排序方式: 共有101条查询结果,搜索用时 15 毫秒
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Dr. Tsubasa Hatanaka Prof. Dr. Yasuhiro Ohki Dr. Takashi Kamachi Dr. Tomonori Nakayama Prof. Dr. Kazunari Yoshizawa Prof. Dr. Motomi Katada Prof. Dr. Kazuyuki Tatsumi 《化学:亚洲杂志》2012,7(6):1231-1242
The reactions of the half‐sandwich iron(II) complex [FeCl(Cp*)(tmeda)] ( 1 ; Cp*=η5‐C5Me5, TMEDA=N,N,N′,N′‐tetramethylethylenediamine) with potassium naphthalenide or potassium anthracenide gave the diamagnetic complexes [(Cp*)Fe(μ‐polyarene)Fe(Cp*)] (polyarene=naphthalene ( 2 ), anthracene ( 3a )), which have two {(Cp*)Fe} units bound to opposite faces of the polyarene. One of two {(Cp*)Fe} units in 3a is located over the central ring of anthracene while the other is positioned over an outer ring. The {(Cp*)Fe} unit bound to the central ring of 3a migrates to the outer ring upon heating in the solid state to give the isomer 3b . The electrochemical potential separations between successive one‐electron redox events for complexes 2 and 3b are large. The mixed valence complexes [ [2]+ ]+ and [ [3b]+ ]+ were synthesized by chemical oxidation. The mixed‐valence complex [ [3b]+ ]+ is charge delocalized on the Mössbauer timescale at 78 K, and its absorption spectrum shows an intervalence charge‐transfer band. Complex [ [2]+ ]+ exhibits two absorption bands in the near‐IR region and a slightly broadened doublet in the Mössbauer spectrum. DFT calculations were carried out to examine the electronic structures of these dinuclear iron(I) complexes to elucidate the factors responsible for their diamagnetism and to determine the degree of charge delocalization in the mixed‐valence complexes. 相似文献
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Dr. Tsubasa Nakashima Haruka Fujimori Dr. Kohsuke Ohmatsu Prof. Takashi Ooi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(36):9253-9256
Intermediary radical cations, generated through single-electron oxidation of enol silyl ethers by excited Ir-based photocatalysts, can be exploited as Brønsted acids for the activation of heteroarylcyanides. This strategy enables the direct allylic C−H heteroarylation of enol silyl ethers under visible-light irradiation. 相似文献
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Nanami Uemura Tsubasa Kobayashi Shintaro Yoshida Ya-xin Li Karel Goossens Xiangbing Zeng Go Watanabe Takahiro Ichikawa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(22):8523-8528
We report a new molecular-design principle for creating double-gyroid nanostructured molecular assemblies based on atropisomerization. Ionic amphiphiles containing two imidazolium rings close to each other were designed and synthesized. NMR data revealed that the rotation of the imidazolium rings is restricted, with an activation energy as high as 63 kJ mol−1 in DMSO-d6 solution (DFT prediction for a model compound in the vacuum: 90–100 kJ mol−1). Due to the restricted rotation, the amphiphiles feature “double” atropisomeric axes in their ionic segments and form three stable atropisomers: meso, R, and S. These isomers co-organize into -type bicontinuous cubic liquid-crystalline mesophases through nanosegregation of the ionic and non-ionic parts. Considering the intrinsic characteristic of -type bicontinuous cubic structures that they are composed of intertwined right- and left-handed single gyroids, we propose that the simultaneous presence of both R- and S-atropisomers is an important contributor to the formation of double-gyroid structures. 相似文献
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Heterologous Expression,Biosynthetic Studies,and Ecological Function of the Selective Gq‐Signaling Inhibitor FR900359 下载免费PDF全文
Dr. Max Crüsemann Raphael Reher Isabella Schamari Dr. Alexander O. Brachmann Dr. Tsubasa Ohbayashi Markus Kuschak Dr. Davide Malfacini Alexander Seidinger Marta Pinto‐Carbó René Richarz Tatjana Reuter Dr. Stefan Kehraus Dr. Asis Hallab Misty Attwood Prof. Dr. Helgi B. Schiöth Dr. Peter Mergaert Dr. Yoshitomo Kikuchi Prof. Dr. Till F. Schäberle Prof. Dr. Evi Kostenis Prof. Dr. Daniela Wenzel Prof. Dr. Christa E. Müller Prof. Dr. Jörn Piel Prof. Dr. Aurélien Carlier Prof. Dr. Leo Eberl Prof. Dr. Gabriele M. König 《Angewandte Chemie (International ed. in English)》2018,57(3):836-840
The cyclic depsipeptide FR900359 (FR), isolated from the tropical plant Ardisia crenata, is a strong and selective inhibitor of Gq proteins, making it an indispensable pharmacological tool to study Gq‐related processes, as well as a promising drug candidate. Gq inhibition is a novel mode of action for defense chemicals and crucial for the ecological function of FR, as shown by in vivo experiments in mice, its affinity to insect Gq proteins, and insect toxicity studies. The uncultured endosymbiont of A. crenata was sequenced, revealing the FR nonribosomal peptide synthetase (frs) gene cluster. We here provide a detailed model of FR biosynthesis, supported by in vitro enzymatic and bioinformatic studies, and the novel analogue AC‐1, which demonstrates the flexibility of the FR starter condensation domains. Finally, expression of the frs genes in E. coli led to heterologous FR production in a cultivable, bacterial host for the first time. 相似文献
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Yanada R Obika S Inokuma T Yanada K Yamashita M Ohta S Takemoto Y 《The Journal of organic chemistry》2005,70(17):6972-6975
We have developed efficient catalytic methods for the stereoselective and diversity synthesis of various (E)-, (Z)-, and disubstituted 3-alkylideneoxindoles and 3-alkylidenebenzofuran-2-ones via palladium-catalyzed Heck/Suzuki-Miyaura, Heck/Heck, and Heck/carbonylation/Suzuki-Miyaura domino reactions. 相似文献
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Takashiro Akitsu Chiaki Ishioka Tsubasa Itoh 《Central European Journal of Chemistry》2009,7(4):690-696
A series of organic/inorganic hybrid materials containing the single-molecule magnet [Mn12(CH3COO)16(H2O)4O12]·2CH3COOH·4H2O with the photochromic compounds azobenzene or disperse red 1 cast into polymethyl methacrylate films was prepared. To understand
the photomodulation of analogous mixtures’ AC susceptibility, we investigated the molecular alignment based on Weigert’s effect
accompanying cycles of cis-trans photoisomerization by alternate irradiations with polarized UV and visible light. Polarized
electronic spectra of the hybrid materials demonstrated gradually increasing anisotropy. These features suggest interactions
between photochromic compounds and the Mn12 complex in polymethyl methacrylate.
相似文献
27.
A coordinatively unsaturated iron‐methyl complex having an N‐heterocyclic carbene ligand, [Cp*Fe(LMe)Me] ( 1 ; Cp*=η5‐C5Me5, LMe=1,3,4,5‐tetramethyl‐imidazol‐2‐ylidene), is synthesized from the reaction of [Cp*Fe(TMEDA)Cl] (TMEDA=N,N,N′,N′‐tetramethylethylenediamine) with methyllithium and LMe. Complex 1 is found to activate the C? H bonds of furan, thiophene, and benzene, giving rise to aryl complexes, [Cp*Fe(LMe)(aryl)] (aryl=2‐furyl ( 2 ), 2‐thienyl ( 3 ), phenyl ( 4 )). The C? H bond cleavage reactions are applied to the dehydrogenative coupling of furans or thiophenes with pinacolborane (HBpin) in the presence of tert‐butylethylene and a catalytic amount of 1 (10 mol % to HBpin). The borylation of the furan/thiophene or 2‐substituted furans/thiophenes occurs exclusively at the 2‐ or 5‐positions, respectively, whereas that of 3‐substituted furans/thiophenes takes place mainly at the 5‐position and gives a mixture of regioisomers. Treatment of 2 with 2 equiv of HBpin results in the quantitative formation of 2‐boryl‐furan and the borohydride complex [Cp*Fe(LMe)(H2Bpin)] ( 5 ). Heating a solution of 5 in the presence of tert‐butylethylene led to the formation of an alkyl complex [Cp*Fe(LMe)CH2CH2tBu] ( 6 ), which was found to cleave the C? H bond of furan to produce 2 . On the basis of these results, a possible catalytic cycle is proposed. 相似文献
28.
Anisotropic Expansion of an M2L4 Coordination Capsule: Host Capability and Frame Rearrangement 下载免费PDF全文
Masahiro Yamashina Tsubasa Yuki Dr. Yoshihisa Sei Prof. Dr. Munetaka Akita Dr. Michito Yoshizawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(11):4200-4204
Anisotropic expansion of a spherical M2L4 coordination capsule through the elongation of the ligand led to a new M2L′4 capsule. The expanded capsule provides an elliptical cavity encircled by polyaromatic frameworks with large openings and thereby can encapsulate elliptical fullerene C70 and monofunctionalized fullerene C60 in high yields. In addition, selective formation of a new M2L2L′2 capsule occurs by mixing the original M2L4 and expanded M2L′4 capsules in a 1:1 ratio upon addition of C60 or monofunctionalized C60 as a template molecule. 相似文献
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