山口大学研究推進体「先端的計測・分析基盤技術の創出」

Ni- and Cu-co-Intercalated Layered Manganese Oxide for Highly Efficient Electro-Oxidation of Ammonia Selective to Nitrogen
K. Nagita, Y. Yuhara, K. Fujii, Y. Katayama, M. Nakayama
ACS Appl. Mater. Interfaces, 2021, 13, 28098-28107.
DOI : 10.1021/acsami.1c04422

Abstract: We fabricated a thin film of layered MnO2 whose interlayer space was occupied by hydrated Ni2+ and Cu2+ ions. The process consisted of electrodeposition of layered MnO2 intercalated with tetrabutylammonium cations (TBA+) by anodic oxidation of aqueous Mn2+ ions in the presence of TBA+, followed by ion exchange of the initially incorporated bulkier TBA+ with the denser transition metals in solution. The resulting layered MnO2 co-intercalated with Ni2+ and Cu2+ ions (NiCu/MnO2) catalyzed the ammonia oxidation reaction (AOR) in an alkaline electrolyte with a much lower overpotential than its Ni2+- and Cu2+-intercalated single-cation counterparts. Surprisingly, the NiCu/MnO2 electrode achieved a faradic efficiency as high as nearly 100% (97.4%) for nitrogen evolution at a constant potential of +0.6 V vs Hg/HgO. This can be ascribed to the occurrence of the AOR in the potential region where water is stable and dimerization of the partially dehydrogenated ammonia species is preferred, thereby forming an N–N bond, rather than to be further oxidized into NOx species.

Integrated Fluorescent Nanoprobe Design for High-Speed In Vivo Two-Photon Microscopic Imaging of Deep-Brain Vasculature in Mice
M. Takezaki, R. Kawakami, S. Onishi, Y. Suzuki, J. Kawamata, T. Imamura, S. Hadano, S. Watanabe, Y. Niko
Dalton Trans., 2021, 31, 2010698
DOI : 10.1002/adfm.202010698

Abstract: High-speed two-photon microscopy can be used to analyze vascular dynamics in living animals and is essential for the understanding of brain diseases. Recent advances in fluorescent probes/optical systems have allowed successful imaging of the hippocampal vasculature in the deep brain of mice (1 mm from the brain surface) under low-speed conditions (1–2 fps); however, using high-speed techniques (>30 fps), observation of the deep-brain vasculature is still challenging. Here, a new nanoemulsion that encapsulates thousands of red-emissive pyrene dye molecules while maintaining their high two-photon brightness [1.5 × 102 GM (GM = 10−50 cm4·s·photon−1·molecule−1) at 960 nm excitation] and delivers a large amount of such pyrene dyes (65 nmol) into the blood vessels of mice is developed. Remarkably, the nanoprobe is found to exploit the inherent performance of a commonly used Ti:sapphire excitation laser and a sensitive gallium arsenide phosphide nondescanned fluorescence detector to the limit, enabling visualization of the brain vasculature under the cortex region of mice (up to 1.5 mm) under very low-speed conditions. As a highlight, such a nanoprobe is successfully used to directly observe the blood flow in the hippocampal CA1 region (1.1 mm) through high-speed resonant scanning (120 fps).

Origin of Catalytic Activity Differences Between Phosphine and Phosphine Oxide-Based Structures in the Water-Crosslinkable Polyalkoxysilane Composition
S.Tanaka, K. Adachi,
Polyolefins J., 2021, 8, 49-62
DOI : 10.22063/POJ.2020.2813.1171

Abstract: Organocatalysts have attracted enormous interest in the water-crosslinking reaction in silane-grafted polyolefins (SGPOs) system owing to their simplicity, low toxicity and environmentally benign nature compared to organotin catalysts, which are most used in SGPOs system. We focus on organophosphorus compounds including four structure types as organocatalysts; phosphoric acids, phosphoric esters, phosphine oxides and phosphine. The catalytic activities of them for the water-crosslinking reaction in 3-methacryloxypropyltrimethoxysilane grafted ethylene-propylene copolymer (EPR-g-MTMS) system were evaluated using the ATR-FTIR technique and gel-fraction method. The phosphine oxides, phosphoric acids, and phosphoric esters possessing an O=PR3 or O=P(OR)3 unit were found to be an excellent catalyst for the water-crosslinking reaction in EPR-g-MTMS system, while phosphine (PR3) showed no catalytic activity on water-crosslinking reaction in this system, indicating the phosphoryl (P=O) moiety played the important role on catalytic performance of these compounds. In comparison, phosphine oxides showed considerably higher catalytic activities than phosphoric acids / esters. Density functional theory (DFT) calculations demonstrated that the difference of catalytic activity could be attributed to an electron density at P=O moiety making the activation for water through hydrogen-bonding. Finally, the possible catalytic mechanism for the phosphoryl compounds in the EPR-g-MTMS system was proposed on the basis of these results and the SN2-Si pathway in silicate sol-gel chemistry.

細胞集団全体の前後極性の源は個々の細胞の前後極性
岩楯好昭
実験医学, 2020, 38, 3093-3095.

微粒子に“光”を当てると“色々”見えてくる
安達健太
化学と教育, 2020, 68, 428-429.

Structural Phase Transitions of a Molecular Metal Oxide
M. Fujibayashi, Y. Watari, R. Tsunashima, S. Nishihara, S. Noro, C.-G. Lin, Y.-F. Song, K. Takahashi, T. Nakamura, T. Akutagawa
Angew. Chem. Int. Ed., 2020, 59, 22446-22450.
DOI : 10.1002/anie.202010748

Abstract: The structural phase of a metal oxide changes with temperature and pressure. During phase transitions, component ions move in multidimensional metal–oxygen networks. Such macroscopic structural events are robust to changes in particle size, even at scales of around 10 nm, and size effects limiting these transitions are particularly important in, for example, high-density memory applications of ferroelectrics. In this study, we examined structural transitions of the molecular metal oxide [Na@(SO3)2(n-BuPO3)4MoV4MoVI14O49]5− (Molecule 1) at approximately 2 nm by using single-crystal X-ray diffraction analysis. The Na+ encapsulated in the discrete metal-oxide anion exhibited a reversible order–disorder transition with distortion of the Mo–O molecular framework induced by temperature. Similar order–disorder transitions were also triggered by chemical pressure induced by removing crystalline solvent molecules in the single-crystal state or by substituting the countercation to change the molecular packing.

Doping of Metal-free Molecular Perovskite with Hexamethylenetetramine to Create Non-centrosymmetric Defects
CrystEngComm., 2020, 22, 2279-2282
H. Morita, R. Tsunashima, S. Nishihara, T. Akutagawa
DOI : 10.1039/D0CE00173B

 

Abstract: The metal-free perovskite (dabcoH22+)(NH4)Br (d-Br) (dabco: 1,4-diazabicyclo[2.2.2]octane) was doped with non-centrosymmetric hexamethylenetetramine. The dopant was not structurally adapted to the original perovskite lattice, and thus caused structural fluctuations in the lattice and increased the thermal motion in the surrounding dabcoH22+.

Spin Crossover between the High-spin and Low-spin States and Dielectric Switching in the Ionic Crystals of a Fe(II) [2 × 2] Molecular Grid
Bull. Chem. Soc. Jpn., 2020, 93, 1583-1587
Y. Uezu, R. Tsunashima, C. Tanaka, M. Fujibayashi, J. Manabe, S. Nishihara, K. Inoue
DOI : 10.1246/bcsj.20200207

 

Abstract: We synthesized an Fe(II) [2 × 2] molecular grid with pyridyl-substituted bis-terdentate ligands. The molecular grid showed abrupt spin crossover between fully high-spin and fully low-spin states in a narrow temperature width of ∼10 K. The spin crossover event also included a first-order structural phase transition, in which the dielectric constant jumped atypically toward a low-spin state.

The Formation Mechanism of ZnTPyP Fibers Fabricated by A Surfactant-Assisted Method
K. Tashiro,T. Murafuji, M. Sumimoto, M. Fujitsuka, S. Yamazaki
New J. Chem., 2020, 44, 13824-13833.
DOI: 10.1039/D0NJ02829K

Abstract: Fibers composed of 5,10,15,20-tetrakis(4-pyridyl)porphyrinatozinc(II) (ZnTPyP) were synthesized by a surfactant-assisted method using cetyltrimethylammonium bromide (CTAB) and chloroform. The presence of CTAB was essential to make and to maintain the fibers and their formation rate became slower with increasing the molar ratio of CTAB to ZnTPyP. Measurements of absorption spectra of the synthesized fibers showed splitting of the Soret band at 426 nm into two peaks at 416 and 454 nm in accordance with the formation of the ZnTPyP fibers as revealed by transmission electron microscopy. The aging process at higher temperature made the fibers longer and the apparent activation energy for the formation of the fibers was estimated to be 74.8 kJ mol−1. When 5,10,15,20-tetrakis(4-pyridyl)porphyrin (TPyP) or 5,10,15,20-tetrakis(phenyl)porphyrinatozinc(II) (ZnTPP) was used instead of ZnTPyP, no fiber formation was observed. On the other hand, when a chloroform solution of ZnTPP was mixed with pyrazine or 4,4′-bipyridine, the fiber formation was observed. Proton nuclear magnetic resonance spectra indicated upfield shifts of the pyridinic proton in the presence of ZnTPP and 4,4′-bipyridine, suggesting the coordination of nitrogen to zinc(II) (Zn–N) in ZnTPP. These findings indicate that the Zn–N coordination is crucial for the formation of the fibers and that nitrogen in the pyridyl moiety of ZnTPyP is coordinated to the central zinc(II) ion of another ZnTPyP molecule to make the ZnTPyP fibers. Theoretical calculations were performed using the DFT/B97D functional to estimate the stability of the π–π stacking and the coordination of Zn–N. The presence of the CTAB micelles suppresses the aggregation of ZnTPyP molecules due to the π–π stacking, which is thermodynamically more favorable. The Zn–N coordination proceeds moderately during the aging process for 10 days by inducing the transition from spherical CTAB micelles to rod-like micelles by fusion.

Importance of Advanced Metrology in Semiconductor Industry and Value-added Creation Using AI/ML
K. Okamoto, M. Sugiyama, S. Mabu
e-J. Surf. Sci. Nanotech., 2020, 184, 214-222.
DOI : 10.1380/ejssnt.2020.214

Abstract: In the Internet of Things (IoT) era using Big Data, metrology is recognized as a crucial process that provides added value in hyper-scaling semiconductor manufacturing processes. Miniaturization of semiconductors requires the discussion of quantum theory on the order of tens of nanometers, and metrology (measurement technology) that supports this requirement has the potential of creating new research fields. Super-resolution optical technology is a common measurement technique that exceeds the physical limit. Moreover, advanced integrated metrology techniques, which include a combination of various kinds of metrology techniques coupled with artificial intelligence (AI) and machine learning (ML), have the potential to evolve into an untapped technological field required by the market. We conduct extensive discussions on the implications of AI/ML. A new way of advanced integrated metrology can be considered as an important role for the fabrication of next generation integrated circuit and be connected to value-added creation.

Visualization of Ultraviolet Irradiation using WO3-Cellulose Derivatives Composite Film
S. Yamazaki, K. Isoyama, D. Shimizu
Optical Mater., 2020, 106, 109929
DOI: 10.1016/j.optmat.2020.109929

Abstract: Tungsten oxide (WO3) based photochromic films consisting of methyl cellulose (MC), hydroxyethyl cellulose, carboxymethyl cellulose (CMC) or cellulose nanofiber (CNF) are fabricated for monitoring ultraviolet (UV) light. The opaque WO3/MC film becomes transparent by adding ethylene glycol (EG) whereas the WO3/CMC and WO3/CNF are transparent without EG. The WO3/EG/MC film possesses much higher sensitivity to the UV light than the WO3/CNF film. Visually, the blue color of the WO3/CNF film after UV irradiation for 8 h is almost equivalent to that of the WO3/EG/MC film after irradiation for 1 min. The color change of the WO3/CNF and the WO3/EG/MC film can be used to monitor UV from the sun light. We also demonstrated that the WO3/EG/MC film can be used to measure the UV intensity quantitatively up to 6 mW cm-2.

Amorphous Carbon Having Higher Catalytic Activity toward Oxygen Reduction Reaction: Quinone and Carboxy Groups Introduced onto its Surface
K. Honda, Y.Waki, A.Matsumoto, B. Kondo, Y. Shimai
Diam. Relat. Mater., 2020, 107, 107900.
DOI: 10.1016/j.diamond.2020.107900

Abstruct: Amorphous carbon (a-C) based catalysts having higher activity and stability for oxygen reduction reaction (ORR) were achieved by introducing quinone and carboxy groups onto a-C surfaces. The surface-bonded quinone groups increased the rate of ORR to hydrogen peroxide. The surface carboxy groups promoted the activity toward electrochemical peroxide reduction. However, few studies have reported on their contribution. ORR activity was controlled by varying density of quinone and carboxy groups on the a-C surfaces. The ORR activity was proceeded by 2 + 2 electron mechanism through H2O2 that acted as an intermediate. The number of electrons transferred per O2 molecule reached 4.08 at a maximum. The catalytic activity of the catalyst was stable in long term measurements (150 times in 20 h) because a-C inherently has high corrosion resistance and oxygen-contained surface functionalities are stable in aqueous solution. Consequently, the a-C catalysts possessed high ORR reproducibility.

Landslide Classification from Synthetic Aperture Radar Images Using Convolutional Neural Network with Multichannel Information
S. Mabu, Y. Nakayama, T. Kuremoto
J. Signal Processing., 2020, 24, 61-73.
DOI : 10.2299/jsp.24.61

Abstract: Detection of disaster-stricken areas using synthetic aperture radar (SAR) images is important in countries and regions with heavy rain and earthquakes. Although it is important to immediately find disaster-stricken areas when a disaster occurs, it takes time to read SAR images and also needs experience and expertise. Therefore, machine learning, especially deep learning, is expected to be applied to the classification of disaster-stricken areas. Classification using deep learning is often executed on patch images of local areas. However, patch-based classification would miss information on the surrounding areas such as topographic features. In this study, a convolutional neural network (CNN) is applied to the classification of SAR images using the following techniques. When making the images input to a CNN, two multichannel image generation methods, i.e, a zero-padding method and map-concatenation method, are used, where the target areas to be classified and their surrounding areas are combined to form multichannel images. In the experiments, the zero-padding method and map-concatenation method are evaluated by the classification performance of SAR images that cover the northern Kyushu area in Japan, where large-scale landslides due to heavy rain occurred in 2017. Through the experiments, we clarify the appropriate CNN structures with multichannel information for landslide classification.

Compartmentalization of Gold Nanoparticle Clusters in Hollow Silica Spheres and Their Assembly Induced by An External Electric Field
K. Watanabe, T.A.J. Welling, S. Sadighikia, H. Ishii, A. Imhof, M.A.van Huis, A. Blaaderen, D. Nagao
J. Colloid Interf. Sci., 2020, 566, 202-210.
DOI : 10.1016/j.jcis.2020.01.094

Abstract: Assembly of plasmonic nanoparticle clusters having hotspots in a specific space is an effective way to efficiently utilize their plasmonic properties. In the assembly, however, bulk-like aggregates of the nanoparticles are readily formed by strong van der Waals forces, inducing a decrease of the properties. The present work proposes an advanced method to avoid aggregation of the clusters by encapsulating into a confined space of hollow silica interior. Hollow spheres incorporating gold nanoparticle clusters were synthesized by a surface-protected etching process. The observation of inner nanoparticles with liquid cell transmission electron microscopy experimentally proved that the nanoparticles moved as a cluster instead of as dispersed nanoparticles within the water-filled hollow compartment. The hollow spheres incorporating the nanoparticle clusters were assembled in the vicinity of electrodes by application of an external AC electric field, resulting in the enhancement of Raman intensities of probe molecules. The nanoparticle-cluster-containing hollow spheres were redispersed when the electric field was turned off, showing that the hollow silica spheres can act as a physical barrier to avoid the cluster aggregation. The Raman intensities were reversibly changed by switching the electric field on and off to control the assembled or dispersed states of the hollow spheres.

A Novel Efficient Catalyst for Water-Crosslinking Reaction of Silane-Grafted Polyolefin System: Specific Influence of Axially Coordinated n-Alkylamine Ligand on Catalytic Abilities of Metal Acetylacetonate Complex
S.Tanaka, K. Adachi,
Mater. Today Comm., 2019, 217, 100584
DOI : 10.1016/j.mtcomm.2019.100584

Abstract: Catalytic activities of the novel acid-base hybrid catalyst on the water-crosslinking reaction (hydrolysis and condensation) of 3-methacryloxypropyltrimehoxysilane-grafted ethylene-propylene copolymer (EPR-g-MTMS) were investigated by means of attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and gel fraction measurements. We have synthesized RNH2-M(acac)2 complex as an acid-base hybrid catalyst which shows the high catalytic activities for water-crosslinking reaction in EPR-g-MTMS system. It is noted that the catalytic activity of RNH2-M(acac)2 complex clearly shows dependence on axially coordinated n-alkylamine compounds in hydrolysis reaction, meanwhile, the center metal ion in RNH2-M(acac)2 complex affects on the catalytic activities for overall water-crosslinking reaction in this study. The design concept of an acid-base hybrid catalyst showed bifunctional catalytic activity for the water-crosslinking reaction in the alkoxysilane-grafted polyolefin system.

Anisotropic Polyoxometalate Cages Assembled via Layers of Heteroanion Templates
Q. Zheng, M. Kupper, W. Xuan, H. Oki, R. Tsunashima, D.-L. Long, L. Cronin
J. Am. Chem. Soc., 2019, 141, 13479–13486.
DOI : 10.1021/jacs.9b04533

Abstract: The synthesis of anisotropic redox-active polyoxometalates (POMs) that can switch between multiple states is critical for understanding the mechanism of assembly of structures with a high aspect ratio, as well as for their application in electronic devices. However, a synthetic methodology for the controlled growth of such clusters is lacking. Here we describe a strategy, using the heteroanion-directed assembly, to produce a family of 10 multi-layered, anisotropic POM cages templated by redox-active pyramidal heteroanions with the composition [W16Mo2O54(XO3)]n−, [W21Mo3O75/76(XO3)2]m−, and [W26Mo4O93(XO3)3]o− for the double, triple, and quadruple layered clusters, respectively. It was found that the introduction of reduced molybdate is essential for self-assembly and results in mixed-metal (W/Mo) and mixed-valence (WVI/MoV) POM cages, as confirmed by an array of analytical techniques. To probe the archetype in detail, a tetrabutyl ammonium (TBA) salt derivative of a fully oxidized two-layered cage is produced as a model structure to confirm that all the cages are a statistical mixture of isostructures with variable ratios of W/Mo. Finally, it was found that multilayered POM cages exhibit dipolar relaxations due to the presence of the mixed valence WVI/MoV metal centers, demonstrating their potential use for electronic materials..

Role of Solvent Size in Ordered Ionic Structure Formation in Concentrated Electrolytes for Lithium-Ion Batteries
M. Sogawa, S. Sawayama, J. Han, C.C. Satou, K. Ohara, M. Matsugami, H. Mimura, M. Morita, K. Fujii
J. Phys. Chem. C, 2019, 123, 8699-8708.
DOI : 10.1021/acs.jpcc.9b01038

Abstract: The structural and electrochemical properties of lithium (Li) ion complexes in concentrated electrolytes based on acetonitrile (AN) and tris(2,2,2-trifluoroethyl) phosphate (TFEP) as solvents and LiTFSA [TFSA: bis(trifluoromethanesulfonyl)amide] as a Li salt were investigated by employing electrochemical measurements, vibrational spectroscopy, and high-energy X-ray total scattering (HEXTS) with all-atom molecular dynamics (MD) simulations. Via electrochemical measurements, reversible Li-ion insertion/deinsertion into/from the graphite electrode was observed in concentrated LiTFSA/AN solutions but not in concentrated LiTFSA/TFEP solutions. The experimental radial distribution functions [Gexp(r)] derived from HEXTS were successfully represented by the corresponding MD-derived values [GMD(r)] for both AN- and TFEP-based electrolyte systems. We found that (1) in the dilute system, Li ions were solvated with only solvent molecules in AN-based solutions to form a completely dissociated [Li(AN)4]+ complex, while contact ion pairs exhibiting Li+···TFSA– interactions were formed in the TFEP-based solutions. (2) In the concentrated system, a specific Li+···Li+ correlation was observed for shorter r values (∼3 Å) in the AN-based solutions, suggesting ordered ionic structure formation based on multinuclear Li-ion complexes. However, no ordered ionic structure formation was found in the TFEP-based solutions. We discussed the relation between the ordered ionic structure and graphite electrode reaction at the molecular level, particularly focusing on the solvent size; that is, the smaller AN more easily forms a compact solution structure (ordered structure) in the concentrated solutions, while bulky TFEP causes steric repulsion among the coordinated species (TFEP and TFSA) in the Li-ion complexes, preventing such ordered formation.

Fluorinated Alkyl-Phosphate-Based Electrolytes with Controlled Lithium-Ion Coordination Structure
S. Sawayama, Y.M. Todorov, H. Mimura, M. Morita, K. Fujii
Phys. Chem. Chem. Phys., 2019, 21, 11435-11443.
DOI : 10.1039/C9CP01974J

Abstract: Herein, we propose Li-ion solvation-controlled electrolytes based on non-flammable organic solvent TFEP and an LiFSA salt [TFEP: tris(2,2,2-trifluoroethyl)phosphate, LiFSA: lithium bis(fluorosulfonyl)amide] to allow Li-ion insertion into a graphite electrode for Li-ion batteries. Comprehensive structural study based on (1) infrared (IR)/Raman spectroscopy, (2) high-energy X-ray total scattering (HEXTS), and (3) molecular dynamics (MD) simulation revealed the solvation (or coordination) structures of Li ions in TFEP-based electrolytes at the molecular level. In binary LiFSA/TFEP with a Li salt concentration (cLi) < 1.0 mol dm−3, Li ions are coordinated with both TFEP and FSA components; in detail, two TFEP molecules coordinate in an O-donating monodentate manner and one FSA in an O-donating bidentate manner to form [Li(TFEP)2(bi-FSA)] as the major species. We demonstrated that adding acetonitrile (AN) to the LiFSA/TFEP electrolytes caused structural changes in the Li-ion complexes. The bi-FSA bound to the Li ion changed its coordination mode to mono-FSA, which was induced by solvating AN molecules to Li ions. The redox reaction corresponding to insertion/deinsertion of Li ions into/from the graphite electrode successfully occurred in 1.0 mol dm−3 LiFSA/TFEP with an AN electrolyte system, while there was no or reduced Li-ion insertion in the electrolyte without AN. We discussed the relationship between the structure and electrode reaction of the Li-ion complexes based on the FSA-coordination characteristics; i.e., in LiFSA/TFEP with the AN system, the mono-FSA bound to the Li ion is easier to decoordinate due to weaker Li+⋯mono-FSA− interactions rather than the Li+⋯bi-FSA− interactions, which mainly contribute to charge-transfer at the electrode/electrolyte interface to allow Li-ion insertion/deinsertion in the graphite anode.

Ferroelectric Behavior of a Hexamethylenetetramine‐Based Molecular Perovskite Structure
H. Morita, R. Tsunashima, S. Nishihara, K. Inoue, Y. Omura, Y. Suzuki, J. Kawamata, N. Hoshino, T. Akutagawa
Angew. Chem. Int. Ed., 2019, 58, 9184-9187.
DOI: 10.1002/anie.201905087

Abstruct: We report the development of a molecular ferroelectric material inspired by the hexamethylenetetramine (hmta) non‐centrosymmetric molecular rotator. The bromide salt of diprotonated hmta (hmtaH2) crystalized as (hmtaH2)(NH4)Br3 in a metal‐free ABX3 perovskite‐type structure, in which the A and B sites are occupied by hmtaH22+ and ammonium cations, respectively. The compound crystallized in the Pma2 polar space group. A distorted polar perovskite structure formed owing to the distortion of {(NH4)Br6} octahedrons that are stabilized through the formation of NH⋅⋅⋅Br hydrogen bonds and the orientational ordering of positive charges on the non‐centrosymmetric hmtaH2 molecules. This spontaneous polarization exhibited ferroelectric behavior with a nominally high Curie temperature (>400 K), in which the electrical switching of polarization originates from the rotation of the hmtaH2 unit.

TetraPEG Network Formation via a Michael Addition Reaction in an Ionic Liquid: Application to Polymer Gel Electrolyte for Electric Double-Layer Capacitors
M. Yoshitake, J. Han, T. Sakai , M. Morita, K. Fujii
Chem. Lett., 2019, 48, 704-707.
DOI : 10.1246/cl.190143

Abstract: Polymer network formation via Michael addition of two tetra-arm poly(ethylene glycol) (TetraPEG) prepolymers possessing maleimide (MA) and thiol (SH) terminals was investigated in a typical aprotic ionic liquid containing a basic catalyst. The gelation reaction proceeded successfully at room temperature to be high network connectivity (~98%). The resulting TetraPEG gel showed ideal liquid-like ion conducting properties and was applied to a polymer electrolyte for electric double-layer capacitors (EDLC).

Solvation Structure of Poly(benzyl methacrylate) in a Solvate Ionic Liquid: Preferential Solvation of Li-Glyme Complex Cation
K. Hashimoto, Y. Kobayashi, H. Kokubo, T. Ueki, K. Ohara, K. Fujii, M. Watanabe
J. Phys. Chem. B, 2019, 123, 4098-4107.
DOI : 10.1021/acs.jpcb.9b02458

Abstract: We report the solvation structure of a lower critical solution temperature (LCST)-type thermoresponsive polymer in a solvate ionic liquid (SIL, i.e., an ionic liquid comprising solvate ions) to elucidate the predominant interaction for the dissolution of the thermoresponsive polymer in SIL at low temperatures. The solvation structure of poly(benzyl methacrylate) (PBnMA) and a model compound of its monomer in a typical glyme-based SIL, [Li(G4)][TFSA] (G4: tetraglyme; TFSA: bis(trifluoromethanesulfonyl)amide), have been investigated using high-energy X-ray total scattering and all-atom molecular dynamics simulations. In the model compound/SIL system, the intermolecular components extracted from the total G(r)s revealed that the ester moiety of BnMA is preferentially solvated by Li cations through a cation–dipole interaction, which induces slight desolvation of the G4 molecules, and the aromatic ring of BnMA is secondarily solvated by the [Li(G4)] cation complex through a cation−π interaction with maintaining the complex structure. In contrast, TFSA anions are attracted only by the [Li(G4)] cation. These interactions result in the formation of a solvation layer of SILs around the aromatic ring, which plays a key role in the negative entropy and enthalpy of mixing. Meanwhile, in the polymer solution, the coordination number of the Li cation around the ester moiety significantly decreased. This could be ascribed to the steric effect of the bulky side chains, preventing the approach of the [Li(G4)] cation complex to the ester moiety located near the main chain. These solvation structures lead to small absolute values of negative entropy and enthalpy of mixing, which together are key factors to understand the LCST-type phase behavior in the IL system.

Actin-Binding Domains Mediate the Distinct Distribution of Two Dictyostelium Talins through Different Affinities to Specific Subsets of Actin Filaments During Directed Cell Migration
M. Tsujioka, T.Q.P. Uyeda, Y. Iwadate, H. Patel, K. Shibata, T. Yumoto, S. Yonemura
PLoS ONE, 2019, 14, e0214736.
DOI : 10.1371/journal.pone.0214736

Abstract: Although the distinct distribution of certain molecules along the anterior or posterior edge is essential for directed cell migration, the mechanisms to maintain asymmetric protein localization have not yet been fully elucidated. Here, we studied a mechanism for the distinct localizations of two Dictyostelium talin homologues, talin A and talin B, both of which play important roles in cell migration and adhesion. Using GFP fusion, we found that talin B, as well as its C-terminal actin-binding region, which consists of an I/LWEQ domain and a villin headpiece domain, was restricted to the leading edge of migrating cells. This is in sharp contrast to talin A and its C-terminal actin-binding domain, which co-localized with myosin II along the cell posterior cortex, as reported previously. Intriguingly, even in myosin II-null cells, talin A and its actin-binding domain displayed a specific distribution, co-localizing with stretched actin filaments. In contrast, talin B was excluded from regions rich in stretched actin filaments, although a certain amount of its actin-binding region alone was present in those areas. When cells were sucked by a micro-pipette, talin B was not detected in the retracting aspirated lobe where acto-myosin, talin A, and the actin-binding regions of talin A and talin B accumulated. Based on these results, we suggest that talin A predominantly interacts with actin filaments stretched by myosin II through its C-terminal actin-binding region, while the actin-binding region of talin B does not make such distinctions. Furthermore, talin B appears to have an additional, unidentified mechanism that excludes it from the region rich in stretched actin filaments. We propose that these actin-binding properties play important roles in the anterior and posterior enrichment of talin B and talin A, respectively, during directed cell migration.

車輪細胞見つけた！
Stress-Fiber Wheel Rotation in Keratocytes
沖村千夏, 谷口篤史, 野中茂紀, 岩楯好昭
生物物理, 2019, 59, 94-96.
DOI: 10.2142/biophys.59.094

Anion Coordination Characteristics of Ion-Pair Complexes in Highly Concentrated Aqueous Lithium Bis(trifluoromethanesulfonyl)amide Electrolytes
T. Tsurumura, Y. Hashimoto, M. Morita, Y. Umebayashi, K. Fujii
Anal. Sci., 2019, 35, 289-294.
DOI : 10.2116/analsci.18P407

Abstract: We report on the structures of Li-ion complexes in salt-concentrated aqueous electrolytes based on lithium bis(trifluoromethanesulfonyl)amide (LiTFSA), particularly focusing on the anion coordination behavior of the ion-pair complexes in the high concentration region cLi > 3.0 mol dm−3. Quantitative data analysis of the Raman spectra revealed the following. (1) Li ions do not coordinate with TFSA anions at lower cLi (<3.0 mol dm−3) to exist as ion pair-free ions. (2) In the concentrated region (cLi = 3.0 – 4.0 mol dm−3), the TFSA anions coordinate as monodentate ligands (mono-TFSA) with Li ions to form ion-pair complexes and coexist with free TFSA in the bulk. (3) Further increasing the cLi (4.0 – 5.2 mol dm−3) results in both monodentate and bidentate coordination (bi-TFSA) modes of TFSA anions to Li ions, yielding complicated ion-pair complexes in the first coordination sphere. The Walden plots, based on ionic conductivity and viscosity data, implied that the ion-conducting mechanism in the highly salt-concentrated region was considerably different from that in the dilute region (i.e., vehicle mechanism).

Electronic States of Acetic Acid in a Binary Mixture of Acetic Acid and 1-Methylimidazole Depend on the Environment
N. Yoshimura, O. Takahashi, M. Oura, Y. Horikawa
J. Phys. Chem. B, 2019, 123, 1332-1339.
DOI : 10.1021/acs.jpcb.8b11437

Abstract: The unique characteristics of an acetic acid/1-methylimidazole (1-MI) mixture, showing higher electrical conductivity than either neat acetic acid or neat 1-MI, yet consisting of electrically neutral molecules, are reported. We have applied soft X-ray spectroscopy to reveal the electronic states of acetic acid in the acetic acid/1-MI mixture at various mole fractions of acetic acid (χHOAc). The results show that the amount of acetic acid monomer increases in the region of especially high electrical conductivity and the amount of complex of acetic acid and 1-MI formed by sharing molecular orbitals increases in the low electrical conductivity region. There is a little amount of acetic acid monomer in the low electrical conductivity region because the complex inhibits acetic acid from creating its monomer. These results suggest the possibility that the acetic acid monomer is related to electrical conduction.

An Ionic Liquid Gel with Ultralow Concentrations of Tetra-Arm Polymers: Gelation Kinetics and Mechanical and Ion-Conducting Properties
A. Ishikawa, T. Sakai, K. Fujii
Polymer, 2019, 166, 38-43.
DOI : 10.1016/j.polymer.2019.01.044

Abstract: We report an ion gel with ultralow polymer content based on two key materials: 1 wt% tetra-arm poly(ethylene glycol) (TetraPEG) and 99 wt% ionic liquid (herein, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)amide, [C2mIm][FSA]). We performed kinetics analysis on the TetraPEG network formation in [C2mIm][FSA], i.e., AB-type cross-end coupling reaction of two different TetraPEGs with thiol (SH) and maleimide (MA) terminals (TetraPEG-SH and TetraPEG-MA). In neat [C2mIm][FSA], no gelation occurred at room temperature, whereas the reaction successfully proceeded when 1-ethylimidazole (C2Im) was added in this reaction as a catalyst. The apparent reaction rate constant (k′gel) was determined by varying C2Im concentration, and the network connectivity (p) was estimated to be p ∼ 98% toward the end of the reaction. The results indicated that the TetraPEG prepolymers could be successfully gelled in [C2mIm][FSA] despite extremely low polymer content (1 wt%), which allows us to prepare an ideally homogeneous polymer network gel with a large amount of ionic liquid. The ionic conductivity measurements demonstrated that the 1 wt% TetraPEG ion gel showed ideal liquid-like ion-conducting properties that were comparable to those of neat ionic liquid.

Efficient Synthesis of Benzofuran Fused 1-Azaazulenet
H. Fujii, Y. Hironaka, N. Abe
Heterocycles, 2018, 99, ASAP.
DOI : 10.3987/COM-18-S(F)69

Abstract: The synthesis of benzofuran fused 1-azaazulene (cyclohepta[d]benzo[4,5]furano[2,3-b]pyrrole) (4) was achieved by one pot reaction of 2-chloro-1-azaazulene (1) with 2-iodophenol (2) under the conditions in the presence of Pd(OAc)2 and without using a ligand.

Structural Phase Transition Behavior Observed for a Single Crystal of the Tetrabutylammonium Salt of a Mo18 Polyoxometalate
H. Oki, M. Shiga, I. Nakamura, K. Nishida, K. Ichihashi, S. Nishihara, K. Inoue, T. Akutagawa, R. Tsunashima
Eur. J. Inorg. Chem., 2018, 46, 492-495.
DOI: 10.1002/ejic.201801044

Abstruct: Ionic single crystals of the polyoxometalate [MoV2MoVI16O54(SO3)2]6– salted with tetrabutylammonium were found to exhibit dielectric anomalies at 235 and 302 K. The clear DSC peak at 235 K indicates the first‐order nature of transition. The next transition at 302 K was concluded to be second‐order in nature, demonstrating the existence of three different phases (α, β, and γ). Temperature‐dependent single‐crystal X‐ray diffraction analysis revealed that the structural phase transitions occur owing to orientational changes in the structures of the cation alkyl chains and the crystalline solvent of acetonitrile where the structure of Mo18 polyoxometalate was comparable. The polymorphous and flexible configuration of the alkyl chains was reasoned to be the origin of the temperature dependence of the structure.

Solvation Structure Analysis of Lithium Ion in Concentrated Lithium Salt Solutions Using Raman Spectroscopy
K. Fujii, H. Fujino
BUNSEKI KAGAKU(分析化学), 2018, 67, 727-732.
DOI : 10.2116/bunsekikagaku.67.727

Abstract: Electrolyte solutions are one of the key liquid materials in the development of high-performance lithium-ion batteries (LIBs). Recently, a new concept, “superconcentrated electrolyte”, i.e., solvent-in-salt in liquid state, was proposed and widely investigated in terms of not only electrochemistry, but also physical chemistry and/or solution chemistry. In this work, we report on a structural study of lithium-ion complexes in highly salt-concentrated electrolytes, lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) salt in N,N-dimethylpropionamide (DMPA), using Raman spectroscopy with the aid of density functional theory (DFT) calculations. In the range of the Li salt concentration, cLi = 0 – 3.2 mol dm−3, the individual solvation numbers of DMPA and TFSA species around Li ions [n(DMPA) and n(TFSA), respectively] were quantitatively determined and the relation between the Li ion complex structure and cLi was discussed at the molecular level.

Morphological Analysis of Self-assembled Structures of Merbromin Molecules Adsorbed on Titanium(IV) Oxide Nanoparticles
K. Adachi, N. Tsuru
BUNSEKI KAGAKU(分析化学), 2018, 67, 719-726.
DOI : 10.2116/bunsekikagaku.67.719

Abstract: A broad understanding of the adsorption and aggregation behavior of organic dye molecules on an inorganic semiconductor surface provides a new strategy for optical and electronic devices. We chose merbromin (Merb) and titanium(IV) oxide (TiO2) colloids in this study. The adsorption and aggregation behavior of Merb in a TiO2 colloid aqueous solution were spectrophotometrically investigated. The absorption spectra of Merb were significantly red-shifted in the visible region upon the addition of a TiO2 colloid solution. Detailed spectral analysis based on Kasha's exciton coupling theory and a modified Langmuir adsorption model revealed that dianionic Merb molecules are adsorbed flat on a positively charged TiO2 colloid surface by an electrostatic interaction, and eventually form "oblique" J-type dimers aligned in a head-to-tail fashion. We envisage new applications of this analysis in the development of advanced dye-sensitized solar cells, where the adsorption/aggregation morphology of organic dyes on the metal oxide is a crucial factor to be considered.

Bright and Two-Photon Active Red Fluorescent Dyes that Selectively Move Back and Forth Between the Mitochondria and Nucleus upon Changing the Mitochondrial Membrane Potential
H. Seki, S. Onishi, N. Asamura, Y. Suzuki, J. Kawamata, D Kaneno, S Hadano, S Watanabe, Y Niko
J. Mater. Chem. B, 2018, 6, 7396-7401.
DOI: 10.1039/C8TB02415D

Abstruct: Since mitochondrial dysfunction was discovered to be the underlying cause of several severe diseases, fluorescent probes with excellent optical properties for visualising and monitoring the mitochondrial membrane potential (MMP) (a parameter of mitochondrial vitality) have been in high demand. Herein, we present novel pyrene-based dyes exhibiting remarkably large two-photon absorption around 900 nm and bright red emission around 620 nm (two-photon brightness (Φσ2) = 425–525 GM), with selective localisation to the mitochondria or nucleus in response to changes in the MMP, providing several advantages over traditional MMP-monitoring probes such as Rhodamine 123 (Φσ2 = 64 GM). The intracellular behavior of the new dyes was investigated in detail. The driving forces for the dyes to dissociate from the mitochondria and migrate toward the nucleus upon decreasing the MMP were two key molecular characteristics: the dyes’ permeability to mitochondrial membranes and their affinity to nuclear DNA. The results provide significant insights into improving the molecular design of the dyes.

Two-photon Absorption Spectrum of Solid Solution Nanocrystals of ZnS-AgInS2
Y. Suzuki, S. Onishi, K. Matsumoto, T. Takiyama, T. Kameyama, T. Torimoto, J. Kawamata
Chem. Lett., 2018, 47, 1475-1477.
DOI: 10.1246/cl.180718

Abstruct: Two-photon absorption behavior of dispersion of solid solution nanocrystals of ZnS-AgInS2 was investigated, the measured maximum two-photon absorption cross-section of this nanoparticle being 3900 GM (1 GM = 10−50 cm4 s photon−1 mol(particle)−1) at 850 nm. The two-photon excited red photoluminescence was observed even by using a femtosecond fiber laser oscillating at 1030 nm.

Effects of Air Exposure on Hard and Soft X-ray Photoemission Spectra of Ultrananocrystalline Diamond/Amorphous Carbon Composite Films
M. Egiza, H. Naragino, A. Tominaga, K. Hanada, K. Kamitani, T. Sugiyama, E. Ikenaga, K. Murasawa, H. Gonda, M. Sakurai, T. Yoshitakee
Coatings, 2018, 8, 359.
DOI: 10.3390/coatings8100359

Abstruct: Hard X-ray photoemission spectroscopy (HAXPES) was employed for the structural evaluation of ultrananocrystalline diamond/amorphous carbon (UNCD/a-C) composite films deposited on cemented carbide substrates, at substrate temperatures up to 550 °C by coaxial arc plasma deposition. The results were compared with those of soft X-ray photoemission spectroscopy (SXPES). Since nanocrystalline diamond grains are easily destroyed by argon ion bombardment, the structural evaluation of UNCD/a-C films, without the argon ion bombardment, is preferable for precise evaluation. For samples that were preserved in a vacuum box after film preparation, the sp3 fraction estimated from HAXPES is in good agreement with that of SXPES. The substrate temperature dependencies also exhibited good correspondence with that of hardness and Young’s modulus of the films. On the other hand, the sp3 fraction estimated from SXPES for samples that were not preserved in the vacuum box had an apparent deviation from those of HAXPES. Since it is possible for HAXPES to precisely estimate the sp3 fraction without the ion bombardment treatment, HAXPES is a feasible method for UNCD/a-C films, comprising nanocrystalline diamond grains.

Developing Active TiO2 Nanorods by Examining the Influence of Morphological Changes from Nanorods to Nanoparticles on Photocatalytic Activity
Y. Yamazaki, K. Azami, R. Katoh, S. Yamazaki
ACS Appl. Nano Mater., 2018, 1, 5927-5935.
DOI: 10.1021/acsanm.8b01617

Abstract: We synthesized rutile TiO2 nanorods with high crystallinity, i.e., degree of crystallinity greater than ca. 90%, by using a hydrothermal method and studied the effect of the morphological change from rod shape to subsphere by the subsequent thermal treatment. The photocatalytic activity was estimated for O2 evolution from water oxidation because this reaction was hardly affected by the specific surface area of photocatalysts. Thermal desorption and gas chromatography-mass spectrometry measurements suggested the decomposition of residual glycolic acid in TiO2 nanorods at 272 and 590 °C. Observation with scanning electron microscopy and physical properties such as specific surface area and crystallite size indicated deformation of the rod shape to subsphere by the calcination above 600 °C. Time-resolved microwave conductivity measurements have revealed that the TiO2 nanorods possess the longest lifetime of photogenerated electrons among all samples. However, the O2 evolution rate of the TiO2 nanorods was much lower than subsphere TiO2 obtained by calcination at 800 °C (TiO2-800). Photodeposition of Pt and PbO2 showed that the oxidation and the reduction sites were separated on TiO2-800 whereas their deposition distributed uniformly on the TiO2 nanorods. The Pt loading on the surface of the TiO2 nanorods increased the O2 evolution rate whereas that on TiO2-800 was hardly affected, indicating that the Pt loading enhances the charge separation on the surface of the TiO2 nanorods. Therefore, the lower photocatalytic activity of the TiO2 nanorods is ascribed to the recombination process on the surface. The suppression of the recombination on the surface and thereby the utilization of the long lifetime of the photogenerated electrons is the key factor to develop superior TiO2 nanorods for photocatalysis.

Ion Gel Network Formation in an Ionic Liquid Studied by Time-Resolved Small-Angle Neutron Scattering
A. Ishikawa, T. Sakai, K. Fujii
J. Phys. Chem. B, 2018, 40, 9419-9424.
DOI : 10.1021/acs.jpcb.8b08111

Abstract: We report the time-resolved small-angle neutron scattering (SANS) study of tetra-arm poly(ethylene glycol) (TetraPEG) polymer network formation in a typical ionic liquid (IL), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([C2mim][TFSA]). To observe time-dependent SANS profiles, the reaction rate for the AB-type cross-end coupling reaction of TetraPEG macromers was controlled by adding an analogous protic IL, 1-ethylimidazolium TFSA ([C2imH][TFSA]). At polymer concentrations higher than the overlap concentration (c*), the SANS profile remained unchanged during the gelation reaction, indicating that the network structure was independent of macromer connectivity in a semidiluted solution. On the other hand, at low polymer concentrations, an increase in the SANS profile intensity was clearly observed. The correlation length (ξ), estimated by a fitting analysis based on the Ornstein–Zernike function, increased as the reaction proceeded. This result indicated that the sparsely dispersed macromers formed clusters during the cross-linking process and polymer size growth followed thereafter. We found that the network formation process and homogeneity of the network structure were strongly dependent on the polymer concentration in IL solutions.

Optical Trapping and Orientation Manipulation of 2D Inorganic Materials using a Linearly Polarized Laser Beam
H. Moritomo, S. Onishi, N. Asamura, K. Matsumoto, Y. Suzuki, J. Kawamata
MRS Comm., 2018, 8, 1064-1069.
DOI: 10.1557/mrc.2018.143

Abstruct: We investigate the two-photon absorption characteristics of hemicyanine dyes that exhibit a one-photon absorption at around 500 nm. The dyes exhibited two-photon-induced fluorescence upon irradiation with an Yb-doped femtosecond fiber laser operating at 1030 nm. Among the dyes, 4-[4-[4-(dimethylamino)phenyl]-1,3-butadienyl]-1-ethyl-pyridinium perchlorate exhibited the most efficient two-photon-induced fluorescence at 1030 nm. Since these dyes possess cationic moiety, the dyes accumulated in the mitochondria of a living cell. Two-photon images of mitochondria were obtained by staining living HEK293 cells with these dyes. When 4-[4-[4-(dimethylamino)phenyl]-1,3-butadienyl]-1-ethyl-pyridinium perchlorate was employed, a two-photon-induced fluorescence image could be obtained even when a 3 mW fiber laser beam was used as the excitation source.

Factors Affecting Photocatalytic Activity of Visible Light-Responsive Titanium Dioxide Doped with Chromium Ions
N. Nishiyama, K. Kozasa, T. Okajima, M. Fujitsuka, T. Majima, S. Yamazaki
Catal. Sci. Technol., 2018, 8, 4726-4733.
DOI: 10.1039/c8cy01411f

Abstract: Titanium dioxide doped with Cr ions (Cr-TiO2) was synthesized by a sol-gel method, with only water as the solvent, and dialysis. For Cr-TiO2 sintered at 200 °C, ca. 90% of 4-chlorophenol (4-CP) was degraded at Cr doping amounts of 0.68–1.3 atom% under visible light irradiation. At doping amounts above 1.7 atom%, the 4-CP degradation ratio increased for Cr–TiO2 sintered at 300–500 °C. X-ray photoelectron spectroscopy and X-ray absorption near edge structure measurements showed that only Cr(III) was present on the surfaces of Cr–TiO2 samples sintered at 200 or 400 °C and some of the Cr(III) in the bulk was oxidized to Cr(VI) by sintering at 400 °C. The 4-CP degradation was enhanced with increasing Cr(VI)/Cr(III) ratio in the bulk, suggesting the spatial separation of Cr(III) on the surface under visible light irradiation: electrons are excited from Cr(III) to the conduction band of TiO2 and then trapped at the doped Cr(VI) whereas the photogenerated Cr(IV) oxidizes 4-CP. Time-resolved diffuse reflectance spectroscopy was used to evaluate the lifetimes of the photogenerated electrons. The highest photocatalytic activity was obtained with ca. 0.8 atom% Cr–TiO2 sintered at 200 °C. This high activity is ascribed to the presence of oxygen vacancies, which act as electron-trapping sites.

Rotation of Stress Fibers as A Single Wheel in Migrating Fish Keratocytes
C. Okimura, A. Taniguchi, S.i Nonaka Y. Iwadate
Sci. Rep., 2018, 8, 10615.
DOI : 10.1038/s41598-018-28875-z

Abstract: Crawling migration plays an essential role in a variety of biological phenomena, including development, wound healing, and immune system function. Keratocytes are wound-healing cells in fish skin. Expansion of the leading edge of keratocytes and retraction of the rear are respectively induced by actin polymerization and contraction of stress fibers in the same way as for other cell types. Interestingly, stress fibers in keratocytes align almost perpendicular to the migration-direction. It seems that in order to efficiently retract the rear, it is better that the stress fibers align parallel to it. From the unique alignment of stress fibers in keratocytes, we speculated that the stress fibers may play a role for migration other than the retraction. Here, we reveal that the stress fibers are stereoscopically arranged so as to surround the cytoplasm in the cell body; we directly show, in sequential three-dimensional recordings, their rolling motion during migration. Removal of the stress fibers decreased migration velocity and induced the collapse of the left-right balance of crawling migration. The rotation of these stress fibers plays the role of a “wheel” in crawling migration of keratocytes.

Cobalt-Doped Goethite-Type Iron Oxyhydroxide (α-FeOOH) for Highly Efficient Oxygen Evolution Catalysis
D. Inohara, H. Maruyama, Y. Kakihara, H. Kurokawa, M. Nakayama
ACS Omega., 2018, 3, 7840-7845.
DOI : 10.1021/acsomega.8b01206

Abstract: It is an urgent challenge to develop low-cost and high-performance catalysts for the oxygen evolution reaction (OER). We synthesized nanoparticulate electrocatalysts consisting of cobalt-doped goethite-type iron oxyhydroxide (α-FeOOH) with controlled Co/Fe ratios [CoxFe1–xOOH (x ≤ 0.20)] based on our own wet process. A Co0.20Fe0.80OOH-coated glassy carbon electrode generated a current density (j) of 10 mA cm–2 at an overpotential (η) as small as 383 mV (1.61 V vs the reversible hydrogen electrode) in an alkaline electrolyte, with a small Tafel slope of 40 mV dec–1 and excellent durability, whereas pure α-FeOOH required η = 580 mV to reach the same current density. This can be ascribed to the effect of Co doping, which resulted in an increase in electrochemically active surface area and a decrease in charge-transfer resistance. The content of cobalt, a scarce resource, in the catalyst is much smaller than those in most of the other Fe-based catalysts reported so far. Thus, this study will provide a new strategy of designing cost-effective and high-performance catalysts for the OER in alkaline solution.

Effect of Amino Group Protonation on the Carboxyl Group in Aqueous Glycine Observed By O1s X-Ray Emission Spectroscopy
Y. Horikawa, T. Tokushima, O. Takahashi, Y. Harada, A. Hiraya, S. Shin
Phys. Chem. Chem. Phys., 2018, 20, 23214-23221.
DOI : 10.1039/C7CP08305J

Abstract: The valence electronic structures of the amino acid glycine in aqueous solution were investigated in detail through X-ray emission spectroscopy at O 1s excitation under selective excitation conditions of the C[double bond, length as m-dash]O site in the carboxyl group. The X-ray emission spectra of glycine were similar to that of acetic acid (CH3COOH), suggesting a resemblance between the molecular orbitals associated with the carboxyl groups in the two molecules. The changes of O 1s X-ray emission spectra as a function of pH were investigated in detail. In addition to spectral changes due to protonation/deprotonation of the carboxyl group for lower pH-values around the pKa value (∼2.3), the spectra of glycine exhibited further changes in the higher-pH region near the pKb value of glycine (dissociation constant of amino group ∼9.5). These results show the effects of amino group protonation on the electronic state around the carboxyl group. X-ray emission spectroscopy might be a tool to investigate intramolecular interactions between functional groups in a molecule.

Enhanced Oxygen Evolution Reaction Activity of Co Ions Isolated in the Interlayer Space of Buserite MnO2
K. Fujimoto, T. Okada, M. Nakayama
J. Phys. Chem. C., 2018 122, 8406-8413.
DOI : 10.1021/acs.jpcc.8b01238

Abstract: We have fabricated a thin film of layered manganese dioxide (MnO2) that accommodates cobalt ions in its interlayer space, constructing the so-called buserite structure, via electrodeposition and the subsequent ion-exchange. The MnO2 layers could isolate Co2+ ions to provide an environment beneficial for oxygen evolution reactions (OERs) in alkaline electrolyte, where fast electron transfer and high utilization efficiency were achieved. The catalyst with isolated Co2+ ions exhibited a mass activity as high as 63.5 A/gCo at an overpotential (η) of 0.4 V, which was much larger than those of Co ions bound in the oxide network. Moreover, it also exhibited excellent stability for long-term OER operation. Namely, the potential needed to generate a current density of 10 mA/cm2 increased only 0.073 V during 100 h operation, and no significant change was seen after 100 consecutive potential cycles between +1.0 and +2.0 V versus the reversible hydrogen electrode.

Chemo-Chromism in an Orthogonal Dabco-Based Co(II) Network Assembled by Methanol-Coordination and Hydrogen Bond Formation
M. Shiga, S. Kawaguchi, M. Fujibayashi, S. Nishihara, K. Inoue, T. Akutagawa, S. Noro, T. Nakamura, R. Tsunashima
Dalton Trans., 2018, 47, 7656-7662.
DOI: 10.1039/c8dt01220b

Abstruct: Newly prepared single crystals of [Co(II)(dabco)(NCS)2(MeOH)2]·dabco (1-pink; dabco: 1,4-diazabicyclo[2.2.2]octane) showed chromotropic behaviour in the solid state, changing from pink to blue upon heating or grinding. The complex 1-pink exhibited a two-dimensional orthogonal network structure with the coordination chain of –dabco–Co– bridged by hydrogen bonds between coordinative methanol and a second dabco molecule, where the methanol molecule was trapped by coordinative and hydrogen bonds. Chromism was demonstrated to stem from the quantitative desorption of methanol from 1-pink to produce [Co(II)(dabco)(NCS)2]·dabco (1-blue(c)) by thermogravimetric (TG) and temperature controlled gas chromatography-mass spectrometry (GC-MS) analyses, and powder X-ray diffraction (XRD) analysis suggests that the transformation between the crystalline phases of 1-pink and 1-blue(c) occurred with similar lattice parameters. Furthermore, the desolvated species showed chemo-chromic behaviour due to the selective size- and polarity-dependent adsorption of solvent molecules.

Synthesis and Antifungal Activities of Pyridine Bioisosteres of a Bismuth Heterocycle Derived from Diphenyl Sulfone
A.F.M. Hafizur Rahman, T. Murafuji, K. Yamashita, M. Narita, I. Miyakawa, Y.Mikata, K. Ishiguro, S. Kamijo
Heterocycles, 2018, 96, 1037-1052.
DOI: 10.3987/COM-18-13876

Abstruct: Heterocyclic iodobismuthanes 7–9 [IBi(C6H4-2-SO2C5H3N-1´-)] derived from phenyl pyridinyl sulfones were synthesized. Their antifungal activities against the yeast Saccharomyces cerevisiae were compared with those of halobismuthanes [XBi(RC6H3-2-SO2C6H4-1´-)] (1: X=Cl; 2: X=I, R=H) derived from diphenyl sulfone derivatives to determine how the bioisosteric replacement of the benzene ring in 2 with the pyridine ring in 7–9 affects their activities. The antifungal activities of 7–9 were higher or comparable to those of 1 and 2. The DFT calculations suggested that the generation of the antifungal activity of the bismuthanes was well understood by the nucleophilic addition of methanethiolate anion as a model biomolecule at the bismuth atom to give an intermediate ate complex.

Effect of Dispersants on Photochromic Behavior of Tungsten Oxide Nanoparticles in Methylcellulose
S. Yamazaki, D. Shimizu, S. Tani, K. Honda, M. Sumimoto, K. Komaguchi
ACS Appl. Mater. Interfaces, 2018, 10, 19889-19896.
DOI: 10.1021/acsami.8b04875

Abstract: Tungsten oxide-based photochromic films that change reversibly in air between colorless-transparent in the dark and dark blue under UV irradiation were prepared by using methylcellulose as a film matrix and various dispersants. Alpha-hydroxyl acid such as glycolic acid (GA) or glyceric acid (GlyA) is the best dispersant because it can make the film transparent by adding a small quantity much less than that of 3-hydroxypropionic acid or ethylene glycol. Fourier-transform infrared spectra and Raman spectra indicate that a strong interaction exists between WO3 and GA or GlyA. The coloration and bleaching processes of the prepared films were investigated to clarify the effect of the dispersants and the moisture contents. The bleaching rate remarkably decreased in the films containing GA or GlyA but accelerated by increasing the contact with O2. Measurements of electron-spin resonance reveals that GA and GlyA as dispersants stabilize the W5+ state. This paper shows that the coloring rate and the period for keeping the blue-colored state are tunable by changing the dispersants. The photochromic films containing α-hydroxyl acid as the dispersant have the potential for application as rewritable film on which information displayed with blue-colored state can be clearly readable for longer times compared with other dispersants.

Hydrogen Bonds of the Imidazolium Rings of Ionic Liquids with DMSO Studied by NMR, Soft X-ray Spectroscopy, and SANS
T. Takamuku, T. Tokuda, T. Uchida, K. Sonoda, B.A. Marekha, A. Idrissi, O. Takahashi, Y. Horikawa, J. Matsumura, T. Tokushima, H. Sakurai, M. Kawano, K. Sadakane, H. Iwase
Phys. Chem. Chem. Phys., 2018, 20, 12858-12869.
DOI : 10.1039/C8CP00963E

Abstract: The hydrogen bonds of the imidazolium-ring H atoms of ionic liquids (ILs), 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amides ([Cnmim][TFSA], n = 2 to 12 where n represents the alkyl chain length), with the O atom of dimethyl sulfoxide (DMSO) have been elucidated using 1H, 13C, and 15N NMR spectroscopy and soft X-ray absorption and emission spectroscopy (XAS and XES). Density functional theory (DFT) calculations have been performed on an isolated DMSO molecule and two cluster models of [Cnmim]+–DMSO by hydrogen bonding to interpret the XES spectra for the [Cnmim][TFSA]–DMSO solutions. The 1H and 13C NMR chemical shifts of the imidazolium ring showed that deshielding of the ring H and C atoms is moderate as the DMSO mole fraction xDMSO increases to ∼0.8; however, it becomes more significant with further increase of xDMSO. This finding suggests that the hydrogen bonds of the three ring H atoms with the DMSO O atoms are saturated in solutions with xDMSO increased to ∼0.8. The 1H and 13C chemical shifts of the alkyl chains revealed that the electron densities of the chain H and C atoms gradually decrease with increasing xDMSO, except for the N1-bound carbon atom C7 of the chain. The 15N NMR chemical shifts showed that the imidazolium-ring N1 atom which is bound to the alkyl chain is shielded with increasing xDMSO in the range from 0 to 0.8 and is then deshielded with further increase of xDMSO. In contrast, the imidazolium ring N3 atom is simply deshielded with increasing xDMSO. Thus, the electron densities of the alkyl chain may be condensed at the C7 and N1 atoms of [Cnmim]+ by the hydrogen bonding of the ring H atoms with DMSO. The hydrogen bonding of DMSO with the ring results in low-energy shifts of the XES peaks of the O K-edge of DMSO. Small-angle neutron scattering experiments showed that [Cnmim][TFSA] and DMSO are homogeneously mixed with each other on the mesoscopic scale. This results from the strong hydrogen bonds of DMSO with the imidazolium-ring H atoms.

Stimuli-Triggered Reversible Switching Mechanism between H- and J-Type Supramolecular Assemblies of Cationic Porphyrins Adsorbed on Tungsten(VI) Oxide Surface
K. Adachi, Y. Ura, N. Kanetada
J. Porphyrins Phthalocyanines, 2018, 22, 658-669.
DOI : 10.1142/S1088424618500372

Abstract: Supramolecular organic dye–inorganic semiconductor nanocrystal assemblies are potentially useful in a broad range of technologies and applications, including photovoltaic systems, but the molecular basis of the adsorption of dye molecules onto the semiconductor surfaces remains poorly understood. Herein, we investigated the pH-dependent adsorption and conformational change of two cationic porphyrin stereoisomers [5,10-diphenyl-15,20-di(N-methyl-4-pyridyl)porphyrin (cis-DMPyP) and 5,15-diphenyl-10,20-di(N-methyl-4- pyridyl)porphyrin (trans-DMPyP)] on the tungsten(VI) oxide (WO3) colloid nanoparticle in aqueous media by means of UV-vis absorption spectroscopy. In accordance with the combination of a modified Langmuir adsorption model and Kasha’s exciton coupling model, the molecular orientation and stacking arrangement of DMPyP derivatives on the WO colloid surface are discussed in detail. In the trans-DMPyP/WO3 aqueous system, trans-DMPyP molecules adopted flat-on orientation with respect to the WO colloid surface and eventually formed head-to-tail J-dimers regardless of pH conditions. cis-DMPyP molecules in the acidic system also lay flat-on and mainly formed H-dimers on the WO3 colloid surface, whereas ones in the neutral system exhibited a dominant edge-on orientation and had a higher tendency to form face-to-face -dimers. Additionally, we have also convincingly demonstrated the pH-triggered switchable π-stacking geometry of cis-DMPyP molecules from H- to J-dimer and vice versa on the WO3 colloid surface. Such findings will undoubtedly provide a pertinent guideline for the rational design of stimuli-responsive organic-inorganic materials.

 

Radiation Pressure Induced Hierarchical Structure of Liquid Crystalline Inorganic Nanosheets
M. Tominaga, T. Nagashita, T. Kumamoto, Y. Higashi, T. Iwai, T. Nakato, Y. Suzuki, J. Kawamata
ACS Photonics, 2018, 5, 1288–1293
DOI: 10.1021/acsphotonics.7b01230

Abstruct: Although hierarchical assemblies of colloidal particles add novel structure-based functions to systems, few local and on-demand colloidal structures have been developed. We have combined the colloidal liquid crystallinity of two-dimensional inorganic particles and laser radiation pressure to obtain a large hierarchical and local structure in a colloidal system. The scattering force of the laser beam converted the parallel nanosheet alignment to the direction of the incident laser beam. At the focal point, the nanosheet orientation depends on the electric field of the polarized laser beam. In contrast, a giant tree-ring-like nanosheet texture of more than 100 μm, and which is independent of the polarization direction, was organized at the periphery of the focal point. This organization resulted from a cooperative effect between the liquid-crystalline nanosheets, which indicates an effectiveness of optical manipulation to construct hierarchical colloidal structures with the aid of interparticle interactions.

アクチンレトログレードフローの意味
岩楯好昭
実験医学, 2018, 36, 61-62.

Synthesis of 2-Iodoazulenes by the Iododeboronation of Azulen-2-ylboronic Acid Pinacol Esters with Copper(I) Iodide
M. Narita, T. Murafuji, S. Yamashita, M. Fujinaga, K. Hiyama, Y. Oka, F. Tani, S. Kamijo, K. Ishiguro
J. Org. Chem., 2018, 83, 1298–1303
DOI : 10.1021/acs.joc.7b02820

Abstract: Azulen-2-ylboronic acid pinacol ester, prepared by iridium-catalyzed C–H borylation of azulene, efficiently underwent iododeboronation with a stoichiometric amount of copper(I) iodide. This reaction allowed the synthesis of 2-iodoazulene in only two steps starting from azulene. This methodology was successfully applied to analogous azulenes.

Effect of Mixed Valence States of Platinum Ion Dopants on the Photocatalytic Activity of Titanium Dioxide under Visible Light Irradiation
N. Nishiyama, S. Yamazaki
ACS Omega, 2017, 2, 9033-9039.
DOI: 10.1021/acsomega.7b01393

Abstract: Titanium dioxide doped with the Pt ion (Pt–TiO2) was synthesized by a sol–gel method using only water as the solvent and conducting dialysis. The photocatalytic activity for the degradation of 4-chlorophenol (4-CP) on Pt–TiO2 was not affected by the Brunauer–Emmett–Teller specific surface area under visible light (VL) irradiation. X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure measurements revealed that only the Pt(IV) ion existed in the TiO2 bulk and both Pt(II) and Pt(IV) were present near the Pt–TiO2 surface. Pt(IV) is most likely substituted in the Ti(IV) site of the TiO2 lattice because of their similar ionic sizes. Quantitative analysis of Pt(II) was performed in the XPS measurements, indicating that the amount of Pt(II) on the surface increased with an increase in the doping amount from 0.2 to 1.0 atom %. We synthesized 0.5 atom % Pt–TiO2 with various Pt(II)/Pt(IV) ratios by changing the Ti(OC3H7)4 concentration used in the sol–gel synthesis. The 4-CP conversion on Pt–TiO2 increased linearly with an increase in the Pt(II)/Pt(IV) ratios. A similar relationship was obtained with Pt–TiO2, which was prepared by a conventional sol–gel method in ethanol–water mixed solvent. Therefore, the Pt(II)/Pt(IV) ratio is a key factor affecting the photocatalytic activity of Pt–TiO2 under VL irradiation. Our results indicate that controlling the mixed valence states of the doped metal ions is a new strategy to developing highly active metal-ion-doped TiO2 under VL irradiation.

Optical Trapping and Orientation Manipulation of 2D Inorganic Materials using a Linearly Polarized Laser Beam
M. Tominaga, Y. Higashi, T. Kumamoto, T. Nagashita, T. Nakato, Y. Suzuki, J. Kawamata
Clays and Clay Minerals, 2018, ASAP.
DOI: 10.1346/CCMN.2017.064075

Abstruct: Owing to the large anisotropy of inorganic nanosheets, such as clay minerals, the orientation manipulation of nanosheets is an important challenge for realizing future functional materials. In this study, the methodology for a novel nanosheet manipulation by using laser radiation pressure is proposed. When a linearly polarized laser beam was used to irradiate a niobate nanosheet colloid, the nanosheet was trapped at the focal point so that its in-plane direction was oriented parallel to the propagation direction of the incident laser beam so as to minimize the scattering force. In addition, the trapped nanosheet was aligned along the polarization direction of the linearly polarized laser beam. Thus, a unidirectional alignment of nanosheet can be realized simply by irradiation with a laser beam.

Hydration Structure of Trimethylamine N-Oxide in Aqueous Solutions as Illuminated by Soft X-Ray Emission Spectroscopy and Chemometric Analysis
T. Ishihara, T. Tokushima, Y. Horikawa, M. Kato, I. Yagi
Rev. Sci. Instrum., 2017, 88, 104101.
DOI : 10.1063/1.4997820

Abstract: We developed a spectro-electrochemical cell for X-ray absorption and X-ray emission spectroscopy, which are element-specific methods to study local electronic structures in the soft X-ray region. In the usual electrochemical measurement setup, the electrode is placed in solution, and the surface/interface region of the electrode is not normally accessible by soft X-rays that have low penetration depth in liquids. To realize soft X-ray observation of electrochemical reactions, a 15-nm-thick Pt layer was deposited on a 150-nm-thick film window with an adhesive 3-nm-thick Ti layer for use as both the working electrode and the separator window between vacuum and a sample liquid under atmospheric pressure. The designed three-electrode electrochemical cell consists of a Pt film on a SiC window, a platinized Pt wire, and a commercial Ag|AgCl electrode as the working, counter, and reference electrodes, respectively. The functionality of the cell was tested by cyclic voltammetry and X-ray absorption and emission spectroscopy. As a demonstration, the electroplating of Pb on the Pt/SiC membrane window was measured by X-ray absorption and real-time monitoring of fluorescence intensity at the O 1s excitation.

Selective MeCN/EtCN Sorption and Preferential Inclusion of Substituted Benzenes in a Cage Structure with Arylsulfonamide-Armed Anthraquinones
T. Takeda, S. Noro, T. Nakamura, Y. Suzuki, J. Kawamata, T. Akutagawa
CrystEngComm, 2018, 20, 17-24 .
DOI: 10.1039/c7ce01752a

Abstruct: We report a series of crystal structures of arylsulfonamide-armed anthraquinones (AQs) (1–4). The arylsulfonamide-armed AQs formed orthogonal aromatic arrangements between the AQ unit and terminal aryl units due to well-defined intramolecular hydrogen bonding between the carbonyl units of AQs and the amino groups of sulfonamide units. Three disubstituted AQs 1–3 formed fundamental dimer structures, which were stabilized by intermolecular π–π interaction between AQs. Subtle differences in the dimer structures led to different packing structures. Among them, the 1,8-bis(arylsulfonamide) derivative (1) formed solvated crystals of 1·(MeCN), which exhibited reversible and selective MeCN and/or EtCN adsorption–desorption behavior. Tetra(arylsulfonamide) AQ (4) with four bulky substituents on its periphery formed various host–guest molecular crystals of 4·X2 (X = toluene, xylene, trimethylbenzenes, 1,2,3,5-tetramethylbenzene, anisole, and benzonitrile) with a rectangular zero-dimensional cage surrounded by the π-planes of 4.

Label-free Colorimetric Sensing of α-Amino Acids Based on Surface-enhanced Photochromic Phenomena of Molybdenum(VI) Oxide Nanoparticles
A. Yamamoto, K. Adachi
Bunseki Kagaku (分析化学), 2017, 66, 639-646.
DOI : 10.2116/bunsekikagaku.66.639

Abstract: Due to the biological importance of α-amino acids and their derivatives, the development of novel colorimetric probes for these molecules has been an active research area in recent years. In this study, surface-enhanced photochromic phenomena by various α-amino acids (L-aspartic acid [Asp], L-leucine [Leu], and L-lysine [Lys]) adsorbed on molybdenum(VI) oxide (MoO3) nanoparticles in an aqueous system were investigated by means of UV-vis absorption spectrometry. No derivatization of α-amino acids is required, and eventually highly accurate determinations are obtained from the UV-induced MoO3 photochromic coloration. Under optimal conditions in this system, limit of quantitation (LOQ) values of 3.45×10-6, 2.08×10-6, and 1.53×10-6 mol dm-3 for Asp, Leu, and Lys, respectively, were achieved at pH 2. During UV irradiation, the detection process could be visually observed by naked eyes. A simple and unique approach to explore sensitive "label-free" colorimetric sensing toward α-amino acids is proposed.

 

Inter-cluster distance dependence of electrical properties in single crystals of a mixed-valence polyoxometalate
R. Tsunashima, I. Nakamura, R. Oue, S. Koga, H. Oki, S. Noro, T. Nakamura, T. Akutagawa
Dalton Trans., 2017, 46, 12619-12624
DOI: 10.1039/C7DT02623D

Abstruct: The electrical conductivity of mixed-valence [MoV2MoVI16O54(SO3)2]6− tetraalkylammonium salts was investigated through dependence on the inter-cluster distance that is controlled by tetraethylammonium, tetrapropylammonium, and tetrabutylammonium cations. The crystallographic analysis of single crystals revealed that the inter-cluster distances are dependent on the chain length of the alkyl groups on the counter cations. In addition, the electrical conductivities of the single crystals were found to be dependent on both temperature and chain length. Mixed-valence polyoxometalate (POM) clusters are considered to be a molecular particle of Mo bronze by which highly ordered networks will be developed using single crystals, where POMs are rather small and have a well-organized structure compared to colloidal nanostructures.

Directional Cell Migration in Response to Repeated Substratum Stretching
C. Okimura, Y. Iwadate
J. Phys. Soc. Jpn., 2017, 86, 101002.
DOI : 10.7566/JPSJ.86.101002

Abstract: Crawling migration plays an essential role in a variety of biological phenomena, including development, wound healing, and immune system function. Migration properties such as anterior-posterior polarity, directionality, and velocity are regulated not only by the reception of a chemoattractant but also by sensing mechanical inputs from the external environment. In this review, we describe the mechanical response of migrating cells, particularly under repeated stretching of the elastic substratum, highlighting the fact that there appear to be two independent mechanosensing systems that generate the polarity needed for migration. Cells that have no stress fibers, such as Dictyostelium cells and neutrophil-like differentiated HL-60 cells, migrate perpendicular to the stretching direction via myosin II localization. Cells that do possess stress fibers, however, such as fish keratocytes, migrate parallel to the stretching via a stress-fiber-dependent process.

The Emergent Intramolecular Hydrogen Bonding Effect on the Electronic Structures of Organic Electron Acceptors
T. Takeda, Y. Suzuki, J. Kawamata, S. Noro, T. Nakamura, T. Akutagawa
Phys. Chem. Chem. Phys., 2017, 19, 23905-23909.
DOI: 10.1039/C7CP04402J

Abstruct: A new strategy for controlling the electron-accepting ability of an anthraquinone (AQ)-based π-molecular system is proposed to take advantage of intramolecular hydrogen bonding interactions. The electron-accepting properties of AQ are enhanced by the introduction of bulky arylsulfonamide groups into AQ derivatives due to the formation of effective intramolecular N–H⋯O hydrogen bonding interaction and stabilization of the anion radical state even in solution.

Effect of Mixed Valence States of Platinum Ion Dopants on the Photocatalytic Activity of Titanium Dioxide under Visible Light Irradiation
T. Seyama, T. Tanimura, K. Tashiro, S. Yamazaki
Res. Chem. Intermed., 2017, 43, 5025-5039.
DOI: 10.1007/s11164-017-3051-z

Abstract: Porous platinum ion-doped TiO2 (Pt–TiO2) was prepared by a sol–gel method and demonstrated to have superior photocatalytic activity for the photodegradation of gaseous trichloroethylene (TCE) under visible light (VL) irradiation from a xenon lamp equipped with 422-nm cut-off filter. Kinetic studies were performed to clarify the effect of the doping amounts, space times, VL intensity, and mole fractions of TCE, O2, and H2O on the degradation of TCE. Under ultraviolet (UV) irradiation, the photocatalytic activity of Pt–TiO2 was the same as that of TiO2, indicating that the doped Pt ion did not act as a recombination center for the photogenerated holes and electrons. Based on the kinetic data and reaction products, we conclude that the photocatalytic degradation of TCE on Pt–TiO2 under VL irradiation proceeds similarly to TiO2 under UV irradiation. We also performed the photocatalytic degradation of TCE at the space time of 7.5 ×107 g s mol−1 in a tubular reactor packed with the Pt–TiO2 pellets which are more suitable than the Pt–TiO2 powder for the practical remediation of the contaminated gas. TCE was completely degraded, i.e. 100% conversion was achieved under VL irradiation but only a small quantity of CO2 was formed with the stoichiometric ratio of [CO2]formed/[TCE]degraded of ca. 0.33. By switching the gas stream containing TCE to humid air, more CO2 was formed, indicating that the dichloroacetates accumulated on the Pt–TiO2 surface are photodegradable to CO2 under VL irradiation.

自動車部材・建材用途を指向した湿気反応性高速硬化型樹脂化合物
－シラン架橋ポリオレフィン複合体を中心に－
Crosslinked Polyolefins for Automotive and Housing Sector: Nontoxic and Efficient Catalysts for Water-Crosslinking Reaction in the Alkoxysilane-Grafted Polyolefin System
安達健太
MATERIAL STAGE., 2017, 17, 49-52.

Resonant Inelastic X-Ray Scattering and Photoemission Measurement of O2: Direct Evidence for Dependence of Rydberg-Valence Mixing on Vibrational States in O1s → Rydberg States
T. Gejo, M. Oura, T. Tokushima, Y. Horikawa, H. Arai, S. Shin, V. Kimberg, N. Kosugii
J. Chem. Phys.,2017, 147, 044310.
DOI : 10.1063/1.4994895

Abstract: High-resolution resonant inelastic x-ray scattering (RIXS) and low-energy photoemission spectra of oxygen molecules have been measured for investigating the electronic structure of Rydberg states in the O 1s → σ* energy region. The electronic characteristics of each Rydberg state have been successfully observed, and new assignments are made for several states. The RIXS spectra clearly show that vibrational excitation is very sensitive to the electronic characteristics because of Rydberg-valence mixing and vibronic coupling in O2. This observation constitutes direct experimental evidence that the Rydberg-valence mixing characteristic depends on the vibrational excitation near the avoided crossing of potential surfaces. We also measured the photoemission spectra of metastable oxygen atoms (O*) from O2 excited to 1s → Rydberg states. The broadening of the 4p Rydberg states of O* has been found with isotropic behavior, implying that excited oxygen molecules undergo dissociation with a lifetime of the order of 10 fs in 1s → Rydberg states.

A Dielectric Anomaly Observed for Doubly Reduced Mixed-Valence Polyoxometalate
I. Nakamura, R. Tsunashima, S. Nishihara, K. Inoue, T. Akutagawa
Dalton Trans., 2017, 46, 12619-12624
DOI: 10.1039/C7CC03361C

Abstruct: Benzimidazolium is revealed to form quasi-isostructural crystals of mixed-valence molecular metal oxides that consist of [PMoV2MoVI10O40]5− and fully oxidized [BWVI12O40]5−. The structure and dielectric behaviour were compared and a dielectric anomaly was evident due to the electric dipole relaxation in the mixed-valence system.

運動性線毛群が示すメタクロナールウェーブの伝播メカニズム
岩楯好昭
実験医学, 2017, 35, 1320-1321.

The Effect of The Negative Charge Density on Switchable Properties of Pseudoisocyanine Dye
M. Matejdes, D. Himeno, Y. Suzuki, J. Kawamata
Appl. Clay Sci., 2017, 144, 54–59
DOI: 10.1016/j.clay.2017.05.005

Abstruct: The effect of Na-montmorillonite (Mt) and synthetic stevensite (Ste) on the switchable properties of intercalated cationic cyanine dye, 1,1′-diethyl-2,2′-cyanine (pseudoisocyanine, PIC) was investigated. The switching between non-aggregated and J-type aggregated states of PIC was performed by adding and removing of dimethyl sulfoxide (DMSO) from the interlayer space. It was found that the photophysical properties of PIC after addition of DMSO are significantly influenced by the negative charge density of layered silicate. Due to this effect the J-type aggregates were after swelling with DMSO formed only in the PIC/Mt hybrid films. Photophysical response and the stability of PIC species in PIC/Mt hybrid film was tested within 20 cycles of adding and removing of DMSO from the interlayer space. During these cycles the stability of PIC species was proved to be sufficient, indicating that presented experimental approach is able to enhance the use and scope of materials consisting of J-type dye molecular assemblies.

XAS and XES Study of Carbonate and Bicarbonate Ions in Aqueous Solution
N. Nishida, Y. Horikawa, T. Tokushima, O. Takahashi
J. Electron Spectrosc., 2017, 220, 96-100.
DOI : 10.1016/j.elspec.2016.12.006

Abstract: We perform theoretical calculations to reproduce the site-selective X-ray emission spectroscopy (XES) spectrum for carbonate and bicarbonate ions in aqueous solution at the oxygen K-edge. We perform structure sampling, and using an ab initio molecular dynamics simulation, we reproduce the solute-solvent model. Relative XES peak intensities with core-hole excited state molecular dynamics simulations are calculated using density functional theory. A comparison of several models shows that a cluster model with surrounding water can describe the experimental XES spectra, and these calculations provide electronic and molecular structure information in an aqueous solution.

基礎講座　水―最も身近な液体の科学
徳島高，石原知子，堀川裕加
現代化学，2017(4)，29-35.

Synthesis and Structural Characterization of Diazulenylborinic Acid
T. Murafuji, K. Shintaku, K. Nagao, Y. Mikata, K. Ishiguro, S. Kamijo
Heterocycles, 2017, 94, 2676-690.
DOI: 10.3987/COM-17-13651

Abstruct: Diazulenylborinic acid 1 was synthesized by the reaction of 1,3-dibromoazulen-2-yllithium (2) with 1,3-dibromoazulen-2-ylboronic acid ethylene glycol ester (7d). The X-ray crystallographic study of 1 revealed that it forms a dimeric structure through intermolecular hydrogen bonding between the hydroxyl groups. To obtain the tetracoordinate borinate derivative from 1, the attempted esterification of 1 with N,N-dimethylethanolamine did not give corresponding borinate 8 but resulted in the unexpected protodeboronation to give parent 1,3-dibromoazulene (4). The 13C and 11B NMR studies of 1 in the presence of Et3N revealed the change in the π-polarization of the azulenyl group accompanied by the change in the geometry of the boron to a tetracoordinate structure.

Aryl Ketone Catalyzed Radical Allylation of C(sp3)–H Bonds under Photoirradiation
S. Kamijo, K. Kamijo, T. Murafuji
J. Org. Chem., 2017, 82, 2664–2671.
DOI: 10.1021/acs.joc.6b03058

Abstruct: The synthesis of alkylated pyrimidines was achieved via benzophenone-mediated photoinduced coupling between saturated heterocycles and sulfonylpyrimidines. The pyrimidine ring was selectively introduced at the nonacidic C(sp3)–H bond proximal to heteroatoms including oxygen, nitrogen, and sulfur. This is a coupling reaction mediated solely by photoexcited benzophenone, an organic molecule, without the aid of any metallic catalysts or reagents.

Controlled Formation of Pseudoisocyanine J-Aggregates in the Interlayer Space of Synthetic Saponite
M. Matejdes, D. Himeno, Y. Suzuki, J. Kawamata
Appl. Clay Sci., 2017, 140, 119–123
DOI: 10.1016/j.clay.2017.02.007

Abstruct: In presented work dye assemblies with J-type intermolecular coupling, which are well recognized not only for their exciton transport but also for hole and electron transport properties were investigated. The use of materials consisting of J-type dye assemblies can be significantly enhanced if their photonic properties can be controlled by some external stimuli. For these reasons the switching abilities between J-type aggregated and non-aggregated states of a cationic cyanine dye, 1,1′-diethyl-2,2′-cyanine (pseudoisocyanine, PIC) intercalated in the interlayer space of synthetic saponite (Sap) were compared. The switching was performed by adding and removing of dimethyl sulfoxide (DMSO) from the interlayer space. The PIC/Sap hybrid film prepared at 70% CEC loading level has shown excellent stability within 20 cycles of photophysical response after adding and removing of DMSO from the interlayer space, indicating that presented experimental approach can be useful in the future development of artificial light harvesting or semiconductor systems with controllable properties.

Gel-Electrophoretic Chromatography of Polyoxometalate Clusters in Aqueous Solution
R. Tsunashima
Polyoxometalate-Based Assemblies and Functional Materials, 121-137.
DOI: 10.1007/430_2017_4

Abstruct: In this chapter, how the electrophoresis works in polyoxometalate chemistry was summarized in detail. Since POM clusters are too small for showing traditional molecular sieving effect required for separation by electrophoresis, they show differences in electrophoretic mobility. The mobility is well understood by a correlation between the cluster mobility and structurally determined surface charge density. By observing these mobility differences in mixed POM solutions, each component can be separated. The electrophoretic chromatography for POMs is now discussed for a genuine analytical technique for investigation of cluster species in solution.

 

Synthesis, Characterization, and Structure of a Reduced Preyssler-type Polyoxometalate
C. Kato, K.Y. Maryunina, K. Inoue, S. Yamaguchi, H. Miyaoka, A. Hayashi, M. Sadakane, R. Tsunashima, S. Nishihara
Chem. Lett., 2017, 46, 602-604.
DOI: 10.1246/cl.170015

Abstruct: We report the synthesis of a reduced Preyssler-type polyoxometalate (POM), using Ag-containing POM. Both parent and reduced clusters were obtained in the monocrystalline form, allowing structure determination by single-crystal X-ray diffraction. Furthermore, X-ray photoelectron spectroscopy, cyclic voltammetry, and magnetic susceptibility measurements suggested that the reduced cluster exhibits a valence of −23 and the Ag present in the reduced POM exists in a neutral state.

Fabrication of Optical Gap Selective Amorphous Carbon Photocatalyst for Hydrogen Production under Irradiation with Visible Light
K. Okafuji, R. Kobayashi, S. Ohtomo, H. Naragino, K. Honda
ECS Trans., 2017 75, 57-74.
DOI: 10.1149/07550.0057ecst

Abstruct: Diazulenylborinic acid 1 was synthesized by the reaction of 1,3-dibromoazulen-2-yllithium (2) with 1,3-dibromoazulen-2-ylboronic acid ethylene glycol ester (7d). The X-ray crystallographic study of 1 revealed that it forms a dimeric structure through intermolecular hydrogen bonding between the hydroxyl groups. To obtain the tetracoordinate borinate derivative from 1, the attempted esterification of 1 with N,N-dimethylethanolamine did not give corresponding borinate 8 but resulted in the unexpected protodeboronation to give parent 1,3-dibromoazulene (4). The 13C and 11B NMR studies of 1 in the presence of Et3N revealed the change in the π-polarization of the azulenyl group accompanied by the change in the geometry of the boron to a tetracoordinate structure.

Direct Growth of Birnessite-Type MnO2 on Activated Carbon Cloth for a Flexible Supercapacitor
M. Nakayama, K. Kaneshige, K. Kominea
ECS Trans., 2017 75, 19-32.
DOI : 10.1149/07536.0019ecst

Abstract: A piece of commercially-available carbon cloth (CC) was treated using a simple wet method and then served as a substrate for the direct growth of MnO2 via an electrochemical process. The treated CC electrode allowed the deposition of a large amount of MnO2 while maintaining its electrochemical utilization efficiency. The optimal mass loading of MnO2 was determined to be 4.27 mg cm-2, a level that gave an areal capacitance of 568 mF cm-2 at a scan rate of 2 mV s-1. This MnO2/CC piece was employed in conjunction with an activated carbon-coated CC section as the positive and negative electrodes, respectively, in a solid-state asymmetric supercapacitor.

A Thin Film Consisting of Stacked Graphene and the Intercalated Manganese Oxide as Efficient OER Catalyst
K. Fujimoto, T. Kobayakawa, M. Nakayama
ECS Trans., 2017 75, 9-17.
DOI : 10.1149/07549.0009ecst

Abstract: A thin film consisting of stacked graphene (GR) and manganese oxide deposits was synthesized electrochemically for oxygen evolution reaction (OER) catalyst in alkaline media. The resulting catalyst was stable in alkaline media under experimental conditions and exhibited high OER electrocatalytic activity: an onset overpotential of 315 mV and a Tafel slope of 60.0 mV per decade. These results can be attributed to a synergistic effect of the catalytic activity of nanosized Mn oxide deposits and the ability of GR to transfer electrons from the catalysts.

Eletrochemical Processing of Commercial Carbon Cloth for Supercapacitor Applications
M. Nakayama, K. Komine, D. Inohara
ECS Trans., 2017 75, 31-39.
DOI : 10.1149/07524.0031ecst

Abstract: Commercial carbon cloth was activated through a cathodic route in neutral electrolyte. The resulting specimen, electrochemically reduced carbon cloth (ER-CC), can be directly used as an electrode for supercapacitors without using polymeric binder, conductive additive, or current collector. X-ray photoelectron spectroscopy revealed that the cathodic polarization reduces the oxygen functional groups involved in the surface of CC, depending on the applied potential. The maximum areal capacitance was observed for the ER-CC piece that had been polarized at -0.8 V (vs Ag/AgCl); i.e., 143 mF cm-2 at a scan rate of 2 mV s-1.

Solid-state Structure and Electronic States of Hydrogen Bonded-dimer of Pyridyl-substituted Tetrathiafulvalene Salted with PF6−
T. Kanetou, R. Tsunashima, N. Hoshino, T. Akutagawa
RSC Adv., 2017, 7, 6236-6241.
DOI : 10.1039/C6RA27814K

Abstract: Hydrogen bonding was investigated in a newly prepared salt of pyridyl-substituted tetrathiafulvalene (TTFPy) that formed a dimer structure by hydrogen bonding and was salted with PF6− anions, namely, (TTFPy2H)PF6 (1). Structural analysis of the salt by single-crystal X-ray diffraction and temperature-dependent FTIR spectra and measurements of its electrical conductivity and dielectric properties were performed. Thermal fluctuations were investigated for protons between two TTFPy molecules. An anisotropic dielectric anomaly was observed owing to local proton transfer between two pyridyl moieties. This behavior was well explained by a model of Debye-type dipole relaxation. In addition, DFT calculations showed that the dipole originated from local proton transfer, but the dipole moment in a network of TTFPy⋯H+⋯TTFPy dimers was amplified by a factor of 2 owing to coupling with the electronic polarization of TTFPy moieties.

Solvent Triggered Transition of Electrical Conductivity of Polyoxomet-alate-Based Hybrid with Ni-Pyridyl-Tetrathiafulvalene
Y. Baba, R. Tsunashima, N. Hoshino, T. Akutagawa, S.-I. Noro, T. Nakamura
Curr. Inorg. Chem.,2016, 7 (E-pub ahead of print)
DOI : 10.2174/1877944107666171101154417

Abstract:
Background: Polyoxometalate (POM) clusters are molecular metal-oxide that possess advantages in integrating functionalities at the molecular level. Redox activity is key characteristic of the POMs where the electron-withdrawing ability is changed accord-ing to environments that surroundings POMs. Achieving switching phenomena of elec-tronic state of POMs are of great interest for various applications.

Objective: It is of fundamental interest to develop switching of electronic state of POMs by outer stimulus. For this purpose, we investigate the solvent effect to electron-withdrawing ability of POM so as to coupling with macroscopic electric property of the POM based salts.

Method: We have developed these characteristics of POMs to design CT system by hybridizing with pyridyl-tetrathiafulvalene (TTFPy) molecule. TTFPy was reacted with Ni(II) and [α-SiW12O40]4-, yielding a single crys-tal with composition of [NiII(DMSO)5(TTFPy)]2[α-SiW12O40] (1). And we have revealed that a single crystal of the compound turns crystal color from orange (1) to black (1’) by immersing crystals in methanol. In this paper, we newly analyses a structure of the single crystal 1 by X-ray diffraction analysis in addition to investigation of this chemo-chromic characteristics using varieties of organic solvent.

Results: It was revealed that solvent acceptor number was important to consider the chromic in which transition from 1 to 1’ was induced with organic solvents whose acceptor number was larger than 18. In addition, electri-cal properties of both crystals and revealed that conductivity was increased in 1’.

Conclusion: Our results show that solvent-induced chemo-chromic characteristics were trig-gered by immersing crystals in a solvent. Other chemo-chromic characteristics will be ex-plored by surrounding crystal in more ion rich environment tuned by Li+ ions toward electrode materials for Li ion batteries, for example. In addition, our findings reported here emphasize interest and importance of POM-based hybrid in which grand state is not in CT state.

Aryl Ketone Catalyzed Radical Allylation of C(sp3)–H Bonds under Photoirradiation
S. Kamijo, K. Kamijo, K. Maruoka, T. Murafuji
Org. Lett., 2016, 18, 6516-6519.
DOI: 10.1021/acs.orglett.6b03586

Abstruct: The catalytic introduction of an allyl group at nonacidic C(sp3)–H bonds was achieved under photoirradiation, in which 1,2-bis(phenylsulfonyl)-2-propene acts as an allyl source and 5,7,12,14-pentacenetetrone (PT) works as a C–H bond-cleaving catalyst. A variety of substances, including alkanes, carbamates, ethers, sulfides, and alcohols, were chemoselectively allylated in a single step under neutral conditions. The present transformation is catalyzed solely by an organic molecule, PT, and proceeds smoothly even under visible light irradiation (425 nm) in the case of alkanes as a starting substance.

Blue Amino Acids Derived from Azulen-1-ylboronic Acid Pinacol Ester via the Petasis Reaction
T. Murafuji, Y. Tasaki, M. Fujinaga, K. Tao, S. Kamijo, K. Ishiguro
Synthesis, 2017, 49, 1037-1042.
DOI: 10.1055/s-0036-1588907

Abstruct: Azulen-1-ylboronic acid pinacol ester undergoes a three-component Petasis reaction with amines and glyoxylic acid hydrate to give azulenylglycine derivatives in good yields. The progress of the reaction is indicated by a characteristic color change from violet to blue due to the altered π-conjugation of the azulene chromophore. The azulenylboronic ester is more reactive than its phenyl counterpart and even 2-styryl- and 2-thienylboronic pinacol esters, which have a strong electron-donating organyl group on boron. These results reflect the unique π-electron system of non-alternant azulene.

Clay–Organic Hybrid Films Exhibiting Reversible Fluorescent Color Switching Induced by Swelling and Drying of a Clay Mineral
M. Tominaga, Y. Oniki, S. Mochida, K. Kasatani, S. Tani, Y. Suzuki, J. Kawamata
J. Phys. Chem. C, 2016, 120, 23813–23822
DOI: 10.1021/acs.jpcc.6b07537

Abstruct: The interlayer space of clays is an interesting microenvironment to control the properties of included organic materials. In this study, chromic hybrid films consisting of synthetic saponite (SSA) and fluorescent organic molecules with planar π-conjugated systems were fabricated. The hybrid films exhibited reversible fluorescence color switching induced by swelling and drying, which caused the gallery height of SSA to change. Ultraviolet–visible absorption, steady-state and time-resolved fluorescence measurements of the hybrid films strongly suggested that the organic molecules formed an excimer in the swollen interlayer space of SSA, while they were a monomer in the dried interlayer space. The different emission wavelengths of the excimer and monomer resulted in the fluorescence color switching of the hybrid films. The reversibility of the color switching was maintained for at least 50 cycles with no change of fluorescence maxima. These chromic hybrid films represent a novel approach to obtain color switching.

Alkylation of Nonacidic C(sp3)–H Bonds by Photoinduced Catalytic Michael-Type Radical Addition
S. Kamijo, G. Takao, K. Kamijo, T. Tsuno, K. Ishiguro, T. Murafuji
Org. Lett., 2016, 18, 4912-4915
DOI: 10.1021/acs.orglett.6b02391

Abstruct: Photoinduced catalytic Michael-type radical addition was achieved via olefin insertion into a nonacidic C(sp3)–H bond, utilizing 2-chloroanthraquinone as a C–H bond-cleaving catalyst and 1,1-bis(phenylsulfonyl)ethylene as an olefinic substrate. The present radical protocol allows carbon chain extension stemming from nonacidic C–H bonds, which complements alkylation at acidic C–H bonds under ionic conditions and installs the active methine site that acts as a versatile synthetic handle for further transformations.

Nitrogen-Incorporated Amorphous Carbon Catalysts with Higher Reactivity toward Oxygen Reduction Reaction
K. Honda, Y. Shimai, Y. Waki, K. Okafuji, S. Ohtomo, R. Kobayashi, H. Naragino
ECS Trans., 2016 75, 1021-1028.
DOI: 10.1149/07514.1021ecst

Abstruct: Amorphous carbon (a-C) based catalysts having higher oxygen reduction reaction (ORR) activity and higher stability for ORR were realized by inserting nitrogen atoms in the valleys of zigzag edges of sp2 cluster surface in a-C. ORR activity could be controlled by varying sizes and volume density of sp2 cluster. The maximum number of electrons of 2.82 for ORR was achieved. The N-doped a-C catalysts have the activity of 4-electron O2 reduction reaction. The catalytic activity was stable in long term (150 times) measurements. Consequently, the N-doped a-C catalysts possesss ly, imes) measurements higher stability for ORR.

Development of High-Sensitive Detection System for Redox Analytes Having a Standard Potential Higher Than O2 Evolution by Using Micropatterned Conductive Boron-Doped DLC Electrodes
S. Ohtomo, H. Naragino, K. Okafuji, R. Kobayashi, K. Honda
ECS Trans., 2016 75, 217-228.
DOI: 10.1149/07516.0217ecst

Abstruct: High sensitive electroanalytical system for redox analytes with standard potential higher than O2 evolution was developed by realizing interdigitated microarray electrodes based on boron-doped DLC (B-DLC-IDA). For Ce3+/4+ with the standard potential of 1.6 V, the amplification of response current derived from redox cycling was observed at B-DLC-IDA in the dual mode measurement. The amperometric current was amplified 180-fold by applying the potential of 1.7 V and 0.8 V to the collector and the generator electrodes in chronoamperometriy (CA) at the dual mode measurement. Theoretical detection limit (S/N = 3) toward Ce3+ was 0.13 μM. This detection limit was able to be improved to the value 2 orders of magnitude lower than that at B-DLC flat electrode by developing the electroanalytical system using B-DLC-IDA electrodes.

Development of Silicon and Carbon Based p-Type Amorphous Semiconductor Films with Optical Gap Variable for High-Efficiency Multi-Junction Solar Cells
H. Naragino, Y. Nagata, K. Okafuji, S. Ohtomo, Y. Shimizu, K. Honda
ECS Trans., 2016 75, 153-159.
DOI: 10.1149/07513.0153ecst

Abstruct: P-type boron-doped amorphous silicon and carbon alloy (B-doped a-SixC1-x) thin films with wide optical gap selective from 1.80 to 2.50 eV were successfully deposited by radio frequency (r.f.) plasma-enhanced chemical vapor deposition (CVD) method using a mixed solution of tetramethylsilane (TMS) and trimethylborate (TMOB) as a liquid source. Optical gaps of the B-doped a-SixC1-x films could be controlled by changing Si/(C + Si) ratio of the film. From photo-electrochemical measurement under UV illumination, it was clarified that the B-doped a-SixC1-x film with an optical gap of 2.50 eV has the p-type semiconducting property and photoelectric conversion function with a quantum yield of 1.63 %. The rectifying action of a p-n heterojunction comprising p-type B-doped a-SixC1-x film and n-type Si (100) substrate was observed. The open circuit voltage (VOC) and short circuit current density (JSC) of the heterojunction were estimated to be 200 mV and 45 mA/cm2, respectively. The results indicate that p-type B-doped a-SixC1-x films with controllable optical gaps is a promising p-layer material for multi-junction solar cells.

Hydration Structure of Trimethylamine N-Oxide in Aqueous Solutions as Illuminated by Soft X-Ray Emission Spectroscopy and Chemometric Analysis
Y. Sasaki, Y. Horikawa, T. Tokushima, K. Okada, M. Oura, M. Aida
Phys. Chem. Chem. Phys., 2016, 18, 27648-27653.
DOI : 10.1039/C6CP03750J

Abstract: The hydration structure of trimethylamine N-oxide (TMAO) in aqueous solutions has been investigated by means of soft X-ray spectroscopy and chemometric analysis. Soft X-ray absorption spectra in the O 1s region have a concentration-dependent shoulder at 533 eV, which is assigned to the 6a1 resonance of TMAO. Soft X-ray emission spectra acquired at this resonance comprise both TMAO and water components, with a prominent peak at 525.6 eV which is assigned to the emission caused by the 5e to O 1s transition. An apparent inverse concentration dependence of around 523 eV suggests that the electronic structure of water is modified by the strong interaction with TMAO. Such an effect has been included in the quantitative spectral analysis, called the classical least squares regression method, to obtain information on the hydration structure of the system. The analysis indicates that nine or more water molecules interact with a TMAO molecule. The present method offers a useful technique for probing the solvation structure around the solute which interacts strongly with the solvent.

Photocatalytic Degradation of 4-Chlorophenol on Titanium Dioxide Modified with Cu(II) or Cr(III) Ion under Visible Light Irradiation
N. Nishiyama, K. Kozasa, S. Yamazaki
Appl. Catal. A: General, 2016, 527, 109-115.
DOI: 10.1016/j.apcata.2016.09.001

Abstract: TiO2 modified with Cu2+ or Cr3+ ion (M-TiO2, M-grafted TiO2) was synthesized by a sol-gel method using Ti(OC3H7)4 as a starting material or a graft method by impregnation of rutile TiO2. In the sol-gel method, the Brunauer-Emmett-Teller (BET) surface area of M-TiO2 was varied by preparing with or without dialysis of TiO2 sol (M-TiO2(D) or M-TiO2(ND), respectively). Even by using the sol-gel method, Cu2+ whose ionic size is larger than Ti4+ cannot be doped but is incorporated in TiO2 due to relatively weak interaction. Dissolution of Cu2+ ion was observed when Cu-TiO2(D), Cu-TiO2(ND) or Cu-grafted TiO2 was immersed into the acidic solution of 0.1 mol dm−3 HCl. The photocatalytic activity for the degradation of 4-chlorophenol (4-CP) under visible light irradiation was the following order: Cu-grafted TiO2 > Cu-TiO2(ND) > Cu-TiO2(D). We have revealed that the photocatalytic activity of Cu-grafted TiO2 decreases linearly with an increase in the number-density of Cu2+ ion on the TiO2 surface. On the other hand, in the case of Cr3+ ion which has a similar size as Ti4+, the photocatalytic activity increased remarkably by doping Cr3+ in TiO2 by the sol-gel method. An increase in the BET surface area by conducting dialysis enhanced the photocatalytic activity. This paper demonstrates from the viewpoint of the higher photocatalytic activity as well as the chemical stability in acidic conditions that Cr-doped TiO2 prepared by the sol-gel method gives an advantage over Cu-grafted TiO2 for the degradation of 4-CP which is one of the non-degradable organic contaminants in water.

Biological Oxygen Sensing via Two-Photon Absorption by an Ir(III) Complex using a Femtosecond Fiber Laser
H. Moritomo, A. Fujii, Y. Suzuki, T. Yoshihara, S. Tobita, J. Kawamata
Jpn. J. Appl. Phys., 2016, 55, 092401
DOI: 10.7567/JJAP.55.092401

Abstruct: Near-infrared two-photon absorption of the phosphorescent Ir(III) complex (2,4-pentanedionato-κO 2,κO 4)bis[2-(6-phenanthridinyl-κN)benzo[b]thien-3-yl-κC]iridium (BTPHSA) was characterized. It exhibited a 800–1200 nm two-photon absorption band, and thus could be electronically excited by 1030-nm femtosecond Ti:sapphire and Yb-doped fiber lasers. By using BTPHSA, oxygen concentrations in human embryonic kidney 293 (HEK293) cells were imaged. These results demonstrate two-photon oxygen sensing of live tissues via easily operable excitation sources.

An Azulene-Fused Tetracene Diimide with a Small HOMO–LUMO Gap
T. Koide, M. Takesue, T. Murafuji, K. Satomi, Y. Suzuki, J. Kawamata, K. Terai, M. Suzuki, H. Yamada, Y. Shiota, K. Yoshizawa, F. Tani
ChemPlusChem, 2017, 82, 1010-1014
DOI: 10.1002/cplu.201600356

Abstract: A newly prepared tetraazulene-fused tetracene diimide (TA-fused TDI) showed absorption in the near-IR region owing to the effective extension of the π-conjugated system as well as a large two-photon absorption cross-section (σ(2)=2140 GM) at 950 nm. Four reversible reduction processes and n-type semiconductivity were also confirmed as attractive electronic properties of this compound.

Exploring the solvent mediated assembly and redox activity of a POM–organic hybrid [Na(SO3)2(PhPO3)4MoV4MoVI14O49]5−
M. Fujibayashia, Y.-F. Song, L. Cronin, R. Tsunashima
New J. Chem., 2016, 40, 8488-8492.
DOI : 10.1039/c6nj01774f

Abstract: We report the electrochemical activity and the mechanism of formation of a mixed valence polyoxometalate-based organic hybrid cluster with the formula [Na(SO3)2(PhPO3)4MoV4MoVI14O49]5− (1). Electrochemical investigations of the mixed valence compound 1 showed three redox couples, in which the electrons were mainly delocalized over eight Mo sites. Furthermore, the synthesis was investigated using 31P-NMR, which showed that the self-assembly of cluster 1 was triggered by the addition of organic solvents, and was largely independent of the nature of the solvents, suggesting that a decrease in the concentration of water promoted cluster assembly. Finally the stability of 1 was explored and we concluded that the use of phenylphosphonate allowed the covalent stabilization of the [MoV4MoVI14] core.

Photo-induced Substitutive Introduction of the Aldoxime Functional Group to Carbon Chains: A Formal Formylation of Non-Acidic C(sp3)−H Bonds
S. Kamijo, G. Takao, K. Kamijo, M. Hirota, K. Tao, T. Murafuji
Angew. Chem. Int. Ed., 2016, 55,9695 –9699
DOI : 10.1002/anie.201603810

Abstract: A photo-induced substitutive introduction of an aldoxime functional group to carbon chains was achieved using photo-excited 4-benzoylpyridine as a C(sp3)−H bond cleaving agent and arylsulfonyl oxime as an aldoxime precursor. The non-acidic C−H bonds in various substances, including cycloalkanes, ethers, azacycles, and cyclic sulfides, were chemoselectively converted at ambient temperature under neutral conditions. The present transformation is a formal formylation of non-acidic C(sp3)−H bonds in a single step.

Hard Coating of Ultrananocrystalline Diamond/Nonhydrogenated Amorphous Carbon Composite Films on Cemented Tungsten Carbide by Coaxial Arc Plasma Deposition
H. Naragino, M. Egiza, A. Tominaga, K. Murasawa, H. Gonda, M. Sakurai, T. Yoshitake
Appl.Phys. A, 2016, 122, 761.
DOI: 10.1007/s00339-016-0284-4

Abstruct: Ultrananocrystalline diamond (UNCD)/nonhydrogenated amorphous carbon (a-C) composite (UNCD/a-C) films were deposited on cemented carbide containing Co by coaxial arc plasma deposition. With decreasing substrate temperature, the hardness was enhanced accompanied by an enhancement in the sp3/(sp2 + sp3). Energy-dispersive X-ray and secondary ion mass spectrometry spectroscopic measurements exhibited that the diffusion of Co atoms from the substrates into the films hardly occurs. The film deposited at room temperature exhibited the maximum hardness of 51.3 GPa and Young’s modulus of 520.2 GPa, which evidently indicates that graphitization induced by Co in the WC substrates, and thermal deformation from sp3 to sp2 bonding are suppressed. The hard UNCD/a-C films can be deposited at a thickness of approximately 3 μm, which is an order larger than that of comparably hard a-C films. The internal compressive stress of the 51.3-GPa film is 4.5 GPa, which is evidently smaller than that of comparably hard a-C films. This is a reason for the thick deposition. The presence of a large number of grain boundaries in the film, which is a structural specific to UNCD/a-C films, might play a role in releasing the internal stress of the films.

Directionally Tunable and Mechanically Deformable Ferroelectric Crystals from Rotating Polar Globular Ionic Molecules
J. Harada, T. Shimojo, H. Oyamaguchi, H. Hasegawa, Y. Takahashi, K. Satomi, Y. Suzuki, J. Kawamata, T. Inabe
Nature Chem., 2016, 8, 946-952.
DOI : 10.1038/nchem.2567

Abstract: Ferroelectrics are used in a wide range of applications, including memory elements, capacitors and sensors. Recently, molecular ferroelectric crystals have attracted interest as viable alternatives to conventional ceramic ferroelectrics because of their solution processability and lack of toxicity. Here we show that a class of molecular compounds—known as plastic crystals—can exhibit ferroelectricity if the constituents are judiciously chosen from polar ionic molecules. The intrinsic features of plastic crystals, for example, the rotational motion of molecules and phase transitions with lattice-symmetry changes, provide the crystals with unique ferroelectric properties relative to those of conventional molecular crystals. This allows a flexible alteration of the polarization axis direction in a grown crystal by applying an electric field. Owing to the tunable nature of the crystal orientation, together with mechanical deformability, this type of molecular crystal represents an attractive functional material that could find use in a diverse range of applications.

XAS And RIXS Study of Acetic Acid and Methyl Formate in Liquid
O. Takahashi, N. Nishida, S.Kanai, Y. Horikawa, T. Tokushima
Phys.: Conf. Ser., 2016, 712, 012040
DOI : 10.1088/1742-6596/712/1/012040

Abstract: Structure of acetic acid (AA) and methyl formate (MF) in the liquid phase is studied using X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) experimentally and theoretically. Two distinct XES spectra are observed by tuning photon energy for both molecules. Model structure in the liquid phase is constructed using the classical and first principle molecular dynamics simulations, and XES spectra are calculated using density functional theory. Calculated XES spectra are consistent with experimental ones. The effect of core-hole induced excited state molecular dynamics are discussed.

Correlation between Soft X-ray Absorption and Emission Spectra of the Nitrogen Atoms within Imidazolium-Based Ionic Liquids
Y. Horikawa, T. Tokushima, Osamu Takahashi, Hiroshi Hoke, T. Takamuku
J. Phys. Chem. B, 2016, 120, 7480–7487.
DOI : 10.1021/acs.jpcb.6b04132

Abstract: Soft X-ray absorption spectroscopy (XAS) has been performed on the N K-edge of two imidazolium-based ionic liquids (ILs), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([C2mim][TFSA]) and 1-ethyl-3-methylimidazolium bromide ([C2mim][Br]), to clarify the electronic structures of the ILs. Soft X-ray emission spectroscopy (XES) has also been applied to the ILs by excitation at various X-ray energies according to the XAS spectra. It was possible to fully associate the XAS peaks with the XES peaks. Additionally, both XAS and XES spectra of the ILs were well reproduced by the theoretical spectra for a single-molecule model on [C2mim]+ and [TFSA]− using density functional theory. The assignments for the XAS and XES peaks of the ILs were accomplished from both experimental and theoretical approaches. The theoretical XAS and XES spectra of [C2mim]+ and [TFSA]− did not significantly depend on the conformations of the ions. The reproducibility of the theoretical spectra for the single-molecule model suggested that the interactions between the cations and anions are very weak in the ILs, thus scarcely influencing the electronic structures of the nitrogen atoms.

Kinetics of Coloration in Photochromic Tungsten(VI) Oxide/Silicon Oxycarbide/Silica Hybrid Xerogel: Insight into Cation Self-diffusion Mechanisms
K. Adachi, M. Tokushige, K. Omata, S. Yamazaki, Y. Iwadate
ACS Appl. Mater. Interfaces, 2016, 8, 14019-14028.
DOI : 10.1021/acsami.6b04115

Abstract: Silicon oxycarbide/silica composites with well-dispersed tungsten(VI) oxide (WO3) nanoparticles were obtained as transparent hybrid xerogels via an acid-catalyzed sol–gel process (hydrolysis/condensation polymerization) of 3-(triethoxysilyl)propyl methacrylate (TESPMA) and tetraethoxysilane (TEOS). The self-diffusion mechanism of alkali-metal cations and the kinetics of the photochromic coloration process in the WO3/TESPMA/TEOS hybrid xerogel systems have been systematically investigated. Under continuous UV illumination, a gradual color change (colorless → blue) corresponding to the reduction of W6+ into W5+ states in WO3 nanoparticles can be confirmed from the WO3/TESPMA/TEOS hybrid xerogels containing alkali-metal sulfates, although no coloration of the hybrid xerogel without alkali-metal sulfate was observed. The coloration behavior depended exclusively on a variety of alkali-metal cations present in the hybrid xerogel system. Furthermore, a detailed analysis of the self-diffusion mechanism confirmed that the alkali-metal cations electrostatically interact with a layer of unreacted silanol groups on the TESPMA/TEOS matrix surface, and subsequently pass through the interconnected pore network of the hybrid xerogel. More interestingly, in the context of an Arrhenius analysis, we found a good coincidence between the activation energies for alkali-metal cation self-diffusion and UV-induced coloration in the WO3/TESPMA/TEOS hybrid xerogel system containing the corresponding alkali-metal sulfate. It is experimentally obvious that the photochromic properties are dominated by the diffusion process of alkali-metal cations in the WO3/TESPMA/TEOS hybrid xerogel system. Such hybrid materials with cation-controlled photochromic properties will show promising prospects in applications demanding energy-efficient "smart windows" and "smart glasses".

 

Three-photon-induced Luminescence of Europium Acetylacetonate-type Complexes
Y. Suzuki, H. Moritomo, A. Fuji, K. Satomi, J. Kawamata, M. Yamamoto, Y. Hasegawa
Chem. Lett., 2016, 45, 538-540.
DOI : 10.1246/cl.160126

Abstract: We measured the three-photon absorption spectra of two europium acetylacetonate-type complexes. The three-photon absorption peak wavelengths of tris(hexafluoroacetylacetonato)europium(III) (Eu(hfa)) and tris(2-naphthoyltrifluoroacetonato)europium(III) (Eu(ntfa)) were 925 and 1025 nm, respectively. The peak values of the 3PA cross-sections of Eu(hfa) and Eu(ntfa) were 1.9 and 13.9 GM (1 GM = 10−82 cm6 s2), respectively. Using Eu(ntfa) as a probe, a three-photon microscope image of a living cell was obtained using a 1030 nm operating femto-second fiber laser as the light-source. Thus, Eu(ntfa) is a fiber laser excitable luminescent probe useful for three-photon microscopy.

 

Hybrid Mechanosensing System to Generate the Polarity Needed for Migration in Fish Keratocytes
C. Okimura, Y. Iwadate
Cell Adhes. Migra., 2016, 10, 406-418.
DOI : 10.1080/19336918.2016.1170268

Abstract: Crawling cells can generate polarity for migration in response to forces applied from the substratum. Such reaction varies according to cell type: there are both fast- and slow-crawling cells. In response to periodic stretching of the elastic substratum, the intracellular stress fibers in slow-crawling cells, such as fibroblasts, rearrange themselves perpendicular to the direction of stretching, with the result that the shape of the cells extends in that direction; whereas fast-crawling cells, such as neutrophil-like differentiated HL-60 cells and Dictyostelium cells, which have no stress fibers, migrate perpendicular to the stretching direction. Fish epidermal keratocytes are another type of fast-crawling cell. However, they have stress fibers in the cell body, which gives them a typical slow-crawling cell structure. In response to periodic stretching of the elastic substratum, intact keratocytes rearrange their stress fibers perpendicular to the direction of stretching in the same way as fibroblasts and migrate parallel to the stretching direction, while blebbistatin-treated stress fiber-less keratocytes migrate perpendicular to the stretching direction, in the same way as seen in HL-60 cells and Dictyostelium cells. Our results indicate that keratocytes have a hybrid mechanosensing system that comprises elements of both fast- and slow-crawling cells, to generate the polarity needed for migration.

Factors Affecting Oxygen Evolution through Water Oxidation on Polycrystalline Titanium Dioxide
Y. Nishimoto, Y. Hasegawa, K. Adachi, S. Yamazaki
RSC Adv., 2016, 6, 46994-47000.
DOI : 10.1039/c6ra06151f

Abstract: The effect of physicochemical properties such as specific surface area, crystalline phase, crystallite size, and crystallinity of TiO2 on photocatalytic water oxidation was investigated. Two types of polycrystalline TiO2 samples which have different physicochemical properties were prepared by a sol–gel method. The photocatalytic activities of the TiO2 samples for water oxidation were evaluated by the O2 evolution rate from an aqueous silver nitrate solution under ultraviolet light irradiation. Comparison of the two types of TiO2 samples revealed that the specific surface area and crystalline phase were not related to the O2 evolution rate. In contrast, a linear relationship between the crystallite sizes and the O2 evolution rates was observed for most of the TiO2 samples. Crystal face selective Pt and PbO2 depositions on the TiO2 samples were observed by photocatalytic reduction of PtCl62− and oxidation of Pb2+ ions, respectively, indicating that the oxidation and reduction sites are separated on the surface. An increase in the crystallite size of the TiO2 promotes a spatial separation of the redox sites and suppresses the electron–hole recombination, leading to the enhancement of the photocatalytic activity.

Shape and Area of Keratocytes are Related to the Distribution and Magnitude of Their Traction Forces
A. Sonoda, C. Okimura, Y. Iwadate
Cell Struct. Funct., 2016, 41, 33-43.
DOI : 10.1247/csf.15008

Abstract: Fish epidermal keratocytes maintain an overall fan shape during their crawling migration. The shape-determination mechanism has been described theoretically and experimentally on the basis of graded radial extension of the leading edge, but the relationship between shape and traction forces has not been clarified. Migrating keratocytes can be divided into fragments by treatment with the protein kinase inhibitor staurosporine. Fragments containing a nucleus and cytoplasm behave as mini-keratocytes and maintain the same fan shape as the original cells. We measured the shape of the leading edge, together with the areas of the ventral region and traction forces, of keratocytes and mini-keratocytes. The shapes of keratocytes and mini-keratocytes were similar. Mini-keratocytes exerted traction forces at the rear left and right ends, just like keratocytes. The magnitude of the traction forces was proportional to the area of the keratocytes and mini-keratocytes. The myosin II ATPase inhibitor blebbistatin decreased the forces at the rear left and right ends of the keratocytes and expanded their shape laterally. These results suggest that keratocyte shape depends on the distribution of the traction forces, and that the magnitude of the traction forces depends on the area of the cells.

Fast-Crawling Cell Types Migrate to Avoid the Direction of Periodic Substratum Stretching
C. Okimura, K. Ueda, Y. Sakumura, Y. Iwadate
Cell Adhes. Migra., 2016, 10, 331-341.
DOI : 10.1080/19336918.2015.1129482

Abstract: To investigate the relationship between mechanical stimuli from substrata and related cell functions, one of the most useful techniques is the application of mechanical stimuli via periodic stretching of elastic substrata. In response to this stimulus, Dictyostelium discoideum cells migrate in a direction perpendicular to the stretching direction. The origins of directional migration, higher migration velocity in the direction perpendicular to the stretching direction or the higher probability of a switch of migration direction to perpendicular to the stretching direction, however, remain unknown. In this study, we applied periodic stretching stimuli to neutrophil-like differentiated HL-60 cells, which migrate perpendicular to the direction of stretch. Detailed analysis of the trajectories of HL-60 cells and Dictyostelium cells obtained in a previous study revealed that the higher probability of a switch of migration direction to that perpendicular to the direction of stretching was the main cause of such directional migration. This directional migration appears to be a strategy adopted by fast-crawling cells in which they do not migrate faster in the direction they want to go, but migrate to avoid a direction they do not want to go.

Crystal Design of Polar One-Dimensional Hydrogen-Bonded Copper Coordination Complexes
K. Takahashi, N. Hoshino, T. Takeda, K. Satomi, Y. Suzuki, S. Noro, T. Nakamura, J. Kawamata, T. Akutagawa
Dalton Trans., 2016, 45, 7153-7158
DOI : 10.1039/c5dt04865f

Abstract: Polar crystals exhibiting second-order harmonic generation (SHG) were designed by adjusting the intermolecular interactions of mononuclear Cu(II) complexes in which one H2O, two pyridines (py), and two p-substituted benzoate (p-RBA) ligands (R = F, Cl, Br, I, CH3, and OCH3) were coordinated to a Cu(II) ion, forming a penta-coordinated asymmetric [Cu(II)(p-RBA)2(py)2(H2O)] mononuclear structure with a permanent dipole moment along the direction of the Cu–OH2 coordination axis. Each asymmetric [Cu(II)(p-RBA)2(py)2(H2O)] complex formed a polar one-dimensional hydrogen-bonded chain, [Cu(II)(p-RBA)2(py)2(H2O)]∞, between the non-coordinated carboxylate oxygen atom of the p-RBA ligand and the hydrogen atom of the H2O molecule. The formation of a polar crystal depended on the arrangement of polar hydrogen-bonded chains; the parallel arrangement of each polar chain resulted in a polar crystal. The chemical design of the R group in the p-RBA ligand enabled tuning of the magnitude of the interchain interactions and crystal polarity; polar crystals were obtained using p-RBA ligands with R = Cl, Br, I, and OCH3. In contrast, apolar crystals were grown from complexes containing p-RBA ligands with R = F and CH3. In all crystals, a polar two-dimensional (2D) layer constructed from the parallel polar [Cu(II)(p-RBA)2(py)2(H2O)]∞ chain arrangement was formed based on weak van der Waals C–H⋯−O– interactions between the hydrogen atom of py and the carboxylate oxygen atom of the p-RBA ligand. Weak interlayer halogen (X)⋯π and multipoint C–H⋯π interactions played important roles in forming parallel arrangements of polar 2D layers and polar crystals, but there were no effective intermolecular interactions between the polar 2D layers in apolar [Cu(II)(p-FBA)2(py)2(H2O)] and [Cu(II)(p-CH3BA)2(py)2(H2O)] crystals. The magnitudes of the interlayer interactions in the polar crystals were larger than those in the apolar ones because of the effective intermolecular interactions. The SHG intensities of the four polar crystals were approximately 0.7 times larger than that of sucrose.

Electrochemical Synthesis of a Nanohybrid Film Consisting of Stacked Graphene Sheets and Manganese Oxide as Oxygen Evolution Reaction Catalyst
M. Nakayama, Y. Fujii, K. Fujimoto, M. Yoshimoto, A. Kaide, T. Saeki, H. Asada
RSC Adv., 2016, 6, 23377-23382
DOI : 10.1039/c6ra00255b

Abstract: A new electrochemical process yielded a thin film consisting of stacked graphene (GR) sheets and manganese oxide. The process involved anodic deposition of manganese oxide nuclei on an electrode substrate and on the surface of GR sheets through electrolysis of aqueous Mn2+ ions in the presence of cationic GR colloids modified with poly(diallydimethylammonium) (PDDA+), followed by extraction of the PDDA. The catalytic activity of Mn oxide for the oxygen evolution reaction in an alkaline electrolyte was dramatically enhanced by hybridizing it with GR; an onset overpotential of 335 mV and a Tafel slope of 58 mV per decade were observed with excellent stability. These results can be attributed to a synergistic effect of the catalytic activity of nanosized Mn oxide deposits and the ability of GR to transfer electrons from the catalysts.

Two-Directional Carbon Chain Elongation via the Consecutive 1,4-Addition of Allyl Malononitrile and the Cope Rearrangement on An Alkynoate Platform
S. Kamijo, K. Kamijo, D. Magarifuchi, R. Ozawa, K. Tao, T. Murafuji
Tetrahedron Lett. 2016, 57 137-140.
DOI : 10.1016/j.tetlet.2015.11.081

Abstract: A one-pot procedure for the regioselective introduction of two different three-carbon units, allyl and malononitrile functionalities, to C–C triple bonds was established. The transformation proceeds through the phosphine-catalyzed 1,4-addition of allyl malononitrile to the alkynoate and the Cope rearrangement with microwave heating, achieving two-directional carbon chain elongation on the alkynoate platform. The operational simplicity, succinct carbon skeletal construction, and high atom economy should make the present procedure appealing for the synthesis of structurally complex organic molecules.

Synthesis of Aliphatic Azides by Photoinduced C(sp3)–H Azidation
S. Kamijo, M. Watanabe, K. Kamijo, K. Tao, T. Murafuji
Synthesis. 2016, 48, 1115-121.
DOI : 10.1055/s-0035-1560705

Abstract: A photoinduced synthesis of aliphatic azides was achieved in a single step starting from the parent cyclic alkanes, as well as from tetrahydrofuran and pyrrolidine derivatives. The reaction proceeds via direct azidation of C(sp3)–H bonds in the presence of 4-benzoylpyridine under photoirradiation conditions utilizing tosyl azide as the azide source. The chemoselective C–H mono-azidation at room temperature and the formation of azide compounds in spite of their potential photolability are the key features of the present transformation.

Photochromic Properties of Tungsten Oxide/Methylcellulose Composite Film Containing Dispersing Agents
S. Yamazaki, H. Ishida, D. Shimizu, K. Adachi
ACS Appl. Mater. Interfaces, 2015, 7, 26326–26332.
DOI : 10.1021/acsami.5b09310

Abstract: Tungsten oxide-based photochromic films which changed reversibly in air between colorless– transparent in the dark and dark blue under UV irradiation were prepared by using methylcellulose as a film matrix and polyols such as ethylene glycol (EG), propylene glycol (PG), and glycerin (Gly) as dispersing agents. Influence of the dispersing agents and water in the films on the photochromic behavior was systematically studied. Under UV irradiation, absorption bands around 640 and 980 nm increased and the coloring rate was the following order: Gly > EG > PG. An increase in the amounts of dispersing agents or water accelerated the coloring rate. By increasing the water content of the film, a new absorption peak appeared at ca. 775 nm and the Raman spectra indicated a shift of W–O–W stretching vibration to lower wavenumber which was due to the formation of hydrogen bonding. All absorption spectra were fit by three Lorentz functions, whose bands were ascribed to various packing of WO6 octahedra. After the light was turned off, the formation of W5+ was stopped and bleaching occurred by the reaction with O2 in air to recover its original transparent state. We anticipate that the biodegradable photochromic films developed in this study can be applied in recyclable display medium and especially in detachable films for glass windows whose light transmission properties are changed by sunlight, i.e., for usage as an alternative of smart windows without applying voltage.

Synthesis and Acid–Base Properties of a Proton-Bridged Biaryl CompoundBased on Pyridylazulene
New J. Chem., 2015, 39, 9079-9085
K. Ninomiya, Y. Harada, T. Kanetou, Y. Suenaga, T. Murafuji, R. Tsunashima
DOI : 10.1039/c5nj01651g

Abstract: Herein, we report the synthesis of 1,1′-bi(2-pyridylazulene) (1), in which pyridyl moieties were coupled to a biaryl framework for hydrogen bonding between the two aryl skeletons. The two 2-pyridylazulene moieties in 1 were linked through facile aryl–aryl coupling between the 1- and 1′-positions of the azulene skeletons, where 1-haloazulene was stabilized by electron withdrawing pyridyl substitution. In addition, single crystals of the mono-protonated species (1H+) were successfully obtained as the BF4− salt. X-ray diffraction analysis at 153 K revealed an intramolecular hydrogen bond between the two pyridyl moieties, giving a racemic mixture of axial chiral species. DFT calculations were performed to understand the hydrogen bonding structure and an almost single minimum potential for thermal proton motion was suggested. The acid–base characteristics were investigated in acetonitrile and 1 was revealed to exhibit two-step protonation of its pyridyl moieties. By comparison with monomeric 2-pyridylazulene, the stronger basic character of 1 was confirmed. This is ascribed to the macrocyclic effect of the two pyridyl moieties bridged by a proton, as seen in the single crystal of 1H+. Furthermore, two different energy shifts associated with intramolecular transition were observed under protonation; the first protonation produced a blue shift in the absorption maximum, whereas a red shift was observed for the second protonation. The unusual blue shift was explained by the stabilization of the HOMO owing to an extended electronic structure between the two azulene skeletons. This unique steric structure was achieved by proton bridging in the pyridyl-substituted biaryl compound.

A Theoretical Study on the Selective Oxygen K-Edge Soft X-Ray Emission Spectroscopy of Liquid Acetic Acid
N. Nishida, S. Kanai, T. Tokushima, Y. Horikawa, O. Takahashi
Chem. Phys. Lett., 2015, 640, 55-60.
DOI : 10.1016/j.cplett.2015.10.021

Abstract: We have performed theoretical calculations to reproduce the site-selective X-ray emission spectroscopy (XES) spectra of liquid acetic acid at the oxygen K-edge (OC=O,1s and O-OH,1s). Structure sampling of an acetic acid cluster model was performed from the ab initio molecular dynamics trajectory. Relative XES intensities for the core-hole excited state dynamics simulations were calculated using density functional theory. We found that the theoretical XES spectra reproduced well the experimental spectra and that these calculations gave us electronic and molecular structure information about liquid acetic acid.

液体状態における酢酸，ギ酸メチルの分子間相互作用依存性
西田尚大, 金井清二, 徳島高, 堀川裕加, 高橋修
J. Comput. Chem. Jpn., 2015, 14, 60-62.
DOI : 10.2477/jccj.2015-0026

Abstract: We performed theoretically to reproduce site-selective X-ray emission spectroscopy (XES) spectra of acetic acid and methyl formate in the liquid phase at two oxygen K-edge (OC=O and OOH,OCH3) to observe the intermolecular interaction dependence of XES spectra. Structure sampling as a cluster model was performed from a snapshot of molecular dynamics simulation. Relative intensities of XES with core-hole excited state dynamics simulation were calculated using density functional theory. We found that theoretical XES spectra were well reproduced experimentally.

ゾル-ゲル法を利用する酸化チタン光触媒の高活性化
山崎鈴子
光化学, 2015, 46, 66-73.

Abstract: Degradation of various pollutants by photocatalysis has been widely studied over the last 30 years. Titanium dioxide is still the widely used photocatalyst for environmental remediation because there is no satisfactory alternative. Sol-gel method is efficient for tailoring nanostructure materials with high specific surface area without the need for using expensive equipment. We have developed a synthetic method to prepare porous TiO2 with BET surface area higher than 200 m2 g-1 by using water as solvent and conducting dialysis in the sol-gel method. Recently, many attempts have been devoted to enhance the photocatalytic activity of TiO2 by extending its spectral response to visible light and/or suppressing the recombination of the photogenerated hole and electron. In this review, the preparation of metal-ion-doped TiO2 working under visible light by conducting dialysis in the sol-gel method and enhancement of the photocatalytic activity obtained by mixing TiO2 and WO3 sol are prepared.

An Investigation on the Degradation Behavior of an Asymmetric Supercapacitor of α-MnO2//AC
H. Abe, T. Tanimoto, M. Nakayama
J. Electrochem. Soc., 2015, 162, A1952-A1956
DOI : 10.1149/2.0051510jes

Abstract: We have investigated the degradation behavior of a typical asymmetric supercapacitor cell operating in an aqueous solution of Na2SO4 with a voltage window of 2 V, where α-MnO2 and activated carbon (AC) were chosen as the active materials for positive and negative electrodes, respectively. In this study, potentials of α-MnO2 and AC electrodes of the asymmetric cell were monitored with respect to an Ag/AgCl reference electrode during repetitive charge/discharge cycling. Since the charges passed at positive and negative electrodes are the same, a change in a certain parameter should be compensated by changes in the other parameters. An irreversible current due to reduction of water on AC electrode triggered capacitance fade in the initial charge/discharge cycling. This phenomenon made the lowest potential more positive to be deviated from the potential region where water reduction can occur, resulting in the following stable operation. Then, α-MnO2 facilitated the oxidation of water, which deactivated α-MnO2 itself probably due to an irreversible increase in reduced Mn sites. The deactivation of α-MnO2 was compensated by expansion of its potential window in the cathodic scan, leading to further capacitance fade due to dissolution.

Dioxomolybdenum(VI) and Dioxotungsten(VI) Complexes: Efficient Catalytic Activity for Crosslinking Reaction in Ethylene-Vinyl Acetate Copolymer/Alkoxysilane Composites
K. Adachi, S. Toyomura, Y. Miyakuni, S. Yamazaki, K. Honda, T. Hirano
Polym. Adv. Technol., 2015, 26, 597-605.
DOI : 10.1002/pat.3491

Abstract: The catalytic performances of several bis(acetylacetonato)metal complexes [Cu(acac)2, Zn(acac)2, TiO(acac)2, VO(acac)2, MoO2(acac)2, and WO2(acac)2] were investigated for the crosslinking reaction via transesterifications in the ethylene-vinyl acetate copolymer/tetraethoxysilane (EVA/TEOS) composite system by means of dynamic attenuated total reflectance Fourier transform infrared, solvent swelling, and solid-state 29Si cross polarization/magic angle spinning nuclear magnetic resonance techniques. Results of the kinetic examination revealed that MoO2(acac)2 and WO2(acac)2 exhibited a higher catalytic activity than di-n-butyltin(IV) oxide, which is a catalyst most commonly used for the transesterification process in polymer system, but has a toxic effect on the environmental health. And furthermore, the crosslink density and final siloxane network structure of crosslinked EVA/TEOS composites are found to be greatly correlated with the catalyst used. On the basis of the SN2-Si pathway, a plausible catalytic mechanism of MoO2(acac)2 and WO2(acac)2 was proposed for the crosslinking reaction via transesterifications of the vinyl acetate moieties in EVA backbone with the ethoxysilane groups in one TEOS molecule. The findings in this study may fill the blank in the high performance and environmentally friendly catalyst in the field of the crosslinking reactions in polymer system and provide useful clue for other transesterifications.

Large In-Plane/Out-of-Olane Anisotropic Conduction in PEDOT-Based Hybrid Films: Lamellar Assemblies Structured by Mono-Layered Nanosheets
S. Fujii, Y. Suzuki, J. Kawamata, R. Tsunashima
J. Mater. Chem. C, 2015, 3, 7153-7158
DOI : 10.1039/c5tc01238d

Abstract: Poly(3,4-ethylenedioxythiophene) (PEDOT) is a promising conductive polymer for electrical applications, and increases in its conductivity, transparency, stability, stiffness and strength have been explored. Herein, we demonstrate a facile fabrication method for a PEDOT film that exhibits large anisotropic conduction along in-plane directions. An aqueous solution of PEDOT added with polystyrene sulfonate (PSS) was mixed with an insulating oxide nanosheet based on montmorillonite (MMT) dispersed in aqueous media. Structural studies demonstrated it to be a hybrid film with a lamellar-like assembly that was structured with mono-layered sheets. In addition, an inhomogeneous mixture of pristine MMT (insulating) and PEDOT-rich (conductive) lamellar grains was proposed. The ratio between these two grains was controlled by tuning the content of the PEDOT:PSS solution in the initial mixing process. Increases in the content of PEDOT increased the electrical conductivity. This dependence is explained by a percolation model with random arrangements of PEDOT-rich conductive and insulating grains. The conductivity showed large anisotropy between in-plane and out-of-plane measurements. The ratio reached almost 105 and remained the same over a wide range of temperatures. The lamellar structure of the PEDOT and nanosheets is ascribed to the large anisotropy.