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Traditional reductive amination of substituted cyclohexanones are either selective toward the formation of cis-products or show low selectivity. Herein we report a selective procedure for the reductive amination of substituted cyclohexanones with primary amines using lithium borohydride that is selective toward formation of trans-products. 相似文献
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Organic extractants play a significant role in the selective removal of radioactive cations from waste streams. Although, literature on the selective removal of man-made radioactive material such as Americium (Am) is widespread, the selective removal of naturally occurring radioactive material such as Ra2+ is only mentioned sporadically. This tutorial review deals with the selective extraction of the highly radiotoxic Ra2+. Special attention is paid to different types of organic extractants used. 相似文献
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Two arms hydrophilic photosensitizer conjugates with vitamin B for cancer‐selective photodynamic therapy
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Cancer‐selective internalization has a great potential for reducing the side effect of photodynamic therapy. Recently, various cancer‐targeted delivery carriers have provided enhanced cancer targeting efficiency. Despite significant advancements in cancer‐targeted carriers, side effects are still present because of non‐selective cellular uptake that occurs in the heterogeneous cancer environment. In this paper, we designed two types of cancer‐selectable two arm hydrophilic photosensitizer (CTAHP2K and CTAHP4K) with silicon‐tetrapyrazinoporphyrazines (ST), polyethylene glycol and the cancer‐specific ligand for cancer‐selective theranostics. The synthesized CTAHP4K exhibits a folate receptor‐mediated cancer‐selective cellular uptake and induces cancer‐selective death. The folate receptor‐mediated cancer‐selective internalization of CTAHP4K was confirmed by competitive interaction with vitamin B in MDA‐MB‐231 human breast carcinoma. The cancer‐selective cytotoxicity of CTAHP4K was confirmed using a 670‐nm laser to irradiate Chang Liver cells and MDA‐MB‐231 cells. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Yuchao Zhu Ziyao Zhang Rui Jin Jianzhong Liu Guoquan Liu Prof. Bing Han Prof. Ning Jiao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(45):20023-20028
Control of selectivity is one of the central topics in organic chemistry. Although unprecedented alkoxyl-radical-induced transformations have drawn a lot of attention, compared to selective C−H activation, selective radical O−H activation remains less explored. Herein, we report a novel selective radical O−H activation strategy of diols by combining spatial effects with proton-coupled electron transfer (PCET). It was found that DMSO is an essential reagent that enables the regioselective transformation of diols. Mechanistic studies indicated the existence of the alkoxyl radical and the selective interaction between DMSO and hydroxyl groups. Moreover, the distal C−C cleavage was realized by this selective alkoxyl-radical-initiation protocol. 相似文献
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A cholesteryl derived monomer was synthesized according to a conventional synthetic route; it exhibits a cholesteric phase above 129°C, and shows a red colour due to selective reflection in the cholesteric phase. Photopolymerization of the monomer was carried out at 135°C in the cholesteric phase. The helical structure of the cholesteric phase of the monomer was frozen by photopolymerization. A peak based on the selective reflection of the cholesteric phase was detected at 615 nm in the transmittance UV-Vis spectrum. Mixtures of the monomer with a binaphthyl derivative were prepared to control the selective reflection wavelength; they all also exhibited a cholesteric phase. The selective reflection wavelength of the mixture was dependent upon the ratio of the binaphthyl derivative in the mixture. This wavelength became shorter with increasing ratio of the binaphthyl derivative. The polymer films obtained by photopolymerization displayed almost the same selective reflection wavelength as the corresponding mixtures before photopolymerization. The selective reflection wavelength of the polymer films did not change up to about 250°C. 相似文献
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乙烯选择性齐聚制备线性α-烯烃是在学术界和工业界均受到高度重视,具有目标产物选择性高、产品易分离和经济效益显著等特点。铬系配合物催化剂在催化乙烯选择性齐聚反应中综合性能较好,有良好的发展和应用前景。近年来的研究表明,配体结构对催化剂性能有重要影响;反应体系中通入H 2可以改善齐聚产物的分布并抑制低聚物的生成;开发不以甲基铝氧烷为助催化剂的催化体系可降低催化剂成本;而乙烯选择齐聚机理及金属中心氧化态对催化剂的设计有重要的指导意义。本文主要从以上几个方面介绍了膦胺铬和双膦铬配合物在催化乙烯选择性齐聚中的研究进展,分析了目前乙烯选择性四聚工业化急需解决的问题,展望了该领域未来的发展方向。 相似文献
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A cholesteryl derived monomer was synthesized according to a conventional synthetic route; it exhibits a cholesteric phase above 129°C, and shows a red colour due to selective reflection in the cholesteric phase. Photopolymerization of the monomer was carried out at 135°C in the cholesteric phase. The helical structure of the cholesteric phase of the monomer was frozen by photopolymerization. A peak based on the selective reflection of the cholesteric phase was detected at 615 nm in the transmittance UV-Vis spectrum. Mixtures of the monomer with a binaphthyl derivative were prepared to control the selective reflection wavelength; they all also exhibited a cholesteric phase. The selective reflection wavelength of the mixture was dependent upon the ratio of the binaphthyl derivative in the mixture. This wavelength became shorter with increasing ratio of the binaphthyl derivative. The polymer films obtained by photopolymerization displayed almost the same selective reflection wavelength as the corresponding mixtures before photopolymerization. The selective reflection wavelength of the polymer films did not change up to about 250°C. 相似文献
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采用飞秒激光改性-化学腐蚀的方法, 分别研究了3种典型玻璃的化学腐蚀性能. 通过测试材料的微观结构, 分析了不同材料的腐蚀速率与脉冲能量及腐蚀时间的关系, 从材料组成、显微结构及化学键特征讨论了玻璃改性-腐蚀机理. 结果表明, 飞秒激光改性后的碲酸盐和PbO硅酸盐玻璃不具有选择性腐蚀特性, 而石英玻璃的选择性腐蚀比高于40; 飞秒激光改性玻璃的选择性腐蚀特性与材料结构有关, 分子体积大、网络结构不紧密的材料不具有选择腐蚀特性. 相似文献
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Hanif M Nazarov AA Legin A Groessl M Arion VB Jakupec MA Tsybin YO Dyson PJ Keppler BK Hartinger CG 《Chemical communications (Cambridge, England)》2012,48(10):1475-1477
Ru(II)(arene) anticancer compounds with maleimide functionality were prepared to allow selective interaction with thiol-containing biomolecules and thereby enforcing the selective delivery of the compounds to the tumour. 相似文献
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Vladislav Stroganov Alexander Ryabchun Alexey Bobrovsky Valery Shibaev 《Macromolecular rapid communications》2012,33(21):1875-1881
For the first time, the films based on polymer‐stabilized cholesteric composites containing crown ether fragments with the optical properties sensitive to the complexation with potassium and barium ions were obtained. The complexation with these ions leads to blue spectral shift of the selective light reflection of planar cholesteric texture of composite films. Peculiarities of spectral changes and kinetics of selective light reflection shift were studied. The proposed approach can be used for the creation of the effective and selective sensor materials for different ions or groups of ions. 相似文献
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A solid-phase extraction sample preparation method using a molecularly imprinted polymer (MIP) selective for the triazine type pesticide terbutylazine has been developed. The method involves preconcentration from large volumes of water samples on a C18 disk coupled to selective clean-up on the MIP. The method has been optimised by studying the recovery and retention of terbutylazine and some other structurally related triazine derivates as a function of the selective washing solvent used. The effect of the water content of the selective washing solvent was also investigated on the recovery of the MIP. River water samples were analysed with the coupled technique, and efficient clean-up of the samples was observed. 相似文献
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《Electroanalysis》2017,29(3):821-827
An all‐solid‐state polymeric membrane Ca2+‐selective electrode based on hydrophobic octadecylamine‐functionalized graphene oxide has been developed. The hydrophobic composite in the ion‐selective membrane not only acts as a transduction element to improve the potential stability for the all‐solid‐state Ca2+‐selective electrode, but also is used to immobilize Ca2+ ionophore with lipophilic side chains through hydrophobic interactions. The developed all‐solid‐state Ca2+‐selective electrode shows a stable potential response in the linear range of 3.0×10−7–1.0×10−3 M with a slope of 24.7±0.3 mV/dec, and the detection limit is (1.6±0.2 )×10−7 M (n =3). Additionally, due to the hydrophobicity and electrical conductivity of the composite, the proposed all‐solid‐state ion‐selective electrode exhibits an improved stability with the absence of water layer between the ion‐selective membrane and the underlying glassy carbon electrode. This work provides a simple, efficient and low‐cost methodology for developing stable and robust all‐solid‐state ion‐selective electrode with ionophore immobilization. 相似文献
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Computer-optimized selective pulses are routinely used in solution-state NMR spectroscopy. At the same time, their utility and importance for solid-state applications has yet to be fully realized. We suggest a new computational approach that makes the design of soft selective pulses with desired properties relatively straightforward. By applying this technique to the generic selective excitation problem, we have arrived at a family of high performance selective excitation pulses, dubbed E-Family, that allows more flexibility and better performance than analogous pulses previously reported in the literature. The new pulses have been successfully tested in both solid- and solution-state NMR experiments. A theoretical treatment of the effects of chemical shift anisotropy (CSA) on the selective excitation in magic-angle spinning (MAS) experiments in solids is presented. The set of heuristics that comprise our new strategy were incorporated into a general NMR simulation program SPINEVOLUTION. 相似文献
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Emil Lindbäck Sami Dawaigher Kenneth Wärnmark 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(42):13432-13481
Substrate selectivity is an important output function for the validation of different enzyme models, catalytic cavity compounds, and reaction mechanisms as demonstrated in this review. In contrast to stereo‐, regio‐, and chemoselective catalysis, the field of substrate‐selective catalysis is under‐researched and has to date generated only a few, but important, industrial applications. This review points out the broad spectrum of different reaction types that have been investigated in substrate‐selective catalysis. The present review is the first one covering substrate‐selective catalysis and deals with reactions in which the substrates involved have the same reacting functionality and the catalysts is used in catalytic or in stoichiometric amounts. The review covers real substrate‐selective catalysis, thus only including cases in which substrate‐selective catalysis has been observed in competition between substrates. 相似文献
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A facile, selective and high yielding bis(trimethylsilyl) chromate (BTSC) catalyzed selective oxidation of alcohols to aldehydes and ketones with periodic acid is reported. 相似文献
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Petrella AJ Roberts NK Craig DC Raston CL Lamb RN 《Chemical communications (Cambridge, England)》2004,(1):64-65
Reaction of p-(t)Bu-calix[4]arene with dimethyl titanocene results in high yield selective 1,3-dimetallation of the calixarene in the cone conformation by selective cleavage of one methyl group. 相似文献
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Park MH Jang YJ Sung-Suh HM Sung MM 《Langmuir : the ACS journal of surfaces and colloids》2004,20(6):2257-2260
We demonstrate a selective atomic layer deposition of TiO2 thin films on patterned alkylsiloxane self-assembled monolayers. Microcontact printing was done to prepare patterned monolayers of the alkylsiloxane on Si substrates. The patterned monolayers define and direct the selective deposition of the TiO2 thin film using atomic layer deposition. The selective atomic layer deposition is based on the fact that the TiO2 thin film is selectively deposited only on the regions exposing the silanol groups of the Si substrates because the regions covered with the alkylsiloxane monolayers do not have any functional group to react with precursors. 相似文献