The gas-phase reactions of [IrC4H2]+ with methane and water have been explored by using mass spectrometry combined with quantum chemical calculations. Interestingly, under the employed conditions, two isomers of [IrC4H2]+ co-exist with different reactivity. One of them only activates methane while the other is solely reactive with water to produce CO. Apparently, upon varying the coordination patterns, the Ir center gains rather distinct capabilities of mediating the bond breaking and making processes. The reactivity toward methane mainly depends on the orbital orientation, while the π-aromaticity of the reaction complex matters for the conversion of water. The experimental and theoretical findings in this work do not only imply the promising role the Ir atom can play in the bulk-system methane conversion, but may also be instructive on how to construct a high-performance center for steam reforming of methane.
相似文献Polymers with metal coordination ability are outstanding precursors of nanocatalysts, attracting numerous attention in nanocatalysis area. It has been rarely reported for the poly(N-sulfonyl amidines) as macromolecular ligands for nanocatalysis. Herein, a catalyst-free multicomponent polymerization (MCP) strategy is developed to facilely prepare a library of amphiphilic poly(N-sulfonyl amidines) with zwitterionic properties starting from disulfonyl azide, hydrophilic dialdehyde and cyclic amino acids including proline and pipecolinic acid. Metals or additives can be thorougly avoided through this method. All the obtained polymers have well-defined structures, high yields and weight-average molecular weights (Mws, up to 99,300 g/mol). The unique zwitterionic property, amphiphilicity and Cu(I) coordination ability of the obtained poly(N-sulfonyl amidines) endow them to form the polymer-Cu(I) complexes as nanocatalysts. Such nanocatalysts exhibite high catalytic efficiency in aqueous Cu-catalyzed azide-alkyne cycloaddition (CuAAC) reaction at a low Cu(I) loading of 50 ppm. Nanocatalysts with high ratio of polymers to Cu(I) have also been demonstrated with Cu(I) stabilization ability. This work provides a “green” MCP method toward zwitterionic and amphiphilic poly(N-sulfonyl amidines), and highlights their unique potentials for nanocatalysis.
相似文献The mechanically compliant single crystals have attracted massive attention. However, the related reports on the single crystals composed of metal-organic complexes remain scarce. In this study, we synthesized a series of isostructural single crystals of ZnII complexes that manifest mechanical bending in response to external stress. In these crystals, the mechanical responses can be shifted between elastic bending and plastic bending by the control of the intermolecular interactions through a rational structural modification in the substituent group of pyridine ligands. As the molecular reorientation corresponding to ligand variation elongates the interfacial distance between molecular slip planes, and the structural disorder of ligands disperses the interplanar intermolecular interactions, the shift from elastic bending to plastic bending of the metal-organic complex-based single crystal was realized. The different mechanical responses of single crystals were comprehensively investigated both experimentally and theoretically.
相似文献Side-chain engineering has been demonstrated as an effective method for fine-tuning the optical, electrical, and morphological properties of organic semiconductors toward efficient organic solar cells (OSCs). In this work, three isomeric non-fullerene small molecule acceptors (SMAs), named BTP-4F-T2C8, BTP-4F-T2EH and BTP-4F-T3EH, with linear and branched alkyl chains substituted on the α or β positions of thiophene as the side chains, were synthesized and systematically investigated. The results demonstrate that the size and substitution position of alkyl side chains can greatly affect the electronic properties, molecular packing as well as crystallinity of the SMAs. After blending with donor polymer D18-Cl, the prominent device performance of 18.25% was achieved by the BTP-4F-T3EH-based solar cells, which is higher than those of the BTP-4F-T2EH-based (17.41%) and BTP-4F-T2C8-based (15.92%) ones. The enhanced performance of the BTP-4F-T3EH-based devices is attributed to its stronger crystallinity, higher electron mobility, suppressed biomolecular recombination, and the appropriate intermolecular interaction with the donor polymer. This work reveals that the side chain isomerization strategy can be a practical way in tuning the molecular packing and blend morphology for improving the performance of organic solar cells.
相似文献Photoresists are essential for the fabrication of flexible electronics through all-photolithographic processes. Single component semiconducting photoresist exhibits both semiconducting and photo-patterning properties, and as a result, the device fabrication process can be simplified. However, the design of semiconducting polymeric photoresist with ambipolar semiconducting property remains challenging. In this paper, we report a single component semiconducting photoresist (PFDPPF4T-N3) by incorporating azide groups and noncovalent conformation locks into the side alkyl chains and conjugated backbones of a diketopyrrolopyrrole-based conjugated polymer, respectively. The results reveal that PFDPP4FT-N3 exhibits ambipolar semiconducting property with hole and electron mobilities up to 1.12 and 1.17 cm2 V?1 s?1, respectively. Moreover, field effect transistors with the individual photo-patterned thin films of PFDPPF4T-N3 also show ambipolar semiconducting behavior with hole and electron mobilities up to 0.66 and 0.80 cm2 V?1 s?1, respectively. These results offer a simple yet effective design strategy for high-performance single component semiconducting photoresists, which hold great potential for flexible electronics processed by all photolithography.
相似文献The development of hetero-π-conjugated molecules is of significance for constructing diverse assembling superstructures based on heteroatom-related bonded or nonbonded interactions. Herein, we developed one-pot P-heteroannulation via palladium-catalyzed dual P—C bonds formation and subsequent sulfidation to construct two isomeric diphosphaperylenediimides (cis-5 and trans-5). The unique out-of-plane anisotropic π-framework induced a cumulative anisotropy with a dipole moment of up to 8.82 D for cis-5, leading to distinct supramolecular packing arrangements. Optical and electrochemical characterizations demonstrated that they showed the largest redshifts extending to 574 nm and rather low-lying LUMO levels of ?4.41 eV. Furthermore, the introduced P=S moieties endowed these diphosphaperylenediimides with prominent coordination ability towards Ag+, thus the first example of perylene diimide (PDI) core-involved metal-organic coordination polymers (MOCPs) with tunable dimensionality varied from 1D, 2D, to 3D were tactfully achieved. In view of easy accessibility and 2D layered porous structure, thus 2D (trans-5)·(AgOTf) based MOCP showed high crystallinity and good CO2 adsorption capacity with surface area of 112 m2/g. The result opens a span-new avenue for exploring rylene imide-based MOCPs and related properties by integrating P functionality.
相似文献We present a new observation of electrochemical oscillation during the reduction of Co2+ from sulfate solution in the presence of but-2-yne-1,4-diol (butynediol) as an additive. Cyclic voltammetry, hydrodynamic voltammetry at galvanostatic condition, and electrochemical impedance spectroscopic studies suggest that the electrochemical oscillation observed was a relaxation type and was the manifestation of adsorbed hydrogen formation by electrochemical reduction of protons on cobalt and their chemical removal by semi-hydrogenation of butynediol to butenediol during the initial stages of electrodeposition.
相似文献Exosomes are membrane-bound vesicles secreted by cells, and contain various important biological molecules, such as lipids, proteins, messenger RNAs, microRNAs, and noncoding RNAs. Emerging evidence demonstrates that proteomic analysis of exosomes is of great significance in studying metabolic diseases, tumor metastasis, immune regulation, and so forth. However, exosome proteomic analysis has high requirements with regard to the purity of collected exosomes. Here recent advances in the methods for isolating exosomes and their applications in proteomic analysis are summarized.
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