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111.
112.
以酰胺-噁唑啉为辅助基团,在廉价的醋酸铜促进下,实现了酰胺衍生物C(sp2)—H键与芳基硫醇S—H键的脱氢偶联反应;以中等到优秀的产率(最高可达90%)简单高效地合成了一系列双硫化的酰胺衍生物.值得一提的是,底物范围并不局限于各种取代苯基酰胺化合物,吡啶基酰胺化合物也可以兼容.该反应的特点是:金属廉价、底物范围广、反应条件温和、无需外加配体、空气作为氧化剂、区域选择性好(仅酰胺基团邻位的C—H键发生反应,而噁唑啉基团邻位的C—H键不发生反应);此外,克级规模的反应表明了其在合成中的实用性. 相似文献
113.
沸石咪唑酯骨架材料(Zeolitic Imidazolate Framework-8,ZIF-8)是由Zn(Ⅱ)与2-甲基咪唑配位自组装形成的多孔结晶材料,具有可调的孔径、高稳定的结构和催化活性等特点,近年来ZIF-8的制备和应用展现出巨大的潜力并引起了广泛关注。本文总结了目前ZIF-8的制备方法,在此基础上介绍了ZIF-8的形成机理及粒径调控方法,重点综述了ZIF-8及其复合材料在吸附分离、催化、生物医学等领域应用的研究进展,并展望了其应用前景与发展方向,以期为ZIF-8 的应用发展开拓新的思路。 相似文献
114.
Lithium-sulfur batteries (LSBs) with high energy density and low cost have been recognized as one of the most promising next-generation energy storage systems. Although it has taken decades of development, the practical application of LSBs has been hindered by several inherent obstacles, particularly the severe shuttle effect and sluggish reaction kinetics in the sulfur cathode. Various strategies have been proposed to address these problems via rational design of electrode materials and configurations. Freestanding sulfur cathode could be a promising strategy to improve the sulfur mass loading at the cathode level and energy density of LSBs. This minireview will briefly summary the recent advances in freestanding cathodes for LSBs. The advantages and disadvantages of various freestanding cathodes are discussed and the prospects for the development of flexible cathodes are envisioned. 相似文献
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116.
Catalytic Performance of Graphite Oxide Supported Au Nanoparticles in Aerobic Oxidation of Benzyl Alcohol: Support Effect 下载免费PDF全文
Various Au/GO catalysts were prepared by depositing Au nanoparticles on thermally- and chemically-treated graphite oxide (GO) supports using a sol-immobilization method. The surface chemistry and structure of GO supports were characterized by a series of analytical techniques including X-ray photoelectron spectroscopy, temperature-programmed desorption and Raman spectroscopy. The results show that thermal and chemical treatments have large influence on the presence of surface oxygenated groups and the crystalline structure of GO supports. A strong support effect was observed on the catalytic activity of Au/GO catalysts in the liquid phase aerobic oxidation of benzyl alcohol. Compared to the amount and the type of surface oxygen functional groups, the ordered structure of GO supports may play a more important role in determining the catalytic performance of Au/GO catalysts. 相似文献
117.
Kedar N. Baryal Sherif Ramadan Guowei Su Changxin Huo Yuetao Zhao Jian Liu Linda C. Hsieh-Wilson Xuefei Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(1):e202211985
Heparan sulfate (HS) has multifaceted biological activities. To date, no libraries of HS oligosaccharides bearing systematically varied sulfation structures are available owing to the challenges in synthesizing a large number of HS oligosaccharides. To overcome the obstacles and expedite the synthesis, a divergent approach was designed, where 64 HS tetrasaccharides covering all possible structures of 2-O-, 6-O- and N-sulfation with the glucosamine-glucuronic acid-glucosamine-iduronic acid backbone were successfully produced from a single strategically protected tetrasaccharide intermediate. This extensive library helped identify the structural requirements for HS sequences to have strong fibroblast growth factor-2 binding but a weak affinity for platelet factor-4. Such a strategy to separate out these two interactions could lead to new HS-based potential therapeutics without the dangerous adverse effect of heparin-induced thrombocytopenia. 相似文献
118.
Jiaxiang Wang Jiahui Gao Tianyun Guo Prof. Dr. Xing Huo Prof. Dr. Wenhua Zhang Prof. Dr. Jian Liu Prof. Dr. Xiaolei Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202213810
Herein, bioinspired total syntheses of A201A, A201D, and A201E based on a previously reported biosynthetic pathway are presented. The challenging 1,2-cis-furanoside, a core structure of the A201 family, was obtained by remote 2-quinolinecarbonyl-assisted glycosylation. We accomplished the total synthesis of A201A and A201E based on the critical 1,2-cis-furanoside moiety through late-stage glycosylation without any interference from basic dimethyl adenosine. We also confirmed the absolute configuration of A201E by total synthesis. This modular synthesis strategy enables efficient preparation of A201 family antibiotics, allowing the study of their structure–activity relationships and mode of action. This study satisfies the increasing demand for developing novel antibiotics inspired by the A201 family. 相似文献
119.
Hui Liang Manlin Lu Zafar Mahmood Zheng Li Zeduan Chen Guowei Chen Prof. Ming-De Li Prof. Yanping Huo Prof. Shaomin Ji 《Angewandte Chemie (International ed. in English)》2023,62(44):e202312600
The design of efficient heavy atom-free triplet photosensitizers (PSs) based on through bond charge transfer (TBCT) features is a formidable challenge due to the criteria of orthogonal donor-acceptor geometry. Herein, we propose using parallel (face-to-face) conformation carbazole-bodipy donor-acceptor dyads (BCZ-1 and BCZ-2) featuring through space intramolecular charge transfer (TSCT) process as efficient triplet PS. Efficient intersystem crossing (ΦΔ=61 %) and long-lived triplet excited state (τT=186 μs) were observed in the TSCT dyad BCZ-1 compared to BCZ-3 (ΦΔ=0.4 %), the dyad involving TBCT, demonstrating the superiority of the TSCT approach over conventional donor-acceptor system. Moreover, the transient absorption study revealed that TSCT dyads have a faster charge separation and slower intersystem crossing process induced by charge recombination compared to TBCT dyad. A long-lived charge-separated state (CSS) was observed in the BCZ-1 (τCSS=24 ns). For the first time, the TSCT dyad was explored for the triplet-triplet annihilation upconversion, and a high upconversion quantum yield of 11 % was observed. Our results demonstrate a new avenue for designing efficient PSs and open up exciting opportunities for future research in this field. 相似文献
120.
In this paper, based on the theory of variable exponent spaces, we study the higher integrability for a class of nonlinear elliptic equations with variable growth and discontinuous coefficients. Under suitable assumptions, we obtain a local gradient estimate in Orlicz space for weak solution. 相似文献