Jorge Olmos-Trigo  Hiroshi Sugimoto  Minoru Fujii 《Laser u0026amp; Photonics Reviews》2024,18(5):2300948

Nanophotonics can enhance the inherent weak signal exhibited by chiral molecules in circular dichroism (CD) spectroscopy experiments. One mechanism to achieve this CD enhancement is based on increasing the optical chirality produced by nanophotonics antennas in their near-field, where chiral molecules are placed. However, ascertaining whether this CD enhancement is reached presents significant experimental challenges due to the complexity of measuring near-field optical chirality. Here, it is demonstrated that a local and single measurement of the degree of circular polarization in the far-field enables quantifying near-field CD enhancements. Thereby, based on this far-field measurement, the optimal response of the antenna is predicted for enhanced chiral sensing. Experimental validation of this near-to-far-field relation is provided for silicon spherical nanoantennas. The experimental results, supported by analytical theory and exact numerical simulations, can be interesting for the experimental characterization of devices capable of enhancing CD from a single far-field Stokes measurement.  相似文献   

    

Yuki Matsumoto  Takafumi Yamamoto  Kousuke Nakano  Hiroshi Takatsu  Taito Murakami  Kenta Hongo  Ryo Maezono  Hiraku Ogino  Dongjoon Song  Craig M. Brown  Cdric Tassel  Hiroshi Kageyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(3):766-769

Square‐planar coordinate Ni²⁺ ions in oxides are exclusively limited to a low‐spin state (S=0) owing to extensive crystal field splitting. Layered oxychalcogenides A₂Ni^IIO₂Ag₂Se₂ (A=Sr, Ba) with the S=1 NiO₂ square lattice are now reported. The structural analysis revealed that the Ni²⁺ ion is under‐bonded by a significant tensile strain from neighboring Ag₂Se₂ layers, leading to the reduction in crystal field splitting. Ba₂NiO₂Ag₂Se₂ exhibits a G‐type spin order at 130 K, indicating fairly strong in‐plane interactions. The high‐pressure synthesis employed here possibly assists the expansion of NiO₂ square lattice by taking the advantage of the difference in compressibility in oxide and selenide layers.  相似文献   

    

Chikashi Shinagawa  Yusuke Morikawa  Shin-ichi Nishimura  Hiroshi Ushiyama  Atsuo Yamada  Koichi Yamashita 《Journal of computational chemistry》2019,40(1):237-246

Na₂FePO₄F is a promising cathode material for a Na-ion battery because of its high electronic capacity and good cycle performance. In this work, first principle calculations combined with cluster expansion and the Monte Carlo method have been applied to analyze the charge and discharge processes of Na₂FePO₄F by examining the voltage curve and the phase diagram. As a result of the density functional theory calculation and experimental verification with structural analysis, we found that the most stable structure of Na_1.5FePO₄F has the P2₁/b11 space group, which has not been reported to date. The estimated voltage curve has two clear plateaus caused by the two-phase structure composed of P2₁/b11 Na_1.5FePO₄F and Pbcn Na₂FePO₄F or Na₁FePO₄F and separated along the c-axis direction. The phase diagram shows the stability of the phase-separated structure. Considering that Na₂FePO₄F has diffusion paths in the a- and c-axis directions, Na₂FePO₄F has both innerphase and interphase diffusion paths. We suggest that the stable two-phase structure and the diffusion paths to both the innerphase and interphases are a key for the very clear plateau. We challenge to simulate a nonequilibrium state at high rate discharge with high temperature by introducing a coordinate-dependent chemical potential. The simulation shows agreement with the experimental discharge curve on the disappearance of the two plateaus. © 2018 Wiley Periodicals, Inc.  相似文献   

    

Zhaoma Shu  Iku Tanaka  Azumi Ota  Daichi Fushihara  Naoko Abe  Saki Kawaguchi  Kosuke Nakamoto  Fumiaki Tomoike  Seiichi Tada  Yoshihiro Ito  Yasuaki Kimura  Hiroshi Abe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(20):6683-6687

Development of intracellular delivery methods for antisense DNA and siRNA is important. Previously reported methods using liposomes or receptor‐ligands take several hours or more to deliver oligonucleotides to the cytoplasm due to their retention in endosomes. Oligonucleotides modified with low molecular weight disulfide units at a terminus reach the cytoplasm 10 minutes after administration to cultured cells. This rapid cytoplasmic internalization of disulfide‐modified oligonucleotides suggests the existence of an uptake pathway other than endocytosis. Mechanistic analysis revealed that the modified oligonucleotides are efficiently internalized into the cytoplasm through disulfide exchange reactions with the thiol groups on the cellular surface. This approach solves several critical problems with the currently available methods for enhancing cellular uptake of oligonucleotides and may be an effective approach in the medicinal application of antisense DNA and siRNA.  相似文献   

    

Bo Huang  Hirokazu Kobayashi  Tomokazu Yamamoto  Takaaki Toriyama  Syo Matsumura  Yoshihide Nishida  Katsutoshi Sato  Katsutoshi Nagaoka  Masaaki Haneda  Wei Xie  Yusuke Nanba  Michihisa Koyama  Fenglong Wang  Shogo Kawaguchi  Yoshiki Kubota  Hiroshi Kitagawa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2252-2257

Ru is an important catalyst in many types of reactions. Specifically, Ru is well known as the best monometallic catalyst for oxidation of carbon monoxide (CO) and has been practically used in residential fuel cell systems. However, Ru is a minor metal, and the supply risk often causes violent fluctuations in the price of Ru. Performance‐improved and cost‐reduced solid‐solution alloy nanoparticles of the Cu‐Ru system for CO oxidation are now presented. Over the whole composition range, all of the Cu_xRu_1?x nanoparticles exhibit significantly enhanced CO oxidation activities, even at 70 at % of inexpensive Cu, compared to Ru nanoparticles. Only 5 at % replacement of Ru with Cu provided much better CO oxidation activity, and the maximum activity was achieved by 20 at % replacement of Ru by Cu. The origin of the high catalytic performance was found as CO site change by Cu substitution, which was investigated using in situ Fourier transform infrared spectra and theoretical calculations.  相似文献   

    

Guruprasad Raghavan  Kumi Hidaka  Hiroshi Sugiyama  Masayuki Endo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(23):7708-7712

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Ken Kato  Shun Kimura  Tetsuro Kusamoto  Hiroshi Nishihara  Yoshio Teki 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(9)

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Hiroshi Shinotsuka  Shigeo Tanuma  Cedric J. Powell  Dave R. Penn 《Surface and interface analysis : SIA》2019,51(4):427-457

We have calculated inelastic mean free paths (IMFPs) for 42 inorganic compounds (AgBr, AgCl, AgI, Al₂O₃, AlAs, AlN, AlSb, cubic BN, hexagonal BN, CdS, CdSe, CdTe, GaAs, GaN, GaP, GaSb, GaSe, InAs, InP, InSb, KBr, KCl, MgF₂, MgO, NaCl, NbC_0.712, NbC_0.844, NbC_0.93, PbS, PbSe, PbTe, SiC, SiO₂, SnTe, TiC_0.7, TiC_0.95, VC_0.76, VC_0.86, Y₃Al₅O₁₂, ZnS, ZnSe, and ZnTe) for electron energies from 50 eV to 200 keV. These calculations were made with energy-loss functions (ELFs) obtained from measured optical constants for 15 compounds while calculated ELFs were utilized for the other 27 compounds. Checks based on ELF sum rules showed that the calculated ELFs were superior to the measured ELFs that we had used previously. Our calculated IMFPs could be fitted to a modified form of the relativistic Bethe equation for inelastic scattering of electrons in matter for energies from 50 eV to 200 keV. The average root-mean-square (RMS) deviation in these fits was 0.60%. The IMFPs were also compared with a relativistic version of our predictive Tanuma-Powell-Penn (TPP-2M) equation. The average RMS deviation in these comparisons was 10.7% for energies between 50 eV and 200 keV. This average RMS deviation is almost the same as that found in a similar comparison for a group of 41 elemental solids (11.9%) although relatively large deviations were found for cubic BN (65.6%) and hexagonal BN (34.3%). If these two compounds are excluded in the comparisons, the average RMS deviation becomes 8.7%. We found generally satisfactory agreement between our calculated IMFPs and values from other calculations and from experiments.  相似文献   

    

Yutaka Matsuo  Ya Wang  Hiroshi Ueno  Takafumi Nakagawa  Hiroshi Okada 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(26):8854-8859

(N‐Phenylfluorenylidene)acridane (Ph‐FA) compounds with electron‐withdrawing and ‐donating substituents (H, MeO, Ph, NO₂, Br, F) at the para position of the phenyl group were successfully synthesized by Barton–Kellogg reactions of N‐aryl thioacridones and diazofluorene. By using the substituent on the nitrogen atom to alter the electronic properties, both the folded and twisted conformers of p‐NO₂‐C₆H₄‐FA could be crystallographically characterized, which enabled the charge transfer from the electron‐donating acridane moiety to the electron‐accepting fluorenylidene moiety to be understood. Ground‐state mechanochromism, thermochromism, vapochromism, and proton‐induced chromism were demonstrated between the folded and twisted conformations of the conformers. Protonation and chemical oxidation of Ph‐FA gave two stable acridinium compounds, namely, the fluorenylacridinium and acridinium radical cations. The present study will contribute to the development of functional dyes and organic semiconductors.  相似文献   

    

Naoki Ogiwara  Hirokazu Kobayashi  Patricia Concepcin  Fernando Rey  Hiroshi Kitagawa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(34):11857-11862

We first studied the reactivity of H₂O vapor in metal–organic frameworks (MOFs) with Pt nanocrystals (NCs) through the water–gas shift (WGS) reaction. A water‐stable MOF, UiO‐66, serves as a highly effective support material for the WGS reaction compared with ZrO₂. The origin of the high catalytic performance was investigated using in situ IR spectroscopy. In addition, from a comparison of the catalytic activities of Pt on UiO‐66, where Pt NCs are located on the surface of UiO‐66 and Pt@UiO‐66, where Pt NCs are coated with UiO‐66, we found that the competitive effects of H₂O condensation and diffusion in the UiO‐66 play important roles in the catalytic activity of Pt NCs. A thinner UiO‐66 coating further enhanced the WGS reaction activity of Pt NCs by minimizing the negative effect of slow H₂O diffusion in UiO‐66.  相似文献