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101.
Tuning Mechanism‐Based Inactivators of Neuraminidases: Mechanistic and Structural Insights 下载免费PDF全文
Dr. Sabrina Buchini François‐Xavier Gallat Dr. Ian R. Greig Dr. Jin‐Hyo Kim Prof. Soichi Wakatsuki Prof. Dr. Leonard M. G. Chavas Prof. Dr. Stephen G. Withers 《Angewandte Chemie (International ed. in English)》2014,53(13):3382-3386
3‐Fluorosialosyl fluorides are inhibitors of sialidases that function by the formation of a long‐lived covalent active‐site adduct and have potential as therapeutics if made specific for the pathogen sialidase. Surprisingly, human Neu2 and the Trypanosoma cruzi trans‐sialidase are inactivated more rapidly by the reagent with an equatorial fluorine at C3 than by its axial epimer, with reactivation following the same pattern. To explore a possible stereoelectronic basis for this, rate constants for spontaneous hydrolysis of the full series of four 3‐fluorosialosyl fluorides were measured, and ground‐state energies for each computed. The alpha (equatorial) anomeric fluorides hydrolyze more rapidly than their beta anomers, consistent with their higher ground‐state energies. However ground‐state energies do not explain the relative spontaneous reactivities of the 3‐fluoro‐epimers. The three‐dimensional structures of the two 3‐fluoro‐sialosyl enzyme intermediates of human Neu2 were solved, revealing key stabilizing interactions between Arg21 and the equatorial, but not the axial, fluorine. Because of changes in geometry these interactions will increase at the transition state, likely explaining the difference in reaction rates. 相似文献
102.
Frontispiece: Diarylethene Self‐Assembled Monolayers: Cocrystallization and Mixing‐Induced Cooperativity Highlighted by Scanning Tunneling Microscopy at the Liquid/Solid Interface 下载免费PDF全文
103.
Rapid Synthesis of Thiophene‐Based,Organic Dyes for Dye‐Sensitized Solar Cells (DSSCs) by a One‐Pot,Four‐Component Coupling Approach 下载免费PDF全文
Keisuke Matsumura Soichi Yoshizaki Dr. Masato. M. Maitani Prof. Yuji Wada Dr. Yuhei Ogomi Prof. Shuzi Hayase Dr. Tatsuo Kaiho Dr. Shinichiro Fuse Dr. Hiroshi Tanaka Prof. Takashi Takahashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9742-9747
This one‐pot, four‐component coupling approach (Suzuki–Miyaura coupling/C?H direct arylation/Knoevenagel condensation) was developed for the rapid synthesis of thiophene‐based organic dyes for dye‐sensitized solar cells (DSSCs). Seven thiophene‐based, organic dyes of various donor structures with/without the use of a 3,4‐ethylenedioxythiophene (EDOT) moiety were successfully synthesized in good yields based on a readily available thiophene boronic acid pinacol ester scaffold (one‐pot, 3‐step, 35–61 %). Evaluation of the photovoltaic properties of the solar cells that were prepared using the synthesized dyes revealed that the introduction of an EDOT structure beside a cyanoacrylic acid moiety improved the short‐circuit current (Jsc) while decreasing the fill factor (FF). The donor structure significantly influenced the open‐circuit voltage (Voc), the FF, and the power conversion efficiency (PCE). The use of a n‐hexyloxyphenyl amine donor, and our originally developed, rigid, and nonplanar donor, both promoted good cell performance (η=5.2–5.6 %). 相似文献
104.
Masato Sakabe Prof. Dr. Soichi Sato 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(18):5658-5665
The hexacoordinated antimony(V) dication [(ppy)3Sb]2+ ([ 1 ]2+; ppy=2-(2-pyridyl)phenyl), stabilized by three intramolecular donor–acceptor interactions, has been isolated as its hexachloroantimonate salt [ 1 ][SbCl6]2, prepared by the oxidative addition of chlorine to the neutral stibine [(ppy)3Sb] ( 1 ), followed by the abstraction of chloride. Air-stable [ 1 ][SbCl6]2 exhibits remarkable thermal stability and the three ppy ligands on the antimony atom are shown to be magnetically inequivalent in the 1H and 13C NMR spectra. A hexacoordinated, meridional octahedral bonding geometry has been determined for [ 1 ][SbCl6]2 by X-ray crystallographic analysis. Theoretical calculations were performed to investigate why the meridional form was generated preferentially over the facial form. In addition, the dynamics of the ppy ligands were investigated by variable-temperature 1H NMR spectroscopy. The potential to generate dications by using a single-electron-transfer reagent has also been investigated. The dication [ 1 ]2+ is the first [12–Sb–6]2+ chemical species to have been structurally determined. 相似文献
105.
Mitsuru Tashiro Nobuaki Ishida Sakurako Shimotakahara Soichi Tanabe Akira Okubo 《Analytical sciences》2003,19(6):933-936
The 1H-magnetic resonance imaging technique was applied for monitoring the extent of the heat coagulation in the shell egg. It is demonstrated that spin-spin relaxation time (T2) is an effective marker to observe the extent of coagulation in egg white and yolk and that the T2 value image is quite useful to recognize non-destructively the extent and status of coagulation of the heated eggs. This technique can also be applied to the material science as well as food science for observation of the inner status of the objects. 相似文献
106.
Katsuhiro Inomata Eiji Nakanishi Yasuo Sakane Masao Koike Takuhei Nose 《Journal of Polymer Science.Polymer Physics》2005,43(1):79-86
Graft copolymers consisting of amorphous main chain, poly(methyl methacrylate) (PMMA), or poly(methyl acrylate) (PMAc), and crystalline side chains, poly(ethylene glycol) (PEG), have been prepared by copolymerization of PEG macromonomers with methyl methacrylate or methyl acrylate (MMAx or MACx, respectively). Because of the compatibility of PMMA/PEG and PMAc/PEG, from small‐angle X‐ray scattering results, the main and side chains in graft copolymers were suggested to be homogeneous in the molten state. Differential scanning calorimetry (DSC) cooling scans revealed that PEG side chains for graft copolymers with large PEG fractions were crystallized when the sample was cooled, with a cooling rate of 10 °C/min. The spherulite pattern observed by a polarized optical microscope suggested the growth of PEG crystalline lamellae. Crystallization of PEG in MMAx was more restrained than in MACx. From these results, we have concluded that the crystallization behavior of the grafted side chains is strongly influenced by the glass transition of a homogeneously molten sample as well as dilution of the crystallizable chains. Domain spacings for isothermally crystallized graft copolymers were described by interdigitating chain packing in crystalline–amorphous lamellar structure. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 79–86, 2005 相似文献
107.
Syntheses and Structure of Hexacoordinated Selenium (λ6-Selane) and Tellurium (λ6-Tellane) Compounds
Soichi Sato Takeshi Ueminami Takahiro Yamashita Hiroshi Arakawa Ernst Horn Ohgi Takahashi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):595-598
The first isolation of bis(2,2′-biphenylylene)dichloro- and difluoro-perchalcogenuranes, [12–Se–6(C4F2)] (λ6-selane); [12–Te–6(C4X2), X = Cl, F] (λ6-tellane) and the corresponding tellurane Te-oxide dimer [12–Te–6(C4O2)]2, and their crystal and molecular structures are described. Furthermore, on the basis of the difference between the 3c-4e bonds of the dodecet species and that of the decet species a new molecular orbital concept has been proposed on the 3c-4e bond of perchalcogenurane species [12–M–6, M = chalcogen atoms]. 相似文献
108.
A. Murotomi M. Yokota Y. Miyano T. Sakane K. Fukuchi 《Journal of Thermal Analysis and Calorimetry》2009,95(2):393-396
The infinite dilution activity coefficients of alkane (hexane, octane, decane and dodecane) in alkane (hexadecane and octadecane)
were measured in the region of 313–470 K using a gas stripping method. The experimental results were predicted by the modified
ASOG previously proposed. 相似文献
109.
Soichi Okada 《Journal of Algebraic Combinatorics》2006,23(1):43-69
An alternating sign matrix is a square matrix with entries 1, 0 and −1 such that the sum of the entries in each row and each
column is equal to 1 and the nonzero entries alternate in sign along each row and each column. To some of the symmetry classes
of alternating sign matrices and their variations, G. Kuperberg associate square ice models with appropriate boundary conditions,
and give determinant and Pfaffian formulae for the partition functions. In this paper, we utilize several determinant and
Pfaffian identities to evaluate Kuperberg's determinants and Pfaffians, and express the round partition functions in terms
of irreducible characters of classical groups. In particular, we settle a conjecture on the number of vertically and horizontally
symmetric alternating sign matrices (VHSASMs).
Dedicated to the memory of David Robbins. 相似文献
110.
T. Sakane 《Optics Communications》1974,12(1):21-23
An actively mode-locked TEA CO2 laser producing pulses consisting of more than 3 lines of the 10.4 μm band by inserting a KCl plate is described. 相似文献