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A general and efficient protocol for the synthesis of 9,10-phenanthraquinone derivatives has been successfully developed involving a copper(0)/Selectfluor system-promoted oxidative carbon-carbon bond cleavage/annulation of o-aryl chalcones. A variety of substituted 9,10-phenanthraquinones were synthesized in moderate to good yields under mild reaction conditions. [ABSTRACT FROM AUTHOR]

The reaction of isolable dialkylstannylene 1 with an excess amount of CS2 produces an isomeric mixture of 3,3'-distanna-2,2',4,4'-tetrathiabicyclobutylidene 8 and 3,7-distanna-2,4,6,8-tetrathiabicyclo[3.3.0]oct-1(5)-ene 9 with a ratio depending on the reaction conditions. Compounds 8 and 9 are separated by column chromatography and characterized by NMR spectroscopy and X-ray crystallography. Detailed investigation of the reaction has revealed that the initial product is 8, which isomerizes to 9 irreversibly under the catalytic influence of 1 as a Lewis acid. The above view is supported by the theoretical DFT calculations. Treatment of 1 with ArN=C=O [Ar = 2,6-iPr2C6H3] affords the corresponding carbamoyl(hydroxyl)stannane 11 via the hydrolysis of the corresponding silaaziridinone formed by the [1 + 2] cycloaddition reaction of 1 with the N=C double bond of the isocyanate. Stannylene 1 reacts with ArN=C=S, giving a mixture of complex products, while 1 does not react with CO2. [ABSTRACT FROM AUTHOR]

Electronic and steric substituent effects on the insertion reactions of dimethylsilylene (1) and 2,2,5,5-tetrasilylsilacyclopentane-1,1-diyl (2′) into Si–H bonds are compared with those into Si–Cl bonds using DFT calculations at the B3LYP/6-31++G(d,p) level. For both 1and 2′, the ΔG⧧value for the insertion into a Si–H bond of SiH4is close to and only ca. 1.5 kcal mol–1lower than that into the Si–Cl bond of H3SiCl. Effects of in-plane substituents on the ΔG⧧values for both Si–H and Si–Cl insertion reactions are mainly electronic and electron-withdrawing substituents lower the ΔG⧧values. Sensitivity of the Si–H insertion to the substituent effects is similar to that of the Si–Cl insertion. Effects of out-of-plane substituents are largely steric, and their sensitivity for the Si–H insertion is close to that for the Si–Cl insertion. The ΔG⧧values for the insertion reactions of sterically bulky 2′are significantly larger than those of 1. The puzzling prior observation that a bulky isolable silylene inserts into the Si–Cl bond of H2SiCl2and the Si–H bond of Me2SiHCl is explained on the basis of the substituent effects on the insertion reactions. [ABSTRACT FROM AUTHOR]

We demonstrate that Ag2S nanocrystals are the bifunctional mediator for controllable growth of semiconductor heterostructures including more complicated multisegments heterostructures in solution- phase, which is a new type of nanomediator and quite different from the metal nanoparticle catalyst. The intrinsic high Ag+ ion mobility makes Ag2S nanocrystals not only exhibit excellent catalytic function for growth of metal sulfide heterostructures but also act as a source-host for growth of ternary semiconductor heterostructures, for example, Ag2S-AglnS2. The semiconductors grow epitaxially from or inward in Ag2S nanocrystals forming single-crystalline heterostructures. Moreover, the method developed here also can construct multisegments heterostructures, for example, Ag2S-CdS-ZnS, AglnS2-Ag2S-AglnS2. The interfacial structure is still stable even if the lattice mismatch is quite large, which is a unique feature of this method. [ABSTRACT FROM AUTHOR]

The interaction of cation/benzene complexes (cation = Na+, Li+, K+) was calculated by using the density functional theory (DFT). The calculated results suggested that the C−H bonds were strengthened and the C−C bonds were weakened in cation/benzene complexes in comparison to that in free benzene. This conclusion was confirmed by the changes in the stretching frequencies. The redistribution of the charges and the rehybridization analysis of the C−H and C−C bonds gave a further understanding. Similar phenomena have also been found in cation/perfluorobenzene, cation/naphthalene, cation/toluene, and cation/aniline systems. [ABSTRACT FROM AUTHOR]

Two-dimensional vibrational spectroscopy is applied to investigate the dilution process of 1-ethyl-3-methyl-imidazolium tetrafluoroborate ([Emim][BF 4]) in water. With increasing water content in ionic liquid (IL)/water mixtures, the C−H stretching vibration of the imidazolium cation showed systematic blue-shifts, which reflect the weakening of the cohesion between the cation and anion of ILs. The two-dimensional IR results reveal that the ILs sense quite different environments during the whole dilution process. First, the three-dimensional network structure of pure ILs was destroyed gradually into ionic clusters, then the clusters were further dissociated into ionic pairs surrounded by water molecules, and finally the latter became the dominant form in bulk water. Within the concentration range we investigated (0.02 < XD2O< 0.90), the intruding water does not dissociate ILs into ions completely. The structure evolution of ILs can be clearly detected and visualized in the asynchronous spectrum. [ABSTRACT FROM AUTHOR]

Presents information pertaining to the releasing of the Mgadenosine triphosphate (MgATP)-dependent and MgATP-independent [3H]noradrenaline from perforated synaptosomes, while referencing to their use of the N-ethylmaleimide-sensitive fusion protein. How vesicle depriming was detected; Indication of results; Reference to the releasing of neurotransmitters.

The article discusses the study on the significance of molecular hydration activation in catalytic hydrogenation of noble metal catalyst. When researchers did the process using neutral fullerene, fullerene anion or both, they found that these metals are excellent catalyst for converting amino aromatics and its selectivity under the ultraviolet (UV) irradiation. Moreover, they concluded that hydrogenation activation method will promote the development of electronically excited state reactions.

Precise control of particles co-assembly has attracted great attention for fabricating intricate structures and functional materials. However, achieving precise coassembly of one-dimensional (1D) binary superstructures remains challenging due to the constrained thermodynamic stability and lack of general strategies to control the 1D ordered arrangement of mixed particles. Here, we propose a facile strategy to achieve programmed coassembly of 1D binary superstructures by liquid soft confinement without particle modification or external field. It reveals that binary particles undergo stepwise confinement and programmed co-assembly in the gradually shrinking and spatially tunable liquid soft confinement. Through tuning the liquid confined space and particles composition, diverse 1D binary superstructures with precisely controlled periodicity, orientation and symmetry are achieved, which shows generality for various particles of di�€erent sizes and materials. This work provides a promising route to refined patterning and manufacturing complex materials. [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging (MRI) compatible neural electrodes are important for combining high-resolution electrophysiological measurements with more global MRI mapping of brain activity, which is critical for fundamental neuroscience studies, as well as clinical evaluation and monitoring. Copper is a favorable material to use in MRI because it has magnetic susceptibility close to water and tissues. However, the cytotoxicity of copper precludes its direct implantation for neural recording. Here, we overcome this limitation by developing a graphene encapsulated copper (G-Cu) microelectrode. The toxicity of copper is largely eliminated, as evidenced by the in vitro cell tests and in vivo histology studies. Local field potentials and single-unit spikes were recorded from rodent brains with the G-Cu microelectrodes. Notably, the G-Cu microelectrodes show no image artifacts in a 7.0 T MRI scanner, indicating minimal magnetic field distortion in their vicinity. This high MRI compatibility of our G-Cu probes would open up new opportunities for fundamental brain activity studies and clinical applications requiring continuous MRI and electrophysiological recordings. [ABSTRACT FROM AUTHOR]

We present four conjugated donor-acceptor (D-A) polymers PBPDT-Si, PBPDSe-Si, PBPDT, and PBPDSe entailing a new electron acceptor Pechmann dye framework, i.e., bipyrrolylidene-2,2′(1H,1′H)-dione (BPD), and thiophene and selenophene as the respective electron donors. PBPDT-Si and PBPDSe-Si contain siloxane-terminated side chains, while PBPDT and PBPDSe bear branching alkyl chains. The respective HOMO energies of PBPDT-Si and PBPDSe-Si are slightly higher than those of PBPDT and PBPDSe, whereas the respective LUMO energies of PBPDT-Si and PBPDSe-Si are slightly lower than those of PBPDT and PBPDSe. The results reveal that (i) thin films of all four polymers show ambipolar semiconducting performances under a nitrogen atmosphere, (ii) hole and electron mobilities are more balanced for PBPDT-Si and PBPDSe-Si, and (iii) the employment of siloxane-terminated side chains is beneficial for improving charge transporting compared to branching alkyl side chains. Thin film hole and electron mobilities of PBPDT-Si can reach 0.74 and 0.87 cm² V-1 s-1, respectively. [ABSTRACT FROM AUTHOR]

A series of donor--acceptor systems incorporating a carbazole moiety as the donating unit and pyridine moiety as the accepting unit have been designed and synthesized. The spectroscopic and electrochemical behaviors of the carbazole derivatives demonstrate that the carbazole unit interacts with the electron-accepting group through the π-conjugated spacer, thus leading to the intramolecular charge transfer (ICT). The pyridine-substituted carbazole derivatives show significant sensing and coordinating properties toward a wide range of metal cations. Compound S2 exhibits fluorescence enhancement upon association with transition metal cations, and compound V3 shows high selectivity for Cu2+ among this series of materials. DFT calculations indicate the different association abilities of the dyes and the enhancement of ICT upon addition of the metal cations. [ABSTRACT FROM AUTHOR]

Highly uniform single crystal ultrathin ZnS nanowires (NWs) with 2 nm diameter and up to 10 μm length were fabricated using a catalyst-free colloidal chemistry strategy. The nanowires crystallized in hexagonal phase structure with preferential growth along the direction of the (001) basal plane. The strong polarity of the (001) plane composed of Zn cations or S anions drives the oriented attachment of ZnS nanocrystals (NCs) along this direction via electrostatic (or dipole) interaction. The ultrathin ZnS nanowires show intrinsic ferromagnetism at room temperature and other unusual properties related to its unique nature, such as large anisotropic lattice expansion, large blue-shift of UV-vis absorption band of the excition, and photoluminescence spectrum of the exciton band edge. First-principles DFT computation results show that Zn vacancies can induce intrinsic ferromagnetism in these undoped ZnS NWs. The main source of the magnetic moment arises from the unpaired 3p electrons at S sites surrounding the Zn vacancies carrying the magnetic moment ranging from 0.26 to 0.66 μB. Calculated results indicate that the magnetic moment of the ultrathin ZnS NWs can be increased by increasing the Zn vacancy concentration without significant energy cost. The calculated magnetization value (1.96 or 0.40 emu/g for Zn vacancies on the surface of NWs or inside, respectively) by Zn53S54 supercell model is larger than our experimental value (0.12 emu/g at 1.8 K and 0.05 emu/g at 300 K), but the ferromagnetic result is qualitatively in agreement. [ABSTRACT FROM AUTHOR]

The blue-shifted C−D stretching vibrations (νCD) of deuteriated dimethyl sulfoxide (DMSO-d6) in mixtures of DMSO-d6/ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) were carefully investigated and compared with those in DMSO-d6/water. Results from FTIR studies indicate that the direct interaction of C−D···F between DMSO-d6and the anion [BF4−] plays a minor role in the blue-shift of νCDin the mixtures of DMSO-d6/IL. They also show that the indirect influence of the hydrogen bond formed by the nearby functional group SO with C2−H of the cation significantly contributes to the blue-shift of νCD, as can be inferred from the significant differences of the blue-shift in [Bmim][BF4] and 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ([Bm2im][BF4]). In contrast, in the case of DMSO-d6/water mixtures, direct hydration of C−H···O between the methyl groups of DMSO-d6with the oxygen atom of water is mainly responsible for the blue shift of νCD. Furthermore, theoretical calculations revealed that charge migrations as well as rehybridization have a dominant effect on the blue-shift in both mixtures. [ABSTRACT FROM AUTHOR]

A highly diastereo- and enantioselective silver-catalyzed azomethine ylide-imine (AYI) cycloaddition reaction of glycine aldimino esters with imines was developed in which the Xing-Phos-controlled syn-selective or DTBM-Segphos-induced anti-selective AYI cycloaddition reaction could be applied to the synthesis of a variety of stereodivergent 1-alkyl-2,5-substituted imidazolidines with high yields and excellent enantioselectivities (up to 99% ee) as well as good diastereoselectivities (up to 99:1 dr) under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Red or near-infrared phosphors, which have a lower absorption in biological tissue, show excellent promise in the field of bioimaging. Here, we design the red phosphor with a broad emission band and realize tunable luminescence of Cr3+ by two methods, i.e., adjusting the Cr3+-doping concentration in Zn3(AlGa)2Ge2O10 solid solution and doping In3+ ions in Zn3Al2Ge2O10 due to a size mismatch. The solid solution is illustrated by density functional theory calculation, X-ray powder diffraction, and high resolution transmission electron microscopy. The Cr3+-doped phosphor shows a red emission band centered at 705 nm, which is ascribed to the 2E → 4A2 and 4T2(4F) → 4A2 transitions. When Cr3+ ions or In3+ ions are introduced, the full width at half-maximum (fwhm) increased due to the combination of crystal field splitting, nephelauxetic effect, and reabsorption. [ABSTRACT FROM AUTHOR]

The enantioselective construction of a family of chiral glycine-derived aldimino esters is described. The asymmetric tandem conjugate addition-elimination procedure is characterized by its exceptional mild reaction conditions and features with an exquisite enantioselectivity profile using commercially available silver/DTBM-SegPhos catalyst, allowing for the facile preparation of a variety of substituted and chiral glutamic acid derivatives (up to 99% ee) bearing Schiff base in a straightforward manner. [ABSTRACT FROM AUTHOR]

Fullerene hierarchical mesocrystals were first prepared by antisolvent induced precipitation method. Their morphologies and sizes can be controlled by adjusting the antisolvent type and the ratio between the solvent (toluene) and antisolvent (ethyl acetate or tetrahydrofuran). The formation of fullerene mesocrystals and their transformation to single crystal were observed by time-dependent experiments with SEM and TEM. Fullerene mesocrystals can be separated from the solution and are stable for several months. HRTEM revealed that mesocrystals were made up of highly oriented nanoparticles. The formation of fullerene mesocrystals and their transformation to single crystals provide a new way for the construction of fullerene nanostructures with different applications. [ABSTRACT FROM AUTHOR]

It is challenging to reduce ground-level ozone (O3) pollution at a given locale, due in part to the contributions of both local and distant sources. We present direct evidence that the increasing regional effects have negated local control efforts for O3 pollution in Hong Kong over the past decade, by analyzing the daily maximum 8 h average O3 and Ox (=O3+NO2) concentrations observed during the high O3 season (September-November) at Air Quality Monitoring Stations. The locally produced Ox showed a statistically significant decreasing trend over 2002-2013 in Hong Kong. Analysis by an observation-based model confirms this decline in in situ Ox production, which is attributable to a reduction in aromatic hydrocarbons. However, the regional background Ox transported into Hong Kong has increased more significantly during the same period, reflecting contributions from southern/eastern China. The combined result is a rise in O3 and a nondecrease in Ox. This study highlights the urgent need for close cross-boundary cooperation to mitigate the O3 problem in Hong Kong. China's air pollution control policy applies primarily to its large cities, with little attention to developing areas elsewhere. The experience of Hong Kong suggests that this control policy does not effectively address secondary pollution, and that a coordinated multiregional program is required. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H2O2) and organic peroxides play an important role in atmospheric chemistry, but knowledge of their abundances, sources, and sinks from heterogeneous processes remains incomplete. Here we report the measurement results obtained in four seasons during 2011-2012 at a suburban site and a background site in Hong Kong. Organic peroxides were found to be more abundant than H2O2, which is in contrast to most previous observations. Model calculations with a multiphase chemical mechanism suggest important contributions from heterogeneous processes (primarily transition metal ion [TMI]-HOx reactions) to the H2O2 budget, accounting for about one-third and more than half of total production rate and loss rate, respectively. In comparison, they contribute much less to organic peroxides. The fast removal of H2O2 by these heterogeneous reactions explains the observed high organic peroxide fractions. Sensitivity analysis reveals that the role of heterogeneous processes depends on the abundance of soluble metals in aerosol, serving as a net H2O2 source at low metal concentrations, but as a net sink with high metal loading. The findings of this study suggest the need to consider the chemical processes in the aerosol aqueous phase when examining the chemical budget of gas-phase H2O2. [ABSTRACT FROM AUTHOR]

Pure perovskite LnFeO3(Ln = La, Pr−Tb) hollow spheres with porous shell and solid spheres (Ln = Dy−Yb, Y) have been successfully synthesized via calcination of a Ln-Fe citrate complex precursor, which was prepared via a convenient and effective hydrothermal method. The reaction parameters to obtain the Ln-Fe citrate complex with Ln/Fe = 1:1 can be calculated using a diagram of reaction species distribution in the solution. The calculated value was coincident well with the experimental one. The composition and the thermal decomposition processes of the Ln-Fe citrate complex were investigated carefully, using elemental analysis, inductively coupled plasma analysis (ICP), energy-dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The formation mechanism of the Ln-Fe citrate complex hollow spheres was proposed as an acidic digestion ripening process. Furthermore, all 13 pure-phase LnFeO3microspheres had an excellent catalytic performance for the NO + CO reaction. The experimental results showed that the completed conversion of NO and specific selectivity of N2were achieved, which could be comparable with the noble metal catalysts and better than that of LnFeO3nanoparticles synthesized via the Pechini process. In addition, the LnFeO3microspheres exhibited good chemical stability and almost invariable catalytic activity during the lifetime test lasting for 96 h. [ABSTRACT FROM AUTHOR]

Nanocubes and hollow cubic microcages of FeCo alloy have been synthesized in large scale by reduction of aqueous Fe 2+and Co 2+with hydrazine in the presence of poly(ethylene glycol) and cyclohexane at a relative low temperature, which were confirmed by X-ray powder diffraction, transmission electron microscopy, and scanning electron microscopy. The morphology and dimensions of FeCo alloy nanocrystals could be controlled by the reaction conditions such as the concentrations of cyclohexane and PEG-400, reaction time, and the molar ratio of Fe 2+to Co 2+in the solution. The concentration of iron in these particles could be varied between 17% and 56%. The highest magnetization of 211.9 emu/g was recorded for 68 ± 6 nm Fe 50Co 50nanocubes. The work demonstrates that shape and size-controlled synthesis can offer a simple solution to fabricate magnetic FeCo nanocubes that are promising for single nanoparticle recording and for high performance exchange-spring nanocomposite magnetic applications. [ABSTRACT FROM AUTHOR]

We have developed a method of controllable synthesis of MgO with various morphologies by adjusting the composition and phase structure of magnesium carbonate hydrate (MCH). The phase structure of the MCH varied from monoclinic Mg 5(CO 3) 4(OH) 2(H 2O) 4to hexagonal MgCO 3by changing the concentration of Mg 2+and HCO 3−; the corresponding morphology of the MCH ranges from nanoflakes and flowerlike microspheres composed of nanoflakes to layer-like rhombohedra and microspheres composed of rhombohedra. After annealing, four kinds of mesoporous cubic MgO micronano structures were obtained with their original morphologies. Because of the high specific surface area, MgO mesoporous nanoflakes and flowerlike microsphers exhibited excellent absorption performance for common toxic heavy metal ions and organic pollutants and are expected to be a potential absorbent in wastewater treatment. [ABSTRACT FROM AUTHOR]

We have developed a template-free hydrothermal method of constructing rare earth phosphate hollow spheres using H 6P 4O 13as the PO 43−source. The mechanism of hollow spheres formation was proposed on the basis of Ostwald ripening. The resulting hollow spheres, especially with the aid of doping of other lanthanide cations, exhibit emission spanning the whole UV−visible wavelength range. [ABSTRACT FROM AUTHOR]

We for the first time report the synthesis of urchinlike BiPO 4structure composed of nanorods and its photoluminescence properties. Scanning electron microscopy (SEM) images show urchinlike BiPO 4structure composed of nanorods. The X-ray powder diffraction (XRD) pattern indicates that the crystal structure of the nanorod is monoclinic. The high-resolution transmission electron microscopy (HRTEM) image and Fast-Fourier-transform (FFT) pattern reveal the single-crystalline nature of the nanorod. The formation mechanism was proposed. BiPO 4displays strong blue emission. Because of the similarities of the crystal structure and lattice constants and the suitable energy level with the rare-earth phosphate, BiPO 4is a useful host for rare-earth ions. Ln 3+is successfully doped in BiPO 4and an efficient energy transfer from Bi 3+to Ln 3+takes place, which makes BiPO 4:Ln (Ln = Eu, Tb, Dy) emit strong luminescence in visible region. BiPO 4:Ln will have promising application in high-performance luminescence devices, etc. [ABSTRACT FROM AUTHOR]

The β-Ni(OH) 2microtubes with hierarchical structure wall composed of interweaved nanolamella were successfully fabricated by the template-free wet-chemical approach. To the best of our knowledge, it is the first report on Ni(OH) 2microtubes with the micro- and nanoscale composite structure. This method is very facile and effective to prepare the tubular materials with high yield and uniform tube diameter. The intermediate product and final composite structures were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform IR (FTIR), and thermogravimetric analysis (TGA), and the formation mechanism was deeply studied. In comparison with β-Ni(OH) 2microrod and particle electrodes, β-Ni(OH) 2microtube electrode has the highest discharge capacity in alkaline battery, indicating the potential applications of the microtubes with the hierarchical structures in alkaline Ni-based batteries, supercapacitor, and catalytic areas. [ABSTRACT FROM AUTHOR]

It is found that Cu 2+is an effective agent for the controlled preparation of shaped gold nanoparticles. As the concentration of Cu 2+increases from 0 mM to 0.2 mM to 1.6 mM, the shape of the gold nanoparticles changes from rod to cuboid to decahedron. A possible mechanism based on selectively retarding the growth rate of the {111} plane is proposed. [ABSTRACT FROM AUTHOR]

The experimental results show that there are two growth modes of crystalline metal oxide in the colloidal crystal template, which depend on the quality of the colloidal crystal. In well-ordered colloidal crystal templates, the metal oxide growth follows the structure of the colloidal crystal; and high quality three-dimensional ordered macroporous (3DOM) Cu2O or ZnO are formed. In contrast, in less-ordered colloidal crystal templates, metal oxide is grown according to its own capital structure, and cubic-shaped macroporous Cu2O or sheetlike macroporous ZnO are formed. Our method provides an easy and convenient way to prepare three-dimensional ordered macroporous materials or shaped macroporous materials via adjusting the level of ordered arrangement of the colloidal crystal templates. [ABSTRACT FROM AUTHOR]