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Zhaoyang Cheng Shipei Xing Jun Guo Biao Cheng Lan‐Fang Hu Xing‐Hong Zhang Zhan Lu 《中国化学》2019,37(5):457-461
A regioselective double 1,1‐hydrosilylation of terminal aliphatic alkynes with primary silanes catalyzed by one cobalt catalyst has been developed. gem‐Bis(dihydrosilyl)alkanes containing four silicon‐hydrogen bonds are efficiently constructed in an atom‐economical manner. Tolerated substrates include simplest alkyne‐ethyne, a complicated drug derivative and various functionalized terminal aliphatic alkynes. Asymmetric approach using two catalysts is achieved with excellent enantioselectivities to access corresponding chiral products. The transformations of Si—H bonds into Si—C, Si—O, and Si—F bonds and the synthesis of enantioriched α‐hydroxysilane show synthetic utility. 相似文献
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The adsorptive denitrogenation from fuels over three metal-organic frameworks(MIL-96(Al),MIL-53(Al)and MIL-101(Cr))was studied by batch adsorption experiments.Four nitrogen-containing compounds(NCCs)pyridine,pyrrole,quinoline and indole were used as model NCCs in fuels to study the adsorption mechanism.The physicochemical properties of the adsorbents were characterized by XRD,N2physical adsorption,FT-IR spectrum and Hammett indicator method.The metal-organic frameworks(MOFs),especially the MIL-101(Cr)containing Lewis acid sites as well as high specific surface area,can adsorb large quantities of NCCs from fuels.In addition,the adsorptive capacity over MIL-101(Cr)will be different for NCCs with different basicity.The stronger basicity of the NCC is,the more it can be absorbed over MIL-101(Cr).Furthermore,pore size and shape also affect the adsorption capacity for a given adsorbate,which can be proved by the adsorption over MIL-53(Al)and MIL-96(Al).The pseudo-second-order kinetic model and Langmuir equation can be used to describe kinetics and thermodynamics of the adsorption process,respectively.Finally,the regeneration of the used adsorbent has been conducted successfully by just washing it with ethanol. 相似文献
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Catalytic asymmetric Reformatsky reactions of benzaldehyde with optically active menthyl bromoacetates in the presence of Zn-Cu couple were performed using 0.25 equiv. of (1R,2S) or (1S,2R)-dimethyl-2-amino-1,2-diphenyl ethanol as chiral ligand to obtain β - hydroxy esters with enantioselectivities up to 60.2%. The obvious double chiral induction effect was observed while chiral ligands matched with optically active substrates. 相似文献
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原子催化剂是零价金属原子锚定于载体上的一种新型催化剂, 具有原子利用率高、 选择性高以及反应活性和稳定性高等优点, 一直是催化领域的研究前沿, 在催化和能量转换领域具有广阔的发展前景. 石墨炔与金属原子之间独特的不完全电荷转移性质实现了零价过渡金属原子的稳定锚定, 解决了传统单原子催化剂易迁移和聚集的问题, 被认为是新一代催化剂. 本综述从石墨炔原子催化剂的结构性质、 表征以及应用等方面出发, 综合评述了相关领域的最新研究成果, 介绍了石墨炔原子催化剂在电催化固氮制氨、 产氢、 全水解和CO2固定等方面的应用和发展前景, 为实现新概念高性能催化材料的设计合成提供了研究思路. 相似文献
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槲皮素是具有丰富生物活性的黄酮类化合物,药理活性显著。本文以槲皮素为先导物,选择性对C环3位羟基进行修饰,以廉价的芦丁为原料,经苄基保护、Williamson成醚反应,再经Pd/C催化加氢脱苄基得到28个未见文献报道的槲皮素-3-O-丙基衍生物,其结构经1H NMR、13C NMR、ESI-MS进行确证。采用MTT法考察了所合成化合物对人食管鳞癌(EC109)、人胃癌(HGC27)、人乳腺癌(MCF-7)、小鼠黑色素瘤(B16-F10)的增殖抑制作用。结果显示,通过化学方法对槲皮素结构进行修饰后,其体外抗肿瘤活性增强。其中,化合物F3(IC50=5.23±0.37μmol/L)、F5(IC50=2.63±0.09μmol/L)对小鼠黑色素瘤(B16-F10)抑制作用比5-氟尿嘧啶(IC50=14.38±0.27μmol/L)好,值得进一步研究。 相似文献
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WU Liting XIN Yujia GUO Zhaoyang GAO Wei ZHU Yanpeng br WANG Yinsong RAN Ruixue YANG Xiaoying 《高等学校化学研究》2022,38(2):562-571
Combining photothermal therapy and radiotherapy(PTT-RT) with reducing tumor hypoxia acts as an important antitumor modality. However, it is a great challenge to realize photothermal therapy, radiotherapy and exogenous oxygen supply in one nanosystem. To realize a combination of the three functions, we fabricated a red blood cell membrane(RBCm)-camouflaged, red blood cell content(RBCc) and the copper sulfide(CuS) co-loaded dendritic large pore mesoporous silica nanoparticle(DLMSN/CuS/RBCc/ RBCm). The cell membrane coating endowed the nanoparticles with good stability in the physiological environment, and CuS allowed the nanoparticle exhibiting good photothermal and radiosensitization properties. RBCc loaded nanoparticle DLMSN/CuS/RBCc enhanced superior anti-tumor effect than DLMSN/CuS during combined PTT-RT therapy because the introduction of RBCc increased the exogenous oxygen supply. The in vitro study further demonstrated that the combination of photothermal therapy and radiotherapy induced superior antitumor efficacy than single therapy. Our work thus presents a unique multifunctional nanoscale platform favorable for combined PTT and RT. 相似文献
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Lignocellulosic biomass, such as wood, grass, agricultural, and forest residues, are potential resources for the production of bioethanol. The current biochemical process of converting biomass to bioethanol typically consists of three main steps: pretreatment, enzymatic hydrolysis, and fermentation. For this process, pretreatment is probably the most crucial step since it has a large impact on the efficiency of the overall bioconversion. The aim of pretreatment is to disrupt recalcitrant structures of cellulosic biomass to make cellulose more accessible to the enzymes that convert carbohydrate polymers into fermentable sugars. This paper reviews several leading acidic, neutral, and alkaline pretreatments technologies. Different pretreatment methods, including dilute acid pretreatment (DAP), steam explosion pretreatment (SEP), organosolv, liquid hot water (LHW), ammonia fiber expansion (AFEX), soaking in aqueous ammonia (SAA), sodium hydroxide/lime pretreatments, and ozonolysis are intensively introduced and discussed. In this minireview, the key points are focused on the structural changes primarily in cellulose, hemicellulose, and lignin during the above leading pretreatment technologies. 相似文献