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41.
Suzuka Kinoshita Ryota Yamano Dr. Yu Shibata Yusuke Tanaka Kyoichi Hanada Dr. Takashi Matsumoto Prof. Dr. Kazunori Miyamoto Dr. Atsuya Muranaka Prof. Dr. Masanobu Uchiyama Prof. Dr. Ken Tanaka 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(27):11113-11120
An S-shaped double helicene-like molecule (>99 % ee), possessing stable helical chirality, has been synthesized by the rhodium(I)/difluorphos complex-catalyzed highly diastereo- and enantioselective intramolecular double [2+2+2] cycloaddition of a 2-naphthol- and benzene-linked hexayne. The collision between two terminal naphthalene rings destabilizes the helical chirality of the S-shaped double helicene-like molecule, but the introduction of two additional fused benzene rings significantly increases the configurational stability. Thus, no epimerization and racemization were observed even at 100 °C. The enantiopure S-shaped double helicene-like molecule forms a trimer through the multiple C−H⋅⋅⋅π and C−H⋅⋅⋅O interactions in the solid-state. The trimers stack to form columnar packing structures, in which neighboring stacks have opposite dipole directions. The accumulation of helical structures in the same direction in the S-shaped double helicene-like molecule enhanced the chiroptical properties. 相似文献
42.
Kenshu Fujiwara Akiyoshi Goto Daisuke Sato Hidetoshi Kawai Takanori Suzuki 《Tetrahedron letters》2005,46(20):3465-3468
A simple stereoselective synthesis of cis- and trans-2,3-disubstituted medium-sized cyclic ethers has been developed based on geometry-selective synthesis of 3-alkoxy-2-propenyl glycolate esters, Ireland-Claisen rearrangement of the glycolate esters, and ring-closing olefin metathesis. 相似文献
43.
Ginet P Montagne K Akiyama S Rajabpour A Taniguchi A Fujii T Sakai Y Kim B Fourmy D Volz S 《Lab on a chip》2011,11(8):1513-1520
Metal electrodes with micron scale width enable the heating of less than a dozen cells in a confluent layer at predictable temperatures up to 85 °C with an accuracy of ±2 °C. Those performances were obtained by a preliminary robust temperature calibration based on biotin-rhodamine fluorescence and by controlling the temperature map on the substrate through thermal modeling. The temperature accuracy was proved by inducing the expression of heat shock proteins (HSP) in a few NIH-3T3 cells through a confined and precise temperature rise. Our device is therefore effective to locally induce a heat shock response with almost single-cell resolution. Furthermore, we show that cells heated at a higher temperature than the one of heat shock remain alive without producing HSP. Electrode deposition being one of the most common engineering processes, the fabrication of electrode arrays with a simple control circuit is clearly within reach for parallel testing. This should enable the study of several key mechanisms such as cell heat shock, death or signaling. In nanomedicine, controlled drug release by external stimuli such as for example temperature has attracted much attention. Our device could allow fast and efficient testing of thermoactivable drug delivery systems. 相似文献
44.
Prof. Dr. Katsuhiro Isozaki Tomoya Yokoi Ryota Yoshida Dr. Kazuki Ogata Dr. Daisuke Hashizume Dr. Nobuhiro Yasuda Prof. Dr. Koichiro Sadakane Prof. Dr. Hikaru Takaya Prof. Dr. Masaharu Nakamura 《化学:亚洲杂志》2016,11(7):1076-1091
Two (ONO pincer)ruthenium‐complex‐bound norvalines, Boc?[Ru(pydc)(terpy)]Nva?OMe ( 1 ; Boc=tert‐butyloxycarbonyl, terpy=terpyridyl, Nva=norvaline) and Boc?[Ru(pydc)(tBu‐terpy)]Nva?OMe ( 5 ), were successfully synthesized and their molecular structures and absolute configurations were unequivocally determined by single‐crystal X‐ray diffraction. The robustness of the pincer Ru complexes and norvaline scaffolds against acidic/basic, oxidizing, and high‐temperature conditions enabled us to perform selective transformations of the N‐Boc and C?OMe termini into various functional groups, such as alkyl amide, alkyl urea, and polyether groups, without the loss of the Ru center or enantiomeric purity. The resulting dialkylated Ru‐bound norvaline, n‐C11H23CO?l ‐[Ru(pydc)(terpy)]Nva?NH‐n‐C11H23 (l ‐ 4 ) was found to have excellent self‐assembly properties in organic solvents, thereby affording the corresponding supramolecular gels. Ru‐bound norvaline l ‐ 1 exhibited a higher catalytic activity for the oxidation of alcohols by H2O2 than parent complex [Ru(pydc)(terpy)] ( 11 a ). 相似文献
45.
Back Cover: Motion Capture and Manipulation of a Single Synthetic Molecular Rotor by Optical Microscopy (Angew. Chem. Int. Ed. 38/2014) 下载免费PDF全文
46.
47.
Hiromichi Aono Hiroki Ebara Ryota Senba Takashi Naohara Tsunehiro Maehara Hideyuki Hirazawa Yuji Watanabe 《Journal of magnetism and magnetic materials》2012
Nano-sized magnetic Y3Fe5O12 ferrite having a high heat generation ability in an AC magnetic field was prepared by bead milling. A commercial powder sample (non-milled sample) of ca. 2.9 μm in particle size did not show any temperature enhancement in the AC magnetic field. The heat generation ability in the AC magnetic field improved with a decrease in the average crystallite size for the bead-milled Y3Fe5O12 ferrites. The highest heat ability in the AC magnetic field was for the fine Y3Fe5O12 powder with a 15-nm crystallite size (the samples were milled for 4 h using 0.1 mm? beads). The heat generation ability of the excessively milled Y3Fe5O12 samples decreased. The main reason for the high heat generation property of the milled samples was ascribed to an increase in the Néel relaxation of the superparamagnetic material. The heat generation ability was not influenced by the concentration of the ferrite powder. For the samples milled for 4 h using 0.1 mm? beads, the heat generation ability (W g−1) was estimated using a 3.58×10−4 fH2 frequency (f/kHz) and the magnetic field (H/kA m−1), which is the highest reported value of superparamagnetic materials. 相似文献
48.
49.
Ryota Seto Takashi Sato Takahiro Kojima Katsumoto Hosokawa Yasuhito Koyama Gen‐Ichi Konishi Toshikazu Takata 《Journal of polymer science. Part A, Polymer chemistry》2010,48(16):3658-3667
Syntheses of 2,2′‐bisalcoholic group‐substituted 9,9′‐spirobifluorene monomers 2 were performed by the reaction of 2,2′‐dihydroxy‐9,9′‐spirobifluorene 2a with haloalcohols. Polycarbonates consisting of 9,9′‐spirobifluorene skeleton in the main chain (PC 4 ) were synthesized by the polycondensation of 2,2′‐bisalcoholic monomers 2 and triphosgene or diphenyl carbonate. PC 4 showed good thermal stability: the 5% weight loss temperature was over 330 °C under both nitrogen and air atmospheres. The glass transition temperature was in a range of 16–269 °C estimated by differential scanning calorimetry, depending on the flexibility of the alkylene or oxyethylene chains of 2 . PC 4 showed high solubility toward ordinary organic solvents such as CHCl3, benzene, and THF, making possible the preparation of the flexible thin films. Very high refractive index in a range of 1.62–1.66 at 589 nm was observed although PC 4 consists only of C, H, and O atoms, whereas very low degree of birefringence was confirmed. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3658–3667, 2010 相似文献
50.
Ryota Inoue Masashi Hasegawa Tohru Nishinaga Kenji Yoza Yasuhiro Mazaki 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(9):2772-2776
A series of thiacalix[n]dithiothiophenes (n=4–10) was prepared by a facile method and X‐ray analysis was used to determine the molecular structures of square‐ (4‐mer) and pentagonal‐shaped macrocycles (5‐mer). In the cyclic voltammograms, reversible multielectron redox processes, which are due to electronic delocalization, were observed at low oxidation potentials. The cyclic 4‐mer acted as a “Janus‐head” cavitand for two C60 molecules, whereas the 5‐ and 6‐mer formed stable 1:1 complexes with C60 . 相似文献