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The general strategy to construct D-A type conjugated polymers is alternating copolymerization of electron-donating(D)monomer and electron-accepting(A) monomer. In this article, we report a new strategy to develop D-A type conjugated polymers, i.e. first fuse the D and A units into a polycyclic structure to produce a building block and then polymerize the building block with another unit. We develop a new building block with ladder structure based on B←N unit, B←N bridged dipyridylbenzene(BNDPB). In the skeleton of BNDPB, one diamine-substituted phenylene ring(D unit) and two B←N-linked pyridyl rings(A unit) are fused together to produce the polycyclic structure. Owning to the presence of intramolecular D-A character, the building block itself exhibits narrow bandgap of 1.74 eV. The conjugated polymers based on BNDPB show unique electronic structures, i.e. localized HOMOs and delocalized LUMOs, which are rarely observed for conventional D-A conjugated polymers. The polymers exhibit smaller bandgap than that of the building block BNDPB and display near-infrared(NIR)light absorption(λabs=ca. 700 nm). This study thus provides not only a new strategy to design D-A conjugated polymers but also a new kind of building block with narrow bandgap. 相似文献
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Hongjuan Chen Peng Fan Xingxin Tu Hui Min Xianyong Yu Xiaofang Li Ju‐Lan Zeng Shaowei Zhang Peng Cheng 《化学:亚洲杂志》2019,14(20):3611-3619
The hydrothermal reaction of Zn2+ ions with a mixture of two ligands, Hcptpy and H3btc (Hcptpy=4‐(4‐carboxyphenyl)‐2,2′:4′,4′′‐terpyridine; H3btc=1,3,5‐benzenetricarboxylic acid), led to the formation of a 3D metal–organic framework (MOF) with 1D channels, [Zn2(cptpy)(btc)(H2O)]n ( 1 ), which was structurally characterized by using single‐crystal X‐ray diffraction (SXRD). In MOF 1 , two independent Zn2+ ions were interconnected by btc3? ligands to form a 1D chain, whilst adjacent Zn2+ ions were alternately bridged by cptpy? ligands to generate a 2D sheet, which was further linked by 1D chains to form a 3D framework with a new (3,3,4,4)‐connected topology. Furthermore, compound 1 also exhibited excellent stability towards air and water and, more importantly, luminescence experiments indicated that it could serve as a probe for the sensitive detection of paraquat (PAQ) and Fe3+ ions in aqueous solution. 相似文献
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隧道下穿既有结构物引起的地表沉降控制标准研究 总被引:3,自引:0,他引:3
解决好隧道下穿既有结构物引起的地表沉降问题,对城市地下交通和高速铁路的建设具有重要的意义。在调研国内大量隧道下穿开挖引起的地表沉降控制标准和方法的基础上,根据隧道下穿公路、铁路、隧道和建筑物时引起的地表沉降的不同特点,结合隧道的施工、开挖面积、埋深和工程地质条件等因素,对隧道下穿不同的结构物提出不同的控制沉降措施和建议沉降标准。作者认为,目前的隧道下穿引起的地表最大沉降控制标准是不合理的,沉降控制标准应综合考虑既有结构物的特点、地质条件和施工特点等因素。 相似文献
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Multi-component reaction of 2-alkynylbenzaldehyde, sulfonohydrazide, electrophile (bromine or iodine), and ketone or aldehyde under mild conditions proceeds smoothly to afford the functionalized H-pyrazolo[5,1-a]isoquinolines in good yields. This one-pot process involves intermolecular condensation, electrophilic cyclization, nucleophilic addition, intramolecular condensation, and aromatization. The resulting halo-containing H-pyrazolo[5,1-a]isoquinolines could be further elaborated via palladium-catalyzed cross-coupling reactions. 相似文献
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Tandem cyclization-addition reaction of 2-alkynylbenzaldehyde with diethyl phosphite catalyzed by AgOTf at room temperature was developed, which afforded the desired 1H-isochromen-1-ylphosphonates in moderate to good yields. 相似文献
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This paper described a facile and direct electrochemical method for the determination of ultra-trace Cu2+ by employing amino-functionalized mesoporous silica (NH2-MCM-41) as enhanced sensing platform. NH2-MCM-41 was prepared by using a post-grafting process and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and fourier transform infrared (FTIR) spectroscopy. NH2-MCM-41 modified glassy carbon (GC) electrode showed higher sensitivity for anodic stripping voltammetric (ASV) detection of Cu2+ than that of MCM-41 modified one. The high sensitivity was attributed to synergistic effect between MCM-41 and amino-group, in which the high surface area and special mesoporous morphology of MCM-41 can cause strong physical absorption, and amino-groups are able to chelate copper ions. Some important parameters influencing the sensor response were optimized. Under optimum experimental conditions the sensor linearly responded to Cu2+ concentration in the range from 5 to 1000 ng L−1 with a detection limit of 0.9 ng L−1 (S/N = 3). Moreover, the sensor possessed good stability and electrode renewability. In the end, the proposed sensor was applied for determining Cu2+ in real samples and the accuracy of the results were comparable to those obtained by inductively coupled plasma optical emission spectrometry (ICP-OES) method. 相似文献
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We developed an analytical method for screening vasoconstriction inhibitors from traditional Chinese medicines (TCMs) by combining vascular smooth muscle/cell membrane chromatography (VSM/CMC) with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Primary cultured VSM cells from rat thoracic aortas were used for preparation of the stationary phase of the VSM/CMC column. Retention fractions from the VSM/CMC column were collected and then analyzed by LC-MS/MS under the optimized conditions offline. The suitability and reliability of the VSM/CMC-offline-LC-MS/MS method was assessed using nitrendipine and nifedipine as positive controls, and this method was then applied to screen vasodilator components from the extracts of Fructus Schisandrae Chinensis (FSC) and Fructus Schisandrae Sphenantherae (FSS). The major components from both species retained by VSM/CMC were identified as deoxyschizandrin (DSD) and schisantherin A (STA) by LC-MS/MS. Competition experiments indicated that DSD and nifedipine bound competitively to membrane receptors, while DSD and STA had partly overlapping binding sites on VSM-cell membranes. In vitro pharmacological trials confirmed that STA and DSD could dose-dependently relax the rat thoracic aortas pre-contracted by KCl. Our VSM/CMC-offline-LC-MS/MS method can be applied for screening vasoconstriction inhibitors from TCMs collected from FSC and FSS, and may be useful in the development of vasodilators from natural products. 相似文献
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Chiral N,O‐Ligand/[Cu(OAc)2]‐Catalyzed Asymmetric Construction of 4‐Aminopyrrolidine Derivatives by 1,3‐Dipolar Cycloaddition of Azomethine Ylides with α‐Phthalimidoacrylates 下载免费PDF全文
Dr. Xingxin Yu Dr. Bo‐Xue Tian Daniel T. Payne Wu‐Lin Yang Yang‐Zi Liu Dr. John S. Fossey Prof. Dr. Wei‐Ping Deng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(29):10457-10465
A protocol to access useful 4‐aminopyrrolidine‐2,4‐dicarboxylate derivatives has been developed. A variety of chiral N,O‐ligands derived from 2,3‐dihydroimidazo[1,2‐a]pyridine motifs have been evaluated in the asymmetric 1,3‐dipolar cycloaddition of azomethine ylides to α‐phthalimidoacrylates. Reactions catalyzed by copper in combination with ligand 7‐Cl‐DHIPOH provided the highest level of stereoselectivity for the 1,3‐dipolar cycloaddition reaction. The reaction tolerates both β‐substituted and β‐unsubstituted α‐phthalimidoacrylate as dipolarophiles, affording the corresponding quaternary 4‐aminopyrrolidine cycloadducts with excellent diastereo‐ (>98:2 d.r.) and enantioselectivities (up to 97 % ee). Removal of the phthalimido protecting group can be accomplished by a simple NaBH4 reduction. Theoretical calculations employing DFT methods show this cycloaddition reaction is likely to proceed through a stepwise mechanism and the stereochemistry was also theoretically rationalized. 相似文献
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One-pot reactions of 2-alkynylbenzaldehydes, amines, and sodium borohydride catalyzed by AgOTf under mild conditions provide a facile protocol for the concise synthesis of 1,2-dihydroisoquinoline derivatives. 相似文献