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101.
The Electronic State of Hydrogen in the α Phase of the Hydrogen‐Storage Material PdH(D)x: Does a Chemical Bond Between Palladium and Hydrogen Exist?
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Shun Dekura Prof. Hirokazu Kobayashi Prof. Ryuichi Ikeda Prof. Mitsuhiko Maesato Haruka Yoshino Prof. Masaaki Ohba Prof. Takayoshi Ishimoto Dr. Shogo Kawaguchi Prof. Yoshiki Kubota Dr. Satoru Yoshioka Prof. Syo Matsumura Prof. Takeharu Sugiyama Prof. Hiroshi Kitagawa 《Angewandte Chemie (International ed. in English)》2018,57(31):9823-9827
The palladium–hydrogen system is one of the most famous hydrogen‐storage systems. Although there has been much research on β‐phase PdH(D)x, we comprehensively investigated the nature of the interaction between Pd and H(D) in α‐phase PdH(D)x (x<0.03 at 303 K), and revealed the existence of Pd?H(D) chemical bond for the first time, by various in situ experimental techniques and first‐principles theoretical calculations. The lattice expansion, magnetic susceptibility, and electrical resistivity all provide evidence. In situ solid‐state 1H and 2H NMR spectroscopy and first‐principles theoretical calculations revealed that a Pd?H(D) chemical bond exists in the α phase, but the bonding character of the Pd?H(D) bond in the α phase is quite different from that in the β phase; the nature of the Pd?H(D) bond in the α phase is a localized covalent bond whereas that in the β phase is a metallic bond. 相似文献
102.
Boron complexes surrounded with organic cages were controlled precisely by a remote atom placed at the bottom of the cage. A replacement of the bottom tether atom (carbon or silicon) changed the characteristics (kinetic and thermodynamic factors) of boron complexes by geometric effects. A theoretical study shows that the bottom atoms also control eigenvalues of MO. This cage complex will provide a systematic template for fine-tuning of metal complexes to create various properties. 相似文献
103.
The heterotrich ciliate Blepharisma japonicum produces red pigment blepharismins, which function as self-defense toxin against predators and as a photoreceptor for step-up photonegativity. The dibenzoperylenequinone moiety of blepharismins was shown to be biosynthesized via the polyketide pathway. In this paper, the starter units of the biosynthetic pathway of blepharismins were determined to be isovaleryl-CoA and butyryl-CoA by HPLC, LC/ESI-MS, and 1H and 2H NMR analyses of the pigments obtained from feeding experiment of l-leucine or sodium butyrate in excess and deuterium-labeled l-leucine. 相似文献
104.
105.
Tobisu M Kitajima A Yoshioka S Hyodo I Oshita M Chatani N 《Journal of the American Chemical Society》2007,129(37):11431-11437
The Br?nsted acid catalyzed formal insertion of an isocyanide into a C-O bond of an acetal is described. A diverse array of acyclic and cyclic acetals can be applied to the catalytic insertion to form alpha-alkoxy imidates. Functional groups, such as nitro, cyano, halogen, ester, and alkoxy groups, are tolerant to the reaction conditions employed. The course of the reaction is highly dependent on the structure of the isocyanide. The use of an electron-deficient aryl isocyanide, such as 2c and 2d, is required to selectively obtain the monoinsertion product. When aryl isocyanides containing alkyl substituents, such as 2a and 2b, are employed, two molecules of the isocyanide are incorporated, and the double-insertion product is obtained. The reaction of tert-octyl isocyanide also induces a double incorporation, but the subsequent acid-mediated fragmentation leads to the 2-alkoxy imidoyl cyanide. The monoinsertion products, alpha-alkoxy imidates, can readily be hydrolyzed to alpha-alkoxy esters, realizing the formal carbonylation of an acetal. 相似文献
106.
Yoshioka H Suzuki M Mugisawa M Naitoh N Sawada H 《Journal of colloid and interface science》2007,308(1):4-10
Fluoroalkanoyl peroxide reacted with 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane (TTRV-Si) to afford fluoroalkyl end-capped oligomers containing some unreacted vinyl segments under very mild conditions. Fluoroalkyl end-capped cyclosiloxane oligomers containing some vinyl segments thus obtained reacted with N,N-dimethylacrylamide and fluoroalkanoyl peroxide to afford new fluorinated dendrimer-type block copolymers in good isolated yield. Similar reactions were also occurred by the use of 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane instead of TTRV-Si, and the corresponding fluorinated dendrimer-type block copolymer was obtained in good isolated yield. These fluorinated dendrimer-type block copolymers had an excellent solubility not only in water but also in traditional organic solvents including aliphatic fluorinated solvents. Interestingly, these fluorinated block copolymers were found to form the self-assembled dendrimer-type polymeric aggregates in aqueous solutions. More interestingly, these fluorinated block copolymers had an extremely higher dispersion ability of not only single-walled carbon nanotube and fullerenes but also magnetic nanoparticles into water, compared to that of the corresponding two fluoroalkyl end-capped oligomers. 相似文献
107.
Saitô H Kawase Y Kira A Yamamoto K Tanio M Yamaguchi S Tuzi S Naito A 《Photochemistry and photobiology》2007,83(2):253-262
The 3D structure of bacteriorhodopsin (bR) obtained by X-ray diffraction or cryo-electron microscope studies is not always sufficient for a picture at ambient temperature where dynamic behavior is exhibited. For this reason, a site-directed solid-state 13C NMR study of fully hydrated bR from purple membrane (PM), or a distorted or disrupted lattice, is very valuable in order to gain insight into the dynamic picture. This includes the surface structure, at the physiologically important ambient temperature. Almost all of the 13C NMR signals are available from [3-13C]Ala or [1-13C]Val-labeled bR from PM, although the 13C NMR signals from the surface areas, including loops and transmembrane alpha-helices near the surface (8.7 angstroms depth), are suppressed for preparations labeled with [1-13C]Gly, Ala, Leu, Phe, Tyr, etc. due to a failure of the attempted peak-narrowing by making use of the interfered frequency of the frequency of fluctuation motions with the frequency of magic angle spinning. In particular, the C-terminal residues, 226-235, are present as the C-terminal alpha-helix which is held together with the nearby loops to form a surface complex, although the remaining C-terminal residues undergo isotropic motion even in a 2D crystalline lattice (PM) under physiological conditions. Surprisingly, the 13C NMR signals could be further suppressed even from [3-13C]Ala- or [1-13C]Val-bR, due to the acquired fluctuation motions with correlation times in the order of 10(-4) to 10(-5) s, when the 2D lattice structure is instantaneously distorted or completely disrupted, either in photo-intermediate, removed retinal or when embedded in the lipid bilayers. 相似文献
108.
Kõta Yoshioka 《Communications in Mathematical Physics》1999,205(3):501-517
Recently, Minahan, Nemeschansky, Vafa and Warner computed partition functions for N = 4 topological Yang–Mills theory on rational
elliptic surfaces. In particular they computed generating functions of Euler characteristics of SU(2)-instanton moduli spaces. In mathematics, they are expected to coincide with those of Gieseker compactifications. In this
paper, we compute Euler characteristics of these spaces and show that our results coincide with theirs. We also check the
modular property of Z
SU
(2) and Z
SO
(3) conjectured by Vafa and Witten.
Received: 8 June 1998 / Accepted: 1 February 1999 相似文献
109.
Hideaki Oike Yuka Yoshioka Shinji Kobayashi Megumi Nakashima Yasuyuki Tezuka Eric J. Goethals 《Macromolecular rapid communications》2000,21(17):1185-1190
Mono‐, bis‐, and tris(trifluoromethanesulfonate ester)s ((triflate ester)s) were prepared by the reaction of benzyl alcohol ( 1 ), 1,4‐bis(hydroxymethyl)benzene ( 2 ) and 1,3,5‐tris(hydroxymethyl)benzene ( 3 ) with trifluoromethanesulfonic anhydride in the presence of 2,6‐di‐tert‐butylpyridine. These benzylic triflate esters were applied in‐situ for the living polymerization of tetrahydrofuran (THF). The subsequent end‐capping reaction with a suitable nucleophile proceeded quantitatively to produce mono, bi‐ and, in particular, novel trifunctional telechelic poly(THF)s, respectively. 相似文献
110.
We discuss the scenario with TeV-scale right-handed neutrinos, which are accessible at future colliders, while holding down tiny seesaw-induced masses and sizable couplings to the standard-model particles. The signal with tri-lepton final states and large missing transverse energy is appropriate for studying collider signatures of the scenario with extra spatial dimensions. We show that the LHC experiment generally has a potential to discover the signs of extra dimensions and the origin of small neutrino masses. 相似文献