共查询到20条相似文献,搜索用时 15 毫秒
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Kasibhatta Josena Datta Dr. Kasibhatta Kumara Ramanatha Datta Dr. Manoj B. Gawande Dr. Vaclav Ranc Dr. Klára Čépe Dr. Victor Malgras Prof. Yusuke Yamauchi Prof. Rajender S. Varma Prof. Dr. Radek Zboril 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(5):1577-1581
A facile synthesis based on the addition of ascorbic acid to a mixture of Na2PdCl4, K2PtCl6, and Pluronic P123 results in highly branched core–shell nanoparticles (NPs) with a micro–mesoporous dandelion‐like morphology comprising Pd core and Pt shell. The slow reduction kinetics associated with the use of ascorbic acid as a weak reductant and suitable Pd/Pt atomic ratio (1:1) play a principal role in the formation mechanism of such branched Pd@Pt core–shell NPs, which differs from the traditional seed‐mediated growth. The catalyst efficiently achieves the reduction of a variety of olefins in good to excellent yields. Importantly, higher catalytic efficiency of dandelion‐like Pd@Pt core–shell NPs was observed for the olefin reduction than commercially available Pt black, Pd NPs, and physically admixed Pt black and Pd NPs. This superior catalytic behavior is not only due to larger surface area and synergistic effects but also to the unique micro–mesoporous structure with significant contribution of mesopores with sizes of several tens of nanometers. 相似文献
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Template‐Free Preparation of Volvox‐like CdxZn1−xS Nanospheres with Cubic Phase for Efficient Photocatalytic Hydrogen Production 下载免费PDF全文
Hangyue Zhou Prof. Qingyun Liu Prof. Weimin Liu Prof. Jiechao Ge Dr. Minhuan Lan Prof. Chao Wang Prof. Jianxin Geng Prof. Pengfei Wang 《化学:亚洲杂志》2014,9(3):811-818
Volvox‐like CdxZn1?xS solid solutions with a cubic zinc blend structure were synthesized through a template‐free ethylene glycol process. Cd(Ac)2 ? 2 H2O, Zn(Ac)2 ? 2 H2O, and thiourea are used as the starting materials and dissolved in ethylene glycol. These reaction precursors and solvent not only contributed to control over the formation of the volvox‐like spherical geometry, but also exerted vigorous domination for existence of cubic‐phase CdxZn1?xS nanostructures. As‐prepared volvox‐like CdxZn1?xS nanospheres have a diameter of around 100 nm with extensional shells. These samples show excellent photocatalytic H2 evolution activity from water splitting under visible‐light irradiation without any cocatalyst or scaffolding, owing to their tunable band gap, cubic zinc blend structure, and unique hierarchical porous structure with a high surface area (as high as 95.2 m2 g?1). 相似文献
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Haiyan Liu Dr. Tingting Wang Lingyu Zhang Lu Li Dr. Y. Andrew Wang Prof. Dr. Chungang Wang Prof. Dr. Zhongmin Su 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(12):3745-3752
The selected‐control preparation of uniform core–shell and yolk–shell architectures, which combine the multiple functions of a superparamagnetic iron oxide (SPIO) core and europium‐doped yttrium oxide (Y2O3:Eu) shell in a single material with tunable fluorescence and magnetic properties, has been successfully achieved by controlling the heat‐treatment conditions. Furthermore, the shell thickness and interior cavity of SPIO@Y2O3:Eu core–shell and yolk–shell nanostructures can be precisely tuned. Importantly, as‐prepared SPIO@Y2O3:Eu yolk–shell nanocapsules (NCs) modified with amino groups as cancer‐cell fluorescence imaging agents are also demonstrated. To the best of our knowledge, this is the first report on the selected‐control fabrication of uniform SPIO@Y2O3:Eu core–shell nanoparticles and yolk–shell NCs. The combined magnetic manipulation and optical monitoring of magnetic–fluorescent SPIO@Y2O3:Eu yolk–shell NCs will open up many exciting opportunities in dual imaging for targeted delivery and thermal therapy. 相似文献
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Aneta Januszewska Dr. Grzegorz Dercz Justyna Piwowar Dr. Rafal Jurczakowski Dr. Adam Lewera 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(50):17159-17164
Small (4 nm) nanoparticles with a narrow size distribution, exceptional surface purity, and increased surface order, which exhibits itself as an increased presence of basal crystallographic planes, can be obtained without the use of any surfactant. These nanoparticles can be used in many applications in an as‐received state and are threefold more active towards a model catalytic reaction (oxidation of ethylene glycol). Furthermore, the superior properties of this material are interesting not only due to the increase in their intrinsic catalytic activity, but also due to the exceptional surface purity itself. The nanoparticles can be used directly (i.e., as‐received, without any cleaning steps) in biomedical applications (i.e., as more efficient drug carriers due to an increased number of adsorption sites) and in energy‐harvesting/data‐storage devices. 相似文献
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Cornelia E. Peña‐González Pilar García‐Broncano Prof. M. Francesca Ottaviani Dr. Michela Cangiotti Dr. Alberto Fattori Margarita Hierro‐Oliva Prof. M. Luisa González‐Martín Dr. Jorge Pérez‐Serrano Dr. Rafael Gómez Prof. M. Ángeles Muñoz‐Fernández Dr. Javier Sánchez‐Nieves Dr. F. Javier de la Mata 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(9):2987-2999
Anionic carbosilane dendrons decorated with sulfonate functions and one thiol moiety at the focal point have been used to synthesize water‐soluble gold nanoparticles (AuNPs) through the direct reaction of dendrons, gold precursor, and reducing agent in water, and also through a place‐exchange reaction. These nanoparticles have been characterized by NMR spectroscopy, TEM, thermogravimetric analysis, X‐ray photoelectron spectroscopy (XPS), UV/Vis spectroscopy, elemental analysis, and zeta‐potential measurements. The interacting ability of the anionic sulfonate functions was investigated by EPR spectroscopy with copper(II) as a probe. Different structures and conformations of the AuNPs modulate the availability of sulfonate and thiol groups for complexation by copper(II). Toxicity assays of AuNPs showed that those produced through direct reaction were less toxic than those obtained by ligand exchange. Inhibition of HIV‐1 infection was higher in the case of dendronized AuNPs than in dendrons. 相似文献
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Xiaohong Li Dr. Yali Shen Liying Song Hongna Wang Haihong Wu Dr. Yueming Liu Dr. Peng Wu Prof. Dr. 《化学:亚洲杂志》2009,4(5):699-706
Trapped! Mesopolymer‐entrapped Pt nanoparticles serve as an efficient catalyst for the hydrogenation of benzaldehydes in water at ambient temperature. In comparison with the commercial Pt/alumina catalyst, the Pt/FDU‐14 catalyst shows superior performance in the hydrogenation reaction. The catalyst afforded high turnover frequencies and was reusable more than nine times without loss of activity or selectivity.
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Template‐Induced Diverse Metal–Organic Materials as Catalysts for the Tandem Acylation–Nazarov Cyclization 下载免费PDF全文
Chao Huang Ran Ding Prof. Chuanjun Song Jingjing Lu Lu Liu Xiao Han Prof. Jie Wu Hongwei Hou Prof. Yaoting Fan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16156-16163
In our continuing quest to develop a metal–organic framework (MOF)‐catalyzed tandem pyrrole acylation–Nazarov cyclization reaction with α,β‐unsaturated carboxylic acids for the synthesis of cyclopentenone[b]pyrroles, which are key intermediates in the synthesis of natural product (±)‐roseophilin, a series of template‐induced Zn‐based ( 1–3 ) metal‐organic frameworks (MOFs) have been solvothermally synthesized and characterized. Structural conversions from non‐porous MOF 1 to porous MOF 2 , and back to non‐porous MOF 3 arising from the different concentrations of template guest have been observed. The anion–π interactions between the template guests and ligands could affect the configuration of ligands and further tailor the frameworks of 1–3 . Futhermore, MOFs 1–3 have shown to be effective heterogeneous catalysts for the tandem acylation–Nazarov cyclization reaction. In particular, the unique structural features of 2 , including accessible catalytic sites and suitable channel size and shape, endow 2 with all of the desired features for the MOF‐catalyzed tandem acylation–Nazarov cyclization reaction, including heterogeneous catalyst, high catalytic activity, robustness, and excellent selectivity. A plausible mechanism for the catalytic reaction has been proposed and the structure–reactivity relationship has been further clarified. Making use of 2 as a heterogeneous catalyst for the reaction could greatly increase the yield of total synthesis of (±)‐roseophilin. 相似文献
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Ying Jia Sergey N. Shmakov Paul Register Eugene Pinkhassik 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(36):12709-12714
Yolk‐shell nanoreactors with metal nanoparticle core and ultrathin porous polymer shells are effective catalysts for heterogeneous reactions. Polymer shells provide size‐selectivity and improved reusability of catalyst. Nanocapsules with single‐nanometer porous shells are prepared by vesicle‐templated directed assembly. Metal nanoparticles are formed either by selective initiation in pre‐fabricated nanocapsules or simultaneously with the creation of a crosslinked polymer shell. In this study, we investigated the oxidation of benzyl alcohol and benzaldehyde catalyzed by gold nanoparticles and hydrogenation of cyclohexene catalyzed by platinum nanoparticles. Comparison of newly created nanoreactors with commercially available nanoparticles revealed superior reusability and size selectivity in nanoreactors while showing no negative effect on reaction kinetics. 相似文献
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Yong Guan Dr. Zhensheng Ding Prof. William D. Wulff 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(46):15565-15571
The active site in the BOROX catalyst is a chiral polyborate anion (boroxinate) that is assembled in situ from three equivalents of B(OPh)3 and one of the VANOL ligand by a molecule of substrate. The substrates are bound to the boroxinate by H bonds to oxygen atoms O1–O3. The effects of introducing substituents at each position of the naphthalene core of the VANOL ligand are systematically investigated in an aziridination reaction. Substituents in the 4,4′‐ and 8,8′‐positions have a negative effect on catalyst performance, whereas, substituents in the 7‐ and 7′‐positions have the biggest impact in a positive direction. 相似文献
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Dr. Christian Kulp Konrad Gillmeister Prof. Dr. Wolf Widdra Prof. Michael Bron 《Chemphyschem》2013,14(6):1205-1210
The synthesis of Cu(core)Pt(shell) model catalysts by the direct electrochemical deposition of Pt on Cu particles is presented. Cu particles with an average diameter of 200 nm have been deposited on glassy‐carbon electrodes by double pulse electrodeposition from a copper sulfate solution. Subsequent deposition from a platinum nitrate solution under potential control allows for a high selectivity of the Pt deposition towards Cu. Using a combination of cyclic voltammetry, XPS and sputtering, the structure of the generated particles has been analyzed and their core–shell configuration proven. It is shown that the electrocatalytic activity for the oxygen reduction is similar to that of other PtCu catalyst systems. The synthesized structures could allow for the analysis of structure–activity relations of core–shell catalysts on the way to the simple and controlled synthesis of supported Cu(core)Pt(shell) nanoparticles as oxygen reduction catalysts. 相似文献
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Dr. In Soo Kim Dr. Zhanyong Li Dr. Jian Zheng Dr. Ana E. Platero‐Prats Dr. Andreas Mavrandonakis Dr. Steven Pellizzeri Dr. Magali Ferrandon Aleksei Vjunov Dr. Leighanne C. Gallington Thomas E. Webber Dr. Nicolaas A. Vermeulen Prof. R. Lee Penn Prof. Rachel B. Getman Prof. Christopher J. Cramer Dr. Karena W. Chapman Dr. Donald M. Camaioni Dr. John L. Fulton Prof. Johannes A. Lercher Prof. Omar K. Farha Prof. Joseph T. Hupp Dr. Alex B. F. Martinson 《Angewandte Chemie (International ed. in English)》2018,57(4):909-913
Single atoms and few‐atom clusters of platinum are uniformly installed on the zirconia nodes of a metal‐organic framework (MOF) NU‐1000 via targeted vapor‐phase synthesis. The catalytic Pt clusters, site‐isolated by organic linkers, are shown to exhibit high catalytic activity for ethylene hydrogenation while exhibiting resistance to sintering up to 200 °C. In situ IR spectroscopy reveals the presence of both single atoms and few‐atom clusters that depend upon synthesis conditions. Operando X‐ray absorption spectroscopy and X‐ray pair distribution analyses reveal unique changes in chemical bonding environment and cluster size stability while on stream. Density functional theory calculations elucidate a favorable reaction pathway for ethylene hydrogenation with the novel catalyst. These results provide evidence that atomic layer deposition (ALD) in MOFs is a versatile approach to the rational synthesis of size‐selected clusters, including noble metals, on a high surface area support. 相似文献
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A Photoactivatable Platinum(IV) Anticancer Complex Conjugated to the RNA Ligand Guanidinoneomycin 下载免费PDF全文
Dr. Evyenia Shaili Marta Fernández‐Giménez Savina Rodríguez‐Astor Albert Gandioso Lluís Sandín Carlos García‐Vélez Dr. Anna Massaguer Dr. Guy J. Clarkson Dr. Julie A. Woods Prof. Peter J. Sadler Dr. Vicente Marchán 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18474-18486
A photoactivatable platinum(IV) complex, trans,trans,trans‐[Pt(N3)2(OH)(succ)(py)2] (succ=succinylate, py=pyridine), has been conjugated to guanidinoneomycin to study the effect of this guanidinum‐rich compound on the photoactivation, intracellular accumulation and phototoxicity of the pro‐drug. Surprisingly, trifluoroacetic acid treatment causes the replacement of an azido ligand and the axial hydroxide ligand by trifluoroacetate, as shown by NMR spectroscopy, MS and X‐ray crystallography. Photoactivation of the platinum–guanidinoneomycin conjugate in the presence of 5′‐guanosine monophosphate (5′‐GMP) led to the formation of trans‐[Pt(N3)(py)2(5′‐GMP)]+, as does the parent platinum(IV) complex. Binding of the platinum(II) photoproduct {PtN3(py)2}+ to guanine nucleobases in a short single‐stranded oligonucleotide was also observed. Finally, cellular uptake studies showed that guanidinoneomycin conjugation improved the intracellular accumulation of the platinum(IV) pro‐drug in two cancer cell lines, particularly in SK‐MEL‐28 cells. Notably, the higher phototoxicity of the conjugate in SK‐MEL‐28 cells than in DU‐145 cells suggests a degree of selectivity towards the malignant melanoma cell line. 相似文献
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Imaging of Oxygen Diffusion in Individual Platinum/Ce2Zr2Ox Catalyst Particles During Oxygen Storage and Release 下载免费PDF全文
Dr. Hirosuke Matsui Dr. Nozomu Ishiguro Kaori Enomoto Dr. Oki Sekizawa Prof. Dr. Tomoya Uruga Prof. Dr. Mizuki Tada 《Angewandte Chemie (International ed. in English)》2016,55(39):12022-12025
The spatial distribution of Ce3+ and Ce4+ in each particle of Ce2Zr2Ox in a three‐way conversion catalyst system was successfully imaged during an oxygen storage/release cycle by scanning X‐ray absorption fine structure (XAFS) using hard X‐ray nanobeams. For the first time, nano‐XAFS imaging visualized and identified the modes of non‐uniform oxygen diffusion from the interface of Pt catalyst and Ce2Zr2Ox support and the active parts in individual catalyst particles. 相似文献
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[2+1] Cycloaddition Affording Methylene‐ and Vinylidenecyclopropane Derivatives: A Journey around the Reactivity of Metal‐Phosphinito–Phosphinous Acid Complexes 下载免费PDF全文
Metal–phosphinito–phosphinous acid complexes are interesting catalysts exhibiting unique reactivities. In this account, we intend to provide a clear overview of palladium– and platinum–phosphinito–phosphinous acid complexes, their preparation from secondary phosphine oxides, and their applications in catalysis. They have been mainly used to develop [2+1] cycloadditions to afford methylenecyclopropane derivatives using norbornenes and various alkynes as partners. As a function of the catalyst, the reaction conditions, or the nature of the reagents, different synthetic transformations have been observed: [2+1] cycloadditions, giving rise to either alkylidenecyclopropanes or vinylidenecyclopropanes; tandem [2+1]/[3+2] cycloadditions, and so forth. The mechanisms of these reactions have been studied to rationalize the different reactivities observed. 相似文献
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Synthesis of Hollow Platinum–Palladium Nanospheres with a Dendritic Shell as Efficient Electrocatalysts for Methanol Oxidation 下载免费PDF全文
Qingqing Lu Prof. Hongjing Wang Kamel Eid Zeid Abdullah Alothman Dr. Victor Malgras Prof. Yusuke Yamauchi Prof. Liang Wang 《化学:亚洲杂志》2016,11(13):1939-1944
Engineering the size, composition, and morphology of platinum‐based nanomaterials can provide a great opportunity to improve the utilization efficiency of electrocatalysts and reinforce their electrochemical performances. Herein, three‐dimensional platinum–palladium hollow nanospheres with a dendritic shell (PtPd‐HNSs) are successfully fabricated through a facile and economic route, during which SiO2 microspheres act as the hard template for the globular cavity, whereas the triblock copolymer F127 contributes to the formation of the dendritic shell. In contrast with platinum hollow nanospheres (Pt‐HNSs) and commercial platinum on carbon (Pt/C) catalyst, the novel architecture shows a remarkable activity and durability toward the methanol oxidation reaction (MOR) owing to the coupled merits of bimetallic nanodendrites and a hollow interior. As a proof of concept, this strategy is also extended to trimetallic gold–palladium–platinum hollow nanospheres (AuPdPt‐HNSs), which paves the way towards the controlled synthesis of other bi‐ or multimetallic platinum‐based hollow electrocatalysts. 相似文献