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951.
Dynamic and Quantitative Control of the DNA‐Mediated Growth of Gold Plasmonic Nanostructures
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Dr. Jianlei Shen Lifeng Xu Dr. Chunpeng Wang Dr. Hao Pei Prof.Dr. Renzhong Tai Prof.Dr. Shiping Song Prof.Dr. Qing Huang Prof.Dr. Chunhai Fan Prof.Dr. Gang Chen 《Angewandte Chemie (International ed. in English)》2014,53(32):8338-8342
Reproducible and controllable growth of nanostructures with well‐defined physical and chemical properties is a longstanding problem in nanoscience. A key step to address this issue is to understand their underlying growth mechanism, which is often entangled in the complexity of growth environments and obscured by rapid reaction speeds. Herein, we demonstrate that the evolution of size, surface morphology, and the optical properties of gold plasmonic nanostructures could be quantitatively intercepted by dynamic and stoichiometric control of the DNA‐mediated growth. By combining synchrotron‐based small‐angle X‐ray scattering (SAXS) with transmission electron microscopy (TEM), we reliably obtained quantitative structural parameters for these fine nanostructures that correlate well with their optical properties as identified by UV/Vis absorption and dark‐field scattering spectroscopy. Through this comprehensive study, we report a growth mechanism for gold plasmonic nanostructures, and the first semiquantitative revelation of the remarkable interplay between their morphology and unique plasmonic properties. 相似文献
952.
Highly Active Bidirectional Electron Transfer by a Self‐Assembled Electroactive Reduced‐Graphene‐Oxide‐Hybridized Biofilm
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Prof. Yang‐Chun Yong Yang‐Yang Yu Prof. Xinhai Zhang Prof. Hao Song 《Angewandte Chemie (International ed. in English)》2014,53(17):4480-4483
Low extracellular electron transfer performance is often a bottleneck in developing high‐performance bioelectrochemical systems. Herein, we show that the self‐assembly of graphene oxide and Shewanella oneidensis MR‐1 formed an electroactive, reduced‐graphene‐oxide‐hybridized, three‐dimensional macroporous biofilm, which enabled highly efficient bidirectional electron transfers between Shewanella and electrodes owing to high biomass incorporation and enhanced direct contact‐based extracellular electron transfer. This 3D electroactive biofilm delivered a 25‐fold increase in the outward current (oxidation current, electron flux from bacteria to electrodes) and 74‐fold increase in the inward current (reduction current, electron flux from electrodes to bacteria) over that of the naturally occurring biofilms. 相似文献
953.
A Protic Ionic Liquid Catalyzes CO2 Conversion at Atmospheric Pressure and Room Temperature: Synthesis of Quinazoline‐2,4(1H,3H)‐diones
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Dr. Yanfei Zhao Bo Yu Dr. Zhenzhen Yang Dr. Hongye Zhang Leiduan Hao Xiang Gao Prof. Zhimin Liu 《Angewandte Chemie (International ed. in English)》2014,53(23):5922-5925
The chemical fixation of CO2 under mild reaction conditions is of significance from a sustainable chemistry viewpoint. Herein a CO2‐reactive protic ionic liquid (PIL), [HDBU+][TFE?], was designed by neutralization of the superbase 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) with a weak proton donor trifluoroethanol (TFE). As a bifunctional catalyst for simultaneously activating CO2 and the substrate, this PIL displayed excellent performance in catalyzing the reactions of CO2 with 2‐aminobenzonitriles at atmospheric pressure and room temperature, thus producing a series of quinazoline‐2,4(1H,3H)‐diones in excellent yields. 相似文献
954.
Catalytic Ethanolysis of Kraft Lignin into High‐Value Small‐Molecular Chemicals over a Nanostructured α‐Molybdenum Carbide Catalyst
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Rui Ma Wenyue Hao Xiaolei Ma Ye Tian Prof. Yongdan Li 《Angewandte Chemie (International ed. in English)》2014,53(28):7310-7315
We report the complete ethanolysis of Kraft lignin over an α‐MoC1?x/AC catalyst in pure ethanol at 280 °C to give high‐value chemicals of low molecular weight with a maximum overall yield of the 25 most abundant liquid products (LP25) of 1.64 g per gram of lignin. The LP25 products consisted of C6–C10 esters, alcohols, arenes, phenols, and benzyl alcohols with an overall heating value of 36.5 MJ kg?1. C6 alcohols and C8 esters predominated and accounted for 82 wt % of the LP25 products. No oligomers or char were formed in the process. With our catalyst, ethanol is the only effective solvent for the reaction. Supercritical ethanol on its own degrades Kraft lignin into a mixture of small molecules and molecular fragments of intermediate size with molecular weights in the range 700–1400, differing in steps of 58 units, which is the weight of the branched‐chain linkage C3H6O in lignin. Hydrogen was found to have a negative effect on the formation of the low‐molecular‐weight products. 相似文献
955.
Hao Sun Xiao You Yishu Jiang Guozhen Guan Xin Fang Jue Deng Peining Chen Dr. Yongfeng Luo Prof. Huisheng Peng 《Angewandte Chemie (International ed. in English)》2014,53(36):9526-9531
Electrically conducting wires play a critical role in the advancement of modern electronics and in particular are an important key to the development of next‐generation wearable microelectronics. However, the thin conducting wires can easily break during use, and the whole device fails to function as a result. Herein, a new family of high‐performance conducting wires that can self‐heal after breaking has been developed by wrapping sheets of aligned carbon nanotubes around polymer fibers. The aligned carbon nanotubes offer an effective strategy for the self‐healing of the electric conductivity, whereas the polymer fiber recovers its mechanical strength. A self‐healable wire‐shaped supercapacitor fabricated from a wire electrode of this type maintained a high capacitance after breaking and self‐healing. 相似文献
956.
Dr. Cheng‐Chung Lee Dr. Manuel Maestre‐Reyna Dr. Kai‐Cheng Hsu Prof. Dr. Hao‐Ching Wang Prof. Dr. Chia‐I Liu Prof. Dr. Wen‐Yih Jeng Li‐Ling Lin Richard Wood Dr. Chia‐Cheng Chou Prof. Dr. Jinn‐Moon Yang Prof. Dr. Andrew H.‐J. Wang 《Angewandte Chemie (International ed. in English)》2014,53(48):13054-13058
Crown ethers are small, cyclic polyethers that have found wide‐spread use in phase‐transfer catalysis and, to a certain degree, in protein chemistry. Crown ethers readily bind metallic and organic cations, including positively charged amino acid side chains. We elucidated the crystal structures of several protein‐crown ether co‐crystals grown in the presence of 18‐crown‐6. We then employed biophysical methods and molecular dynamics simulations to compare these complexes with the corresponding apoproteins and with similar complexes with ring‐shaped low‐molecular‐weight polyethylene glycols. Our studies show that crown ethers can modify protein surface behavior dramatically by stabilizing either intra‐ or intermolecular interactions. Consequently, we propose that crown ethers can be used to modulate a wide variety of protein surface behaviors, such as oligomerization, domain–domain interactions, stabilization in organic solvents, and crystallization. 相似文献
957.
958.
Rhodium‐Catalyzed Cyclization of Diynes with Nitrones: A Formal [2+2+5] Approach to Bridged Eight‐Membered Heterocycles
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Dr. Chunxiang Wang Dr. Dongping Wang Hao Yan Dr. Haolong Wang Dr. Bin Pan Dr. Xiaoyi Xin Dr. Xincheng Li Fan Wu Prof. Dr. Boshun Wan 《Angewandte Chemie (International ed. in English)》2014,53(44):11940-11943
N‐aryl‐substituted nitrones were employed as five‐atom coupling partners in the rhodium‐catalyzed cyclization with diynes. In this reaction, the nitrone moiety served as a directing group for the catalytic C? H activation of the N‐aryl ring. This formal [2+2+5] approach allows rapid access to bridged eight‐membered heterocycles with broad substrate scope. The results of this study may provide new insight into the chemistry of nitrones and find applications in the synthesis of other heterocycles. 相似文献
959.
Transfer of Aryl Halide to Alkyl Halide: Reductive Elimination of Alkylhalide from Alkylpalladium Halides Containing syn‐β‐Hydrogen Atoms
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Wei Hao Junnian Wei Weizhi Geng Prof. Dr. Wen‐Xiong Zhang Prof. Dr. Zhenfeng Xi 《Angewandte Chemie (International ed. in English)》2014,53(52):14533-14537
β‐Hydride abstraction is a well‐accepted elementary step for catalytic cycles in organometallic chemistry. It is usually anticipated that alkylpalladium halides containing syn‐β‐hydrogen atoms will undergo β‐hydride abstraction to afford the Heck‐type products. However, this study discloses that the above general knowledge is only conditionally correct. Our experimental results demonstrate that the reductive elimination of alkylhalides from alkylpalladium halides containing syn‐β‐hydrogen atoms may surpass the β‐hydride abstraction or even become exclusive in certain cases. 相似文献
960.
Ionizable Amphiphilic Dendrimer‐Based Nanomaterials with Alkyl‐Chain‐Substituted Amines for Tunable siRNA Delivery to the Liver Endothelium In Vivo
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Dr. Omar F. Khan Edmond W. Zaia Dr. Hao Yin Dr. Roman L. Bogorad Dr. Jeisa M. Pelet Dr. Matthew J. Webber Iris Zhuang Dr. James E. Dahlman Prof. Robert Langer Prof. Daniel G. Anderson 《Angewandte Chemie (International ed. in English)》2014,53(52):14397-14401
A library of dendrimers was synthesized and optimized for targeted small interfering RNA (siRNA) delivery to different cell subpopulations within the liver. Using a combinatorial approach, a library of these nanoparticle‐forming materials was produced wherein the free amines on multigenerational poly(amido amine) and poly(propylenimine) dendrimers were substituted with alkyl chains of increasing length, and evaluated for their ability to deliver siRNA to liver cell subpopulations. Interestingly, two lead delivery materials could be formulated in a manner to alter their tissue tropism within the liver—with formulations from the same material capable of preferentially delivering siRNA to 1) endothelial cells, 2) endothelial cells and hepatocytes, or 3) endothelial cells, hepatocytes, and tumor cells in vivo. The ability to broaden or narrow the cellular destination of siRNA within the liver may provide a useful tool to address a range of liver diseases. 相似文献