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991.
Crystalline Hetero‐Stereocomplexed Polycarbonates Produced from Amorphous Opposite Enantiomers Having Different Chemical Structures
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Dr. Ye Liu Meng Wang Wei‐Min Ren Yue‐Chao Xu Prof. Dr. Xiao‐Bing Lu 《Angewandte Chemie (International ed. in English)》2015,54(24):7042-7046
Stereocomplexation is the stereoselective interaction between two opposite enantiomeric polymers through an interlocked orderly assembly. Most studies focus on the stereocomplex formation from the crystalline opposite enantiomers having the identical structure; nevertheless, rare examples were reported regarding the crystalline stereocomplexes from enantiomeric polymers having different chemical structures. Herein we show a strategy for polymer orderly assembly through the formation of crystalline hetero‐stereocomplexed polymeric materials by the cocrystallization of amorphous isotactic polycarbonates with different chemical structures and opposite configurations. The behaviors in the crystalline state are significantly different from that of the component enantiomeric polymers or their homo‐stereocomplexes. This study is expected to open up a new way to prepare various semicrystalline materials having a wide variety of physical properties and degradability. 相似文献
992.
Rhodium(III)‐Catalyzed [3+2]/[5+2] Annulation of 4‐Aryl 1,2,3‐Triazoles with Internal Alkynes through Dual C(sp2)H Functionalization
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Yuan Yang Ming‐Bo Zhou Xuan‐Hui Ouyang Rui Pi Dr. Ren‐Jie Song Prof. Dr. Jin‐Heng Li 《Angewandte Chemie (International ed. in English)》2015,54(22):6595-6599
A rhodium(III)‐catalyzed [3+2]/[5+2] annulation of 4‐aryl 1‐tosyl‐1,2,3‐triazoles with internal alkynes is presented. This transformation provides straightforward access to indeno[1,7‐cd]azepine architectures through a sequence involving the formation of a rhodium(III) azavinyl carbene, dual C(sp2)? H functionalization, and [3+2]/[5+2] annulation. 相似文献
993.
Reversible Modulation of Surface Plasmons in Gold Nanoparticles Enabled by Surface Redox Chemistry
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Dr. Zheng Li Dr. Jonathan J. Foley IV Dr. Sheng Peng Dr. Cheng‐Jun Sun Dr. Yang Ren Dr. Gary P. Wiederrecht Dr. Stephen K. Gray Dr. Yugang Sun 《Angewandte Chemie (International ed. in English)》2015,54(31):8948-8951
Switchable surface redox chemistry is demonstrated in gold@iron/iron oxide core–shell nanoparticles with ambient oxidation and plasmon‐mediated reduction to modulate the oxidation state of shell layers. The iron shell can be oxidized to iron oxide through ambient oxidation, leading to an enhancement and red‐shift of the gold surface plasmon resonance (SPR). This enhanced gold SPR can drive reduction of the iron oxide shell under broadband illumination to reversibly blue‐shift and significantly dampen gold SPR absorption. The observed phenomena provide a unique mechanism for controlling the plasmonic properties and surface chemistry of small metal nanoparticles. 相似文献
994.
Flexible,Stretchable, and Rechargeable Fiber‐Shaped Zinc–Air Battery Based on Cross‐Stacked Carbon Nanotube Sheets
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Yifan Xu Ye Zhang Ziyang Guo Jing Ren Prof. Yonggang Wang Prof. Huisheng Peng 《Angewandte Chemie (International ed. in English)》2015,54(51):15390-15394
The fabrication of flexible, stretchable and rechargeable devices with a high energy density is critical for next‐generation electronics. Herein, fiber‐shaped Zn–air batteries, are realized for the first time by designing aligned, cross‐stacked and porous carbon nanotube sheets simultaneously that behave as a gas diffusion layer, a catalyst layer, and a current collector. The combined remarkable electronic and mechanical properties of the aligned carbon nanotube sheets endow good electrochemical properties. They display excellent discharge and charge performances at a high current density of 2 A g?1. They are also flexible and stretchable, which is particularly promising to power portable and wearable electronic devices. 相似文献
995.
Synthesis and magnetic properties of organic multilayer films based on the layer‐by‐layer assembly
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Two polymers containing pyridine rings were prepared by free‐radical polymerization and confirmed by Fourier transform infrared and 1H NMR spectra. The preparation of four multilayer films that were obtained by self‐assembly of the polymer and the transition metal neutralized polyelectrolyte on PE substrate was described. UV–vis spectra and atomic force microscopy images were applied to characterize these films and indicate the uniform assembling process. The driving force for building up the multilayer films was identified by infrared spectroscopy to be the coordination interaction. The magnetic behavior was examined as a function of magnetic field strength at 30 kOe and as a function of temperature (5–300 K). All films display strong soft ferromagnetic properties and higher than those of the bulk materials. The magnetic results show that the layer‐by‐layer self‐assembling approach is beneficial to the ordered alignment of adjacent paramagnetic spins and induces better magnetic phenomena. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
996.
Dr. Guang‐Ping Hao Giovanni Mondin Dr. Zhikun Zheng Tim Biemelt Stefan Klosz René Schubel Prof. Alexander Eychmüller Prof. Stefan Kaskel 《Angewandte Chemie (International ed. in English)》2015,54(6):1941-1945
There is significant interest in high‐performance materials that can directly and efficiently capture water vapor, particularly from air. Herein, we report a class of novel porous carbon cuboids with unusual ultra‐hydrophilic properties, over which the synergistic effects between surface heterogeneity and micropore architecture is maximized, leading to the best atmospheric water‐capture performance among porous carbons to date, with a water capacity of up to 9.82 mmol g?1 at P/P0=0.2 and 25 °C (20 % relative humidity or 6000 ppm). Benefiting from properties, such as defined morphology, narrow pore size distribution, and high heterogeneity, this series of functional carbons may serve as model materials for fundamental research on carbon chemistry and the advance of new types of materials for water‐vapor capture as well as other applications requiring combined highly hydrophilic surface chemistry, developed hierarchical porosity, and excellent stability. 相似文献
997.
Formation of DNA:RNA Hybrid G‐Quadruplex in Bacterial Cells and Its Dominance over the Intramolecular DNA G‐Quadruplex in Mediating Transcription Termination
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998.
Realizing both High Energy and High Power Densities by Twisting Three Carbon‐Nanotube‐Based Hybrid Fibers
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Ye Zhang Yang Zhao Dr. Xunliang Cheng Dr. Wei Weng Jing Ren Xin Fang Yishu Jiang Peining Chen Zhitao Zhang Prof. Yonggang Wang Prof. Huisheng Peng 《Angewandte Chemie (International ed. in English)》2015,54(38):11177-11182
Energy storage devices, such as lithium‐ion batteries and supercapacitors, are required for the modern electronics. However, the intrinsic characteristics of low power densities in batteries and low energy densities in supercapacitors have limited their applications. How to simultaneously realize high energy and power densities in one device remains a challenge. Herein a fiber‐shaped hybrid energy‐storage device (FESD) formed by twisting three carbon nanotube hybrid fibers demonstrates both high energy and power densities. For the FESD, the energy density (50 mWh cm?3 or 90 Wh kg?1) many times higher than for other forms of supercapacitors and approximately 3 times that of thin‐film batteries; the power density (1 W cm?3 or 5970 W kg?1) is approximately 140 times of thin‐film lithium‐ion battery. The FESD is flexible, weaveable and wearable, which offers promising advantages in the modern electronics. 相似文献
999.
The aim of this research was to determine the chemical composition, antioxidant and antibacterial properties of the essential oils from Cynanchum chinense and Ligustrum compactum and isolation of antioxidant and antibacterial constituents from the essential oils. Thirty-eight components were identified in essential oils. Based on bioactivity-guided fractionation, guaiacol, linalool and 2-phenylethanol were isolated and identified as active constituents. Both L. compactum flower oil and 2-phenylethanol showed high antibacterial performance, with inhibition zone from 22.8 ± 0.8 to 11.9 ± 2.0 mm at highest concentration, and minimum inhibitory concentration values ranging from 0.25% to 1%. In both DPPH and ABTS assay, the active constituent guaiacol (IC50 = 4.15 ± 0.72 and 9.12 ± 0.98 μg mL? 1, respectively) exhibited high antioxidant activity, and the oils showed moderate antioxidant activity. These results indicate potential efficacy of active constituents and essential oils of L. compactum and C. chinense to control food-borne pathogenic and spoilage bacteria. 相似文献
1000.
Yuanyuan Zheng Xuesong Wang Sumei Gao Min Ma Guiming Ren Huabing Liu 《Natural product research》2015,29(19):1804-1810
In the present study, using chalcone as a lead compound, a series of its derivatives (compounds 1–30) were designed and synthesised. Their activity of anti-pathogenic fungi of plants has been evaluated. It is found that these compounds have good antifungal activity against Sclerotinia sclerotiorum, Helminthosprium maydis, Botrytis cinerea, Rhizoctonia solani and Gibberella zeae. Among them, the inhibition of growth for compound 30 against S. sclerotiorum showed 89.9%, with the median effective concentrations (EC50) of 15.4 μg mL? 1. The inhibition of growth for compounds 28, 29 and 30 at a concentration of 100 μg mL? 1 against H. maydis is 90.3%, 90.7% and 91.1%, with EC50 of 15.1, 18.3 and 18.1μg mL? 1, respectively. 相似文献