bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synergistic effect of organo‐montmorillonite on intumescent flame retardant ethylene‐octene copolymer
Authors: Guo Jianbing , He Min , Li Qingfeng , Yu Jie , Qin Shuhao 
Published: January 2013

AbstractNanocomposite of thermoplastic elastomer ethylene‐octene copolymer/maleated ethylene‐octene (POE/POE‐g‐MAH) with organo‐montmorillonite (OMMT, 11 wt %) as masterbatch have been obtained by melt blending and it has been characterized by transmission electron microscopy (TEM). Flame retardant POE/POE‐g‐MAH/OMMT/ammonium polyphosphate‐pentaerythritol (APP‐PER) (an intumescent flame retardant with 75 wt % ammonium polyphosphate and 25 wt % pentaerythritol) composites were prepared by using melting processing to study their structures, flame‐retardancy, thermal, and mechanical properties. TEM showed exfoliated structures throughout POE/POE‐g‐MAH/OMMT masterbatch and POE/POE‐g‐MAH/OMMT/APP‐PER nanocomposites. Synergistic effect was observed between OMMT and APP‐PER resulting in significant improvements on thermal stability, flame‐retardancy and mechanical properties in the POE/POE‐g‐MAH/OMMT/APP‐PER nanocomposites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Layer‐by‐layer assembly of poly(allylamine hydrochloride)/polyurethane and its loading and release behavior for methylene orange
Authors: Jian Wenjiao , Xu Shimei , Wang Jide , Feng Shun 
Published: January 2013

AbstractHere, layer‐by‐layer technique was used for sequential adsorption of oppositely charged polymer poly(allylamine hydrochloride) (PAH) and polyurethane (PU) through electrostatic interaction. 10 and 10.5 bilayer films were prepared separately, methylene orange (MO) was used as a model drug to evaluate the potential ability of this multilayer film used in drug delivery system. Experimental results showed the ability of loading and release of MO from the film was significantly influenced by pH and salt concentration, the loading rate of MO was faster and larger with increasing salt concentration or decreasing pH of MO solution, the release rate of MO was faster at higher salt concentration or in alkali solution. The result also indicated that the film had a good reversibility of loading and release. PAH/PU film could be a promising drug delivery system because of its biocompatibility, biodegradation and above properties. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis of functional poly(styrene)‐block‐(methyl methacrylate/methacrylic acid) by homogeneous reverse atom transfer radical polymerization: Spherical nanoparticles, thermal behavior, self‐aggregation, and morphological properties
Authors: Pizarro Guadalupe del C. , Jeria‐Orell Manuel , Marambio Oscar G. , Olea Andrés F. , Valdés Daniela T. , Geckeler Kurt E. 
Published: January 2013

AbstractThis study investigates the use of homogeneous reverse atom transfer radical polymerization for the synthesis of polystyrene (PS) initiated by conventional radical peroxide with copper bromide in the lower oxidation state and a 2,2′‐bypyridine complex as the catalyst. In a second stage, an amphiphilic block copolymer containing methyl methacrylate (MMA) was synthesized via normal atom transfer radical polymerization in two steps, followed by partial hydrolysis of the methyl ester linkage of the MMA block under acidic conditions. The block copolymer PS699‐b‐P(MMA232/MAA58) obtained had a narrow molecular weight dispersity (Ð < 1.3). The structure of the precursor, PS‐b‐PMMA, and resultant polymer, was characterized and verified by FTIR and 1H‐NMR spectroscopy as well as size exclusion chromatography. The self‐aggregation of PS699‐b‐P(MMA232/MAA58) in organic solvents was monitored by UV spectroscopy, whereas the morphology and size of the formed microaggregates were investigated by transmission electron microscopy and dynamic light scattering. The results indicate that this copolymer formed regular spherical reverse micelles with a core–shell structure. The atomic force micrographs of PS699‐b‐P(MMA232/MAA58) showed a rough surface morphology owing to microphase separation of the block copolymer. In addition, thermal characterization was performed by differential scanning calorimetry and thermogravimetric analysis. The glass transition temperature of PS699‐b‐P(MMA232/MAA58) decreased significantly (65°C), when compared to PS and PMMA, suggesting that an enhanced movement of the polymer chains resulted by the segregation of the hydrolyzed P(MMA232/MAA58) block. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Tuning Catalysts to Tune the Products: Phosphine‐Catalyzed Aza‐Michael Addition Reaction of Hydrazones with Allenoates
Authors: Li Erqing , Xie Peizhong , Yang Lihua , Liang Ling , Huang You 
Published: January 2013

AbstractA new tunable phosphine‐catalyzed aza‐Michael β‐addition reaction between allenoates and various hydrazones has been developed. These reactions are most‐efficiently promoted by a catalytic amount of phosphine catalysts. These atom‐economical reactions are operationally simple and their corresponding adducts can been achieved in high yields and high selectivity under mild reaction conditions. Further studies revealed that different phosphine catalyst can produce different adducts from the same starting materials.
Efficient Oxidative Degradation of Azo Dyes by a Water‐Soluble Manganese Porphyrin Catalyst
Authors: Saha Tapan Kumar , Frauendorf Holm , John Michael , Dechert Sebastian , Meyer Franc 
Published: January 2013

AbstractDyes in wastewater severely affect the nature and quality of water by inhibiting the sunlight penetration into the stream, which thereby reduces the photosynthesis reaction. This poses a serious environmental threat in many developing countries. Recently, new methods for the treatment of colored dye effluent streams have attracted much attention. The [MnIII(tmpyp)]/H2O2 system (tmpyp=meso‐tetrakis(1‐methylpyridinium‐4‐yl)porphyrinato) was now found to degrade various azo dyes with remarkably high efficiency under ambient conditions in aqueous solution at certain pH values. Main products of the catalytic degradation of the dye amaranth by [MnIII(tmpyp)]/H2O2 were analyzed. The reaction mechanism was studied in more detail by using rapid‐scan stopped‐flow spectrophotometry as a function of pH, [catalyst], [H2O2], [dye], and [surfactants]. Spectral analyses and kinetic data suggested rapid formation of an intermediate [MnIII(tmpyp)(OOH)] (a compound 0‐type intermediate), followed by the formation of a relatively stable trans‐dioxomanganese(V) porphyrin complex, [MnV(O)2(tmpyp)] (a compound I analog). The one‐electron reduction of [MnV(O)2(tmpyp)] to [MnIV(O)(tmpyp)] (a compound II analog) was accelerated greatly by amaranth. On the basis of the kinetic and spectroscopic data, a reaction mechanism of the formation of reactive intermediates [MnIII(tmpyp)(OOH)], [MnV(O)2(tmpyp)], and [MnIV(O)(tmpyp)] was proposed.
Structure and Dynamics of Molecular Rods in Membranes: Application of a Spin‐Labeled Rod
Authors: Grimm Christiane , Meyer Thomas , Czapla Sylvia , Nikolaus Jörg , Scheidt Holger A. , Vogel Alexander , Herrmann Andreas , Wessig Pablo , Huster Daniel , Müller Peter 
Published: January 2013

AbstractMolecular rods consisting of a hydrophobic backbone and terminally varying functional groups have been synthesized for applications for the functionalization of membranes. In the present study, we employ a spin‐labeled analogue of a recently described new class of molecular rods to characterize their dynamic interactions with membranes. By using the different approaches of ESR and NMR spectroscopy, we show that the spin moiety of the membrane‐embedded spin‐labeled rod is localized in the upper chain/glycerol region of membranes of different compositions. The rod is embedded within the membrane in a tilted orientation to adjust for the varying hydrophobic thicknesses of these bilayers. This orientation does not perturb the membrane structure. The water solubility of the rod is increased significantly in the presence of certain cyclodextrins. These cyclodextrins also allow the rods to be extracted from the membrane and incorporated into preformed membranes. The latter will improve the future applications of these rods in cellular systems as stable membrane‐associated anchors for the functionalization of membrane surfaces.
Ionic‐Liquid‐Assisted Synthesis of Uniform Fluorinated B/C‐Codoped TiO2 Nanocrystals and Their Enhanced Visible‐Light Photocatalytic Activity
Authors: Yu Jiaguo , Li Qin , Liu Shengwei , Jaroniec Mietek 
Published: January 2013

AbstractExploiting advanced photocatalysts under visible light is of primary significance for the development of environmentally relevant photocatalytic decontamination processes. In this study, the ionic liquid (IL), 1‐butyl‐3‐methylimidazolium tetrafluoroborate, was employed for the first time as both a structure‐directing agent and a dopant for the synthesis of novel fluorinated B/C‐codoped anatase TiO2 nanocrystals (TIL) through hydrothermal hydrolysis of tetrabutyl titanate. These TIL nanocrystals feature uniform crystallite and pore sizes and are stable with respect to phase transitions, crystal ripening, and pore collapse upon calcination treatment. More significantly, these nanocrystals possess abundant localized states and strong visible‐light absorption in a wide range of wavelengths. Because of synergic interactions between titania and codopants, the calcined TIL samples exhibited high visible‐light photocatalytic activity in the presence of oxidizing Rhodamine B (RhB). In particular, 300 °C‐calcined TIL was most photocatalytically active; its activity was much higher than that of TiO1.98N0.02 and reference samples (TW) obtained under identical conditions in the absence of ionic liquid. Furthermore, the possible photocatalytic oxidation mechanism and the active species involved in the RhB degradation photocatalyzed by the TIL samples were primarily investigated experimentally by using different scavengers. It was found that both holes and electrons, as well as their derived active species, such as .OH, contributed to the RhB degradation occurring on the fluorinated B/C‐codoped TiO2 photocatalyst, in terms of both the photocatalytic reaction dynamics and the reaction pathway. The synthesis of the aforementioned novel photocatalyst and the identification of specific active species involved in the photodegradation of dyes could shed new light on the design and synthesis of semiconductor materials with enhanced photocatalytic activity towards organic pollutants.
Periodic Behavior of Lanthanide Coordination within Reverse Micelles
Authors: Ellis Ross J. , Meridiano Yannick , Chiarizia Renato , Berthon Laurence , Muller Julie , Couston Laurent , Antonio Mark R. 
Published: January 2013

AbstractTrends in lanthanide(III) (LnIII) coordination were investigated within nanoconfined solvation environments. LnIII ions were incorporated into the cores of reverse micelles (RMs) formed with malonamide amphiphiles in n‐heptane by contact with aqueous phases containing nitrate and LnIII; both insert into pre‐organized RM units built up of DMDOHEMA (N,N′‐dimethyl‐N,N′‐dioctylhexylethoxymalonamide) that are either relatively large and hydrated or small and dry, depending on whether the organic phase is acidic or neutral, respectively. Structural aspects of the LnIII complex formation and the RM morphology were obtained by use of XAS (X‐ray absorption spectroscopy) and SAXS (small‐angle X‐ray scattering). The LnIII coordination environments were determined through use of L3‐edge XANES (X‐ray absorption near edge structure) and EXAFS (extended X‐ray absorption fine structure), which provide metrical insights into the chemistry across the period. Hydration numbers for the Eu species were measured using TRLIFS (time‐resolved laser‐induced fluorescence spectroscopy). The picture that emerges from a system‐wide perspective of the LnO interatomic distances and number of coordinating oxygen atoms for the extracted complexes of LnIII in the first half of the series (i.e., Nd, Eu) is that they are different from those in the second half of the series (i.e., Tb, Yb): the number of coordinating oxygen atoms decrease from 9 O for early lanthanides to 8 O for the late ones—a trend that is consistent with the effect of the lanthanide contraction. The environment within the RM, altered by either the presence or absence of acid, also had a pronounced influence on the nitrate coordination mode; for example, the larger, more hydrated, acidic RM core favors monodentate coordination, whereas the small, dry, neutral core favors bidentate coordination to LnIII. These findings show that the coordination chemistry of lanthanides within nanoconfined environments is neither equivalent to the solid nor bulk solution behaviors. Herein we address atomic‐ and mesoscale phenomena in the under‐explored field of lanthanide coordination and periodic behavior within RMs, providing a consilience of fundamental insights into the chemistry of growing importance in technologies as diverse as nanosynthesis and separations science.
Popcorn‐Shaped Magnetic Core–Plasmonic Shell Multifunctional Nanoparticles for the Targeted Magnetic Separation and Enrichment, Label‐Free SERS Imaging, and Photothermal Destruction of Multidrug‐Resistant Bacteria
Authors: Fan Zhen , Senapati Dulal , Khan Sadia Afrin , Singh Anant Kumar , Hamme Ashton , Yust Brian , Sardar Dhiraj , Ray Paresh Chandra 
Published: January 2013

AbstractOver the last few years, one of the most important and complex problems facing our society is treating infectious diseases caused by multidrug‐resistant bacteria (MDRB), by using current market‐existing antibiotics. Driven by this need, we report for the first time the development of the multifunctional popcorn‐shaped iron magnetic core–gold plasmonic shell nanotechnology‐driven approach for targeted magnetic separation and enrichment, label‐free surface‐enhanced Raman spectroscopy (SERS) detection, and the selective photothermal destruction of MDR Salmonella DT104. Due to the presence of the “lightning‐rod effect”, the core–shell popcorn‐shaped gold‐nanoparticle tips provided a huge field of SERS enhancement. The experimental data show that the M3038 antibody‐conjugated nanoparticles can be used for targeted separation and SERS imaging of MDR Salmonella DT104. A targeted photothermal‐lysis experiment, by using 670 nm light at 1.5 W cm−2 for 10 min, results in selective and irreparable cellular‐damage to MDR Salmonella. We discuss the possible mechanism and operating principle for the targeted separation, label‐free SERS imaging, and photothermal destruction of MDRB by using the popcorn‐shaped magnetic/plasmonic nanotechnology.
Halogenation of Graphene with Chlorine, Bromine, or Iodine by Exfoliation in a Halogen Atmosphere
Authors: Poh Hwee Ling , Šimek Petr , Sofer Zdeněk , Pumera Martin 
Published: January 2013

AbstractNanoarchitectonics on graphene implicates a specific and exact anchoring of molecules or nanoparticles onto the surface of graphene. One such example of an effective anchoring group that is highly reactive is the halogen moiety. Herein we describe a simple and scalable method for the introduction of halogen (chlorine, bromine, and iodine) moieties onto the surface of graphene by thermal exfoliation/reduction of graphite oxide in the corresponding gaseous halogen atmosphere. We characterized the halogenated graphene by using various techniques, including scanning and transmission electron microscopy, Raman spectroscopy, high‐resolution X‐ray photoelectron spectroscopy, and electrochemistry. The halogen atoms that have successfully been attached to the graphene surfaces will serve as basic building blocks for further graphene nanoarchitectonics.
Conformational Analysis of δ‐Lactones by DFT Calculations: The Parent Compound and its Monomethyl and Selected Dimethyl Derivatives
Authors: Weber Fabian , Brückner Reinhard 
Published: January 2013

AbstractThe static and dynamic stereochemistry of unsubstituted δ‐valerolactone, all monomethylated δ‐lactones, and all nongeminally dimethylated δ‐lactones was explored with the B3LYP functional and def2‐TZVPP basis set. A search strategy was employed which allowed the entire conformational space of any (poly‐)substituted δ‐lactone to be scanned. It allowed the lowest threshold conformational interconversion pathways to be mapped. The latter can be visualized in appealingly intuitive yet unprecedented diagrams. They trace the energy versus a circular abscissa which describes the passage of the molecule through one complete conformation interchange. The respective plot is C2‐symmetrical for the parent compound, which is achiral, and C1‐symmetrical for all methylated δ‐lactones, which are chiral.
Phospholipid–Detergent Conjugates as Novel Tools for siRNA Delivery
Authors: Pierrat Philippe , Laverny Gilles , Creusat Gaëlle , Wehrung Patrick , Strub Jean‐Marc , VanDorsselaer Alain , Pons Françoise , Zuber Guy , Lebeau Luc 
Published: January 2013

AbstractOne of the potential benefits of drug delivery systems in medicine is the creation of nanoparticle‐based vectors that deliver a therapeutic cargo in sufficient quantity to a target site to enable a selective effect, width of the therapeutic window depending on the toxicity of the vector and the cargo. In this work, we intended to improve the siRNA delivery efficiency of a new kind of nucleic acid carrier, which is the result of the conjugation of the membrane phospholipid 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine (DOPC) to the membrane‐active species Triton X‐100 (TX100). We hypothesized that by improving the biodegradability the cytotoxicity of the conjugate might by reduced, whereas its original transfection potential would be tentatively preserved. DOPC was conjugated to Triton X‐100 through spacers displaying various resistance to chemical hydrolysis and enzyme degradation. The results obtained through in vitro siRNA delivery experiments showed that the initial phosphoester bond can be replaced with a phospho(alkyl)enecarbonate group with no loss in the transfection activity, whereas the associated cytotoxicity was significantly decreased, as assessed by metabolic activity and membrane integrity measurements. The toxicity of the conjugates incorporating a phospho(alkyl)enesuccinnate moiety proved even lower but was clearly balanced with a reduction of the siRNA delivery efficiency. Hydrolytic stability and intracellular degradation of the conjugates were investigated by NMR spectroscopy and mass spectrometry. A general trend was that the more readily degraded conjugates were those with the lower toxicity. Otherwise, the phospho(alkyl)enecarbonate conjugates revealed some hemolytic activity, whereas the parent phosphoester did not. The reason why these conjugates behave differently with respect to hemolysis might be a consequence of unusual fusogenic properties and probably reflects the difference in the stability of the conjugates in the intracellular environment.
Sulfination by Using Pd‐PEPPSI Complexes: Studies into Precatalyst Activation, Cationic and Solvent Effects and the Role of Butoxide Base
Authors: Sayah Mahmoud , Lough Alan J. , Organ Michael G. 
Published: January 2013

AbstractThe activation of PEPPSI precatalysts has been systematically studied in Pd‐catalysed sulfination. Under the reactions conditions of the sulfide and KOtBu in toluene, the first thing that happens is exchange of the two chlorides on the PEPPSI precatalyst with the corresponding sulfides, creating the first resting state; it is via this complex that all Pd enters the catalytic cycle. However, it is also from this same complex that a tri‐Pd complex forms, which is a more persistent resting state. Under standard reaction conditions, this complex is catalytically inactive. However, if additional pyridine or a smaller base (i.e., KOEt) is added, this complex is broken down, presumably initially back to the first resting state and it is again capable of entering the catalytic cycle and completing the sulfination. Of note, once the tri‐Pd complex forms, one equivalent of Pd is lost to the transformation. Related to this, the nature of the cation of the sulfide salt and solvent dielectric is very important to the success of this transformation. That is, the less soluble the salt the better the performance, which can be attributed to lowering sulfide concentration to avoid the movement of the Pd‐NHC complex into the above described off‐cycle sulfinated resting states.
Diastereoselective Access to Polyoxygenated Polycyclic Spirolactones through a Rhodium‐Catalyzed [3+2] Cycloaddition Reaction: Experimental and Theoretical Studies
Authors: Rodier Fabien , Rajzmann Michel , Parrain Jean‐Luc , Chouraqui Gaëlle , Commeiras Laurent 
Published: January 2013

AbstractThe synthetic utility of γ‐alkylidenebutenolides is demonstrated as highly competent dipolarophile partners in both intra‐ and intermolecular rhodium(II)‐catalyzed 1,3‐dipolar cycloaddition reactions. The strength of this approach lies in the formation of spiro[6,4]lactone moieties with the concomitant construction of quaternary spiro stereocenters. Typically, the construction of spirolactones involves an esterification step, which has often been reported as a “biosynthetic pathway”, and often occurs either as or near to the final step of a total synthesis. Furthermore, a convergent and versatile route is reported for the formation of the (5,7) skeleton of molecules that were isolated from the Schisandra genus. Computational studies were performed to provide an overall picture of the mechanism of the intermolecular [3+2] cycloaddition between 2‐diazo‐1,3‐ketoester and protoanemonin and to rationalize the empirical observations. In particular, we have demonstrated for the first time that the rhodium center plays an important role during the cyclization step itself and reacts with the dipolarophile as a complex with the ylide.
One‐Step Synthesis of Small‐Sized and Water‐Soluble NaREF4 Upconversion Nanoparticles for In Vitro Cell Imaging and Drug Delivery
Authors: Yang Dongmei , Dai Yunlu , Ma Pingan , Kang Xiaojiao , Cheng Ziyong , Li Chunxia , Lin Jun 
Published: January 2013

AbstractSmall (2–28 nm) NaREF4 (rare earth (RE)=Nd–Lu, Y) nanoparticles (NPs) were prepared by an oil/water two‐phase approach. Meanwhile, hydrophilic NPs can be obtained through a successful phase‐transition process by introducing the amphiphilic surfactant sodium dodecylsulfate (SDS) into the same reaction system. Hollow‐structured NaREF4 (RE=Y, Yb, Lu) NPs can be fabricated in situ by electron‐beam lithography on solid NPs. The MTT assay indicates that these hydrophilic NPs with hollow structures exhibit good biocompatibility. The as‐prepared hollow‐structured NPs can be used as anti‐cancer drug carriers for drug storage/release investigations. Doxorubicin hydrochloride (DOX) was taken as model drug. The release of DOX from hollow α‐NaLuF4:20 % Yb3+, 2 % Er3+ exhibits a pH‐sensitive release patterns. Confocal microscopy observations indicate that the NPs can be taken up by HeLa cells and show obvious anti‐cancer efficacy. Furthermore, α‐NaLuF4:20 % Yb3+, 2 % Er3+ NPs show bright‐red emission under IR excitation, making both the excitation and emission light fall within the “optical window” of biological tissues. The application of α‐NaLuF4:20 % Yb3+, 2 % Er3+ in the luminescence imaging of cells was also investigated, which shows a bright‐red emission without background noise.
Synthesis and Characterization of Some N‐Aryl‐4‐nitroimidazoles as Potential Insensitive Energy Materials
Authors: Hou Kehui , Liu Zuliang 
Published: January 2013

AbstractN‐Aryl derivatives of 4‐nitroimidazole have been synthesized under CuI/TBAB catalytic system in excellent yields, using KOH as base in DMF solvent.
A Formal Synthesis of Iridoid 9‐Deoxygelsemide
Authors: Liu Yang , Zhao Gang 
Published: January 2013

AbstractA formal total synthesis of iridoid 9‐deoxygelsemide has been accomplished. Our approach features the use of (S)‐carvone as starting material, Favorskii rearrangement to construct the functionalized cyclopentane core, Chugeav elimination to introduce the endocyclic double bond, and the ring‐opening reaction of epoxide to build the second five‐membered ring.