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161.
Time‐Resolved Assembly of Cluster‐in‐Cluster {Ag12}‐in‐{W76} Polyoxometalates under Supramolecular Control 下载免费PDF全文
Caihong Zhan Jamie M. Cameron Jing Gao Jamie W. Purcell De‐Liang Long Leroy Cronin 《Angewandte Chemie (International ed. in English)》2014,53(39):10362-10366
We report the time‐resolved supramolecular assembly of a series of nanoscale polyoxometalate clusters (from the same one‐pot reaction) of the form: [H(10+m)Ag18Cl(Te3W38O134)2]n, where n=1 and m=0 for compound 1 (after 4 days), n=2 and m=3 for compound 2 (after 10 days), and n=∞ and m=5 for compound 3 (after 14 days). The reaction is based upon the self‐organization of two {Te3W38} units around a single chloride template and the formation of a {Ag12} cluster, giving a {Ag12}‐in‐{W76} cluster‐in‐cluster in compound 1 , which further aggregates to cluster compounds 2 and 3 by supramolecular Ag‐POM interactions. The proposed mechanism for the formation of the clusters has been studied by ESI‐MS. Further, control experiments demonstrate the crucial role that TeO32?, Cl?, and Ag+ play in the self‐assembly of compounds 1 – 3 . 相似文献
162.
Voltage‐Driven Reversible Insertion into and Leaving from a Lipid Bilayer: Tuning Transmembrane Transport of Artificial Channels 下载免费PDF全文
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
163.
Hui Zhang Kan Zhan Yulu Chen Guoxia Chen Xiaomei Zhou Junxiu Liu Min Wu Henmei Ni 《Journal of Sol-Gel Science and Technology》2014,71(3):597-605
Three dimensional Liesegang spherical layers of CaHPO4 in gelatin ball were performed by employing CaCl2 and Na2HPO4 as the inner and outer electrolyte, respectively. Effects of concentrations of inner and outer electrolyte as well as pH on the morphologies of Liesegang rings (LRs) were investigated. As a result, it was observed that the time law, spacing law and width law found in 1D/2D gel systems were obeyed in this 3D gelatin system. The interaction of Ca2+ and HPO4 2? with gelatin matrix played a key role to the formation of LRs due to the existence of carboxylic groups on the gelatin chains. Using Ca2+ as the inner electrolyte, LRs were prepared. However, employing HPO4 2? as inner electrolyte, LRs were not obtained. Moreover, pH of gelatin solution greatly impacted on the formation of LRs. The number of LRs increased with the decrease of pH, whereas the width inversely decreased. pH 4.40 was a turn point, from which the spacing coefficient abruptly increased as pH increased. All these results indicated that the network was created by the interaction of Ca2+ and –COO? of gelatin chains, which dominated the formation of CaHPO4 LRs in gelatin. 相似文献
164.
165.
Qingyi Cao Yahui Qian Handong Liang Zhanping Li Siyao Chen Liu Yang Qin Zhan 《Surface and interface analysis : SIA》2020,52(5):283-292
Pyrite is considered to be the major carrier of mercury in coal. Here, the chemical characteristics of two natural pyrite samples of different weathering degrees were characterized by time-of-flight secondary ion mass spectrometry (TOF-SIMS). Thermal stability of Hg was also analyzed via temperature programmed desorption experiment (TPD). Characteristic ions such as S−, Fe+, FeS−, and FeS2− were detected on the surface of fresh pyrite. The release temperature of Hg ranged between 180°C and 300°C, and the characteristic peak of black HgS was recorded. In addition, abundant Fe2O3−, FeSO−, SO4−, and HSO4− were detected on the surface of weathered pyrite, and the release temperature of Hg therein was mainly distributed at 260°C to 380°C and 520°C to 600°C, corresponding to the characteristic peaks of red HgS and HgSO4, respectively. The results show that pyrite is acidified during weathering and that Hg forms in pyrite are transformed from the original state (HgS) to HgSO4. 相似文献
166.
3-(噁唑-5-基)吲哚类天然产物如Pimprinine,Streptochlorin等,广泛存在于海洋微生物中,因其具有多样的生物活性,在医药和农药领域中很有研究潜力.3-(噁唑-5-基)吲哚类天然产物的合成方法有很多研究报道,在吲哚结构上构建噁唑环是合成此类天然产物的关键.总结了已报道的3-(噁唑-5-基)吲哚类天然产物的生物活性,并对构建3-(噁唑-5-基)吲哚骨架的合成方法及部分主要反应机理进行了综述,探讨了3-(噁唑-5-基)吲哚类骨架作为一种优势活性结构在未来的应用前景. 相似文献
167.
The three-dimensional morphology has sufficient interface contact and can be in favor of the electronic transport process. In this work, the demand for high-performance electrodes such as energy storage devices has been designed. Polypyrrole and tungsten oxide composite materials (PPy-WO3) have been synthesized by cyclic voltammetry (CV) technology at −0.6 to 0.9 V versus saturated calomel electrode (SCE) for 20 cycles. The PPy-WO320 mV/s, PPy-WO360 mV/s, and PPy-WO3120 mV/s electrodes have been prepared by CV technology at sweep rates of 20, 60, and 120 mV/s. The influences of scan rate on morphologies and charge storage properties of the composites are discussed. Among them, a three-dimensional flake structure for PPy-WO320 mV/s with a size of up to several micrometers was synthesized. PPy-WO320 mV/s composites as electrode materials exhibit a wide charge storage potential window of 1.4 V (between −0.9 and 0.5 V vs. SCE) and a specific capacitance of 145.13 F/g at 1 mA/cm2. Moreover, the long-term stability of PPy-WO320 mV/s and PPy has been investigated in 5 M LiCl aqueous electrolyte. The stability of the materials can be improved by inorganic and organic composites. 相似文献
168.
元素化学是药学专业无机化学的重要组成部分,其内容繁多,规律性不强,传统教学方式枯燥乏味,影响了学生的学习兴趣。笔者针对这些问题,结合多年的教学经验,从优化教学内容和教学方法等方面对元素化学教学进行了探究。 相似文献
169.
ABSTRACTWe demonstrate a spatially and electrically tunable random lasing based on polymer-stabilized blue phase liquid crystal (PS-BPLC)-wedged cell. The spatially tunable random lasers can be obtained from the laser dye-doped PS-BPLC-wedged cell through changing the pump positions, where the emission wavelength of the random laser can be tuned due to the thickness gradient of the wedged cell, which affects the scattering mean free path. Additionally, applying different electric fields can also tune the laser emission wavelength. The changing of refractive index due to the Kerr effect leads to a change in the scattering mean free path, resulting in shift of lasing wavelength. This PS-BPLC-wedged cell device has a great potential in applications of speckle-free imaging, document coding, biomedicine and other photonic devices. 相似文献
170.
Xing‐Ben Wang Zhan‐Jiang Zheng Jia‐Le Xie Xing‐Wei Gu Qiu‐Chao Mu Guan‐Wu Yin Fei Ye Zheng Xu Li‐Wen Xu 《Angewandte Chemie (International ed. in English)》2020,59(2):790-797
A novel and unusual palladium‐catalyzed [4+2] annulation of cyclopropenes with benzosilacyclobutanes is reported. This reaction occurred through chemoselective Si?C(sp2) bond activation in synergy with ring expansion/insertion of cyclopropenes to form new C(sp2)?C(sp3) and Si?C(sp3) bonds. An array of previously elusive bicyclic skeleton with high strain, silabicyclo[4.1.0]heptanes, were formed in good yields with excellent diastereoselectivity under mild conditions. An asymmetric version of the reaction with a chiral phosphoramidite ligand furnished a variety of chiral bicyclic silaheterocycle derivatives with good enantioselectivity (up to 95.5:4.5 er). Owing to the mild reaction conditions, the good stereoselectivity profile, and the ready availability of the functionalized precursors, this process constitutes a useful and straightforward strategy for the synthesis of densely functionalized silacycles. 相似文献