Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 31

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Distance-selected topochemical dehydro-diels-alder reaction of 1,4-Diphenylbutadiyne toward crystalline graphitic nanoribbons

Zhang, P.*; Tang, X.*; Wang, Y.*; Wang, X.*; Gao, D.*; Li, Y.*; Zheng, H.*; Wang, Y.*; Wang, X.*; Fu, R.*; et al.

Journal of the American Chemical Society, 142(41), p.17662 - 17669, 2020/10

 Times Cited Count:6 Percentile:75.63(Chemistry, Multidisciplinary)

Solid-state topochemical polymerization (SSTP) is a promising method to construct functional crystalline polymeric materials, but in contrast to various reactions that happen in solution, only very limited types of SSTP reactions are reported. Diels-Alder (DA) and dehydro-DA (DDA) reactions are textbook reactions for preparing six-membered rings in solution but are scarcely seen in solid-state synthesis. Here, using multiple cutting-edge techniques, we demonstrate that the solid 1,4-diphenylbutadiyne (DPB) undergoes a DDA reaction under 10-20 GPa with the phenyl as the dienophile. The crystal structure at the critical pressure shows that this reaction is "distance-selected". The distance of 3.2${AA}$ between the phenyl and the phenylethynyl facilitates the DDA reaction, while the distances for other DDA and 1,4-addition reactions are too large to allow the bonding. The obtained products are crystalline armchair graphitic nanoribbons, and hence our studies open a new route to construct the crystalline carbon materials with atomic-scale control.

Journal Articles

First ionization potentials of Fm, Md, No, and Lr; Verification of filling-up of 5f electrons and confirmation of the actinide series

Sato, Tetsuya; Asai, Masato; Borschevsky, A.*; Beerwerth, R.*; Kaneya, Yusuke*; Makii, Hiroyuki; Mitsukai, Akina*; Nagame, Yuichiro; Osa, Akihiko; Toyoshima, Atsushi; et al.

Journal of the American Chemical Society, 140(44), p.14609 - 14613, 2018/11

 Times Cited Count:16 Percentile:70.21(Chemistry, Multidisciplinary)

The first ionization potential (IP$$_1$$) yields information on valence electronic structure of an atom. IP$$_1$$ values of heavy actinides beyond einsteinium (Es, Z = 99), however, have not been determined experimentally so far due to the difficulty in obtaining these elements on scales of more than one atom at a time. Recently, we successfully measured IP$$_1$$ of lawrencium (Lr, Z = 103) using a surface ionization method. The result suggests that Lr has a loosely-bound electron in the outermost orbital. In contrast to Lr, nobelium (No, Z = 102) is expected to have the highest IP$$_1$$ among the actinide elements owing to its full-filled 5f and the 7s orbitals. In the present study, we have successfully determined IP$$_1$$ values of No as well as fermium (Fm, Z = 100) and mendelevium (Md, Z = 101) using the surface ionization method. The obtained results indicate that the IP$$_1$$ value of heavy actinoids would increase monotonically with filling electrons up in the 5f orbital like heavy lanthanoids.

Journal Articles

Encapsulating mobile proton carriers into structural defects in coordination polymer crystals; High anhydrous proton conduction and fuel cell application

Inukai, Munehiro*; Horike, Satoshi*; Itakura, Tomoya*; Shinozaki, Ryota*; Ogiwara, Naoki*; Umeyama, Daiki*; Nagarker, S.*; Nishiyama, Yusuke*; Malon, M.*; Hayashi, Akari*; et al.

Journal of the American Chemical Society, 138(27), p.8505 - 8511, 2016/07

 Times Cited Count:97 Percentile:95.53(Chemistry, Multidisciplinary)

Journal Articles

Melting of Pb charge glass and simultaneous Pb-Cr charge transfer in PbCrO$$_{3}$$ as the origin of volume collapse

Yu, R.*; Hojo, Hajime*; Watanuki, Tetsu; Mizumaki, Masaichiro*; Mizokawa, Takashi*; Oka, Kengo*; Kim, H.*; Machida, Akihiko; Sakaki, Koji*; Nakamura, Yumiko*; et al.

Journal of the American Chemical Society, 137(39), p.12719 - 12728, 2015/10

 Times Cited Count:23 Percentile:65.97(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

Insights into the proton transfer mechanism of a bilin reductase PcyA following neutron crystallography

Unno, Masayoshi*; Ishikawa, Kumiko*; Kusaka, Katsuhiro*; Tamada, Taro; Hagiwara, Yoshinori*; Sugishima, Masakazu*; Wada, Kei*; Yamada, Taro*; Tomoyori, Katsuaki; Hosoya, Takaaki*; et al.

Journal of the American Chemical Society, 137(16), p.5452 - 5460, 2015/04

 Times Cited Count:23 Percentile:65.97(Chemistry, Multidisciplinary)

Phycocyanobilin, a light-harvesting and photoreceptor pigment in higher plants, algae, and cyanobacteria, is synthesized from biliverdin IX$$alpha$$ (BV) by phycocyanobilin:ferredoxin oxidoreductase (PcyA) via two steps of two-proton-coupled two-electron reduction. We determined the neutron structure of PcyA from cyanobacteria complexed with BV, revealing the exact location of the hydrogen atoms involved in catalysis. Notably, approximately half of the BV bound to PcyA was BVH$$^{+}$$, a state in which all four pyrrole nitrogen atoms were protonated. The protonation states of BV complemented the protonation of adjacent Asp105. The "axial "water molecule that interacts with the neutral pyrrole nitrogen of the A-ring was identified. His88 N$$delta$$ was protonated to form a hydrogen bond with the lactam O atom of the BV A-ring. His88 and His74 were linked by hydrogen bonds via H$$_{3}$$O$$^{+}$$. These results imply that Asp105, His88, and the axial water molecule contribute to proton transfer during PcyA catalysis.

Journal Articles

Active sites and mechanisms for oxygen reduction reaction on nitrogen-doped carbon alloy catalysts; Stone-Wales defect and curvature effect

Chai, G.-L.*; Hou, Z.*; Shu, D.-J.*; Ikeda, Takashi; Terakura, Kiyoyuki*

Journal of the American Chemical Society, 136(39), p.13629 - 13640, 2014/10

 Times Cited Count:198 Percentile:97.69(Chemistry, Multidisciplinary)

Carbon alloy catalysts (CACs) are promising catalysts for oxygen reduction reaction (ORR) to substitute Pt. However, despite extensive studies on CACs the reaction sites and mechanisms for ORR are still in controversy. Herein, we present rather general consideration on possible ORR mechanisms for various structures in nitrogen doped CACs based on the first principles calculations. Our study indicates that only a particular structure of a nitrogen pair doped Stone-Wales defect provides a good active site. The ORR activity of this structure can be tuned by the curvature around the active site, which makes its limiting potential approaching the maximum limiting potential (0.80 V) in the volcano plot for the ORR activity of CACs. The calculated results can be compared with the recent experimental ones of the half wave potential for CAC systems that range from 0.60 V to 0.80 V in the reversible-hydrogen-electrode scale.

Journal Articles

Synthesis, structural transformation, thermal stability, valence state, and magnetic and electronic properties of PbNiO$$_{3}$$ with perovskite- and LiNbO$$_{3}$$-type structures

Inaguma, Yoshiyuki*; Tanaka, Kie*; Tsuchiya, Takeshi*; Mori, Daisuke*; Katsumata, Tetsuhiro*; Oba, Tomonori*; Hiraki, Koichi*; Takahashi, Toshihiro*; Saito, Hiroyuki

Journal of the American Chemical Society, 133(42), p.16920 - 16929, 2011/09

 Times Cited Count:75 Percentile:86.04(Chemistry, Multidisciplinary)

Journal Articles

Dynamic structural changes at LiMn$$_{2}$$2O$$_{4}$$/electrolyte interface during lithium battery reaction

Hirayama, Masaaki*; Ido, Hidekazu*; Kim, K.-S.*; Cho, W.*; Tamura, Kazuhisa; Mizuki, Junichiro; Kanno, Ryoji*

Journal of the American Chemical Society, 132(43), p.15268 - 15276, 2010/11

 Times Cited Count:275 Percentile:97.95(Chemistry, Multidisciplinary)

Epitaxial LiMn$$_{2}$$O$$_{4}$$ thin films with restricted lattice planes (111) and (110) are grown on SrTiO$$_{3}$$ substrates by pulsed laser deposition. In situ SXRD studies have revealed dynamic structural changes that reduce the atomic symmetry at the electrode surface during the initial electrochemical reaction. The surface structural changes commence with the formation of an electric double layer, which is followed by surface reconstruction when a voltage is applied in the first charge process. Transmission electron microscopy images after 10 cycles confirm the formation of a solid electrolyte interface (SEI) layer on both the (111) and (110) surfaces and Mn dissolution from the (110) surface. The (111) surface is more stable than the (110) surface. The electrode stability of LiMn$$_{2}$$O$$_{4}$$ depends on the reaction rate of SEI formation and the stability of the reconstructed surface structure.

Journal Articles

Mechanochemical transduction of externally applied forces to mechanophores

Ribas-Arino, J.*; Shiga, Motoyuki; Marx, D.*

Journal of the American Chemical Society, 132(30), p.10609 - 10614, 2010/08

 Times Cited Count:77 Percentile:85.89(Chemistry, Multidisciplinary)

We present a theoretical study on the role played by aliphatic polymer chains in the transduction of external forces to mechanophores. Upon introducing a rigorous approach rooted in catastrophe theory we demonstrate that the rupture force of a cis 1,2 disubstituted benzocyclobutene features a remarkable dependence on the length of attached polymer chains. Not only do our findings highlight the necessity of taking into account the polymer chains explicitly when thinking about mechanochemical manipulation, but they also announce the possibility of tuning the properties of mechanoresponsive polymers by tailoring the force-transducing chain molecules.

Journal Articles

Anisotropic and inhomogeneous magnetic interactions observed in all-organic nitroxide radical liquid crystals

Uchida, Yoshiaki*; Suzuki, Katsuaki*; Tamura, Rui*; Ikuma, Naohiko*; Shimono, Satoshi*; Noda, Yohei; Yamauchi, Jun*

Journal of the American Chemical Society, 132(28), p.9746 - 9752, 2010/06

 Times Cited Count:47 Percentile:75.13(Chemistry, Multidisciplinary)

An anisotropic and inhomogeneous magnetic interaction (the average spin-spin interaction constant, $$bar{rm J}$$ $$>$$ 0) was observed in the various liquid crystalline (LC) phases of racemic and nonracemic all-organic radical LC compounds. We discussed how the LC superstructures induced the magnetic interaction to operate in the LC phases in terms of spin-spin dipole and exchange interactions by means of VT-EPR spectroscopy. The magnitude of the magnetic interaction depended on the type of LC phase, or the superstructure. Furthermore, these radical LC droplets floating on water were commonly attracted to a permanent magnet and moved freely under the influence of this magnet, whereas the crystallized particles of the same compounds never responded to the magnet. The response of the LC droplets to the magnet also varied depending on the type of LC phase, that is, the extent of the magnetic interaction.

Journal Articles

Crystal and magnetic structures and properties of BiMnO$$_{3+delta}$$

Belik, A. A.*; Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Kosuda, Kosuke*; Muromachi, Eiji*

Journal of the American Chemical Society, 132(23), p.8137 - 8144, 2010/05

 Times Cited Count:44 Percentile:74.1(Chemistry, Multidisciplinary)

Journal Articles

Various valence states of square-coordinated Mn in A-site-ordered perovskites

Long, Y.*; Saito, Takashi*; Mizumaki, Masaichiro*; Agui, Akane; Shimakawa, Yuichi*

Journal of the American Chemical Society, 131(44), p.16244 - 16247, 2009/10

 Times Cited Count:49 Percentile:77.95(Chemistry, Multidisciplinary)

A-site-ordered perovskites LaMn$$_{3}$$Cr$$_{4}$$O$$_{12}$$ and LaMn$$_{3}$$Ti$$_{4}$$O$$_{12}$$ were synthesized under high-pressure and high-temperature conditions. The charge formula of LaMn$$_{3}$$Cr$$_{4}$$O$$_{12}$$ was found to be LaMn$$_{3}$$Cr$$_{4}$$O$$_{12}$$ with Mn$$^{3+}$$ at the square-coordinated A site. The valence of the A-site Mn ions in LaMnTi$$_{4}$$O$$_{12}$$ appeared to be less than +2, and the charge combination in this compound seemed to be LaMnTi$$_{4}$$O$$_{12}$$. Although the square-coordinated A site in A-site-ordered perovskites has been widely known to be occupied by Jahn-Teller active Mn$$^{3+}$$, the present results show that the valence of Mn at the A site can vary from +3 to possible +1.67.

Journal Articles

Oxidation of element 102, nobelium, with flow electrolytic column chromatography on an atom-at-a-time scale

Toyoshima, Atsushi; Kasamatsu, Yoshitaka*; Tsukada, Kazuaki; Asai, Masato; Kitatsuji, Yoshihiro; Ishii, Yasuo; Tome, Hayato; Nishinaka, Ichiro; Haba, Hiromitsu*; Oe, Kazuhiro*; et al.

Journal of the American Chemical Society, 131(26), p.9180 - 9181, 2009/07

 Times Cited Count:13 Percentile:47.75(Chemistry, Multidisciplinary)

We report here on the successful oxidation of element 102, nobelium (No), on an atom-at-a-time scale in 0.1 M $$alpha$$-hydroxyisobutyric acid ($$alpha$$-HIB) solution using newly developed flow electrolytic column chromatography. It is found that the most stable No$$^{2+}$$ is oxidized to No$$^{3+}$$ within 3 min and that the oxidized No complex with $$alpha$$-HIB holds the trivalent state in the column above the applied potential of 1.0 V.

Journal Articles

Combined high-resolution neutron and X-ray analysis of inhibited elastase confirms the active-site oxyanion hole but rules against a low-barrier hydrogen bond

Tamada, Taro; Kinoshita, Takayoshi*; Kurihara, Kazuo; Adachi, Motoyasu; Ohara, Takashi; Imai, Keisuke*; Kuroki, Ryota; Tada, Toshiji*

Journal of the American Chemical Society, 131(31), p.11033 - 11040, 2009/07

 Times Cited Count:48 Percentile:77.51(Chemistry, Multidisciplinary)

To help resolve long-standing questions regarding the catalytic activity of the serine proteases the structure of porcine pancreatic elastase has been analyzed by high-resolution neutron and X-ray crystallography. In order to mimic the tetrahedral transition intermediate a peptidic inhibitor was used. A single large crystal was used to collect room-temperature neutron data to 1.65 ${AA}$ resolution and X-ray data to 1.20 ${AA}$ resolution. Another crystal provided a low-temperature X-ray data set to 0.94 ${AA}$ resolution. The neutron data are to higher resolution than previously reported for a serine protease and the X-ray data are comparable with other studies. The neutron and X-ray data show that the hydrogen bond between His57 and Asp102 (chymotrypsin numbering) is 2.60 ${AA}$ in length and that the hydrogen-bonding hydrogen is 0.80-0.96 ${AA}$ from the histidine nitrogen. This is not consistent with a low-barrier hydrogen which is predicted to have the hydrogen midway between the donor and acceptor atom. The observed interaction between His57 and Asp102 is essentially a short but conventional hydrogen bond, sometimes described as a short ionic hydrogen bond. The neutron analysis also shows that the oxygen of the oxopropyl group of the inhibitor is present as an oxygen anion rather than a hydroxyl group, supporting the role of the "oxyanion hole" in stabilizing the tetrahedral intermediate in catalysis.

Journal Articles

Synthesis, crystal structure, and magnetic properties of Bi$$_3$$Mn$$_4$$O$$_{12}$$(NO$$_3$$) oxynitrate comprising $$S$$=3/2 honeycomb lattice

Smirnova, O.*; Azuma, Masaki*; Kumada, Nobuhiro*; Kusano, Yoshihiro*; Matsuda, Masaaki; Shimakawa, Yuichi*; Takei, Takahiro*; Yonesaki, Yoshinori*; Kinomura, Nobukazu*

Journal of the American Chemical Society, 131(23), p.8313 - 8317, 2009/05

 Times Cited Count:109 Percentile:91.5(Chemistry, Multidisciplinary)

Neutron diffraction and FT-IR analysis revealed that the novel oxynitrate Bi$$_3$$Mn$$_4$$O$$_{12}$$ (NO$$_3$$) prepared by hydrothermal synthesis is of a new structural type including flat NO$$_3$$ layers alternating with blocks of two PbSb$$_2$$O$$_6$$-like layers. Mn$$^{4+}$$ ($$S$$=3/2) forms a regular honeycomb lattice, and magnetic susceptibility data indicated two-dimensional magnetism. Despite its Weiss constant of $$-$$257K, no long-range ordering was observed down to 0.4K because of the magnetic frustration due to the competition between the nearest and the next-nearest antiferromagnetic interactions.

Journal Articles

Does Gd@C$$_{82}$$ have an anomalous endohedral structure? Synthesis and single crystal X-ray structure of the carbene adduct

Akasaka, Takeshi*; Kono, Takayoshi*; Takematsu, Yuji*; Nikawa, Hidefumi*; Nakahodo, Tsukasa*; Wakahara, Takatsugu*; Ishitsuka, Midori*; Tsuchiya, Takahiro*; Maeda, Yutaka*; Liu, M. T. H.*; et al.

Journal of the American Chemical Society, 130(39), p.12840 - 12841, 2008/10

 Times Cited Count:70 Percentile:84.61(Chemistry, Multidisciplinary)

We report here the results on single crystal X-ray crystallographic analysis of the Gd@C$$_{82}$$ carbene adduct (Gd@C$$_{82}$$(ad), Ad=adamantylidene). The Gd atom in Gd@C$$_{82}$$(Ad) is located at an off-centered position near a hexagonal ring in the C2v-C$$_{82}$$ cage, as found for M@C$$_{82}$$ (M = Sc and La) and La@C$$_{82}$$(Ad). Theoretical calculation also confirms the position of the Gd atom in the X-ray crystal structure.

Journal Articles

Protonation states of buried histidine residues in human deoxyhemoglobin revealed by neutron crystallography

Chatake, Toshiyuki*; Shibayama, Naoya*; Park, S. Y.*; Kurihara, Kazuo; Tamada, Taro; Tanaka, Ichiro*; Niimura, Nobuo*; Kuroki, Ryota; Morimoto, Yukio*

Journal of the American Chemical Society, 129(48), p.14840 - 14841, 2007/12

 Times Cited Count:22 Percentile:59.17(Chemistry, Multidisciplinary)

Journal Articles

${it Ab initio}$ study of ultrafast photochemical reaction dynamics of phenol blue

Kobayashi, Takao*; Shiga, Motoyuki; Murakami, Akinori*; Nakamura, Shinichiro*

Journal of the American Chemical Society, 129(20), p.6405 - 6424, 2007/05

 Times Cited Count:7 Percentile:30.6(Chemistry, Multidisciplinary)

Phenol Blue (PB) is a primary skeletal structure part of indoaniline dyes. It has been recently observed by pump-probe transient absorption measurements that PB show ultrafast ground state recovery within a few hundred femtoseconds after photoexcitation. In this work, the ultrafast photochemical reaction mechanism of PB has been investigated using direct ${it ab initio}$ non-adiabatic molecular dynamics with the trajectory surface hopping method.

Journal Articles

Origin of the monoclinic-to-monoclinic phase transition and evidence for the centrosymmetric crystal structure of BiMnO$$_3$$

Belik, A. A.*; Iikubo, Satoshi; Yokosawa, Tadahiro*; Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Azuma, Masaki*; Takano, Mikio*; Kimoto, Koji*; Matsui, Yoshio*; et al.

Journal of the American Chemical Society, 129(4), p.971 - 977, 2007/01

 Times Cited Count:167 Percentile:95.31(Chemistry, Multidisciplinary)

Structural properties of polycrystalline single-phased BiMnO$$_3$$ samples prepared at 6 GPa and 1383 K have been studied by selected area electron diffraction (SAED), convergent beam electron diffraction (CBED), and the Rietveld method using neutron diffraction data measured at 300 and 550 K. The SAED and CBED data showed that BiMnO$$_3$$ crystallizes in the centrosymmetric space group C2/c at 300 K. The analysis of Mn-O bond lengths suggested that the orbital order present in BiMnO$$_3$$ at 300 K melts above T= 474 K. The phase transition at 474 K is of the first order and accompanied by a jump of magnetization and small changes of the effective magnetic moment and Weiss temperature.

Journal Articles

Hsc70 ATPase; An Insight into water dissociation and joint catalytic role of K$$^{+}$$ and Mg$$^{2+}$$ metal cations in the hydrolysis reaction

Boero, M.*; Ikeda, Takashi; Ito, Etsuro*; Terakura, Kiyoyuki*

Journal of the American Chemical Society, 128(51), p.16798 - 16807, 2006/12

 Times Cited Count:55 Percentile:78.71(Chemistry, Multidisciplinary)

Hybrid quantum-mechanics/molecular mechanics simulations, coupled to the recently introduced metadynamics method, performed on the adenosine triphosphate (ATP) of the bovine Hsc70 ATPase protein, show which specific water molecule of the solvation shell of the Mg$$^{2+}$$ metal cation acts as a trigger in the initial phase of the ATP hydrolysis reaction in ATP synthase. Furthermore, we provide a detailed picture of the reaction mechanism, not accessible to experimental probes.

31 (Records 1-20 displayed on this page)