238 research outputs found

    Synthesis and Catalytic Property of Iron Pincer Complexes Generated by C<sub>sp<sup>3</sup></sub>–H Activation

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    When the diphosphinito PCP ligand (Ph<sub>2</sub>P­(C<sub>6</sub>H<sub>4</sub>))<sub>2</sub>CH<sub>2</sub> (<b>1</b>) was treated with Fe­(PMe<sub>3</sub>)<sub>4</sub> and FeMe<sub>2</sub>(PMe<sub>3</sub>)<sub>4</sub>, the C<sub>sp<sup>3</sup></sub>–H activation products [(Ph<sub>2</sub>P­(C<sub>6</sub>H<sub>4</sub>))<sub>2</sub>CH]­Fe­(H)­(PMe<sub>3</sub>)<sub>2</sub> (<b>2</b>) and [(Ph<sub>2</sub>P­(C<sub>6</sub>H<sub>4</sub>))­(PhP­(C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>)­CH]­Fe­(PMe<sub>3</sub>)<sub>2</sub> (<b>3</b>) were obtained at room temperature. The generation of product <b>3</b> underwent one C<sub>sp<sup>3</sup></sub>–H and one C<sub>sp<sup>2</sup></sub>–H bond activation process. The new iron hydride complex <b>2</b> showed good activity in the catalytic hydrosilylation of aldehydes and ketones by using (EtO)<sub>3</sub>SiH as the hydrogen source under mild conditions. Complexes <b>2</b> and <b>3</b> were characterized by spectroscopic methods and X-ray diffraction analysis

    Imine Nitrogen Bridged Binuclear Nickel Complexes via N–H Bond Activation: Synthesis, Characterization, Unexpected C,N-Coupling Reaction, and Their Catalytic Application in Hydrosilylation of Aldehydes

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    The reactions of NiMe<sub>2</sub>(PMe<sub>3</sub>)<sub>3</sub> with 2,6-difluoroarylimines were explored. As a result, a series of binuclear nickel complexes (<b>5</b>–<b>8</b>,<b> 11</b>) were synthesized. Meanwhile, from the reactions of NiMe<sub>2</sub>(PMe<sub>3</sub>)<sub>3</sub> with [2-CH<sub>3</sub>C<sub>6</sub>H<sub>4</sub>-C­(NH)-2,6-F<sub>2</sub>C<sub>6</sub>H<sub>3</sub>] (<b>9</b>) and [2,6-(CH<sub>3</sub>)<sub>2</sub>C<sub>6</sub>H<sub>3</sub>-C­(NH)-2,6-F<sub>2</sub>C<sub>6</sub>H<sub>3</sub>] (<b>10</b>), two unexpected C,N-coupling products (<b>12</b> and <b>13</b>) were obtained. It is believed that these coupling reactions underwent activation of the N–H and C–F bonds. The binuclear nickel complexes showed excellent catalytic activity in the hydrosilylation of aldehydes. The mechanism of the reaction was studied through stoichiometric reactions, and the double-(η<sup>2</sup>-Si–H)–Ni<sup>II</sup> intermediate was detected by in situ <sup>1</sup>H NMR spectroscopy, which may be the key point in the catalytic cycle

    Synthesis and Catalytic Property of Iron Pincer Complexes Generated by C<sub>sp<sup>3</sup></sub>–H Activation

    No full text
    When the diphosphinito PCP ligand (Ph<sub>2</sub>P­(C<sub>6</sub>H<sub>4</sub>))<sub>2</sub>CH<sub>2</sub> (<b>1</b>) was treated with Fe­(PMe<sub>3</sub>)<sub>4</sub> and FeMe<sub>2</sub>(PMe<sub>3</sub>)<sub>4</sub>, the C<sub>sp<sup>3</sup></sub>–H activation products [(Ph<sub>2</sub>P­(C<sub>6</sub>H<sub>4</sub>))<sub>2</sub>CH]­Fe­(H)­(PMe<sub>3</sub>)<sub>2</sub> (<b>2</b>) and [(Ph<sub>2</sub>P­(C<sub>6</sub>H<sub>4</sub>))­(PhP­(C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>)­CH]­Fe­(PMe<sub>3</sub>)<sub>2</sub> (<b>3</b>) were obtained at room temperature. The generation of product <b>3</b> underwent one C<sub>sp<sup>3</sup></sub>–H and one C<sub>sp<sup>2</sup></sub>–H bond activation process. The new iron hydride complex <b>2</b> showed good activity in the catalytic hydrosilylation of aldehydes and ketones by using (EtO)<sub>3</sub>SiH as the hydrogen source under mild conditions. Complexes <b>2</b> and <b>3</b> were characterized by spectroscopic methods and X-ray diffraction analysis

    Heavy-Atom-Free Nanoparticles Based on Boron Dipyrromethene Derivatives for Combined Photothermal and Photodynamic Cancer Therapy

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    Boron dipyrromethenes (BODIPYs) have been extensively studied in phototherapy against cancer. However, heavy-atom-free BODIPYs have been relatively less explored, and some of them are only used for photothermal therapy. Here, four heavy-atom-free BODIPYs with phenyl, naphthyl, anthracyl, or pyrenyl were synthesized and named B-mPh, B-mNa, B-mAn, and B-mPy, respectively. Stable nanoparticles (NPs) of the BODIPYs were prepared via the assembly with pluronic F127, which were named B-mPh NPs, B-mNa NPs, B-mAn NPs, and B-mPy NPs. The spin–orbit charge transfer (SOCT) of the anthracene group enhances the intersystem crossing (ISC) effect and improves the ability of B-mAn to generate singlet oxygen. Compared with other NPs, B-mAn NPs showed enhanced cytotoxicity upon irradiation. This kind of heavy-atom-free nanomaterials based on BODIPY, which promotes ISC by SOCT and enhances the generation of reactive oxygen species, plays an active part in the realization of combined photothermal and photodynamic therapy

    Reduced Graphene Oxide-Immobilized Tris(bipyridine)ruthenium(II) Complex for Efficient Visible-Light-Driven Reductive Dehalogenation Reaction

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    A sodium benzenesulfonate (PhSO<sub>3</sub>Na)-functionalized reduced graphene oxide was synthesized via a two-step aryl diazonium coupling and subsequent NaCl ion-exchange procedure, which was used as a support to immobilize tris­(bipyridine)­ruthenium­(II) complex (Ru­(bpy)<sub>3</sub>Cl<sub>2</sub>) by coordination reaction. This elaborated Ru­(bpy)<sub>3</sub>-rGO catalyst exhibited excellent catalytic efficiency in visible-light-driven reductive dehalogenation reactions under mild conditions, even for ary chloride. Meanwhile, it showed the comparable reactivity with the corresponding homogeneous Ru­(bpy)<sub>3</sub>Cl<sub>2</sub> catalyst. This high catalytic performance could be attributed to the unique two-dimensional sheet-like structure of Ru­(bpy)<sub>3</sub>-rGO, which efficiently diminished diffusion resistance of the reactants. Meanwhile, the nonconjugated PhSO<sub>3</sub>Na-linkage between Ru­(II) complex and the support and the very low electrical conductivity of the catalyst inhibited energy/electron transfer from Ru­(II) complex to rGO support, resulting in the decreased support-induced quenching effect. Furthermore, it could be easily recycled at least five times without significant loss of catalytic reactivity

    Flaw Insensitive Fracture in Nanocrystalline Graphene

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    We show from a series of molecular dynamics simulations that the tensile fracture behavior of a nanocrystalline graphene (nc-graphene) nanostrip can become insensitive to a pre-existing flaw (e.g., a hole or a notch) below a critical length scale in the sense that there exists no stress concentration near the flaw, the ultimate failure does not necessarily initiate at the flaw, and the normalized strength of the strip is independent of the size of the flaw. This study is a first direct atomistic simulation of flaw insensitive fracture in high-strength nanoscale materials and provides significant insights into the deformation and failure mechanisms of nc-graphene

    Means and standard deviations of vMMN amplitudes (μV) in each expression condition.

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    <p>Means and standard deviations of vMMN amplitudes (μV) in each expression condition.</p

    Cytochrome <i>cd1</i>-Containing Nitrite Reductase Encoding Gene <i>nirS</i> as a New Functional Biomarker for Detection of Anaerobic Ammonium Oxidizing (Anammox) Bacteria

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    A newly designed primer set (AnnirS), together with a previously published primer set (ScnirS), was used to detect anammox bacterial <i>nirS</i> genes from sediments collected from three marine environments. Phylogenetic analysis demonstrated that all retrieved sequences were clearly different from typical denitrifiers’ <i>nirS</i>, but do group together with the known anammox bacterial <i>nirS</i>. Sequences targeted by ScnirS are closely related to <i>Scalindua nirS</i> genes recovered from the Peruvian oxygen minimum zone (OMZ), whereas sequences targeted by AnnirS are more closely affiliated with the <i>nirS</i> of <i>Candidatus</i> ‘Kuenenia stuttgartiensis’ and even form a new phylogenetic <i>nirS</i> clade, which might be related to other genera of the anammox bacteria. Analysis demonstrated that retrieved sequences had higher sequence identities (>60%) with known anammox bacterial <i>nirS</i> genes than with denitrifiers’ <i>nirS</i>, on both nucleotide and amino acid levels. Compared to the 16S rRNA and hydrazine oxidoreductase (<i>hzo</i>) genes, the anammox bacterial <i>nirS</i> not only showed consistent phylogenetic relationships but also demonstrated more reliable quantification of anammox bacteria because of the single copy of the <i>nirS</i> gene in the anammox bacterial genome and the specificity of PCR primers for different genera of anammox bacteria, thus providing a suitable functional biomarker for investigation of anammox bacteria

    The topographic maps of vMMN components in both happy and fearful conditions during the time windows of 50–130 ms and 320–450 ms.

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    <p>The topographic maps of vMMN components in both happy and fearful conditions during the time windows of 50–130 ms and 320–450 ms.</p

    vMMN componentsin the fearful (Fig 3A) and happy oddball (Fig 3B) conditions.

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    <p>The vMMNs in the deviant fearful minus standard fearful condition, and the left frontal waveform was the average neural activation at electrodes of F1, F3, and F5. The right frontal waveform was obtained from F2, F4, and F6. The left occipito-temporal waveform was from TP7, P7, PO7, CB1, and O1. The right occipito-temporal waveform was from TP8, P8, PO8, CB2, and O2.</p
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