly manner changed significantly. Only in the case of bolaamphiphilic glutamic acid, N,N′-hexadecanedioyl-di-l-glutamic acid (L-HDGA), were the hydrogel formation as well as the nanotube structures maintained. The addition of Cu2誉 caused a transition from monolayer nanotube of L-HDGA to a multilayer nanotube with the thickness of the tubular wall about 10 nm. For the other amphiphiles, the gel was destroyed and nanofiber structures were mainly formed. The formed Cu2+containing nanostructures can function as an asymmetric catalyst for Diels–Alder cycloaddition between cyclopentadiene and aza-chalcone. In comparison with the other Cu2+containing nanostructures, the Cu2+mediated nanotube structure showed not only accelerated reaction rate, but enhanced enantiomeric selectivity. It was suggested that, through the Cu2駧扪힝 nanotube formation, the substrate molecules could be anchored on the nanotube surfaces and produced a stereochemically favored alignment. When adducts reacted with the substrate, both the enantiomeric selectivity and the reaction rate were increased. Since the Cu2+mediated nanotube can be fabricated easily and in large amount, the work opened a new way to perform efficient chiral catalysis through the supramolecular gel. [ABSTRACT FROM AUTHOR]

Metal-semiconductor hybrid heteronanostructures may exhibit not only a combination of properties from the disparate components but also further enhanced property tunability and new synergistic properties that arise from the interactions between the metal and semiconductor components. Here we demonstrate that the Au–Cu2O hybrid core–shell nanoparticles not only combine the optical signatures of Cu2O nanoshells and the plasmonic properties of Au nanoparticles but exhibit further enhanced and expanded plasmonic tunability as well due to the dielectric properties of the Cu2O shells surrounding the Au cores. We have developed a robust wet chemistry approach through which we can fine-control several important geometrical parameters of the Au–Cu2O core–shell nanoparticles, such as Cu2O shell thickness, size of the Au core, and the spacing between the core and shell, to systematically and selectively fine-tune the synergistic light absorption and scattering properties of the particles over a broad spectral range across the visible and near-infrared regions. We have further performed Mie scattering theory calculations to theoretically interpret the correlation between the geometrical parameters and optical characteristics of the Au–Cu2O hybrid nanoparticles. Such optical tunability achieved through the fine-control over core and shell geometries is believed to be important to the optimization of the overall performance of hybrid heteronanostructure-based materials and/or devices for photonic, electronic, and optoelectronic applications. [ABSTRACT FROM AUTHOR]

We report on the spontaneous formation of superhydrophobic poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP)/graphene composite microspheres with uniform size via gelation. When the suspension of PVDF-HFP/graphene (0.25 wt. % with respect to PVDF-HFP) in DMF adsorbs water vapor, it changes to a hybrid gel. A dried porous gel is obtained after solvent exchange and freeze drying. Morphology characterization shows that this hybrid gel is composed of PVDF-HFP/graphene microspheres with a diameter of 8–10 μm. In contrast, PVDF-HFP solution gives rise to a cellular microstructure following the same experimental procedures. We further elucidate the formation mechanism on the basis of the characterization by freeze fracture transmission electron microscopy, X-ray diffraction, and differential scanning calorimetry characterizations. Furthermore, contact angle measurements of water on PVDF-HFP/graphene indicates that the hydrophobic nature of PVDF-HFP combined with the micro/nanoscale hierarchical texture creates a superhydrophobic surface. Such superhydrophobic microspheres may have potential applications as water-repellent catalyst-supporting materials. [ABSTRACT FROM AUTHOR]

We report a new approach to selectively deliver antimicrobials to the sites of bacterial infections by utilizing bacterial toxins to activate drug release from gold nanoparticle-stabilized phospholipid liposomes. The binding of chitosan-modified gold nanoparticles to the surface of liposomes can effectively prevent them from fusing with one another and from undesirable payload release in regular storage or physiological environments. However, once these protected liposomes "see" bacteria that secrete toxins, the toxins will insert into the liposome membranes and form pores, through which the encapsulated therapeutic agents are released. The released drugs subsequently impose antimicrobial effects on the toxin-secreting bacteria. Using methicillin-resistant Staphylococcus aureus (MRSA) as a model bacterium and vancomycin as a model anti-MRSA antibiotic, we demonstrate that the synthesized gold nanoparticle-stabilized liposomes can completely release the encapsulated vancomycin within 24 h in the presence of MRSA bacteria and lead to inhibition of MRSA growth as effective as an equal amount of vancomycin-loaded liposomes (without nanoparticle stabilizers) and free vancomycin. This bacterial toxin enabled drug release from nanoparticle-stabilized liposomes provides a new, safe, and effective approach for the treatment of bacterial infections. This technique can be broadly applied to treat a variety of infections caused by bacteria that secrete pore-forming toxins. [ABSTRACT FROM AUTHOR]

A novel TBAF-promoted intermolecular crossed-conjugate addition has been developed. For a range of cyclic β-halo-α,β-unsaturated carbonyl compounds, the vinylogous enolates generated by deprotonation at the γ-position preferentially reacted with Michael acceptors at the α-position to deliver cross-coupling products in good yields. [ABSTRACT FROM AUTHOR]

We demonstrate a general approach to the preparation of layered graphene oxide structures with sandwiched conducting polymers of different morphologies. The approach is conceptualized on the basis of the electrostatic interactions between negatively charged graphene oxide sheets and positively charged surfactant micelles. A graphene oxide−polypyrrole composite prepared from this approach exhibited an excellent electrocapacitive performance with a high specific capacitance over 500 F g−1. Good rate performance and cycle ability were realized by the composite electrode. The simple method described here opens up a generalized route to making a wide range of graphene oxide-based and graphene-based composite materials for applications beyond electrochemical energy storage. [ABSTRACT FROM AUTHOR]

The regioselective N-alkylation of 1,2,3-triazoles 1−6was studied. Good to excellent N-2 selectivity and high chemical yields for N-2-substituted 4,5-dibromotriazoles 7were obtained with 4,5-dibromo- and 4-bromo-5-trimethylsilyl-1,2,3-triazoles. These building blocks can be readily converted to 2-mono-, 2,4-di-, and 2,4,5-polysubstituted triazoles 10−15, providing a general, protective, group-free method for the synthesis of N-2-substituted triazoles. Observed regioselectivities can be rationalized by a combination of Frontier Molecular Orbital, steric, and electrostatic directing effects on the heterocyclic scaffolds. [ABSTRACT FROM AUTHOR]

Conducting polymer-macroporous carbon composite electrode materials were prepared by deposition of a thin layer of polyaniline (PANI) on the surface of three-dimensionally ordered macroporous carbon. A specific capacitance of 1490 F/g was observed over the deposited PANI in the composite electrode. Good rate performance and cycle ability were realized on the composite electrode, attributed to the combined contribution from both the unique properties of the carbon matrix (e.g., highly ordered interconnected pores and good electrical conductivity) and pseudocapacitance of the deposited PANI layer. The three-dimensionally ordered pore structure of the carbon favored the diffusion of the electrolyte ions, hence not only improving the energy storage capacity but also enhancing power density. [ABSTRACT FROM AUTHOR]

The self-assembly and induced supramolecular chirality of a dianionic meso-tetraphenylsulfonato porphyrin (TPPS) on the optically active polylysine has been investigated. Our research has confirmed that in the presence of poly(l-lysine) (PLL) or poly(d-lysine) (PDL), TPPS could form both H and J aggregates and the exciton type Cotton effect was induced in the corresponding absorption bands of H and J-aggregates. We have further revealed that the induced chirality of the H-band always followed the chirality of PLL or PDL, while the sign of the exciton couplet in the J-band could be the same as or opposite to that of the H-band depending on the mixing sequence and the ratio of PLL or PDL to TPPS (P/Tratio). At a P/Tratio less than 4, both the J and H aggregates showed the same symbolic CD signal. At a P/Tratio larger than 4, the opposite sign of the exciton couplet was observed for H and J-bands when TPPS was added into PLL, while the same sign was obtained when PLL was added into TPPS. Interestingly, the J-band with the same sign as that of the H-band can be inverted into the opposite sign under heating. A mechanism relating to the dynamic and thermodynamic formation of the chiral aggregates in the presence of PLL or PDL was proposed. [ABSTRACT FROM AUTHOR]

We present the first examples of a group of effective ruthenium catalysts for polycyclotrimerization. The polymerization reactions of an arylene bipropiolate monomer initiated by the Ru(II−IV) complexes of CpRu(PPh3)2Cl, Cp*Ru(PPh3)2Cl, [Cp*RuCl2]n, and [Ru(η3:η3-C10H16)(μ-Cl)Cl]2(Cp = cyclopentadienyl, Cp* = pentamethyl-Cp, and C10H16= 2,7-dimethylocta-2,6-diene-1,8-diyl) produce ester-functionalized poly(aroxycarbonylphenylene) (PACP) with high molecular weights (Mwup to 200 × 103) in good yields (up to 90%). Topological structure of the polymer product can be hyperbranched or cross-linked, tunable by the extent of triple-bond conversion. The degree of branching (DB) of the PACP is ∼0.76, much higher than those of the “conventional” hyperbranched polymers (DB ∼ 0.5). The PACP exhibits high transparency in the visible spectral region. It works as a molecular container, effectively trapping small molecules in its cavities with the aid of hydrogen-bond interaction. The polymer undergoes a bursting hydrolysis reaction, and the collapse of its hyperbranched skeleton rapidly releases the loaded molecules, showing promise as a drug carrier for missile therapy. [ABSTRACT FROM AUTHOR]

In this manuscript, we describe the synthesis of a bicyclic β-benzyloxy and β-hydroxy amide library from cyanohydrin ethers. The benzyloxy amides were prepared through a one-pot sequence of hydrozirconation, acylation, and intramolecular Friedel−Crafts alkylation. Selected benzyl ethers were converted to alcohols by hydrogenolysis in a continuous flow reactor. Chemistry space BCUT metrics and 2D fingerprint similarity calculations showed that these compounds contribute chemical diversity value to existing chemical libraries. [ABSTRACT FROM AUTHOR]

In this contribution, a general one-step route to synthesize Au crystals with the shape of twinned tabular crystals, single-crystalline nanoplates, and multitwinned decahedra is proposed. By employing HAuCl4in an aqueous medium as the oxidizing reagent, tetracycline hydrochloride as the reducing agent, and cetyltrimethylammonium bromide (CTAB) as the capping agent, we found it is very easy to get the three types of Au crystals by modulating the molar ratio of CTAB with HAuCl4. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and high-resolution TEM (HRTEM) have been employed to characterize the three types of symmetric morphologies. Further investigations involve side-face analysis and growth mechanism of Au twinned tabular crystals, and the optical properties of the obtained crystals. Absorption and dark field light scattering images demonstrate their potential applications in cancer cell diagnostics and photothermal therapy. Moreover, a tentative explanation for the growth mechanism of Au crystals with different morphologies has been made. [ABSTRACT FROM AUTHOR]