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.