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941.
利用均相反应器,在没有添加剂的条件下合成了具有多孔结构的Cu2O微球.考察了合成时间以及反应器旋转速度对Cu2O微球结构的影响.通过增加聚乙烯吡咯烷酮(PVP)的用量,使得Cu2O从多孔微球转变为立方体孪晶,最终形成十四面体孪晶结构.同时,将不同结构的Cu2O多晶应用于催化高氯酸铵(AP)的热分解,结果表明:多孔Cu2O微球较其它结构的Cu2O对AP的热分解具有更高的催化活性,使得AP的低温分解温度降低了37.4°C,而AP在低温阶段的分解量也由8.7%增加至49.0%. 相似文献
942.
Voltage‐Driven Reversible Insertion into and Leaving from a Lipid Bilayer: Tuning Transmembrane Transport of Artificial Channels
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Wen Si Prof. Zhan‐Ting Li Prof. Jun‐Li Hou 《Angewandte Chemie (International ed. in English)》2014,53(18):4578-4581
Three new artificial transmembrane channel molecules have been designed and synthesized by attaching positively charged Arg‐incorporated tripeptide chains to pillar[5]arene. Fluorescent and patch‐clamp experiments revealed that voltage can drive the molecules to insert into and leave from a lipid bilayer and thus switch on and off the transport of K+ ions. One of the molecules was found to display antimicrobial activity toward Bacillus subtilis with half maximal inhibitory concentration (IC50) of 10 μM which is comparable to that of natural channel‐forming peptide alamethicin. 相似文献
943.
Manganese‐Catalyzed Dehydrogenative [4+2] Annulation of NH Imines and Alkynes by CH/NH Activation
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Ruoyu He Prof. Dr. Zhi‐Tang Huang Prof. Dr. Qi‐Yu Zheng Prof. Dr. Congyang Wang 《Angewandte Chemie (International ed. in English)》2014,53(19):4950-4953
Described herein is a manganese‐catalyzed dehydrogenative [4+2] annulation of N? H imines and alkynes, a reaction providing highly atom‐economical access to diverse isoquinolines. This transformation represents the first example of manganese‐catalyzed C? H activation of imines; the stoichiometric variant of the cyclomanganation was reported in 1971. The redox neutral reaction produces H2 as the major byproduct and eliminates the need for any oxidants, external ligands, or additives, thus standing out from known isoquinoline synthesis by transition‐metal‐catalyzed C? H activation. Mechanistic studies revealed the five‐membered manganacycle and manganese hydride species as key reaction intermediates in the catalytic cycle. 相似文献
944.
Qi Wang Chenxi Zhang Dr. Bruce C. Noll Dr. Hai Long Dr. Yinghua Jin Prof. Dr. Wei Zhang 《Angewandte Chemie (International ed. in English)》2014,53(40):10663-10667
Shape‐persistent covalent organic polyhedrons (COPs) with ethynylene linkers are usually prepared through kinetically controlled cross‐coupling reactions. The high‐yielding synthesis of ethynylene‐linked rigid tetrameric cages via one‐step alkyne metathesis from readily accessible triyne precursors is presented. The tetrameric cage contains two macrocyclic panels and exhibits D2h symmetry. The assembly of such a COP is a thermodynamically controlled process, which involves the initial formation of macrocycles as key intermediates followed by the connection of two macrocycles with ethynylene linkages. With a large internal cavity, the cage exhibits a high binding selectivity toward C70 (K=3.9×103 L mol?1) over C60 (no noticeable binding). 相似文献
945.
Copper‐Catalyzed Aerobic Oxidative Transformation of Ketone‐Derived N‐Tosyl Hydrazones: An Entry to Alkynes
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Xianwei Li Xiaohang Liu Huoji Chen Dr. Wanqing Wu Dr. Chaorong Qi Prof. Dr. Huanfeng Jiang 《Angewandte Chemie (International ed. in English)》2014,53(52):14485-14489
A novel strategy involving Cu‐catalyzed oxidative transformation of ketone‐derived hydrazone moiety to various synthetic valuable internal alkynes and diynes has been developed. This method features inexpensive metal catalyst, green oxidant, good functional group tolerance, high regioselectivity and readily available starting materials. Oxidative deprotonation reactions were carried out to form internal alkynes and symmetrical diynes. Cross‐coupling reactions of hydrazones with halides and terminal alkynes were performed to afford functionalized alkynes and unsymmetrical conjugated diynes. A mechanism proceeding through a Cu‐carbene intermediate is proposed for the C? C triple bond formation. 相似文献
946.
Jun‐Jie Shen Prof. Shou‐Fei Zhu Dr. Yan Cai Huan Xu Xiu‐Lan Xie Prof. Qi‐Lin Zhou 《Angewandte Chemie (International ed. in English)》2014,53(48):13188-13191
An iron‐catalyzed asymmetric intramolecular cyclopropanation was realized in high yields and excellent enantioselectivity (up to 97 % ee) by using the iron complexes of chiral spiro‐bisoxazoline ligands as catalysts. The superiority of iron catalysts exhibited in this reaction demonstrated the potential abilities of this sustainable metal in asymmetric carbenoid transformation reactions. 相似文献
947.
Gabor Butora Ning Qi Wenlang Fu Truyen Nguyen Hsueh‐Cheng Huang Ian W. Davies 《Angewandte Chemie (International ed. in English)》2014,53(51):14046-14050
The cytosolic conversion of therapeutically relevant nucleosides into bioactive triphosphates is often hampered by the inefficiency of the first kinase‐mediated step. Nucleoside monophosphate prodrugs can be used to bypass this limitation. Herein we describe a novel cyclic‐disulfide class of nucleoside monophosphate prodrugs with a cytosol‐specific, reductive release trigger. The key event, a charge‐dissipating reduction‐triggered cyclodeesterification leads to robust cytosolic production of the cyclic 3′,5′‐monophosphate for downstream enzymatic processing. The antiviral competence of the platform was demonstrated with an O‐benzyl‐1,2‐dithiane‐4,5‐diol ester of 2′‐C‐methyluridine‐3′,5′‐phosphate. Both in vitro and in vivo comparison with the clinically efficacious ProTide prodrug of 2′‐deoxy‐2′‐α‐fluoro‐β‐C‐methyluridine is provided. The cytosolic specificity of the release allows for a wide range of potential applications, from tissue‐targeted drug delivery to intracellular imaging. 相似文献
948.
Geometry‐Assisted Three‐Dimensional Superlocalization Imaging of Single‐Molecule Catalysis on Modular Multilayer Nanocatalysts
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Dr. Rui Han Dr. Ji Won Ha Dr. Chaoxian Xiao Yuchen Pei Zhiyuan Qi Bin Dong Nicholas L. Bormann Prof. Dr. Wenyu Huang Prof. Dr. Ning Fang 《Angewandte Chemie (International ed. in English)》2014,53(47):12865-12869
To establish the structure–catalytic property relationships of heterogeneous catalysts, a detailed characterization of the three‐dimensional (3D) distribution of active sites on a single catalyst is essential. Single‐particle catalysis of a modular multilayer catalytic platform that consists of a solid silica core, a mesoporous silica shell, and uniformly distributed Pt nanoparticles sandwiched in between these layers is presented. The first 3D high‐resolution super‐localization imaging of single fluorescent molecules produced at active sites on the core‐shell model nanocatalysts is demonstrated. The 3D mapping is aided by the well‐defined geometry and a correlation study in scanning electron microscopy and total internal reflection fluorescence and scattering microscopy. This approach can be generalized to study other nano‐ and mesoscale structures. 相似文献
949.
Huilong Dong Fenglou Gu Min Li Bencai Lin Zhihong Si Prof. Tingjun Hou Prof. Feng Yan Dr. Shuit‐Tong Lee Youyong Li 《Chemphyschem》2014,15(14):3006-3014
Imidazolium cations are promising candidates for preparing anion‐exchange membranes because of their good alkaline stability. Substitution of imidazolium cations is an efficient way to improve their alkaline stability. By combining density functional theory calculations with experimental results, it is found that the LUMO energy correlates with the alkaline stability of imidazolium cations. The results indicate that alkyl groups are the most suitable substituents for the N3 position of imidazolium cations, and the LUMO energies of alkyl‐substituted imidazolium cations depend on the electron‐donating effect and the hyperconjugation effect. Comparing 1,2‐dimethylimidazolium cations (1,2‐DMIm+) and 1,3‐dimethylimidazolium cations (1,3‐DMIm+) with the same substituents reveals that the hyperconjugation effect is more significant in influencing the LUMO energy of 1,3‐DMIms. This investigation reveals that LUMO energy is a helpful aid in predicting the alkaline stability of imidazolium cations. 相似文献
950.
提出了反相高效液相色谱法同时测定壮阳类保健品中4种PDE5抑制剂和达泊西汀含量的方法。样品溶于水中,再加甲醇提取。分取10μL提取液进样,并用Inertsil ODS-SP色谱柱为分离柱和由(A)三乙胺-乙酸-水(8+4+988)混合液,(B)乙腈和(C)0.02%(φ)磷酸溶液三者按不同比例相混的混合液作流动相进行梯度淋洗和分离。在检测波长290nm处进行测定。他达那非的质量浓度在1.25~25.0mg·L-1范围内与其峰面积呈线性关系,其余4种化合物的质量浓度在5.0~100mg·L-1范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.05~0.2mg·L-1之间。加标回收率在94.1%~109%之间,测定值的相对标准偏差(n=6)均小于1.0%。 相似文献