Royal Society of Chemistry
Acta Medica Okayama
1359-7345
46
48
2010
Electrochemical generation of silver acetylides from terminal alkynes with a Ag anode and integration into sequential Pd-catalysed coupling with arylboronic acids
9256
9258
EN
Koichi
Mitsudo
Takuya
Shiraga
Jun-ichi
Mizukawa
Seiji
Suga
Hideo
Tanaka
An electro-oxidative method for generating silver acetylides from acetylenes with a Ag anode was developed. The reaction could be integrated into a Pd-catalysed electrochemical Sonogashira-type reaction. In the presence of the catalytic amount of Pd(OAc)(2) and 4-BzO-TEMPO, electro-generated silver acetylides reacted immediately with arylboronic acids to afford the corresponding coupling adducts in high yields.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
1359-7345
46
5
2010
A novel method for screening peptides that bind to proteins by using multiple fluorescent amino acids as fluorescent tags
761
763
EN
Mizuki
Kitamatsu
Midori
Futami
Masahiko
Sisido
We describe a new screening method for simultaneously detecting peptides that bind to a target protein by fluorescence obtained from fluorescent amino acid-modified peptides.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
1744-683X
7
21
2011
Continuous fabrication of monodisperse polylactide microspheres by droplet-to-particle technology using microfluidic emulsification and emulsion–solvent diffusion
9894
9897
EN
Takaichi
Watanabe
Department of Material and Energy Science, Graduate School of Environmental Science, Okayama University
Tsutomu
Ono
Department of Material and Energy Science, Graduate School of Environmental Science, Okayama University
Yukitaka
Kimura
Department of Material and Energy Science, Graduate School of Environmental Science, Okayama University
Monodisperse polylactide (PLA) microspheres were continuously fabricated by microfluidic emulsification and subsequent dilution in water. The diameter was precisely tuned from 6 to 50 ƒÊm by changing the flow rate of the fluids in microfluidics or the PLA concentration in the dispersed phase. The use of amphiphilic oil-soluble poly(ethylene glycol)-b-polylactide (o-PEG–PLA) as a matrix resulted in a highly porous microsphere morphology, and the porosity was controlled by blending PLA. Therefore, monodisperse PLA microspheres with the predetermined surface porosity were continuously produced by just enough reagents and energy.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
20462069
3
31
2013
Effects of hydrophobic hydration on polymer chains immersed in supercooled water
12743
12750
EN
Tomonari
Sumi
Department of Chemistry, Okayama University
Hideo
Sekino
Department of Computer Science and Engineering, Toyohashi University of Technology
A multiscale simulation of a hydrophobic polymer chain immersed in water including the supercooled region is presented. Solvent effects on the polymer conformation were taken into account via liquid–state density functional theory in which a free-energy functional model was constructed using a density response function of bulk water, determined from a molecular dynamics (MD) simulation. This approach overcomes sampling problems in simulations of high-viscosity polymer solutions in the deeply supercooled region. Isobars determined from the MD simulations of 4000 water molecules suggest a liquid–liquid transition in the deeply supercooled region. The multiscale simulation reveals that a hydrophobic polymer chain exhibits swelling upon cooling along isobars below a hypothesized second critical pressure; no remarkable swelling is observed at higher pressures. These observations agree with the behavior of a polymer chain in a Jagla solvent model that qualitatively reproduces the thermodynamics and dynamics of liquid water. A theoretical analysis of the results obtained from the multiscale simulation show that a decrease in entropy due to the swelling arises from the formation of a tetrahedral hydrogen bond network in the hydration shell.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2046-2069
4
10
2013
Monodisperse polylactide microcapsules with a single aqueous core prepared via spontaneous emulsification and solvent diffusion
4872
4877
EN
Takaichi
Watanabe
Department of Applied Chemistry and Biotechnology, Graduate School of Natural Science and Technology, Okayama University
Yukitaka
Kimura
Department of Material and Energy Science, Graduate School of Environmental and Life Science, Okayama University
Tsutomu
Ono
Department of Applied Chemistry and Biotechnology, Graduate School of Natural Science and Technology, Okayama University
A simple approach to preparing monodisperse poly(D,L-lactide) (PDLLA) microcapsules with a single aqueous core is developed. The method is based on automatic water-in-oil-in-water double emulsion formation from oil-in-water single emulsion via spontaneous emulsification which voluntarily disperses part of continuous aqueous phase into the dispersed oil phase dissolving oil-soluble amphiphilic diblock copolymer, poly(D,L-lactide)-b-poly(2-dimethylaminoethyl methacylate)(PDLLA-b-PDMAEMA), followed by coalescence of tiny water droplets within the polymer droplets, coupled with quick precipitation of polymers by diluting the emulsion with water. In this study, we have investigated the effect of PDLLA to PDLLA-b-PDMAEMA ratios and flow rates of each solution during preparing the emulsion on the final morphology and the size of the microcapsules. It was found that the polymer blend ratio played a crucial role in determining internal structure of the microcapsules. The microcapsules size decreased with the increment of the flow rate ratios of the continuous phase to the dispersed phase and eventually reached 10 ƒÊm, while maintaining narrow size distribution. In addition, we have demonstrated that the microcapsules can encapsulate both hydrophilic and hydrophobic compounds during the formation.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
14639076
16
46
2014
Model-potential-free analysis of small angle scattering of proteins in solution: insights into solvent effects on protein-protein interaction
25492
25497
EN
Tomonari
Sumi
Department of Chemistry, Faculty of Science, Okayama University
Hiroshi
Imamura
Graduate School of Advanced Integration Science, Chiba University
Takeshi
Morita
Graduate School of Advanced Integration Science, Chiba University
Yasuhiro
Isogai
Department of Biotechnology, Toyama Prefectural University
Keiko
Nishikawa
Graduate School of Advanced Integration Science, Chiba University
To extract protein-protein interaction from experimental small-angle scattering of proteins in solutions using liquid state theory, a model potential consisting of a hard-sphere repulsive potential and the excess interaction potential has been introduced. In the present study, we propose a model-potential-free integral equation method that extracts the excess interaction potential by using the experimental small-angle scattering data without specific model potential such as the Derjaguin-Landau-Verwey-Overbeek (DLVO)-type model. Our analysis of experimental small-angle X-ray scattering data for lysozyme solution shows both the stabilization of contact configurations of protein molecules and a large activation barrier against the formation of the contact configurations in addition to the screened Coulomb repulsion. These characteristic features, which are not well-described by the DLVO-type model, are interpreted as solvent effects.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
14770520
15
26
2017
Late-stage divergent synthesis and antifouling activity of geraniol-butenolide hybrid molecules
5549
5555
EN
Hiroyoshi
Takamura
Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University
Takumi
Ohashi
Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University
Takahiro
Kikuchi
Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University
Noriyuki
Endo
Himeji EcoTech Co., Ltd.
Yuji
Fukuda
Himeji EcoTech Co., Ltd.
Isao
Kadota
Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University
Hybrid molecules consisting of geraniol and butenolide were designed and synthesized by the late-stage divergent strategy. In the synthetic route, ring-closing metathesis was utilized for the construction of a butenolide moiety. A biological evaluation of the eight synthetic hybrid compounds revealed that these molecules exhibit antifouling activity against the cypris larvae of the barnacle Balanus (Amphibalanus) amphitrite with EC50 values of 0.30-1.31 ƒÊg mL-1. These results show that hybridization of the geraniol and butenolide structural motifs resulted in the enhancement of the antifouling activity.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
17599660
11
2018
Chromatographic paper-based analytical devices using an oxidized paper substrate
179
184
EN
Yuki
Hashimoto
Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University
Takashi
Kaneta
Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University
A novel detection scheme using chromatographic retention was proposed for paper-based analytical devices (PADs). Using a wax printer and an ink-jet printer, the PADs consisted of a straight-flow channel, a circular sample zone, and a band of brilliant green (BG) printed at the connection between the sample zone and the flow channel. When a constant volume of a sample solution was applied to the sample zone, the BG band formed a colored bar along the flow channel that marked the adsorption and desorption of the paper substrate according to the principles of chromatography. If the sample solution contained an anionic complex of boric acid with chromotropic acid, the anionic complex enhanced desorption of the BG from the paper substrate via the formation of an ion-pair with the BG, which resulted in an elongated colored bar. Fundamental equations for the retention behavior of the BG on the PADs were derived using a model based on chromatographic principles and ion-pairing formation. A retardation factor, Rf, was correlated with the concentration of boric acid contained in the sample solutions. To enhance the adsorption of the BG, 2,2,6,6-tetramethylpiperidine 1-oxyl was used to oxidize the paper substrate. The oxidized paper substrate shortened the colored bar of a blank solution and formed a clear boundary for the color. When the analytical conditions were optimized for pH and the concentration of chromotropic acid, the PAD permitted the measurement of boric acid for a concentration ranging from 0.3 to 3 mM. The proposed model was validated when the fitting curve was calculated using the derived equations, which resulted in good agreement with the experimental data.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
1359-7345
55
27
2019
Catalytic enantioselective Hosomi-Sakurai reaction of ƒ¿-ketoesters promoted by chiral copper(ii) complexes
3923
3926
EN
Yutaro
Niwa
Graduate School of Natural Science and Technology, Okayama University
Mayu
Miyake
Graduate School of Natural Science and Technology, Okayama University
Ichiro
Hayakawa
Graduate School of Natural Science and Technology, Okayama University
Akira
Sakakura
Graduate School of Natural Science and Technology, Okayama University
A catalytic enantioselective Hosomi–Sakurai reaction of ƒ¿-ketoesters has been developed. A copper(II) complex with a chiral bis(oxazoline) ligand bearing methanesulfonamide groups shows excellent catalytic activity to give ƒ¿,ƒ¿-disubstituted ƒ¿-hydroxyesters in high yields with high enantioselectivities. This is the first successful method for the catalytic enantioselective 1,2-addition of ƒ¿-ketoesters with allylic silanes.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
14668033
22
3
2019
Transition-metal(ii) complexes with a tripodal hexadentate ligand, 1,1,1-tris[2-aza-3-(imidazol-4-yl)prop-2-enyl]ethane, exhibiting incomplete total or absolute spontaneous resolution
458
466
EN
Misaki
Matsushima
Graduate School of Natural Science and Technology, Okayama University
Koki
Wada
Graduate School of Natural Science and Technology, Okayama University
Kazuma
Takahara
Graduate School of Natural Science and Technology, Okayama University
Yukinari
Sunatsuki
Graduate School of Natural Science and Technology, Okayama University
Takayoshi
Suzuki
Graduate School of Natural Science and Technology, Okayama University
Crystal structures and crystallisation behaviours of a series of first-row transition-metal(II) complexes bearing 1,1,1-tris[2-aza-3-(imidazol-4-yl)prop-2-enyl]ethane (H3L), [MII(H3L)]Cl(ClO4) (M = Mn, Fe, Co, Ni and Zn) were examined. These compounds crystallise in an orthorhombic crystal system with a non-enantiogenic (Sohncke) space group P212121, resulting in spontaneous resolution of the chiral complex cations. Hydrogen bonds between the imidazole N–H atoms in the tripodal ligand and chloride anions give enantiomorphic crystals with a homochiral three-dimensional network structure. In order to verify the spontaneous resolution of these compounds, solid-state circular dichroism spectra of the resulting single crystals were measured (KBr disk method). Unexpectedly, the observed spectra indicated that imbalanced formation of the enantiomorphic crystals (i.e., left-handed ƒ©-form vs. right-handed ƒ¢-form complex cations) in all cases. Moreover, in the cases of NiII and ZnII compounds, predominant enantiomorphic crystals formed by spontaneous resolution were always the same (in at least ten of our recrystallisation experiments). These observations suggest that there is a certain (but as yet unknown) factor that affects the predominant deposition of either enantiomorphic crystal when spontaneous resolution takes place from a solution of a racemic mixture in which rapid racemisation occurs.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
1744-683X
16
6
2019
Preparation of tough, thermally stable, and water-resistant double-network ion gels consisting of silica nanoparticles/poly(ionic liquid)s through photopolymerisation of an ionic monomer and subsequent solvent removal
1572
1581
EN
Takaichi
Watanabe
Department of Applied Chemistry, Graduate School of Natural Science, Okayama University
Ruri
Takahashi
Department of Applied Chemistry, Graduate School of Natural Science, Okayama University
Tsutomu
Ono
Department of Applied Chemistry, Graduate School of Natural Science, Okayama University
We report the preparation of tough, thermally stable, and water-resistant double-network (DN) ion gels, which consist of a partially-clustered silica nanoparticle network and poly(ionic liquid) (PIL) network holding an ionic liquid. Silica nanoparticles/poly([Evim][Tf2N]) DN ion gels are prepared by photo-induced radical polymerisation of [Evim][Tf2N] in a mixture containing silica nanoparticles, [Bmim][Tf2N], ionic liquid based cross-linker [(VIM)2C4][Tf2N]2, and ethyl acetate, followed by subsequent solvent evaporation. Tensile strength measurements show that the mechanical properties of the PIL DN ion gels were higher than those of the PIL single-network (SN) ion gel. A rheological study indicates that an enhancement in mechanical strength of the PIL DN ion gels can be achieved when silica nanoparticles form partial clusters in [Bmim][Tf2N]. The cyclic stress–strain measurement of the PIL DN ion gels shows hysteresis loops, suggesting that the silica nanoparticle clusters rupture and dissipate the loading energy when the PIL DN ion gels undergo a large deformation. The fracture strength and Young's modulus of the PIL DN ion gels increase as the diameter of the silica nanoparticles is decreased. Thermogravimetric analysis measurement shows that the PIL DN ion gel has a high decomposition temperature of approximately 400 ‹C. Moreover, the swelling test shows that the PIL DN ion gel possesses an excellent water-resistant property because of the hydrophobic nature of the PIL backbone. We believe that such tough, thermally stable, and water-resistant PIL DN ion gels can be used as carbon dioxide separation membranes, sensors, and actuators for soft robotics.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2050-7526
8
22
2020
Synthesis of [7]phenacene incorporating tetradecyl chains in the axis positions and its application in field-effect transistors
7422
7435
EN
Hideki
Okamoto
Graduate School of Natural Science and Technology, Okayama University
Shino
Hamao
Research Institute for Interdisciplinary Science, Okayama University
Keiko
Kozasa
Graduate School of Natural Science and Technology, Okayama University
Yanan
Wang
Research Institute for Interdisciplinary Science, Okayama University
Yoshihiro
Kubozono
Research Institute for Interdisciplinary Science, Okayama University
Yong-He
Pan
Department of Physics & Center for Quantum Technology, National Tsing Hua University
Yu-Hsiang
Yen
Department of Physics & Center for Quantum Technology, National Tsing Hua University
Germar
Hoffmann
Department of Physics & Center for Quantum Technology, National Tsing Hua University
Fumito
Tani
Institute for Materials Chemistry and Engineering, Kyushu University
Kenta
Goto
Institute for Materials Chemistry and Engineering, Kyushu University
Field-effect transistors (FETs) were fabricated using a new type of phenacene molecule, 3,12-ditetradecyl[7]phenacene ((C14H29)2-[7]phenacene), and solid gate dielectrics or an electric double layer (EDL) capacitor with an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate (bmim[PF6])). The new molecule, (C14H29)2-[7]phenacene, was efficiently synthesized via the Mallory photoreaction. Its crystal structure and electronic properties were determined, using X-ray diffraction, scanning tunneling microscopy/spectroscopy (STM and STS), absorption spectroscopy, and photoelectron yield spectroscopy, which showed a monoclinic crystal lattice (space group P21 (no. 4)) and an energy gap of ∼3.0 eV. The STM image clearly showed the molecular structure of (C14H29)2-[7]phenacene, as well as the closed molecular stacking, indicative of a strong fastener effect between alkyl chains. The X-ray diffraction pattern of thin films of (C14H29)2-[7]phenacene formed on a SiO2/Si substrate suggested that the molecule stood on the surface with an inclined angle of 30‹ with respect to the normal axis of the surface. The FET properties were recorded in two-terminal measurement mode, showing p-channel normally-off characteristics. The averaged values of field-effect mobility, ƒÊ, were 1.6(3) cm2 V|1 s|1 for a (C14H29)2-[7]phenacene thin-film FET with a SiO2 gate dielectric and 6(4) ~ 10|1 cm2 V|1 s|1 for a (C14H29)2-[7]phenacene thin-film EDL FET with bmim[PF6]. Thus, higher FET performance was obtained with an FET using a thin film of (C14H29)2-[7]phenacene compared to parent [7]phenacene. This study could pioneer an avenue for the realization of high-performance FETs through the addition of alkyl chains to phenacene molecules.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2041-6520
11
22
2020
Aluminum porphyrins with quaternary ammonium halides as catalysts for copolymerization of cyclohexene oxide and CO2: metal–ligand cooperative catalysis
5669
5675
EN
Jingyuan
Deng
Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo
Manussada
Ratanasak
Institute for Catalysis, Hokkaido University
Yuma
Sako
Graduate School of Natural Science and Technology, Okayama University
Hideki
Tokuda
Graduate School of Natural Science and Technology, Okayama University
Chihiro
Maeda
Graduate School of Natural Science and Technology, Okayama University
Jun-ya
Hasegawa
Institute for Catalysis, Hokkaido University
Kyoko
Nozaki
Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo
Tadashi
Ema
Graduate School of Natural Science and Technology, Okayama University
Bifunctional AlIII porphyrins with quaternary ammonium halides, 2-Cl and 2-Br, worked as excellent catalysts for the copolymerization of cyclohexene oxide (CHO) and CO2 at 120 ‹C. Turnover frequency (TOF) and turnover number (TON) reached 10 000 h|1 and 55 000, respectively, and poly(cyclohexene carbonate) (PCHC) with molecular weight of up to 281 000 was obtained with a catalyst loading of 0.001 mol%. In contrast, bifunctional MgII and ZnII counterparts, 3-Cl and 4-Cl, as well as a binary catalyst system, 1-Cl with bis(triphenylphosphine)iminium chloride (PPNCl), showed poor catalytic performances. Kinetic studies revealed that the reaction rate was first-order in [CHO] and [2-Br] and zero-order in [CO2], and the activation parameters were determined: ƒ¢Hö = 12.4 kcal mol|1, ƒ¢Sö = |26.1 cal mol|1 K|1, and ƒ¢Gö = 21.6 kcal mol|1 at 80 ‹C. Comparative DFT calculations on two model catalysts, AlIII complex 2Œ and MgII complex 3Œ, allowed us to extract key factors in the catalytic behavior of the bifunctional AlIII catalyst. The high polymerization activity and carbonate-linkage selectivity originate from the cooperative actions of the metal center and the quaternary ammonium cation, both of which facilitate the epoxide-ring opening by the carbonate anion to form the carbonate linkage in the key transition state such as TS3b (ƒ¢Hö = 13.3 kcal mol|1, ƒ¢Sö = |3.1 cal mol|1 K|1, and ƒ¢Gö = 14.4 kcal mol|1 at 80 ‹C).
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2050-7488
8
29
2020
Mechanisms for overcharging of carbon electrodes in lithium-ion/sodium-ion batteries analysed by operando solid-state NMR
14472
14481
EN
Kazuma
Gotoh
Graduate School of Natural Science & Technology, Okayama University
Tomu
Yamakami
Graduate School of Natural Science & Technology, Okayama University
Ishin
Nishimura
Graduate School of Natural Science & Technology, Okayama University
Hina
Kometani
Graduate School of Natural Science & Technology, Okayama University
Hideka
Ando
Graduate School of Natural Science & Technology, Okayama University
Kenjiro
Hashi
National Institute for Materials Science
Tadashi
Shimizu
National Institute for Materials Science
Hiroyuki
Ishida
Graduate School of Natural Science & Technology, Okayama University
A precise understanding of the mechanism for metal (Li and Na) plating on negative electrodes that occurs with overcharging is critical to managing the safety of lithium- and sodium-ion batteries. In this work, an in-depth investigation of the overlithiation/oversodiation and subsequent delithiation/desodiation of graphite and hard carbon electrodes in the first cycle was conducted using operando7Li/23Na solid-state NMR. In the 7Li NMR spectra of half cells of carbon electrodes and metal counter electrodes, three types of signals corresponding to Li dendrites that formed on the surface of graphite, hard carbon, and the counter electrode were distinguished from the signal of Li metal foil of the counter electrode by applying an appropriate orientation of the testing cell. For graphite overlithiation, the deposition of Li dendrites started immediately or soon after the minimum electric potential in the lithiation curve. In contrast, the deposition of Li dendrites in hard carbon started after the end of quasimetallic lithium formation for overlithiation at rates below 3.0C. Similar behaviour was also observed for the oversodiation of hard carbon. The formation of quasimetallic Li or Na in the pores of hard carbon serves as a buffer for the metal plating that occurs with overcharging of the batteries. Furthermore, some of the deposited Li/Na dendrites contribute to reversible capacities. A mechanism for the inhomogeneous disappearance of quasimetallic Li during delithiation of hard carbon is also proposed.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2041-6539
11
23
2020
Carbon-rich materials with three-dimensional ordering at the angstrom level
5866
5873
EN
Shixin
Fa
Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University
Masanori
Yamamoto
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
Hirotomo
Nishihara
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
Ryota
Sakamoto
Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University
Kazuhide
Kamiya
Graduate School of Engineering Science, Osaka University
Yuta
Nishina
Research Core for Interdisciplinary Sciences, Okayama University
Tomoki
Ogoshi
Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University
Carbon-rich materials, which contain over 90% carbon, have been mainly synthesized by the carbonization of organic compounds. However, in many cases, their original molecular and ordered structures are decomposed by the carbonization process, which results in a failure to retain their original three-dimensional (3D) ordering at the angstrom level. Recently, we successfully produced carbon-rich materials that are able to retain their 3D ordering at the angstrom level even after the calcination of organic porous pillar[6]arene supramolecular assemblies and cyclic porphyrin dimer assemblies. Other new pathways to prepare carbon-rich materials with 3D ordering at the angstrom level are the controlled polymerization of designed monomers and redox reaction of graph. Electrocatalytic application using these materials is described.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2046-2069
10
45
2020
A new protocol for the preparation of superconducting KBi2
26686
26692
EN
Huan
Li
Research Institute for Interdisciplinary Science, Okayama University
Yanan
Wang
Research Institute for Interdisciplinary Science, Okayama University
Saki
Nishiyama
Research Institute for Interdisciplinary Science, Okayama University
Xiaofan
Yang
Research Institute for Interdisciplinary Science, Okayama University
Tomoya
Taguchi
Research Institute for Interdisciplinary Science, Okayama University
Akari
Miura
Research Institute for Interdisciplinary Science, Okayama University
Ai
Suzuki
Research Institute for Interdisciplinary Science, Okayama University
Lei
Zhi
Research Institute for Interdisciplinary Science, Okayama University
Hidenori
Goto
Research Institute for Interdisciplinary Science, Okayama University
Ritsuko
Eguchi
Research Institute for Interdisciplinary Science, Okayama University
Takashi
Kambe
Department of Physics, Okayama University
Yen-Fa
Liao
National Synchrotron Radiation Research Center
Hirofumi
Ishii
National Synchrotron Radiation Research Center
Yoshihiro
Kubozono
Research Institute for Interdisciplinary Science, Okayama University
A superconducting KBi2 sample was successfully prepared using a liquid ammonia (NH3) technique. The temperature dependence of the magnetic susceptibility (M/H) showed a superconducting transition temperature (Tc) as high as 3.6 K. In addition, the shielding fraction at 2.0 K was evaluated to be 87%, i.e., a bulk superconductor was realized using the above method. The Tc value was the same as that reported for the KBi2 sample prepared using a high-temperature annealing method. An X-ray diffraction pattern measured based on the synchrotron X-ray radiation was analyzed using the Rietveld method, with a lattice constant, a, of 9.5010(1) Å under the space group of Fd[3 with combining macron]m (face-centered cubic, no. 227). The lattice constant and space group found for the KBi2 sample using a liquid NH3 technique were the same as those reported for KBi2 through a high-temperature annealing method. Thus, the superconducting behavior and crystal structure of the KBi2 sample obtained in this study are almost the same as those for the KBi2 sample reported previously. Strictly speaking, the magnetic behavior of the superconductivity was different from that of a KBi2 sample reported previously, i.e., the KBi2 sample prepared using a liquid NH3 technique was a type-II like superconductor, contrary to that prepared using a high-temperature annealing method, the reason for which is fully discussed. These results indicate that the liquid NH3 technique is effective and simple for the preparation of a superconducting KBi2. In addition, the topological nature of the superconductivity for KBi2 was not confirmed.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2516-0230
2
10
2020
Bottom-up synthesis of nitrogen-doped nanocarbons by a combination of metal catalysis and a solution plasma process
4417
4420
EN
Yang
Zhou
Graduate School of Natural Science and Technology, Okayama University
Yuta
Nishina
Research Core for Interdisciplinary Sciences, Okayama University
We aimed to develop the bottom-up synthesis of nanocarbons with specific functions from molecules without any leaving group, halogen atom and boronic acid, by employing a metal catalyst under solution plasma irradiation. Pyridine was used as a source of carbon. In the presence of a Pd catalyst, the plasma treatment enabled the synthesis of N-doped carbons with a pyridinic configuration, which worked as an active catalytic site for the oxygen reduction reaction.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2046-2069
10
52
2020
Facile synthesis of picenes incorporating imide moieties at both edges of the molecule and their application to n-channel field-effect transistors
31547
31552
EN
Yuxin
Guo
Division of Earth, Life, and Molecular Sciences, Graduate School of Natural Science and Technology, Okayama University
Kaito
Yoshioka
Division of Earth, Life, and Molecular Sciences, Graduate School of Natural Science and Technology, Okayama University
Shino
Hamao
Research Institute for Interdisciplinary Science, Okayama University
Yoshihiro
Kubozono
Research Institute for Interdisciplinary Science, Okayama University
Fumito
Tani
Institute for Materials Chemistry and Engineering, Kyushu University
Kenta
Goto
Institute for Materials Chemistry and Engineering, Kyushu University
Hideki
Okamoto
Division of Earth, Life, and Molecular Sciences, Graduate School of Natural Science and Technology, Okayama University
Picene derivatives incorporating imide moieties along the long-axis direction of the picene core (Cn-PicDIs) were conveniently synthesized through a four-step synthesis. Photochemical cyclization of dinaphthylethenes was used as the key step for constructing the picene skeleton. Field-effect transistor (FET) devices of Cn-PicDIs were fabricated by using ZrO2 as a gate substrate and their FET characteristics were investigated. The FET devices showed normally-off n-channel operation; the averaged electron mobility (ƒÊ) was evaluated to be 2(1) ~ 10|4, 1.0(6) ~ 10|1 and 1.4(3) ~ 10|2 cm2 V|1 s|1 for C4-PicDI, C8-PicDI and C12-PicDI, respectively. The maximum ƒÊ value as high as 2.0 ~ 10|1 cm2 V|1 s|1 was observed for C8-PicDI. The electronic spectra of Cn-PicDIs in solution showed the same profiles irrespective of the alkyl chain lengths. In contrast, in thin films, the UV absorption and photoelectron yield spectroscopy (PYS) indicated that the lowest unoccupied molecular orbital (LUMO) level of Cn-PicDIs gradually lowered upon the elongation of the alkyl chains, suggesting that the alkyl chains modify intermolecular interactions between the Cn-PicDI molecules in thin films. The present results provide a new strategy for constructing a high performance n-channel organic semiconductor material by utilizing the electronic features of phenacenes.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2040-3364
12
42
2020
Iron nanoparticle templates for constructing 3D graphene framework with enhanced performance in sodium-ion batteries
21780
21787
EN
Benoît D. L.
Campéon
Graduate School of Natural Science and Technology, Okayama University
Chen
Wang
Research Core for Interdisciplinary Sciences, Okayama University
Yuta
Nishina
Graduate School of Natural Science and Technology, Okayama University
This study examines the synthesis and electrochemical performance of three-dimensional graphene for Li-ion batteries and Na-ion batteries. The in situ formation of iron hydroxide nanoparticles (Fe(OH)x NPs) of various weights on the surface of graphene oxide, followed by thermal treatment at elevated temperature and washing using hydrochloric acid, furnished 3D graphene. The characterization studies confirmed the prevention of graphene layer stacking by over 90% compared with thermal treatment without Fe(OH)x. The electrochemical performance of the 3D graphene was evaluated as a counter electrode for lithium metal and sodium metal in a half-cell configuration. This material showed good performances with a charging capacity of 507 mA h g|1 at 372 mA g|1 in Li-ion batteries and 252 mA h g|1 at 100 mA g|1 in Na-ion batteries, which is 1.4 and 1.9 times higher, respectively, than the graphene prepared without Fe(OH)x templates.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2046-2069
10
62
2020
One-pot synthesis of poly(ionic liquid)s with 1,2,3-triazolium-based backbones via clickable ionic liquid monomers
37743
37748
EN
Ruka
Hirai
Department of Applied Chemistry, Graduate School of Natural Science, Okayama University
Tatsuki
Hibino
Department of Applied Chemistry, Graduate School of Natural Science, Okayama University
Takaichi
Watanabe
Department of Applied Chemistry, Graduate School of Natural Science, Okayama University
Tsutomu
Ono
Department of Applied Chemistry, Graduate School of Natural Science, Okayama University
Clickable ƒ¿-azide-ƒÖ-alkyne ionic liquid monomers were developed and subsequently applied to the one-pot synthesis of ionically conducting poly(ionic liquid)s with 1,2,3-triazolium-based backbones through a click chemistry strategy. This approach does not require the use of solvents, polymerisation mediators, or catalysts. The obtained poly(ionic liquid)s were characterized by NMR, differential scanning calorimetry, thermogravimetric analysis, and impedance spectroscopy analysis. Moreover, these poly(ionic liquid)s were cross-linked via N-alkylation with a dianion quarternizing agent to achieve enhanced ionic conductivity and mechanical strength. The resulting free-standing films showed a Young's modulus up to 4.8 MPa and ionic conductivities up to 4.60 ~ 10|8 S cm|1 at 30 ‹C. This facile synthetic strategy has the potential to expand the availability of poly(ionic liquid)s and promote the development of functional materials.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2041-6520
2021
Chromium carbides and cyclopropenylidenes
1
EN
Takashi
Kurogi
Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
Keiichi
Irifune
Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
Kazuhiko
Takai
Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
Carbon tetrabromide can be reduced with CrBr2 in THF to form a dinuclear carbido complex, [CrBr2(thf)(2))][CrBr2(thf)(3)](mu-C), along with formation of [CrBr3(thf)(3)]. An X-ray diffraction (XRD) study of the pyridine adduct displayed a dinuclear structure bridged by a carbido ligand between 5- and 6-coordinate chromium centers. The carbido complex reacted with two equivalents of aldehydes to form alpha,beta-unsaturated ketones. Treatment of the carbido complex with alkenes resulted in a formal double-cyclopropanation of alkenes by the carbido moiety to afford spiropentanes. Isotope labeling studies using a C-13-enriched carbido complex, [CrBr2(thf)(2))][CrBr2(thf)(3)](mu-C-13), identified that the quaternary carbon in the spiropentane framework was delivered by carbide transfer from the carbido complex. Terminal and internal alkynes also reacted with the carbido complex to form cyclopropenylidene complexes. A solid-state structure of the diethylcyclopropenylidene complex, prepared from 3-hexyne, showed a mononuclear cyclopropenylidene chromium(iii) structure.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2046-2069
11
2
2021
Adsorption enhancement of nitrogen gas by atomically heterogeneous nanospace of boron nitride
838
846
EN
Jun
Kimura
Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University
Takahiro
Ohkubo
Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University
Yuta
Nishina
Research Core for Interdisciplinary Sciences, Okayama University
Koki
Urita
Graduate School of Engineering, Nagasaki University
Yasushige
Kuroda
Department of Chemistry, Graduate School of Natural Science and Technology, Okayama University
In this study, porous boron nitride (p-BN) with hexagonal phase boron nitride (h-BN) pore walls was synthesized using high-temperature calcination. Negligible variation in pore-wall structure can be observed in powder X-ray diffraction (XRD) profiles and infrared (IR) spectra. However, a highly stable p-BN with a stable pore structure even at 973 K under the oxidative conditions is obtained when synthesized at higher than 1573 K under nitrogen gas flow. For p-BN, this stability is obtained by generating h-BN microcrystals. Nitrogen adsorption–desorption isotherms at 77 K provide type-IV features and typical adsorption–desorption hysteresis, which suggests micropore and mesopore formation. Moreover, adsorption–desorption isotherms of Ar at 87 K are measured and compared with those of nitrogen. The relative adsorbed amount of nitrogen (i.e., the amount of nitrogen normalized by that of Ar at each relative pressure or adsorption potential value) on p-BN is considerably larger than that on microporous carbon at low-pressure regions, which suggests the existence of strong adsorption sites on the p-BN surface. In fact, the relative number of adsorbed nitrogen molecules to that of Ar on p-BN is, at most, 150%–200% larger than that on microporous carbon for the same adsorption potential state. Furthermore, additional adsorption enhancement to nitrogen between P/P0 = 10|5 and 10|3 can be observed for p-BN treated at 1673 K, which suggests the uniformly adsorbed layer formation of nitrogen molecules in the vicinity of a basal planar surface. Thus, unlike typical nanoporous sp2 carbons, p-BN materials have the potential to enhance adsorption for certain gas species because of their unique surface state.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2041-6520
12
10
2021
Structural elucidation of a methylenation reagent of esters: synthesis and reactivity of a dinuclear titanium(iii) methylene complex
3509
3515
EN
Takashi
Kurogi
Division of Applied Chemistry, Graduate School of National Science and Technology, Okayama University
Kaito
Kuroki
Division of Applied Chemistry, Graduate School of National Science and Technology, Okayama University
Shunsuke
Moritani
Division of Applied Chemistry, Graduate School of National Science and Technology, Okayama University
Kazuhiko
Takai
Division of Applied Chemistry, Graduate School of National Science and Technology, Okayama University
Transmetallation of a zinc methylene complex [ZnI(tmeda)](2)(mu-CH2) with a titanium(iii) chloride [TiCl3(tmeda)(thf)] produced a titanium methylene complex. The X-ray diffraction study displayed a dinuclear methylene structure [TiCl(tmeda)](2)(mu-CH2)(mu-Cl)(2). Treatment of an ester with the titanium methylene complex resulted in methylenation of the ester carbonyl to form a vinyl ether. The titanium methylene complex also reacted with a terminal olefin, resulting in olefin-metathesis and olefin-homologation. Cyclopropanation by methylene transfer from the titanium methylene proceeded by use of a 1,3-diene. The mechanistic study of the cyclopropanation reaction by the density functional theory calculations was also reported.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2041-6520
2021
Chiral exciplex dyes showing circularly polarized luminescence: extension of the excimer chirality rule
EN
Kazuto
Takaishi
Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
Sho
Murakami
Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
Kazuhiro
Iwachido
Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
Tadashi
Ema
Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University
A series of axially chiral binaphthyls and quaternaphthyls possessing two kinds of aromatic fluorophores, such as pyrenyl, perylenyl, and 4-(dimethylamino)phenyl groups, arranged alternately were synthesized by a divergent method. In the excited state, the fluorophores selectively formed a unidirectionally twisted exciplex (excited heterodimer) by a cumulative steric effect and exhibited circularly polarized luminescence (CPL). They are the first examples of a monomolecular exciplex CPL dye. This versatile method for producing exciplex CPL dyes also improved fluorescence intensity, and the CPL properties were not very sensitive to the solvent or to the temperature owing to the conformationally rigid exciplex. This systematic study allowed us to confirm that the excimer chirality rule can be applied to the exciplex dyes: left- and right-handed exciplexes with a twist angle of less than 90 degrees exhibit (-)- and (+)-CPL, respectively.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2046-2069
13
11
2023
Correction: Convergent evolution of animal and microbial rhodopsins
7222
7224
EN
Keiichi
Kojima
Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
Yuki
Sudo
Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
Correction for 'Convergent evolution of animal and microbial rhodopsins' by Keiichi Kojima et al., RSC Adv., 2023, 13, 5367-5381, https://doi.org/10.1039/D2RA07073A.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
1744-683X
19
15
2023
Toughening of poly(ionic liquid)-based ion gels with cellulose nanofibers as a sacrificial network
2745
2754
EN
Takaichi
Watanabe
Department of Applied Chemistry, Graduate School of Natural Science, Okayama University
Emiho
Oe
Department of Applied Chemistry, Graduate School of Natural Science, Okayama University
Yuna
Mizutani
Department of Applied Chemistry, Graduate School of Natural Science, Okayama University
Tsutomu
Ono
Department of Applied Chemistry, Graduate School of Natural Science, Okayama University
Ion gels have the potential to be used in a broad range of applications, such as in carbon dioxide separation membranes and soft electronics. However, their low mechanical strength limits their practical applications. In this study, we developed double-network (DN) ion gels composed of TEMPO-oxidized cellulose nanofibers with hydrophobic groups (TOCNF) and cross-linked poly[1-ethyl-3-vinylimidazolium bis(trifluoromethanesulfonyl)imide] (PC2im-TFSI) networks. The mechanical strength of the gel increased as the amount of TOCNF in the gels increased up to 6 wt%. Moreover, the fracture energy of the DN ion gels with 6 wt% TOCNF was found to be 19 times higher than that of the PC2im-TFSI single network (SN) ion gels. Cyclic stress-strain measurements of the DN gels showed that the loading energy on the gels dissipates owing to the destruction of the physically cross-linked TOCNF network in the gels. The DN ion gels also exhibited a high decomposition temperature of approximately 400 degrees C because of the thermal stability of all components. Additionally, the fracture energy of the TOCNF/poly(ionic liquid) (PIL) DN ion gel was two times higher than that of the silica nanoparticles/PIL DN ion gel developed in our previous study [Watanabe et al., Soft Matter, 2020, 16, 1572-1581]. This suggests that fiber-shaped nanomaterials are more effective than spherical nanomaterials in enhancing the mechanical properties of ion gels. These results show that TOCNF can be used to toughen PIL-based ion gels and hence broaden their applications.
No potential conflict of interest relevant to this article was reported.
Royal Society of Chemistry
Acta Medica Okayama
2041-6520
14
42
2023
An emissive charge-transfer excited-state at the well-defined hetero-nanostructure interface of an organic conjugated molecule and two-dimensional inorganic nanosheet
11914
11923
EN
Tomokazu
Umeyama
Department of Applied Chemistry, Graduate School of Engineering, University of Hyogo
Daizu
Mizutani
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University
Yuki
Ikeda
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University
W. Ryan
Osterloh
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University
Futa
Yamamoto
Department of Applied Chemistry, Graduate School of Engineering, University of Hyogo
Kosaku
Kato
Graduate School of Natural Science and Technology, Okayama University
Akira
Yamakata
Graduate School of Natural Science and Technology, Okayama University
Masahiro
Higashi
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University
Takumi
Urakami
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University
Hirofumi
Sato
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University
Hiroshi
Imahori
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University
Precise engineering of excited-state interactions between an organic conjugated molecule and a two-dimensional semiconducting inorganic nanosheet, specifically the manipulation of charge-transfer excited (CTE) states, still remains a challenge for state-of-the-art photochemistry. Herein, we report a long-lived, highly emissive CTE state at structurally well-defined hetero-nanostructure interfaces of photoactive pyrene and two-dimensional MoS2 nanosheets via an N-benzylsuccinimide bridge (Py-Bn-MoS2). Spectroscopic measurements reveal that no charge-transfer state is formed in the ground state, but the locally-excited (LE) state of pyrene in Py-Bn-MoS2 efficiently generates an unusual emissive CTE state. Theoretical studies elucidate the interaction of MoS2 vacant orbitals with the pyrene LE state to form a CTE state that shows a distinct solvent dependence of the emission energy. This is the first example of organic-inorganic 2D hetero-nanostructures displaying mixed luminescence properties by an accurate design of the bridge structure, and therefore represents an important step in their applications for energy conversion and optoelectronic devices and sensors.
No potential conflict of interest relevant to this article was reported.