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1.
Kanna Adachi Tomoshi Yamada Hayate Ishizuka Mana Oki Shunsuke Tsunogae Noriko Shimada Osamu Chiba Tatsuya Orihara Prof. Dr. Masafumi Hidaka Prof. Dr. Takatsugu Hirokawa Dr. Minami Odagi Prof. Dr. Keiichi Konoki Prof. Dr. Mari Yotsu-Yamashita Prof. Dr. Kazuo Nagasawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(9):2025-2033
A novel series of C12-keto-type saxitoxin (STX) derivatives bearing an unusual nonhydrated form of the ketone at C12 has been synthesized, and their NaV-inhibitory activity has been evaluated in a cell-based assay as well as whole-cell patch-clamp recording. Among these compounds, 11-benzylidene STX ( 3 a ) showed potent inhibitory activity against neuroblastoma Neuro 2A in both cell-based and electrophysiological analyses, with EC50 and IC50 values of 8.5 and 30.7 nm , respectively. Interestingly, the compound showed potent inhibitory activity against tetrodotoxin-resistant subtype of NaV1.5, with an IC50 value of 94.1 nm . Derivatives 3 a – d and 3 f showed low recovery rates from NaV1.2 subtype (ca 45–79 %) compared to natural dcSTX ( 2 ), strongly suggesting an irreversible mode of interaction. We propose an interaction model for the C12-keto derivatives with NaV in which the enone moiety in the STX derivatives 3 works as Michael acceptor for the carboxylate of Asp1717. 相似文献
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Self‐Assembled Fibers Containing Stable Organic Radical Moieties: Alignment and Magnetic Properties in Liquid Crystals 下载免费PDF全文
Hiroki Eimura Yoshikazu Umeta Prof. Dr. Hiroko Tokoro Prof. Dr. Masafumi Yoshio Prof. Dr. Shin‐ichi Ohkoshi Prof. Dr. Takashi Kato 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(26):8872-8878
Macroscopically oriented stable organic radicals have been obtained by using a liquid–crystalline (LC) gel composed of an l ‐isoleucine‐based low molecular weight gelator containing a 2,2,6,6‐tetramethylpiperidine 1‐oxyl moiety. The LC gel has allowed magnetic measurements of the oriented organic radical. The gelator has formed fibrous aggregates in liquid crystals via intermolecular hydrogen bonds. The fibrous aggregates of the radical gelator are formed and oriented on cooling by applying a magnetic field to the mixture of liquid crystals and the gelator. Superconducting quantum interference device (SQUID) measurements have revealed that both oriented and nonoriented fibrous aggregates exhibited antiferromagnetic interactions, in which super‐exchange interaction constant J is estimated as ?0.89 cm?1. 相似文献
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Abstract Some dicarhoxyphenylphosphonic acids (DCPPA) were prepared by new process. We succeeded in introducing two carhoxyl groups into the phenyl group of phenylphosphonic acid. The dialkyl iso- and tere-phthalate (DACB) were conveniently hrominated with NBS /H2SO4 system to provide the corresponding hromidcs (DACBB) in good yields and good selectivities. 相似文献
7.
Shin-ichi Kondo Naoya Watanabe Fubuki Takahashi Nobuhiro Takeda Masafumi Unno 《Journal of inclusion phenomena and macrocyclic chemistry》2013,75(1-2):31-38
Two trimethylsilyl groups were introduced at 5- and 5′-positions of 2,2′-binaphthalene to improve the solubility of 2,2′-binaphthalene-based receptors. The X-ray crystallographic analysis revealed the twisted structure of 2 in the solid state. The solubility of 2 was moderately improved by 3.1-fold comparing with mother skeleton 1. As a practical example of 2, receptor 8 bearing two aza-15-crown-5 moieties was prepared and the selective binding of 8 with Ba2+ can be observed by the formation of sandwich-like complex, which shows no prevention of binding ability of the receptor by introduction of the bulky substituents. 相似文献
8.
Lifang Chen Yulv Yu Masako Kuwa Tao Cheng Yan Liu Hiroshi Murakami Harada Masafumi Yuan Wang 《物理化学学报》2020,36(1):1907008-0
碱-乙二醇法制备的"非保护型"金属及合金纳米簇由表面吸附的溶剂分子和简单离子实现稳定化,它们被广泛用于制备高性能复相催化剂和研究复相催化剂中的尺寸、组成、载体表面基团以及修饰剂对催化性能的影响。关于此类非保护金属纳米簇的形成过程及机理的认识尚有待进一步深化。本文采用原位快速扫描X射线吸收精细结构谱(QXAFS)、原位紫外-可见(UV-Vis)吸收光谱、透射电子显微镜和动态光散射技术研究了碱-乙二醇法合成中非保护型金属胶体纳米簇的形成过程与机理。结果表明,在碱-乙二醇法合成非保护型Pt金属纳米簇的过程中,室温下即有部分Pt(IV)被还原至Pt(II)。随着反应温度的升高,OH-逐渐取代与Pt离子配位的Cl-,在Pt―Pt键形成之前,反应体系的UV-Vis吸收光谱中可观察到明显的纳米粒子的散射信号,原位QXAFS分析表明Pt纳米簇是由Pt氧化物纳米粒子还原所形成的;在Ru金属纳米簇的形成过程中,OH-首先取代了Ru Cl_3中的Cl~-,形成羟基配合物Ru(OH) _6~(3-),后者进一步缩合形成氧化钌纳米粒子,最终Ru金属纳米簇由乙二醇还原氧化钌纳米粒子形成。由于先形成了氧化物纳米粒子,后续的还原反应被限制在氧化物纳米粒子内,使最终得到的非保护型金属纳米簇具有尺寸小、分布窄的特点。本工作所获得的知识对发展高性能能源转化催化剂、精细化学合成催化剂、传感器等功能体系具有重要意义。 相似文献
9.
Tsuyoshi Mayama Masafumi NodaRyoichi Chiba Mitsutoshi Kuroda 《International Journal of Plasticity》2011,27(12):1916-1935
The texture development mechanism during the extrusion of magnesium alloy is investigated by experimental observation and numerical analysis. First, we perform a finite element analysis of a full extrusion process using a phenomenological constitutive equation, and it is confirmed that the loading condition of the extrusion process near the central axis of the billet is approximated by an equi-biaxial compression mode. Then, the equi-biaxial compression problem is adopted as a simplified boundary value problem to be solved using a crystal plasticity model to clarify the detailed texture development mechanism during the extrusion process. The crystal plasticity analysis of equi-biaxial compression successfully reproduces the texture development from an initial random texture to the final experimentally observed texture. The effects of the deformation modes (i.e. slip and twinning systems) implemented in the calculation and the reference stress ratio of basal to nonbasal slip systems on texture development are studied in detail. Finally, the mechanism of texture development during the extrusion process is discussed in terms of the lattice rotation caused by the activated slip systems. 相似文献
10.
Palladium–N‐Heterocyclic Carbene (NHC)‐Catalyzed Asymmetric Synthesis of Indolines through Regiodivergent C(sp3)H Activation: Scope and DFT Study 下载免费PDF全文
Dmitry Katayev Dr. Evgeny Larionov Dr. Masafumi Nakanishi Dr. Céline Besnard Prof. Dr. E. Peter Kündig 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):15021-15030
Two bulky, chiral, monodentate N‐heterocyclic carbene ligands were applied to palladium‐catalyzed asymmetric C?H arylation to incorporate C(sp3)?H bond activation. Racemic mixtures of the carbamate starting materials underwent regiodivergent reactions to afford different trans‐2,3‐substituted indolines. Although this CAr?Calkyl coupling requires high temperatures (140–160 °C), chiral induction is high. This regiodivergent reaction, when carried out with enantiopure starting materials, can lead to single structurally different enantiopure products, depending on the catalyst chirality. The C?H activation at a tertiary center was realized only in the case of a cyclopropyl group. No C?H activation takes place alpha to a tertiary center. A detailed DFT study is included and analyses of methyl versus methylene versus methine C?H activation is used to rationalize experimentally observed regio‐ and enantioselectivities. 相似文献