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Five differently substituted phthalimide nucleosides were studied by NMR spectroscopic techniques for their ability to recognize and bind a cytosine–guanosine (CG) Watson–Crick base pair in CD2Cl2. Whereas only rather weak binding was observed for analogs with an amino, acetamido, or benzamido substituent, strong binding was observed with the analogs carrying an ureido and n‐butyl ureido residue. 2D NOE measurements at low temperatures confirm the proposed binding mode for the high‐affinity ligands but indicate binding interactions for the weakly bound analogs different from the expected geometry. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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将一些发色团分子组装成具有特定功能的分子器件,是近年来随超分子化学和分子信息科学兴起而十分活跃的领域[1],其中具有逻辑功能的光控开关器件是下一代分子计算机的核心,它们可在分子水平实现信息的存储和数据的处理、传输[2].国内外这方面的研究主要有顺反异... 相似文献
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《Journal of polymer science. Part A, Polymer chemistry》2018,56(3):340-350
To further extend temperature range of application and low temperature performance of the ethylene‐styrene copolymers, a series of poly(ethylene‐styrene‐propylene) samples with varying monomer compositions and relatively low glass‐transition temperatures (Tg = −28 – 22 °C) were synthesized by Me2Si(Me4Cp)(N‐t‐Bu)TiCl2/MMAO system. Since the 13C NMR spectra of the terpolymers were complex and some new resonances were present, 2D‐1H/13C heteronuclear single quantum coherence and heteronuclear multiple bond correlation experiments were conducted. A complete 13C NMR characterization of these terpolymers was performed qualitatively and quantitatively, including chemical shifts, triad sequence distributions, and monomer average sequence lengths. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 340–350 相似文献
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二维超音速边界层中三波共振和二次失稳机制的数值模拟研究 总被引:2,自引:1,他引:1
通过直接数值模拟的方法,探讨在超音速边界层的转捩问题中,是否存在和不可压缩流情况相似的产生亚谐波的机制.结果表明,三波共振和二次失稳这两种机制都存在.讨论了这两种机制在层流至湍流的转捩中的重要性是否的确很大的问题. 相似文献
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Viacheslav Kuropatov Svetlana Klementieva Aleksander Mitin Yulia Budnikova Gleb Abakumov 《Tetrahedron》2010,66(38):7605-716
In search of a synthesis of o-quinone-tetrathiafulvalene-o-quinone triads a novel facile route was developed. Sodium tetrathiooxalate was for the first time used as a synthon in functionalized TTF preparation. The main purpose of this work was to construct an organic compound, which on the one hand possesses a redox-amphotericity, and on the other hand can act as a bridging ligand in construction of linear, 2D and 3D assemblies. Properties of new acceptor-donor-acceptor ligand in respect to application as a building block for the molecular devices have been investigated. 相似文献
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The observation of the Asp–His–Ser triad (Asp: aspartate, His: histidine, Ser: serine) triad both in mammalian and bacterial proteases suggests a special efficiency. A series of B3LYP/D95*(d,p) calculations on various [X–HβY]? dyads (as part of the [X–HβY–HαAc]? model triad, HAc: acetic acid) made from eight different anions X? and 15 different coupling elements HβY was done to analyze the molecular origin of this efficiency. The X? anion acts merely as an electron density donor independent of its chemical nature, and the evolutionary selection of Asp for the catalytic triad therefore seems to be caused by the pH of the triads environment. As the linking proton Hβ moves from Y? to X?, electron density is effectively moved from X? to Y? thereby increasing the proton affinity (PA) of the [X–HY]? dyad, which finally leads to the deprotonization of the HAc molecule. The degree to which the position of Hα controls the PA is dominatly determined by the coupling element HY. The model calculations indicate that 4‐methyl‐1H‐imidazole (HMim) is a very efficient coupling element, which suggest that the evolutionary convergence to the Asp–His–Ser is not only controlled by the ready availability of the imidazole motive in His but also by its high efficiency. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 相似文献
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Solid-State Near-Infrared Circularly Polarized Luminescence from Chiral YbIII-Single-Molecule Magnet
Bertrand Lefeuvre Carlo Andrea Mattei Dr. Jessica Flores Gonzalez Dr. Frédéric Gendron Dr. Vincent Dorcet Dr. François Riobé Dr. Claudia Lalli Dr. Boris Le Guennic Prof. Olivier Cador Dr. Olivier Maury Prof. Stéphan Guy Dr. Amina Bensalah-Ledoux Dr. Bruno Baguenard Dr. Fabrice Pointillart 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(26):7362-7366
A field-induced chiral YbIII Single-Molecule Magnet (SMM) displayed an unprecedented near-infrared circularly polarized luminescence (NIR-CPL) in the solid-state. The bridging bis(1,10-phenantro[5,6b])tetrathiafulvalene triad ( L ) allowed an efficient sensitization of the NIR 2F5/2→2F7/2 emission while the NIR-CPL is associated to the f-f transitions of the YbIII ion bearing chiral β-diketonate derived-camphorate ancillary ligands. 相似文献
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Phototoxicity of some novel porphyrin hybrids against the human leukemic cell line TF-1 总被引:1,自引:0,他引:1
A. Viola P. Mannoni M. Chanon M. Julliard G. Mehta B.G. Maiya S. Muthusamy T. Sambaiah 《Journal of photochemistry and photobiology. B, Biology》1997,40(3):263-272
Photodynamic induced cytotoxicity by porphyrin-DNA cross linker/intercalator hybrid diads and triads has been studied on the human leukemic cell line TF-1. Cells were incubated for 1 to 4 h with these new photosensitizers and irradiated with white light. Cell survival was assessed by the propidium iodide staining, using flow cytometry analysis. A comparison of the dark and light cell survival factor values suggests that irradiation has a significant effect on the toxicity at low concentrations for the porphyrin-chlorambucil diad and to a lesser extent at high concentrations for the porphyrin-acridone diad, the porphyrin-acridine diad and the porphyrin-cholic acid-chlorambucil triad. While the intrinsic antileukemic (via DNA cross-linking) activity of the chlorambucil moiety and the structural details may be responsible for the photoenhancement of the toxicity, the presence of acridine or acridone which are avid intercalators of DNA, is responsible for a similar effect seen for diads. 相似文献
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By direct numerical simulation, a supersonic boundary layer was studied to see whether the mechanism for the generation of sub-harmonic waves, similar to those for the incompressible flows, existed in the process of laminar-turbulent transition. The results showed that mechanisms of both resonant triad and secondary instability did exist. Discussions were made on whether these two mechanisms are really important in laminarturbulent transition. 相似文献