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11.
Dr. Jiawei Zhang Dr. Daisuke Ishikawa Dr. Michael M. Koza Prof. Dr. Eiji Nishibori Dr. Lirong Song Dr. Alfred Q. R. Baron Prof. Dr. Bo B. Iversen 《Angewandte Chemie (International ed. in English)》2023,62(13):e202218458
Loosely bonded (“rattling”) atoms with s2 lone pair electrons are usually associated with strong anharmonicity and unexpectedly low thermal conductivity, yet their detailed correlation remains largely unknown. Here we resolve this correlation in thermoelectric InTe by combining chemical bonding analysis, inelastic X-ray and neutron scattering, and first principles phonon calculations. We successfully probe soft low-lying transverse phonons dominated by large In1+ z-axis motions, and their giant anharmonicity. We show that the highly anharmonic phonons arise from the dynamic lone pair expression with unstable occupied antibonding states induced by the covalency between delocalized In1+ 5s2 lone pair electrons and Te 5p states. This work pinpoints the microscopic origin of strong anharmonicity driven by rattling atoms with stereochemical lone pair activity, important for designing efficient materials for thermoelectric energy conversion. 相似文献
12.
Dr. Tomoyuki Ikai Sayaka Miyoshi Dr. Kosuke Oki Dr. Ranajit Saha Dr. Yuh Hijikata Prof. Eiji Yashima 《Angewandte Chemie (International ed. in English)》2023,62(20):e202301962
Fully π-conjugated ladder polymers with a spiral geometry represent a new class of helical polymers with great potential for organic nanodevices, but there is no precedent for an optically active helical ladder polymer totally composed of achiral units. We now report the defect-free synthesis and resolution of a fully π-conjugated helical ladder polymer with a rigid helical cavity, which has been achieved by quantitative and chemoselective acid-promoted alkyne benzannulations of a rationally designed, random-coil achiral polymer followed by chromatographic enantioseparation. Because of a sufficiently high helix-inversion barrier, the isolated excess one-handed helical ladder polymer with a degree of polymerization of more than 15 showed a strong circular dichroism with a dissymmetry factor of up to 1.7×10−2 and is thermally stable, maintaining its optical activity in solution even at 100 °C, as well-supported by molecular dynamics simulation. 相似文献
13.
Glycosyl‐Templated Chiral Helix Stapling of Ethynylpyridine Oligomers by Alkene Metathesis between Inter‐Pitch Side Chains 下载免费PDF全文
Dr. Hajime Abe Dr. Fumihiro Kayamori Prof. Dr. Masahiko Inouye 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(26):9405-9413
Ethynylpyridine polymers and oligomers consisting of 4‐substituted pyridine rings linked by acetylene bonds at the 2‐ and 6‐positions have been investigated. Ethynylpyridine oligomers covalently linked with a glycosyl chiral template form chiral helical complexes by intramolecular hydrogen bonding, in which the chirality of the template is translated to the helix. With a view to fixation of the chiral architecture, D /L ‐galactosyl‐ and D /L ‐mannosyl‐linked ethynylpyridine oligomers have been developed with 4‐(3‐butenyloxy)pyridine units having alkene side chains. The helical structures are successfully stapled by alkene metathesis of the side chains. Subsequent removal of the chiral templates by acidolysis produces template‐free stapled oligomers. The chiral, template‐free, stapled oligomers show chiral helicity, which is resistant to polar solvents and heating. 相似文献
14.
Dr. Shintaro Ishida Dr. Takashi Abe Dr. Fumiya Hirakawa Tomoyuki Kosai Katsuhiro Sato Prof. Dr. Mitsuo Kira Prof. Dr. Takeaki Iwamoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(43):15100-15103
A persistent dialkylsilanone was synthesized by the dehydrobromination of a dialkylbromosilanol with tris(trimethylsilyl)silyl potassium in solution at ?80 °C: It was characterized by NMR and IR spectroscopy, and was tested in several reactions. In 29Si NMR spectrum in [D8]toluene, the signal due to the unsaturated silicon nuclei was observed at 128.7 ppm. Reactions of the dialkylsilanone with water and mesitonitrile oxide gave a silanediol and a [2+3] cycloadduct, respectively. The silanone remains intact in [D8]toluene below ?80 °C for at least two days, while it undergoes unprecedented isomerization to give a siloxysilene by means of 1,3‐silyl migration at higher temperatures. 相似文献
15.
Native Mannose‐Dominant Extraction by Pyridine–Phenol Alternating Oligomers Having an Extremely Efficient Repeating Motif of Hydrogen‐Bonding Acceptors and Donors 下载免费PDF全文
Yuki Ohishi Dr. Hajime Abe Prof. Dr. Masahiko Inouye 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(46):16504-16511
Pyridine–phenol alternating oligomers in which pyridine and phenol moieties are alternatingly linked through acetylene bonds at the 2,6‐positions of the aromatic rings were designed and synthesized. The pyridine nitrogen atom and the neighboring phenolic hydroxyl group were oriented so that they do not form an intramolecular hydrogen bond but cooperatively act as hydrogen‐bonding acceptor and donor in a push–pull fashion for the hydroxyl group of saccharides. The longer oligomer strongly bound to lipophilic glycosides in 1,2‐dichloroethane, and association constants approached 108 M ?1. Moreover, the oligomer extracted native saccharides from a solid phase to apolar organic solvents up to the extent of an equal amount of the oligomer and showed mannose‐dominant extraction among naturally abundant hexoses. The oligomer bound to native saccharides even in 20 % DMSO‐containing 1,2‐dichloroethane and exhibited association constants of greater than 10 M ?1 for D ‐mannose and D ‐glucose. 相似文献
16.
Crystal Structure of the Isopropylzinc Alkoxide of Pyrimidyl Alkanol: Mechanistic Insights for Asymmetric Autocatalysis with Amplification of Enantiomeric Excess 下载免费PDF全文
Dr. Arimasa Matsumoto Takaaki Abe Atsushi Hara Takayuki Tobita Taisuke Sasagawa Prof. Dr. Tsuneomi Kawasaki Prof. Dr. Kenso Soai 《Angewandte Chemie (International ed. in English)》2015,54(50):15218-15221
Asymmetric amplification during self‐replication is a key feature that is used to explain the origin of homochirality. Asymmetric autocatalysis of pyrimidyl alkanol in the asymmetric addition of diisopropylzinc to pyrimidine‐5‐carbaldehyde is a unique example of this phenomenon. Crystallization of zinc alkoxides of this 5‐pyrimidyl alkanol and single‐crystal X‐ray diffraction analysis of the alkoxide crystals reveal the existence of tetramer or higher oligomer structures in this asymmetric autocatalytic system. 相似文献
17.
Non-negative matrix factorization (NMF) is a technique of multivariate analysis used to approximate a given matrix containing non-negative data using two non-negative factor matrices that has been applied to a number of fields. However, when a matrix containing non-negative data has many zeroes, NMF encounters an approximation difficulty. This zero-inflated situation occurs often when a data matrix is given as count data, and becomes more challenging with matrices of increasing size. To solve this problem, we propose a new NMF model for zero-inflated non-negative matrices. Our model is based on the zero-inflated Tweedie distribution. The Tweedie distribution is a generalization of the normal, the Poisson, and the gamma distributions, and differs from each of the other distributions in the degree of robustness of its estimated parameters. In this paper, we show through numerical examples that the proposed model is superior to the basic NMF model in terms of approximation of zero-inflated data. Furthermore, we show the differences between the estimated basis vectors found using the basic and the proposed NMF models for \(\beta \) divergence by applying it to real purchasing data. 相似文献
18.
Eri?Takano Nobuaki?Shimura Takeshi?Akiba Yukiya?Kitayama Hirobumi?Sunayama Koichi?Abe Kazunori?Ikebukuro Toshifumi?TakeuchiEmail authorView authors OrcID profile 《Mikrochimica acta》2017,184(6):1595-1601
The authors describe a pipette type of biosensor for detecting target genes and using a zinc finger protein fused to luciferase (ZF luciferase). The ZF protein binds to a specific DNA sequence, and the target double-stranded (ds) DNA can be detected by monitoring the enzymatic activity of ZF luciferase. A small avidin-immobilized reaction plate is placed on a plastic pipette tip (referred to as Biologi tip). The dsDNA detection procedures are carried out by using a programmable dispensing robot equipped with a photodetector. These procedures include (a) the aspiration of an analyte to capture the biotinylated target dsDNA (a product of a polymerase chain reaction) on the small reaction plate inside the pipette tip, (b) the introduction of ZF luciferase and luciferin into the pipette tip, and (c) migration of the pipette tip to the detection port to measure bioluminescence on the small reaction plate. The emission originating from luciferase activity is observed on the reaction plate containing immobilized biotin-tagged target dsDNA, whereas plates containing non-target or biotinylated single-stranded DNA only do not yield a signal. The intensity of emission increases proportionally to the concentration of dsDNA, and the detection limit of the target dsDNA is as low as 62 pM. An actual genomic DNA sample from Escherichia coli O157 was successfully detected by this automatic analyzer using the Biologi tip equipped with a reaction plate. This indicates that this system has a large potential for practical applications, including in particular point-of-care analyses in hygiene control, food safety testing, and clinical diagnosis. 相似文献
19.
Yoshimasa Makita Tomofumi Danno Keisuke Ikeda Hsien-Han Lee Taro Abe Kento Sogawa Akihiro Nomoto Shin-ichi Fujiwara Akiya Ogawa 《Tetrahedron letters》2017,58(48):4507-4509
Hemicryptophanes are covalent molecular cages, constructed from a cyclotriveratrylene-based host unit and a functional unit linked by covalent spacers, which have been designed to accommodate endohedral functionalities in the cavity. In this study, the synthesis and characterization of the rigid, biphenyl-linked hemicryptophane 1 were investigated by NMR, ESI-MS, and X-ray crystallography. The structure of the inclusion complex, in which a dichloromethane molecule was constructed encapsulated within 1, was characterized by X-ray crystallography. An endohedral, cobalt(II) hemicryptophane complex 2 was also synthesized and characterized ESI-MS and X-ray crystallography. The X-ray crystal structure of 2 showed that the biphenyl-linked hemicryptophane had three components—a molecule each of chloroform and acetonitrile, and a cobalt(II) ion—within its cavity. 相似文献
20.
Circular autocorrelation of stationary circular Markov processes 总被引:1,自引:0,他引:1
Toshihiro Abe Hiroaki Ogata Takayuki Shiohama Hiroyuki Taniai 《Statistical Inference for Stochastic Processes》2017,20(3):275-290
The stationary Markov process is considered and its circular autocorrelation function is investigated. More specifically, the transition density of the stationary Markov circular process is defined by two circular distributions, and we elucidate the structure of the circular autocorrelation when one of these distributions is uniform and the other is arbitrary. The asymptotic properties of the natural estimator of the circular autocorrelation function are derived. Furthermore, we consider the bivariate process of trigonometric functions and provide the explicit form of its spectral density matrix. The validity of the model was assessed by applying it to a series of wind direction data. 相似文献