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Reductive dimerization of isatin and its derivatives can be regarded as a step-economical pathway to construct 3,3'-disubstituted bisoxindoles, which was unfortunately accompanied by severe direct reduction as well as low efficiency. A visible-light driven, photoredox-catalytic protocol was developed to readily furnish 3,3'-dihydroxy- (dl-, > 20:1 dr) and 3,3'-diamino-bisoxindoles (meso-, 3.5:1 to 5:1 dr) in moderate to good yields, successfully circumventing the common problem. Two vicinal quaternary carbon centers were effectively assembled under the irradiation of visible light. [ABSTRACT FROM AUTHOR]

Iron(III)-tetraamidomacrocyclic ligand (Fe(III)-TAML) activators have received widespread attentions for their abilities to activate hydrogen peroxide to oxidize many organic pollutants. In this study, Fe(III)-TAML/layered double hydroxide (LDH) composite was developed by intercalating Fe(III)-TAML into the interlayer of LDH. Electrostatic interaction and hydrogen bonding might account for the adsorption of Fe(III)-TAML on LDH. The newly synthesized Fe(III)-TAML/LDH composite showed superior reactivity as indicated by efficient decomposition of tetrabromobisphenol A (TBBPA) in the presence of hydrogen peroxide, which can be fully degraded within 20 s and the degradation rate increased up to 8 times compared to free Fe(III)-TAML. In addition, the toxicity of the system was significantly reduced after the reaction. The higher reactivity of Fe(III)-TAML/LDH system is attributed to the enhanced adsorption of TBBPA on LDH, which could increase the contact possibility between Fe(III)-TAML and TBBPA. On the basis of the analysis of reaction intermediates, ?-scission at the middle carbon atom and C-Br bond cleavage in phenyl ring of TBBPA were involved in the degradation process. Furthermore, our results demonstrated that the Fe(III)-TAML/LDH composite can be reused several times, which could lower the overall cost for environmental implication and render Fe(III)-TAML/LDH as the potential environmentally friendly catalyst for future wastewater treatment under mild reaction conditions. [ABSTRACT FROM AUTHOR]

The forced translocation of diblockcopolymers (ANABNB) through compound channelscomposed of part α with length Lαnear the cisside and part β with length Lβnear the transsidewas investigated. The interaction between monomer A and channel αis strongly attractive, while all other interactions are purely repulsive.We study the translocation mode that the block A threads the channelahead of the block B since it is the most probable translocation event.Simulation results show that the translocation process is remarkablydependent on Lαand there are twomaxima of translocation time. The physical mechanisms are discussedfrom the free energy landscape of polymer translocation. The placeof the first maximum, at which there is a deepest free energy wellbefore the block A completely enters the channel, is independent of NA. The place of the second one is at NAbxwith bxthe mean bondlength along the channel, resulted from the matching of block A withchannel α. Results show that the translocation time of diblockcopolymer can be tuned by using compound channels. [ABSTRACT FROM AUTHOR]

Triterpenesaponins are a major group of active components in natural productswith nonspecific antiviral activities, while T20 peptide (enfuvirtide),which contains a helix zone-binding domain (HBD), is a gp41-specificHIV-1 fusion inhibitor. In this paper, we report the design, synthesis,and structure–activity relationship (SAR) of a group of hybridmolecules in which bioactive triterpene sapogenins were covalentlyattached to the HBD-containing peptides via click chemistry. We foundthat either the triterpenes or peptide part alone showed weak activityagainst HIV-1 Env-mediated cell–cell fusion, while the hybridsgenerated a strong cooperative effect. Among them, P26–BApcexhibited anti-HIV-1 activity against both T20-sensitive and -resistantHIV-1 strains and improved pharmacokinetic properties. These resultssuggest that this scaffold design is a promising strategy for developingnew HIV-1 fusion inhibitors and possibly novel antiviral therapeuticsagainst other viruses with class I fusion proteins. [ABSTRACT FROM AUTHOR]

In this study, the Li2ZrO3based sorbentswith different compositions were synthesized by the solid-state reactionmethod from the mixtures of Li2CO3, K2CO3and ZrO2. CO2sorption propertiesof Li2ZrO3based sorbents were investigatedby analyzing the phases and microstructure changes with the help ofthermogravimetric analysis, X-ray diffraction and scanning electronmicroscopy. The thermodynamic calculations were carried out basedon the second law of thermodynamics. Li2CO3/K2CO3-doped Li2ZrO3sorbentwith the composition of 36.23 wt % Li2CO3, 55.12wt % ZrO2and 8.65 wt % K2CO3wasconsidered to achieve excellent capability for high temperature CO2sorption and presented the maximum sorption rate at 525 °Cand 0.15 atm of CO2partial pressure. The sorbent keptrather stable for multicycles sorption and regeneration, and maintainedits original capacity during 12 cycle processes. There were threedistinct phases in the nonisothermal CO2sorption processwhile the main CO2sorption occurred during the secondphase. An improved iterative Coats–Redfern method was usedto evaluate nonisothermal kinetics of the CO2sorptionprocess, and the kinetic parameters were derived by the MATLAB model.The Fn nth-order reaction model predictedaccurately the main phases and differences in the activation energiesand the frequency factors for different sorbents in the sorption phasescorroborated different mechanism integral functions and reaction orders. [ABSTRACT FROM AUTHOR]

Thisarticle describes a novel CO2mineralization approachusing natural insoluble K-feldspar and phosphogypsum for the emissionof CO2, reduction of phosphogypsum waste, and productionof soluble potash. K-feldspar was activated with CaSO4athigh temperature and then mineralized with CO2to extractpotassium under hydrothermal conditions. Activation and mineralizationconditions (e.g., ore/CaSO4mass ratio, calcination andmineralization temperatures, initial pressure of CO2) weresystematically investigated with an optical potassium extraction ratioof ∼87% and a CO2mineralization ratio of ∼7.7%.A reaction mechanism was proposed based on the experimental resultsand the characterizations, such as polarized light microscopy, X-raydiffraction, and thermogravimetric and differential thermal analyses.This new methodology is a promising process and has the potentialto reduce emissions of CO2and phosphogypsum from a practicalpoint of view. [ABSTRACT FROM AUTHOR]

This work highlights a real-timeand label-free method to monitorthe dehydrogenative polymerization of monolignols initiated by horseradishperoxidase (HRP) physically immobilized on surfaces using a quartzcrystal microbalance with dissipation monitoring (QCM-D). The dehydrogenativepolymer (DHP) films are expected to provide good model substratesfor studying ligninolytic enzymes. The HRP was adsorbed onto goldor silica surfaces or onto and within porous desulfated nanocrystallinecellulose films from an aqueous solution. Surface-immobilized HRPretained its activity and selectivity for monolignols as coniferyland p-coumaryl alcohol underwent dehydrogenativepolymerization in the presence of hydrogen peroxide, whereas sinapylalcohol polymerization required the addition of a nucleophile. Themorphologies of the DHP layers on the surfaces were investigated viaatomic force microscopy (AFM). Data from QCM-D and AFM showed thatthe surface-immobilized HRP-initiated dehydrogenative polymerizationof monolignols was greatly affected by the support surface, monolignolconcentration, hydrogen peroxide concentration, and temperature. [ABSTRACT FROM AUTHOR]

Chitinasesare widely distributed in nature and have wide-rangingpharmaceutical and biotechnological applications. This work highlightsa real-time and label-free method to assay Chitinase activity viaa quartz crystal microbalance with dissipation monitoring (QCM-D)and atomic force microscopy (AFM). The chitin substrate was preparedby spincoating a trimethylsilyl chitin solution onto a silica substrate,followed by regeneration to amorphous chitin (RChi). The QCM-D andAFM results clearly showed that the hydrolysis rate of RChi filmsincreased as Chitinase (from Streptomyces griseus) concentrations increased, and the optimal temperature and pH forChitinase activity were around 37 °C and 6–8, respectively.The Chitinase showed greater activity on chitin substrates, havinga high degree of acetylation, than on chitosan substrates, havinga low degree of acetylation. [ABSTRACT FROM AUTHOR]

Gold nanorod-cored biodegradablemicelles were prepared by coatinggold nanorods (AuNRs) with lipoylated poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-PCL-LA) block copolymerand investigated for remotely triggered release of doxorubicin (DOX)and effective inhibition of drug-sensitive and multidrug-resistant(MDR) cancer cells. The micelles had uniform sizes and excellent colloidalstability. The in vitro release studies showed that drug release fromDOX-loaded AuNR-cored micelles (AuNR-M-DOX) was minimal under physiologicalconditions but markedly enhanced upon NIR irradiation at a low powerdensity of 0.2 W/cm2, most likely due to photothermallyinduced phase transition of PCL regime. As revealed by confocal microscopyand flow cytometry, NIR could also trigger effective DOX release indrug-sensitive as well as drug-resistant MCF-7 cells. MTT assays showedthat antitumor activity of AuNR-M-DOX to drug-sensitive MCF-7 cellswas significantly boosted by mild NIR irradiation, reaching a comparablelevel to free DOX. Most remarkably, AuNR-M-DOX combined with NIR irradiationcould also effectively kill drug-resistant MCF-7 cells, in which acell viability of 38% was observed at a DOX dosage of 10 μgequiv/mL, whereas 100% cell viability was maintained for cells treatedwith free DOX under otherwise the same conditions. These AuNR-coredbiodegradable micelles with high stability, photo-triggered drug release,and effective reversal of multidrug resistance in cancer cells haveappeared as a novel platform for targeted cancer therapy. [ABSTRACT FROM AUTHOR]

Thesmall molecule fusion inhibitors N-(4-carboxy-3-hydroxyphenyl)-2,5-dimethylpyrrole(NB-2) and N-(3-carboxy-4-hydroxyphenyl)-2,5-dimethylpyrrole(A12) target a hydrophobic pocket of HIV-1 gp41 and havemoderate anti-HIV-1 activity. In this paper, we report the design,synthesis, and structure–activity relationship of a group ofhybrid molecules in which the pocket-binding domain segment of theC34 peptide was replaced with NB-2 and A12derivatives.In addition, the synergistic effect between the small molecule andpeptide moieties was analyzed, and lead compounds with a novel scaffoldwere discovered. We found that either the nonpeptide or peptide partalone showed weak activity against HIV-1-mediated cell–cellfusion, but the conjugates properly generated a strong synergisticeffect. Among them, conjugates Aoc−βAla–P26 andNoc−βAla–P26 exhibited a low nanomolar IC50in the cell–cell fusion assay and effectively inhibitedT20-sensitive and -resistant HIV-1 strains. Furthermore, the new moleculesexhibited better stability against proteinase K digestion than T20and C34. [ABSTRACT FROM AUTHOR]

Chitosan and adenosine-5′-triphosphate (ATP) areemployedas building blocks to fabricate polymeric supra-amphiphiles basedon electrostatic interactions, whichcan self-assemble to form spherical aggregates. The spherical aggregatesinherit the phosphotase responsiveness of ATP. Compared to our previouswork, this enzyme-responsive system can be more biocompatibleand block polymers are not needed in preparation, which makes it possibleto fabricate the chitosan-based enzyme-responsive assemblies in alarge-scale, cheap way. Therefore, the application of the assembliesfor nanocontainers and drug delivery is greatly anticipated. [ABSTRACT FROM AUTHOR]

The imine bond, a kind of dynamic covalent bond, is usedto bindtwo bolaform amphiphiles together with spacers, yielding H-shapedsupra-amphiphiles. Micellar aggregates formed by the self-assemblyof the H-shaped supra-amphiphiles are observed. When pH is tuned downfrom basic to slightly acidic, the benzoic imine bond can be hydrolyzed,leading to the dissociation of H-shaped supra-amphiphiles. Moreover,H-shaped supra-amphiphiles have a lower critical micelle concentrationthan their building blocks, which is very helpful in enhancing thestability of the benzoic imine bond being hydrolyzed by acid. Thesurface tension isotherms of the H-shaped supra-amphiphiles with differentspacers indicate their twisty conformation at a gas–water interface.The study of H-shaped supra-amphiphiles can enrich the family of amphiphiles,and moreover, the pH-responsiveness may make them apply to controlledor targetable drug delivery in a biological environment. [ABSTRACT FROM AUTHOR]

The process of self-assembly spontaneously creates well-defined structures from various chemical building blocks. Self-assembly can include different levels of complexity: it can be as simple as the dimerization of two small building blocks driven by hydrogen bonding or as complicated as a cell membrane, a remarkable supramolecular architecture created by a bilayer of phospholipids embedded with functional proteins. The study of self-assembly in simple systems provides a fundamental understanding of the driving forces and cooperativity behind these processes. Once the rules are understood, these guidelines can facilitate the research of highly complex self-assembly processes. [ABSTRACT FROM AUTHOR]

We have fabricated enzyme responsive polymeric supra-amphiphilesby mixing a block copolymer of poly(ethylene glycol)-block-poly(acrylic acid) with myristoylcholine chloride in water. Thepolymeric supra-amphiphiles self-assemble into spherical aggregateswith sizes varying from about 40 to 150 nm. Moreover, the sphericalaggregates can be disassembled triggered by acetylcholinesterase,an enzyme which can cut off the ester linkage of myristoylcholinechloride. Nile red can be loaded into the spherical aggregates andreleased in several hours upon the treatment of acetylcholinesterase.The releasing rate is rather fast considering that it takes more than150 h for Nile red to diffuse out of the spherical aggregates withoutaddition of acetylcholinesterase. It is anticipated that the new enzymeresponsive polymeric supra-amphiphile may be explored as a carrierfor drug delivery. [ABSTRACT FROM AUTHOR]

Chitin is the second most abundant biopolymer and insightintoits natural synthesis, enzymatic degradation, and chemical interactionswith other biopolymers is important for bioengineering with this renewableresource. This work is the first report of smooth, homogeneous, ultrathinchitin films, opening the door to surface studies of binding interactions,adsorption kinetics, and enzymatic degradation. The chitin films wereformed by spincoating trimethylsilyl chitin onto gold or silica substrates,followed by regeneration to a chitin film. Infrared and X-ray photoelectronspectroscopy, X-ray diffraction, ellipsometry, and atomic force microscopywere used to confirm the formation of smooth, homogeneous, and amorphouschitin thin films. Quartz crystal microbalance with dissipation monitoring(QCM-D) solvent exchange experiments showed these films swelled with49% water by mass. The utility of these chitin films as biosensorswas evident from QCM-D and surface plasmon resonance studies thatrevealed the adsorption of a bovine serum albumin monolayer. [ABSTRACT FROM AUTHOR]

For the reactive distillation column involving a kineticallycontrolledexothermic reaction, operating pressure can present nonmonotonic influenceson process dynamics and operation. While the enhancement of operatingpressure benefits process dynamics and controllability in the lowerpart of its feasible region (which is confined by the temperaturelevels of the available cold and hot utilities), it turns to deteriorateprocess dynamics and controllability in the higher part of its feasibleregion. Three reactive distillation systems, including an ideal reactivedistillation column performing a hypothetical exothermic reaction,A B ⇀↽kbkfC D, and two real ones producing, respectively,methyl acetate from acetic acid and methanol and methyl tertiary butylether (MTBE) from isobutylene and methanol, are thoroughly studiedin this work, and the results confirm the existence of this uniquephenomenon. The intricate behavior of such kind of reactive distillationcolumns is essentially governed by the conflicting effects of operatingpressure on reaction rate and chemical equilibrium constant and determinesactually a favorable region of operating pressure for process dynamicsand operation. Because the region may or may not coincide with theone in terms of process synthesis and design, operating pressure cantherefore serve as an important decision variable to trade-off processdesign and operation, rendering the resultant process design withbalanced steady-state performance and process dynamics and controllability. [ABSTRACT FROM AUTHOR]

A comprehensive two-dimensional system coupling ultra-performance liquid chromatography (UPLC) and ion mobility-mass spectrometry (IM-MS) has been applied for the separation and analysis of hydroxylated polybrominated diphenyl ethers (OH-PBDEs). A complex mixture containing 23 OH-PBDE congeners ranging from hydroxylated monobromodiphenyl ether (OH-monoBDE) to hydroxylated octabromodiphenyl ether (OH-octaBDE) was satisfactorily separated within 16 min of analysis time. The first-dimensional reversed-phase UPLC was performed on a sub-2 μm BEH C chromatographic column using acetonitrile-water gradient elution program with a flow rate ramp. It enabled excellent chromatographic separation for both between-class and within-class OH-PBDEs based on their differences in hydrophobicity. Following the pre-ionization resolution in the first dimension, the second-dimensional IM-MS employed a hybrid electrospray quadrupole ion mobility time-of-flight mass spectrometer and added an extra post-ionization separation for between-class OH-PBDE congeners on account of their relative mobility disparity during a very short period of 8.80 ms. The orthogonality of the developed two-dimensional system was evaluated with the correlation coefficient of 0.9665 and peak spreading angle of 14.87°. The peak capacity of the system was calculated to be approximately 2 and 15 times higher than that of the two dimensions used alone, respectively. The two-dimensional separation plane also contributed to the removal of background interference ions and the enhanced confidence in the characterization of OH-PBDEs of interest. [ABSTRACT FROM AUTHOR]

7,7′-Dihydroxy-8,8′-biquinolyl (azaBINOL) was prepared from 2-chloroaniline in four steps: (1) the Skraup reaction, (2) Ni-catalyzed reductive coupling of 8-chloroquinoline, (3) Pd(II)-catalyzed double C–H functionalization of 8,8′-biquinolyl mediated by PhI(OAc)2, and (4) saponification. During the third step, an axially chiral (atropostype) biaryl molecule was directly generated from an essentially achiral (tropostype) biaryl starting material. [ABSTRACT FROM AUTHOR]

We report herein the self-organization of the polymerizable bolaamphiphile (noted, l-Asp-DA) that contains a diacetylene group and two l-aspartic groups. We found that l-Asp-DA can self-organize into stable fiberlike nanostructures at the mica−water interface. The micellar nanostructures of l-Asp-DA can be polymerized both in the bulk solution and in the film on UV irradiation, and the nanostructures of the l-Asp-DA micelles at the mica−water interface can be maintained after polymerization. The polymerized l-Asp-DA nanostructures can go through blue−red transition upon pH stimuli arising from the transformation of polydiacetylene skeleton. In addition, the concentration (above cmc) of l-Asp-DA has a great effect on the nanostructures. At a concentration of 3.2 × 10−4mol/L, l-Asp-DA can self-organize into stable fiberlike nanostructure at the mica−water interface, while cylindrical nanostructures self-organize at a concentration of 6.0 × 10−4mol/L. This work may provide a new approach for designing and fabricating molecular assemblies with controlled sizes and shapes, leading to the development of novel functional polymer nanostructure materials. [ABSTRACT FROM AUTHOR]

The article reports that fuel cell science and technology cuts across multiple disciplines, including materials science, interfacial science, transport phenomena, electrochemistry, and catalysis. Because of the diversity and complexity of electrochemical and transport phenomena involved in a fuel cell and occurring at disparate length and time scales, fuel cell modeling and simulation requires a systematic framework parallel to computational fluid dynamics, here termed computational fuel cell dynamics (CFCD). CFCD deals with the coupling of multidimensional transport phenomena with electrochemical kinetics and the transport of charge electrons and ions to provide a comprehensive understanding of fuel cell dynamics.

The article focuses on the facile synthesis of single crystalline ulthrathin gold (Au) nanowires (NWs) and its transport properties. It says that Au NWs is made up of certain properties, making it an ideal candidate for linking molecular devises. An overview of the method developed to synthesize Au NWs is discussed. The study concludes that chemically made ultrathin single crystalline AU NWs can be used as a molecular-scale interconnect for nanoparticle applications.

Molecular level insight into the interaction between volatile organic compounds (VOCs) and aerosols is crucial for improvement of atmospheric chemistry models. In this paper, the interaction between adsorbed toluene, one of the most significant VOCs in the urban atmosphere, and the aqueous surface of aerosols was studied by means of combined molecular dynamics simulations and ab initio quantum chemistry calculations. It is revealed that toluene can be stably adsorbed on the surface of aqueous droplets via hydroxyl-π hydrogen bonding between the H atoms of the water molecules and the C atoms in the aromatic ring. Further, significant modifications on the electrostatic potential map and frontier molecular orbital are induced by the solvation effect of surface water molecules, which would affect the reactivity and pathway of the atmospheric photooxidation of toluene. This study demonstrates that the surface interactions should be taken into consideration in the atmospheric chemical models on oxidation of aromatics. [ABSTRACT FROM AUTHOR]

A successful protocol has been developedfor δ-arylationof β-arylethamines at the ortho position under mild conditions.The newly developed methodology first presents broad substrate scope,great functional group tolerance, and good to excellent yield in thesynthesis of substituted β-arylethylamines. The transformationrepresents a practical advantage of oxalyl amide in assistance withC–H functionalization at a remote position. [ABSTRACT FROM AUTHOR]

To investigate the hydrodynamics,a cold model of triple-bed combinedcirculating fluidized bed (TBCFB) has been built with an electrostaticsensor and a twin-plane electrical capacitance tomography (ECT) sensor.Experimental results show that with the increase in the superficialair velocity, the flow regime in the riser would transit from a denseplug flow to a core-annular flow, and finally to a dilute suspensionflow. In the dense plug flow regime, the passage of the solids plugsin the riser can be monitored and the velocity measured using thetwin-plane ECT sensor. In the core-annular flow regime, when the solidsholdup is moderate, the measured solids velocities by the electrostaticsensor and the ECT sensor are comparable and complementary. With adilute suspension flow in the riser, a homogeneous flow is observedwith a nearly flat velocity profile of solid particles. On the contrary,in the downer the flow becomes inhomogeneous, and the solids velocitiesin the center of the downer are higher than those near the wall. Thisstudy provides a proof-of-concept design to monitor the flow dynamicsin the fluidized bed by the combination of electrostatic and ECT sensorsover a wide range of flow regimes. [ABSTRACT FROM AUTHOR]

A concise total synthesis of rugulovasine A is achieved by using Uhle’s ketone derivative as the key intermediate, which was synthesized by intramolecular cyclization via metal–halogen exchange. Two different routes to construct a spirocyclic butyrolactone subunit involving a Ru-catalyzed cyclocarbonylation and a special Ru-catalyzed double bond rearrangement were studied. [ABSTRACT FROM AUTHOR]

The self-condensation of alkynals was for the first time implemented under mild organocatalytic conditions and was successfully linked with a domino organocatalytic inverse-electron-demand oxa-Diels–Alder reaction, which led to the development of a facile one-pot method to produce a wide variety of polysubstituted chiral 3,4-dihydropyrans with good to high yields and diastereoselectivities and high enantioselectivities. The unprecedented alkynal self-condensation was revealed to pass through secondary amine-catalyzed C–C triple bond hydration and subsequent aldol condensation. [ABSTRACT FROM AUTHOR]

We demonstrate that increasing the hydrophobic environmentaroundthe charge center of a polyelectrolyte (PE) not only decreases thewater content of an adsorbed PE layer but can even dewater up to ∼50%of an initially hydrated substrate. The results of this work are expectedto yield new stratagies to dewater PE systems and have potential applicationsin mineral recovery, paper manufacturing, and biomedical materials.Adsorption of a series of cationically derivatized dextran polyelectrolytesonto sulfated nanocrystalline cellulose (SNC) has been studied usingquartz crystal microbalance with dissipation monitoring (QCM-D) andsurface plasmon resonance (SPR). Synthesized samples of (N,N-dimethylamino)ethyldextran (DMAE-Dex), (N,N-diethylamino)ethyldextran (DEAE-Dex), and (N,N-diisopropylamino)ethyldextran (DIAE-Dex) had degrees of substitution(DS) ranging from 0.05 to 0.82. DMAE-Dex, DEAE-Dex, and DIAE-Dex allshowed decreasing adsorption onto SNC and decreasing water contentof the adsorbed film with increasing DS. Additionally, DEAE-Dex andDIAE-Dex films adsorbed onto SNC contained less water than DMAE-Dexfilms with the same DS. Interestingly, QCM-D results for high DS DIAE-Dexadsorbed onto SNC revealed mass loss, whereas SPR results clearlyshowed DIAE-Dex adsorbed. These observations were consistent withdehydration of the SNC substrate. This study indicates that the watercontent of the substrate could be tailored by controlling the DS andhydrophobic character of the adsorbed polyelectrolytes. [ABSTRACT FROM AUTHOR]

Carbonaceous materials are commonly used in agronomic and environmental applications primarily as geosorbents, but their redox properties that may affect biogeochemical reactions are rarely documented. Herein, the role of activated carbon (AC) mediating microbial reduction of ferrihydrite is studied. Our batch experiment results show that AC facilitated the reduction of ferrihydrite by Shewanella oneidensis MR-1, but the pretreatment of AC with HNO3 further increased the rate of reduction. The redox-active oxygen-containing functional groups in AC were found to be responsible for the enhancement of the microbial reduction of ferrihydrite. This conclusion was supported by the electrochemical evidence that showed that the electron exchange capacity (EEC) of AC was facilitated due to the presence of quinone/hydroquinone groups and strongly positively correlated with the content of CO groups. Moreover, the coprecipitation of vivianite and siderite was found in the products in the presence of AC, but siderite only was present in the absence of AC. The proper identification of potential functional groups in AC-mediating electron transfer during microbial reduction of ferrihydrite provides insights into the mechanism of reaction and potential roles carbonaceous materials may play in biogeochemical redox processes and, consequently, the fate of contaminants in the environment. [ABSTRACT FROM AUTHOR]

Pyrroles are an important group of heterocyclic compounds with a wide range of interesting properties, which have resulted in numerous applications in a variety of fields. Despite the importance of these compounds, there have been few reports in the literature pertaining to the synthesis of pyrroles from simple alkenes using a one-pot sequential 1,3-dipolar cycloaddition/aromatization reaction sequence. Herein, we report the development of a benzoyl peroxide-mediated oxidative dehydrogenative aromatization reaction for the construction of pyrroles. We subsequently developed a one-pot tandem reaction that combined this new method with a well-defined silver-catalyzed 1,3-dipolar cycloaddition reaction, thereby providing a practical method for the synthesis of multisubstituted pyrroles from easy available alkenes. The mechanism of this oxidative dehydrogenative aromatization reaction was also examined in detail. [ABSTRACT FROM AUTHOR]

Poylcyclic tetrahydroxanthones comprise a large class of cytototoxic natural products. No mechanism of action has been described for any member of the family. We report the synthesis of kibdelone C and several simplified analogs. Both enantiomers of kibdeleone C show low nanomolar cytotoxicity toward multiple human cancer cell lines. Moreover, several simplified derivatives with improved chemical stability display higher activity than the natural product itself. In vitro studies rule out interaction with DNA or inhibition of topoisomerase, both of which are common modes of action for polycyclic aromatic compounds. However, celluar studies reveal that kibdelone C and its simplified derivatives disrupt the actin cytoseketon without directly binding actin or affecting its polymerization in vitro. [ABSTRACT FROM AUTHOR]

A novelnanoporous metal–organic framework NPC-4 with excellentthermal stability was assembled from 2,3,5,6-tetramethylbenzene-1,4-diisophthalate(TMBDI) and the paddle-wheel secondary building unit (Cu2(COO)4). The porous structure comprises a single typeof nanoscale cage (16 Å diameter) interconnected by windows (5.2× 6.3 Å), which give a high pore volume. CH4(195–290K), CO2(198–303 K), N2(77 K), and H2(77 K) adsorption isotherms were studied for pressures upto 20 bar. NPC-4 exhibits excellent methane and carbon dioxide storagecapacities on a volume basis with very high adsorbate densities, underambient conditions. Isobars were investigated to establish the relationshipfor adsorption capacities over a range of storage temperatures. Theisosteric enthalpies of adsorption for both CH4and CO2adsorption did not vary significantly with amount adsorbedand were ∼15 and ∼25 kJ mol–1, respectively.The adsorption/desorption kinetics for CH4and CO2were investigated and activation energies, enthalpies of activation,and diffusion parameters determined using various kinetic models.The activation energies for adsorption obtained over a range of uptakesfrom the stretched exponential kinetic model were 5.1–6.3 kJmol–1(2–13.5 mmol g–1)for CO2and 2.7–5.6 kJ mol–1(2–9mmol g–1) for CH4. The activation energiesfor surface barriers and diffusion along pores for both CH4and CO2adsorption obtained from a combined barrier resistancediffusion model did not vary markedly with amount adsorbed and were<9 kJ mol–1. Comparison of kinetic and thermodynamicparameters for CH4and CO2indicates that asurface barrier is rate determining at high uptakes, while intraparticlediffusion involving diffusion through pores, consisting of narrowwindows interconnecting with nanocages, being rate determining atvery low uptakes. The faster CH4intraparticle adsorptionkinetics compared with CO2for NPC-4 was attributed tofaster surface diffusion due to the lower isosteric enthalpy of adsorptionfor CH4. [ABSTRACT FROM AUTHOR]

The present research relates a universallypractical and feasibleapproach toward chemically deconstructing the macromolecular architectureof lignin, specifically alkali lignin (AL), for the production ofa number of valuable side-stream aromatic nuclei byproducts. The hydrothermolysatesobtained at different subcritical conditions were tentatively qualitativelyidentified by gas chromatography mass spectrometry (GC-MS) and subsequentlyquantified by gas chromatography (GC). The influence of temperature(220–340 °C), residence time (0–60 min), and ethanolvolume-% in a water–ethanol cosolvent (0–100%) on theconversion of AL and the yield of the side-stream (liquid) productswere explored. The results show that the yield and identity of thephenolic and methoxy-benzene compounds were strongly correlated tothe conversion temperature and the ethanol volume-%, whereas residencetime in the autoclave had only a minor influence. The following individualchemicals (mg liquid side-stream/g lignin) and associated yields weredetermined from the optimal hydrothermal conditions (30 min, 310 °C,25% ethanol): phenol (4.25 mg/g), 4-methylguaiacol (2.93 mg/g), 3,5-dimethoxyacetophenone(0.78 mg/g), 1,2,4-trimethoxybenzene (2.47 mg/g), and 2,6-dihydroxy-4-methoxyacetophenone(2.47 mg/g). The highest yield of guaiacol (11.87 mg/g) and 2,6-dimethoxyphenol(12.17 mg/g) was obtained at a reaction temperature of 310 °Cover 60 min in neat water. [ABSTRACT FROM AUTHOR]

An unprecedented Rh-catalyzed directmethylation of ketones with N,N-dimethylformamide(DMF) is disclosed.The reaction shows a broad substrate scope, tolerating both aryl andalkyl ketones with various substituents. Mechanistic studies suggestthat DMF delivers a methylene fragment followed by a hydride in themethylation process. [ABSTRACT FROM AUTHOR]

With the elaborate engineering of supra-amphiphiles basedon dualcharge-transfer interactions, the rational design and programmabletransformation of well-defined 1D and 2D nanostructures have beendemonstrated. First, H-shaped supra-amphiphiles are successfully obtainedon the basis of the directional charge-transfer interactions of naphthalenediimide and naphthalene, which self-assemble in water to form 2D nanosheets.Second, by complexation of the H-shaped supra-amphiphiles with pyrenederivatives, the 2D nanosheets transform into ultralong 1D nanofibers.Therefore, this line of research represents a successful example ofsupramolecular engineering and has enriched its realm. [ABSTRACT FROM AUTHOR]