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  2. Fujita Masahiro

Fujita Masahiro

  (藤田 正博)

Profile Information

Affiliation
Professor, Faculty of Science and Technology, Department of Materials and Life Sciences, Sophia University
Degree
博士（工学）(Mar, 2002, 東京農工大学)
Contact information
masahi-fsophia.ac.jp
Other name(s) (e.g. nickname)
Yoshizawa
Researcher number
50433793
J-GLOBAL ID
200901014332520864
researchmap Member ID
6000003382

(Subject of research)
Developement of fast proton conductive plastic crystals

Research Interests

 7

Research Areas

 1

Awards

 4

Papers

 191
  • Arata Matsui, Deandra Ayu Putri, Morgan L. Thomas, Yuko Takeoka, Masahiro Rikukawa, Masahiro Yoshizawa‐Fujita
    ChemSusChem, 18(6) e202401848, Mar 15, 2025  Peer-reviewedLast authorCorresponding author
    Abstract Cellulose is one of the main components of plant cell walls, abundant on earth, and can be acquired at a low cost. Furthermore, there has been increasing interest in its use in environmentally friendly, carbon‐neutral, sustainable materials. It is expected that the applications of cellulose will expand with the development of a simple processing method. In this study, we dissolved cellulose in aqueous N‐butyl‐N‐methylpyrrolidinium hydroxide solution ([C4mpyr][OH]/H2O) and investigated the cellulose regeneration process based on changes in solubility upon application of CO2 gas. We investigated the effect of transformation of the anion chemical structure on cellulose solubility by flowing CO2 gas into [C4mpyr][OH]/H2O and conducted pH, FT‐IR, and 13C NMR measurements. We observed that the changes in anion structure allowed for the modulation of cellulose solubility in [C4mpyr][OH]/H2O, thus establishing a simple and safe cellulose regeneration process. This regeneration process was also applied to enable the production of cellulose hydrogels. The hydrogel formed using this method was revealed to have higher mechanical strength than an analogous hydrogel produced using the same dissolution solvent with the addition of a cross‐linker. The ability to produce cellulose‐based hydrogels of different mechanical properties is expected to expand the possible applications.
  • Yoshifumi Hirotsu, Morgan L. Thomas, Yuko Takeoka, Masahiro Rikukawa, Masahiro Yoshizawa-Fujita
    Science and Technology of Advanced Materials, 26(1) 2466417, Mar 5, 2025  Peer-reviewedInvitedLast authorCorresponding author
  • Yutaro Hayashi, Mariya Usami, Elisabeth R. D. Ito, Yuko Takeoka, Masahiro Rikukawa, Masahiro Yoshizawa-Fujita
    ACS Applied Polymer Materials, 7(5) 3024-3032, Feb 26, 2025  Peer-reviewedInvitedLast authorCorresponding author
  • Futa Koyama, Justin Lamb, Moena Hirao, Noriyuki Suzuki, Masahiro Yoshizawa-Fujita, Toyonobu Usuki, Yumiko Suzuki
    Advanced Synthesis & Catalysis, 367(3) e202400955, Feb 4, 2025  Peer-reviewed
    With a number of biologically active members, 2‐aroylchromones are valuable synthetic targets. A direct route towards 2‐aroylchromones from 2‐(methylsulfonyl)chromones and aldehydes via NHC‐catalyzed C‐C bond formation was developed. Yields of the synthesized 2‐aroylchromones were up to 85%. Chromones with angioprotective or antibacterial properties were easily synthesized using the method developed. Additionally, the synthetic utility of the afforded chromones was demonstrated by using them to synthesize the anticancer compound wrightiadione and analogues of it.
  • Ryoto Inaba, Tomohiro Imai, Showa Kitajima, Hitoshi Kasai, Kouki Oka, Ryoyu Hifumi, Ikuyoshi Tomita, Masahiro Yoshizawa-Fujita, Kensuke Naka, Hiroaki Imoto
    Chemical Communications, 60(95) 14022-14025, Dec 11, 2024  Peer-reviewed
  • Yoshifumi Hirotsu, Ryotaro Sekiguchi, Yuko Takeoka, Masahiro Rikukawa, Masahiro Yoshizawa-Fujita
    Bulletin of the Chemical Society of Japan, 97(10) uoae101, Oct, 2024  Peer-reviewedLast authorCorresponding author
  • Keiko Nishikawa, Kozo Fujii, Kazuhiko Matsumoto, Hiroshi Abe, Masahiro Yoshizawa-Fujita
    Bulletin of the Chemical Society of Japan, Aug 19, 2024  Peer-reviewedLast author
    Abstract The temperature dependences of the spin–spin relaxation times (T2) of 1H and 19F nuclei were measured for N, N-diethylpyrrolidinium bis(fluorosulfonyl)amide with a plastic crystal (PC) phase. In the PC phase, two types of T2 were observed in both 1H and 19F experiments, which was considered to be the appearance of heterogeneous dynamics of diffusive motion. By examining temperature dependences of the T2 values and the existence ratios, the following conclusions were reached. (1) The prepared PC sample was in a polycrystalline state, and each crystallite comprised two phases: the core phase (PC phase) and the surface phase formed to relieve surface stress. (2) The 1H-T2 (19F-T2) values of the two phases differed, and ions in the surface phase were more mobile. The 1H-T2 (19F-T2) values for the two phases increased with temperature rise. In particular, the 1H-T2 (19F-T2) values of the surface phase were smoothly connected to the liquid T2 values. (3) The cations and anions exhibited a cooperative diffusive motion. (4) When the temperature was considerably lower than the melting point, the ratio of the surface phase did not significantly differ from when it first formed. However, it rapidly increased near the melting point and became liquid.
  • Takuto Ootahara, Kan Hatakeyama-Sato, Morgan L. Thomas, Yuko Takeoka, Masahiro Rikukawa, Masahiro Yoshizawa-Fujita
    ACS Applied Electronic Materials, 6(8) 5866-5878, Jul 29, 2024  Peer-reviewedLast authorCorresponding author
  • Kotoko Ariga, Shuho Akakabe, Ryotaro Sekiguchi, Morgan L. Thomas, Yuko Takeoka, Masahiro Rikukawa, Masahiro Yoshizawa-Fujita
    ACS Omega, 9(20) 22203-22212, May 21, 2024  Last authorCorresponding author
  • N.M. Mustafa, F.N. Jumaah, M. Yoshizawa-Fujita, N.A. Ludin, M. Akhtaruzzaman, N.H. Hassan, A. Ahmad, K.M. Chan, M.S. Su’ait
    Construction and Building Materials, 428 136283-136283, May 17, 2024  Peer-reviewed
  • F.N. Jumaah, N.M. Mustafa, N.N. Mobarak, N.H. Hassan, S.A.M. Noor, N.A. Ludin, K.H. Badri, A. Ahmad, M. Yoshizawa-Fujita, M.S. Su'ai
    Electrochimica Acta, 472 143383-143383, Dec 20, 2023  Peer-reviewed
  • Miru Yoshida-Hirahara, Masahiro Yoshizawa-Fujita, Yuko Takeoka, Masahiro Rikukawa
    Materials Advances, 4(19) 4555-4570, Sep 8, 2023  Peer-reviewed
    S-6X multi-block copolymers can be developed by direct one-pot copolymerization via Ni(0) coupling reaction, allowing high conductivity and strength on a wide-range of IECs.
  • Morgan L. Thomas, Kan Hatakeyama-Sato, Shinkoh Nanbu, Masahiro Yoshizawa-Fujita
    Energy Advances, 2(6) 748-764, Apr 25, 2023  Peer-reviewedLast authorCorresponding author
  • F.N. Jumaah, N.N. Mobarak, N.H. Hassan, S.A.M. Noor, S.N.S. Nasir, N.A. Ludin, K.H. Badri, A. Ahmad, Elisabeth R.D. Ito, M. Yoshizawa-Fujita, M.S. Su'ait
    Journal of Molecular Liquids, 376 121378-121378, Apr 15, 2023  Peer-reviewed
  • Masahiro Yoshizawa‐Fujita, Hiroyuki Ohno
    The Chemical Record, 23(8) e202200287, Feb 13, 2023  Peer-reviewedInvitedLead authorCorresponding author
  • Keiko Nishikawa, Kozo Fujii, Taisei Yamada, Masahiro Yoshizawa-Fujita, Kazuhiko Matsumoto
    Chemical Physics Letters, 803 139771-139771, Sep 16, 2022  Peer-reviewedInvited
  • Isabell L. Johansson, Christofer Sångeland, Tamao Uemiya, Fumito Iwasaki, Masahiro Yoshizawa-Fujita, Daniel Brandell, Jonas Mindemark
    ACS Applied Energy Materials, 5(8) 10002-10012, Aug 22, 2022  Peer-reviewed
  • Masahiro Yoshizawa-Fujita, Ryoma Ota, Jun Ishii, Yuko Takeoka, Masahiro Rikukawa
    MACROMOLECULAR CHEMISTRY AND PHYSICS, 223(8) 2100363, Apr, 2022  Peer-reviewedInvitedLead authorCorresponding author
    Rechargeable magnesium (Mg) batteries are envisioned as next generation batteries. The development of solid polymer electrolytes with high ionic conductivity will contribute to realize not only high performance Mg batteries but also reliable and safe devices. In this study, diblock copolymers (PPEGMA(m)-b-SPBn) with oligoether (PEGMA) and zwitterionic (SPB) side-chains are synthesized in order to develop novel Mg-ion electrolytes. PPEGMA(m)-b-SPBn copolymers with various unit ratios are synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. PPEGMA(m)-b-SPBn exhibited two distinct glass transition temperatures. Phase-separated structures are observed by atomic force microscope (AFM) measurements. PPEGMA(m)-b-SPBn/Mg-salt composites exhibited a glass transition temperature due to the mixture formation of PEGMA and SPB blocks. When the unit numbers of m and n are 44 and 75, respectively, PPEGMA(m)-b-SPBn/Mg-salt ([EO]: [Mg] = 6: 1) exhibits the highest ionic conductivity of over 10(-4) S cm(-1) at 60 degrees C among 11 composites prepared in this study.
  • Masahiro Yoshizawa-Fujita, Satoshi Kubota, Shuichi Ishimoto
    Frontiers in Energy Research, 10 854090, Mar 8, 2022  Peer-reviewedInvitedLead authorCorresponding author
    Recently, ionic plastic crystals (IPCs) have been actively investigated to develop all-solid-state rechargeable batteries, such as lithium-ion batteries. Herein, we report supercapacitors assembled with mesoporous carbon electrodes and an IPC electrolyte, N-ethyl-N-methylpyrrolidinium bis(fluorosulfonyl)amide ([C2mpyr][FSA]). [C2mpyr][FSA] with a 10 mol% lithium bis(fluorosulfonyl)amide (LiFSA) dopant was used as the solid electrolyte in the supercapacitors. The charge–discharge tests of the supercapacitors were performed at various C-rates in the voltage range of 0–2.5 V at 25°C. The capacitance of the cells was 12.3 Fg−1 at a lower C rate (1 C = 8.9 mA g−1). The capacitance retention of the supercapacitors was maintained at approximately 100% up to 20 C, which was comparable to that of the cells containing organic electrolyte solutions. The advantage of using solid electrolytes was the fabrication of bipolar cells using two pairs of mesoporous carbon electrodes and a [C2mpyr][FSA]/LiFSA composite. The charge–discharge tests of the bipolar cells were also performed in the voltage range of 0–5.0 V at 25°C. The capacitance of the bipolar cells was 6.4 Fg−1 at a lower C rate. The bipolar cells exhibited a typical charge–discharge profile for 1,000 cycles, confirming their stable cyclic performance. Thus, IPC electrolytes are interesting materials for developing all-solid-state high-voltage supercapacitors.
  • Masahiro Yoshizawa-Fujita, Masanori Nakazawa, Yuko Takeoka, Masahiro Rikukawa
    Journal of Non-Crystalline Solids: X, 13 100078-100078, Mar, 2022  Peer-reviewedInvitedLead authorCorresponding author
  • Elisabeth R. D. Seiler, Kohei Koyama, Tomoyuki Iijima, Tamao Saito, Yuko Takeoka, Masahiro Rikukawa, Masahiro Yoshizawa-Fujita
    Polymers, 13(12) 1942-1942, Jun 11, 2021  Peer-reviewedLast authorCorresponding author
    Cellulose is the main component of biomass and is the most abundant biopolymer on earth; it is a non-toxic, low-cost material that is biocompatible and biodegradable. Cellulose gels are receiving increasing attention as medical products, e.g., as wound dressings. However, the preparation of cellulose hydrogels employing unmodified cellulose is scarcely reported because of the cumbersome dissolution of cellulose. In previous studies, we developed the new promising cellulose solvent N-butyl-N-methylpyrrolidinium hydroxide in an aqueous solution, which can dissolve up to 20 wt% cellulose within a short time at room temperature. In this study, we employed this solvent system and investigated the gelation behavior of cellulose after crosslinker addition. The swelling behavior in water (swelling ratio, water uptake), the mechanical properties under compression, and the antibacterial activity against Escherichia coli and Bacillus subtilis were investigated. We have developed a simple and fast one-pot method for the preparation of cellulose gels, in which aqueous pyrrolidinium hydroxide solution was acting as the solvent and as an antibacterial reagent. The pyrrolidinium hydroxide content of the gels was controlled by adjustment of the water volume employed for swelling. Simple recovery of the solvent system was also possible, which makes this preparation method environmentally benign.
  • Mariah Zuliana Dzulkipli, Jamilah Karim, Azizan Ahmad, Nurul Akmaliah Dzulkurnain, Mohd Sukor Su’ait, Masahiro Yoshizawa-Fujita, Lee Tian Khoon, Nur Hasyareeda Hassan
    Polymers, 13(8) 1277-1277, Apr 14, 2021  Peer-reviewed
    After decades of development, ionic liquid gel polymer electrolytes (ILGPEs) are currently experiencing a renaissance as a promising electrolyte to be used in electrochemical devices. Their inherent tendency towards poor electrochemical properties have limited their applications and commercialization activities. Henceforth, gel polymer electrolyte (GPE) is being introduced to alleviate the abovementioned issues. In this work, the assessment of the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4] in poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) to form ILGPE was done. The relationship of [BMIM][BF4] towards the dielectric properties at different wt. % ratios and temperature was ascertained. The results indicated that [BMIM]BF4 is able to facilitate fast conduction. Moreover, it was found that [BMIM][BF4] could serve as an effective agent in reducing crystallinity and glass transition temperature of the polymer and thus enhanced the ionic conductivity of the samples. Notwithstanding, the ILGPE sample possessed a high thermal stability up to 300 °C and good electrochemical stability of 4.2 V which are beneficial for operation in electrochemical devices. All in all, the correlation between the ionic liquid chemistry and electrochemical performances could provide a valuable insight to rational selection and design for ILGPE electrolytes.
  • Masahiro Yoshizawa-Fujita, Shunsuke Horiuchi, Tamao Uemiya, Jun Ishii, Yuko Takeoka, Masahiro Rikukawa
    Frontiers in Energy Research, 9 663270, Apr 12, 2021  Peer-reviewedInvitedLead authorCorresponding author
    Solid polymer electrolytes mainly based on polyethers have been actively investigated for over 40 years to develop safe, light, and flexible rechargeable batteries. Here, we report novel supramolecular electrolytes (SMEs) composed of polyether derivatives and a two-dimensional boroxine skeleton synthesized by the dehydration condensation of 1,4-benzenediboronic acid in the presence of a polyether with amines on both chain ends. The formation of SMEs based on polyether derivatives and boroxine skeleton was confirmed by Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (PXRD), and thermogravimetric (TG) analysis. Linear sweep voltammetry (LSV) and cyclic voltammetry (CV) were performed to evaluate the electrochemical stability and lithium conductive properties of SMEs with given amounts of lithium bis(trifluoromethylsulfonyl)amide (LiTFSA). The ionic conductivity of SME/LiTFSA composites increased with increasing lithium-salt concentration and reached a maximum value at a higher concentration than those of simple polyether systems. The lithium-ion transference number (<italic>t</italic><italic>Li</italic>+) of SME/LiTFSA was higher than those of polyether electrolytes. This tendency is unusual for a polyether matrix. SME/LiTFSA composite electrolytes exhibited a stable lithium plating/striping process even after 100 cycles. The current density increased with an increasing number of cycles. The combination of ion conductive polymers and a two-dimensional boroxine skeleton will be an interesting concept for developing solid electrolytes with good electrochemical properties.
  • Masahiro Yoshizawa-Fujita, Jun Ishii, Yuko Takeoka, Masahiro Rikukawa
    Polymers, 13(5) 800-800, Mar 5, 2021  Peer-reviewedLead authorCorresponding author
    Poly (ethylene oxide) (PEO) has been investigated as an ion-conductive matrix for several decades due to its excellent properties. However, further improvements are needed to enable a PEO-based ion-conductive matrix for practical applications. In order to develop novel solid polymer electrolytes based on zwitterions, we synthesized diblock copolymers (PPEGMA-b-SPBs) with oligoether and zwitterionic side-chains and evaluated their physico-chemical properties. PPEGMA-b-SPBs with various unit ratios were synthesized by RAFT polymerization. PPEGMA-b-SPBs with/without LiTFSA exhibited two distinct glass transition temperatures regardless of the unit ratio of PEGMA and SPB. AFM observations clearly revealed phase-separated structures. The ionic conductivity of PPEGMA-b-SPBs increased even at a high salt concentrations such as [EO]:[Li] = 6:1 and was over 10−5 S cm−1 at 25 °C. This tendency is unusual in a PEO matrix. The oxidation stability of PPEGMA-b-SPBs was about 5.0 V vs. Li/Li+, which is a higher value than that of PEO. The improvement of the electrochemical properties is attributed to the introduction of the SPB block into the block copolymers. PPEGMA-b-SPBs were evaluated as cathode-coating materials for Li batteries. The discharge capacity and coulombic efficiency of the cells employing the cathode (LiNi1/3Mn1/3Co1/3O2 (NMC)) coated with the block copolymers were much higher than those of the cell employing the pristine cathode at the 50th cycle in the cut-off voltage range of 3.0–4.6 V.
  • Misato Akiyoshi, Masahiro Yoshizawa-Fujita, Yuko Takeoka, Masahiro Rikukawa
    Chemical Communications, 57(27) 3395-3398, 2021  Peer-reviewed
    <p>Additive-induced perpendicularly oriented 2D perovskite films prepared using the bar-coating method.</p>
  • Satoshi Horikoshi, Satoshi Yamazaki, Yuhei Arai, Daisuke Sakemi, Masahiro Yoshizawa-Fujita, Nick Serpone
    Journal of Oleo Science, 70(5) 737-743, 2021  Peer-reviewed
  • Luke Wylie, Thomas Blesch, Rebecca Freeman, Kan Hatakeyama-Sato, Kenichi Oyaizu, Masahiro Yoshizawa-Fujita, Ekaterina I. Izgorodina
    ACS Sustainable Chemistry & Engineering, 8(49) 17988-17996, Dec 14, 2020  Peer-reviewed
  • Chengzi Qi, Takashi Iwahashi, Wei Zhou, Doseok Kim, Seitaro Yamaguchi, Masahiro Yoshizawa-Fujita, Yukio Ouchi
    Electrochimica Acta, 361 137020-137020, Nov 20, 2020  Peer-reviewed
  • Masahiro Yoshizawa‐Fujita, Hiromasa Yamada, Shun Yamaguchi, Haijin Zhu, Maria Forsyth, Yuko Takeoka, Masahiro Rikukawa
    Batteries & Supercaps, 3(9) 884-891, Sep, 2020  Peer-reviewedInvitedLead authorCorresponding author
  • Miru Yoshida-Hirahara, Satoshi Takahashi, Masahiro Yoshizawa-Fujita, Yuko Takeoka, Masahiro Rikukawa
    RSC Advances, 10 12810-12822, Mar 31, 2020  Peer-reviewed
    <p>Poly(<italic>p</italic>-phenylene)-based sulfonated polymers with well-controlled IECs were synthesized <italic>via</italic> a three-step procedure including preceding sulfonation of precursor monomers.</p>
  • E. R. D. Seiler, Y. Takeoka, M. Rikukawa, M. Yoshizawa-Fujita
    RSC Advances, 10(19) 11475-11480, Mar 20, 2020  Peer-reviewedLast authorCorresponding author
    Cellulose processing remains a challenge as it is insoluble in water and common organic solvents. Ionic liquids (ILs) are organic salts with a melting point below 100 degrees C and are known for their excellent solvent properties. Unlike common organic solvents, which can form toxic or flammable vapours due to their high volatility, ILs can be considered as more environmentally friendly due to their negligible vapour pressure and flame retardant properties. We found that N-butyl-N-methylpyrrolidinium hydroxide enables rapid dissolution of up to 20 wt% Avicel (R) cellulose at 25 degrees C in aqueous solution (50 wt% water), making it the first pyrrolidinium-based salt capable of dissolving cellulose. Furthermore, solubility studies are currently carried out mainly with the naked eye, microscopy or spectroscopy. The former is a subjective method because it depends on the observer, and particles at the micro-level cannot be seen with the human eye. Microscopic and spectroscopic analyses are suitable for the verification of solubility; however, the acquisition costs of the instruments are high, and sample preparation is time-consuming. We propose that turbidity is a suitable measure for solubility, and investigated a simple and fast method to evaluate cellulose solubility in aqueous N-butyl-N-methylpyrrolidinium hydroxide by employing a turbidimeter which was compared with microscopy and ocular (eye) observation. In this study, we have not only found a promising new solvent for cellulose processing, but also offer a reliable solubility analysis.
  • T. Eriksson, A. Mace, Y. Manabe, M. Yoshizawa-Fujita, Y. Inokuma, D. Brandell, J. Mindemark
    Journal of The Electrochemical Society, 167(7) 070537-070537, Mar 13, 2020  Peer-reviewed
  • R. Arai, M. Yoshizawa-Fujita, Y. Takeoka, M Rikukawa
    CrystEngComm, 21(31) 4529-4533, Aug 21, 2019  Peer-reviewed
    A two-dimensional perovskite incorporating an amine moiety with a carboxyl group exhibited variations in orientation with changes in the ambient humidity. It was possible to increase the degree of vertical orientation by optimizing the film thickness and promoting crystallization at the interface between the film and the film-forming atmosphere.
  • S. Shimizu, M. Yoshizawa-Fujita, Y. Takeoka, M. Rikukawa
    ACS Omega, 4(8) 13260-13264, Aug 20, 2019  Peer-reviewed
    Organic-inorganic perovskites are composed of organic cations and [PbX6](4-) octahedra, and the properties change depending on the type of organic cations. To identify the effect of organic cations and control the properties of the perovskite, thin films were prepared using quaternary alkylammonium and quaternary alkylphosphonium cations, which have big steric effects. A big steric effect can generate the distortion of [PbX6](4-) octahedra leading to changes in properties. A thin film of a Pb-based organic-inorganic perovskite having quaternary alkylphosphonium cations was prepared for the first time. An exciton absorption was observed at a lower wavelength than other perovskites prepared from primary and quaternary ammonium salts. The perovskite with phosphonium groups was thermally stable compared with ammonium groups.
  • M. Yoshizawa-Fujita, H. Hanabusa, Y. Takeoka, M. Rikukawa
    Kobunshi Ronbunshu, 76(4) 330-334, Jul 25, 2019  Peer-reviewedLead authorCorresponding author
    Five kinds of protic ionic liquids (PILs) were synthesized by the neutralization reaction of amidine and carboxylic acid (acetic acid, propionic acid, or butyric acid), and the esterification reaction of cellulose, using acetic anhydride, was carried out in PILs. The obtained cellulose derivatives were soluble in DMSO. In the H-1 NMR spectra of the cellulose derivatives, not only the chemical shift of acetyl group derived from acetic anhydride, but also the chemical shift, based on the anion of PILs, were observed. The degree of substitution (DS) of the produced cellulose derivatives varied depending on the structure of PILs. The obtained cellulose derivatives showed a thermal decomposition temperature above 270 degrees C and a glass transition temperature below 170 degrees C.
  • H. Yamada, Y. Miyachi, Y. Takeoka, M. Rikukawa, M. Yoshizawa-Fujita
    Electrochimica Acta, 303 293-298, Apr 20, 2019  Peer-reviewedLast authorCorresponding author
    Organic ionic plastic crystals (OIPCs) have been studied as solid-state electrolytes because of their desirable properties such as non-flammability, plasticity, and ionic conductivity. However, the temperature range of their conductive plastic crystal phase is narrow. We previously reported that N-ethyl-N-methylpyrrolidinium bis(fluorosulfonyl) amide ([C(2)mpyr][FSA]) exhibited a wide temperature range of plastic crystal behavior and high ionic conductivity at room temperature. In this study, the relationship between the side chain structure of pyrrolidinium and the physicochemical properties of their compounds with FSA was investigated. With two introduced ethyl groups, N, N-diethylpyrrolidinium bis(fluorosulfonyl) amide ([C(2)epyr][FSA]) showed higher ionic conductivity than [C(2)mpyr][FSA], while maintaining a sufficient temperature range of plastic crystal phase. The ionic conductivity of [C2epyr] [FSA] was further improved by the addition of 5 mol% LiFSA. For the [C(2)epyr][FSA] composited with 5 mol % LiFSA, the lithium transference number was determined to be 0.27 at 60 degrees C. Reversible lithium plating/ stripping reaction was observed on a Ni electrode in the CV measurement. Symmetric pyrrolidinium cation with a longer alkyl chain (up to two carbons) showed conductive plastic solid phase in a wide temperature range and a higher lithium transference number. (c) 2019 Elsevier Ltd. All rights reserved.
  • M. Suzuki, N. Kurahashi, Y. Takeoka, M. Rikukawa, M. Yoshizawa-Fujita
    Frontiers in Chemistry, 7 90, Feb 20, 2019  Peer-reviewedLast authorCorresponding author
    Ionic liquids (Ls) are promising electrolyte materials for developing next-generation rechargeable batteries. In order to improve their properties, several kinds of additives have been investigated. In this study, beta-cyclodextrin (beta-CD) was chosen as a new additive in IL electrolytes because it can form an inclusion complex with bis(trifluoromethylsulfonyl)amide (TFSA) anions. We prepared the composites by mixing N-methyl-N-propylpyrrolidinium bis(trifluoromethylsulfony)amide/LiTFSA and a given amount of triacetyl-beta-cyclodextrin (Ac beta-CD). The thermal behaviors and electrochemical properties of the composites were analyzed by several techniques. In addition, pulse field gradient NMR measurements were conducted to determine the self- diffusion coefficients of the component ions. The addition of Ac beta-CD to the IL electrolytes results in the decrease in the conductivity value and the increase in the viscosity value. In contrast, the addition of Ac beta-CD to the IL electrolytes induced an improvement in the anodic stability because of the formation of an inclusion complex between the Ac beta-CD and TFSA anions. CDs are potential candidates as additives in IL electrolytes for electrochemical applications.
  • L. Wylie, K. Oyaizu, A. Karton, M. Yoshizawa-Fujita, E. I. Izgorodina
    ACS Sustainable Chemistry & Engineering, 7(5) 5367-5375, Feb 1, 2019  Peer-reviewedInvited
  • H. Ohno, M. Yoshizawa-Fujita, Y. Kohno
    Bulletin of the Chemical Society of Japan, 92(4) 852-868, Jan 26, 2019  Peer-reviewedInvited
  • S. Yamaguchi, H. Yamada, Y. Takeoka, M. Rikukawa, M. Yoshizawa-Fujita
    New Journal of Chemistry, 43(10) 4008-4012, Jan 25, 2019  Peer-reviewedLast authorCorresponding author
    In this work, pyrrolidinium-based OIPCs were synthesised together with various anionic species to investigate the effect of the anion structure on the OIPC properties. In particular, the relationship between the ionic conductivity and ionic radius ratio (q) of the anion and cation was investigated. The results suggested that OIPCs with a smaller q value were found to exhibit a higher ionic conductivity.
  • H. Hanabusa, Y. Takeoka, M. Rikukawa, M. Yoshizawa-Fujita
    Australian Journal of Chemistry, 72(1-2) 55-60, Jan, 2019  Peer-reviewedLast authorCorresponding author
    A protic ionic liquid (PIL) composed of 1,8-diazabicyclo[5.4.0]-undec-7-ene (DBU) and acetic acid can dissolve cellulose under mild conditions and catalyse its transesterification. To investigate the relationship between physicochemical properties and chemical structures, PILs composed of DBU and carboxylic acids with varying alkyl chain lengths were prepared as cellulose-dissolving solvents. The thermal behaviours of the PILs were analysed by thermogravimetry and differential scanning calorimetry, and their viscosities, ionic conductivities, and cellulose-dissolution abilities were determined. The effect of the alkyl chain length in the carboxylate ion on the physicochemical properties of the PILs was investigated. With increasing chain length, the thermal stability and ionic conductivity increased, whereas the melting point (T-m), glass-transition temperature (T-g), cellulose solubility, and viscosity decreased. The cellulose solubility increased as the difference between the pK(a) values of the DBU and carboxylic acid (Delta pK(a)) increased. In addition, the cellulose solubility increased with the increasing density of the PIL. It was revealed that PILs with a high DpKa value and a carboxylate ion with a short alkyl chain are suitable for cellulose dissolution.
  • H. Nagasaka, M. Yoshizawa-Fujita, Y. Takeoka, M. Rikukawa
    ACS Omega, 3(12) 18925-18929, Dec 31, 2018  Peer-reviewed
    Organic-inorganic perovskites, (RNH3)(2)PbX4, have attracted much attention as one of the most promising light-harvesting and light-emitting materials. The present work investigated the steric effects of the organic parts on the perovskites by varying the alkylamine type and chain length. Primary, secondary, and tertiary amines with various chain lengths were introduced into organic-inorganic perovskites. Extending the chain length raised the phase transition point and shortened the absorption wavelength. In addition, the introduction of secondary and tertiary amines resulted in red-and blue-shifting of the absorption peaks, respectively.
  • Toyonobu Usuki, Masahiro Yoshizawa-Fujita
    Application of Ionic Liquids in Biotechnology, 227-240, Nov 16, 2018  
  • Suzuki Mio, Kurahashi Naoya, Takeoka Yuko, Rikukawa Masahiro, Fujita Masahiro
    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 256, Aug 19, 2018  Peer-reviewed
  • Takashi Hirahara, Masahiro Yoshizawa-Fujita, Yuko Takeoka, Masahiro Rikukawa
    Chirality, 30(6) 699-707, Jun 1, 2018  Peer-reviewed
    This study demonstrates the supramolecular chirality control of a conjugated polymer via solvent polarity. We designed and synthesized a chiral polyfluorene-thiophene copolymer having two different chiral side chains at the 9-position of the fluorene unit. Chiral cyclic and alkyl ethers with different polarities were selected as the chiral side chains. The sign of the circular dichroism spectra in the visible wavelength region was affected by the solvent system, resulting from the change of supramolecular structure. The estimation of the solubility parameter revealed that the solubility difference of the side chains contributed to the change of the circular dichroism sign, which was also observed in spin-coated films prepared from good solvents having different polarities.
  • Hideki Hanabusa, Ekaterina I. Izgorodina, Shiori Suzuki, Yuko Takeoka, Masahiro Rikukawa, Masahiro Yoshizawa-Fujita
    Green Chemistry, 20(6) 1412-1422, 2018  Peer-reviewedLast authorCorresponding author
    Cellulose acetate (CA) is a resin derived from biomass. In addition to its various superior properties, CA is preferable to existing petroleum-derived resins from the viewpoint of green chemistry. Therefore, the acetylation of cellulose is one of the most important subjects in cellulose research. In this study, we found that the acetylation of cellulose could proceed in some protic ionic liquids (PILs) composed of amidine and acetic acid with ΔpKa = ca. 8.4-8.7 under mild conditions without any catalyst. The degree of substitution (DS) of the produced CA was above 1.84, and the maximum DS was 2.87 when the ΔpKa of the PIL was about 8.5. In propionate-based PILs, cellulose was not only acetylated but also propionated however, the cellulose acetylation did not occur in formate-based PILs. It was revealed that the esterification of cellulose proceeded through the anion exchange between carboxylic anhydride and anion species of the PIL.
  • Hiroyuki Ohno, Masahiro Yoshizawa-Fujita, Yuki Kohno
    Physical Chemistry Chemical Physics, 20(16) 10978-10991, 2018  Peer-reviewedInvited
    A zwitterion, an ion pair where cation and anion are covalently tethered, is known to be a type of salt. These ions have not been recognised as interesting, but they are physicochemically unique and fascinating ions. In the present review, some functional zwitterions derived from ionic liquids are mentioned to emphasise the usefulness of the tethering of the component cations and anions of ionic liquids. Basic properties, advantages and disadvantages after the functional design of zwitterions, and some applications are summarised.
  • Shiori Suzuki, Yuko Takeoka, Masahiro Rikukawa, Masahiro Yoshizawa-Fujita
    RSC Advances, 8(26) 14623-14632, 2018  Peer-reviewedLast authorCorresponding author
    The conversion of cellulose into valuable chemicals has attracted much attention, due to the concern about depletion of fossil fuels. The hydrolysis of cellulose is a key step in this conversion, for which Brønsted acidic ionic liquids (BAILs) have been considered promising acid catalysts. In this study, using BAILs with various structures, their acidic catalytic activity for cellulose hydrolysis assisted by microwave irradiation was assessed using the Hammett acidity function (H0) and theoretical calculations. The glucose yields exceeded 10% when the H0 values of the BAIL aqueous solutions were below 1.5. The highest glucose yield was about 36% in 1-(1-octyl-3-imidazolio)propane-3-sulfonate (Oimps)/sulfuric acid (H2SO4) aqueous solution. A long alkyl side chain on the imidazolium cation, which increased the hydrophobicity of the BAILs, enhanced the glucose yield.
  • Toyonobu Usuki, Shingo Onda, Masahiro Yoshizawa-Fujita, Masahiro Rikukawa
    Scientific Reports, 7(1) 6890, Dec 1, 2017  Peer-reviewed
    Sweet potato, Ipomoea batatas, is a widely cultivated vegetable worldwide. The leaves contain polyphenolic natural products called caffeoylquinic acids (CQAs), which possess biological activities including inhibition of aggregation of amyloid peptides. The present study describes an efficient extraction and isolation procedure for CQAs from sweet potato leaves using a cellulose-dissolving ionic liquid. The results showed that, compared to methanol, use of 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) allowed the extraction of a 6.5-fold greater amount of CQAs. This protocol will enable the efficient extraction of other organic compounds and biopolymers from natural materials.
  • T. Sato, M. Yoshizawa-Fujita, Y. Takeoka, M. Rikukawa
    Journal of Analytical & Bioanalytical Techniques, 8(6) 388, Dec, 2017  Peer-reviewed

Misc.

 64
  • 畠山歓, 藤田正博
    機能材料, 45(3) 56-64, Mar 7, 2025  InvitedLast authorCorresponding author
  • Takuto Ootahara, Kan Hatakeyama-Sato, Morgan L. Thomas, Yuko Takeoka, Masahiro Rikukawa, Masahiro Yoshizawa-Fujita
    ChemRxiv, May 13, 2024  Last authorCorresponding author
    Ionic plastic crystals (IPCs), which are soft crystals with plasticity and ionic conductivity, are expected to be applied as solid electrolytes in battery applications. Further improvement of ionic conductivity is necessary for practical use as an electrolyte for energy storage devices. Materials Informatics (MI) is a method of incorporating information science in materials development. In this research, MI is being used to develop IPCs with high ionic conductivity. By using informatics science in addition to chemical knowledge, this research can be carried out efficiently and innovatively. The synthesis of eight new compounds resulted in six of them being solid at room temperature, while two of them were in a liquid state, namely ionic liquids. We evaluated the phase transition temperatures and ionic conductivity for each compound. Notably, N-ethyl-N-methylpyrrolidinium trifluoromethyltrifluoroborate ([C2mpyr][CF3BF3]) exhibited a high ionic conductivity of 1.75×10-4 S cm-1 at 25 oC, which is one of the highest values reported among IPCs to date. The combination of an experimental and MI based approach revealed an improved understanding of the relationship between ion size and ionic conductivity for a series of pyrrolidinium-based IPCs, and it is expected that further improvements to this approach will yield greater understanding of structure-property relationships.
  • Yutaro Hayashi, Mariya Usami, Elisabeth R. D. Ito, Yuko Takeoka, Masahiro Rikukawa, Masahiro Yoshizawa-Fujita
    ChemRxiv, Feb 14, 2024  Last authorCorresponding author
    Cellulose is attracting attention for the development of environmentally friendly, carbon-neutral, sustainable materials. Cellulose derivatives with cationic groups have the potential for applications in various fields, e.g., electrolytes. However, the current situation is marked by a low degree of cationic group incorporation and a need for more efficient synthesis methods. In this study, cationic cellulose was synthesized using an epoxy derivative, 2,3-epoxypropyltrimethylammonium chloride (EPTMAC), in an aqueous pyrrolidinium hydroxide solution. Since an aqueous pyrrolidinium hydroxide solution is a strong alkaline solution, the solution not only exhibits a high cellulose solubility at room temperature but also facilitates the reaction between cellulose and the epoxy derivative. We investigated the influence of reaction time, temperature, cellulose concentration, cationic reagent concentration, and the selection of a precipitation solvent for purification on the degree of substitution (DS) value of cationic cellulose. The structure of the obtained cationic cellulose was examined using 1H NMR, 1H-1H TOCSY, 1H-13C HSQC measurements, and Fourier-transform infrared spectroscopy (FT-IR). As a result of increasing cellulose and EPTMAC concentrations, the DS value increased, reaching a maximum value of 1.9. Solubility tests indicated that the cationic cellulose with chloride counter-anions exhibited notable solubility even in ethanol when the DS values were over 1.2. Cationic cellulose with bis(trifluoromethylsulfonyl)amide (TFSA) anion synthesized with a view to battery applications was insoluble in water and exhibited a film-forming property. Thus, the solubility of cationic cellulose could be controlled by varying the anionic species.
  • Arata Matsui, Deandra Ayu Putri, Morgan L. Thomas, Yuko Takeoka, Masahiro Rikukawa, Masahiro Yoshizawa-Fujita
    ChemRxiv, Jan 17, 2024  Last authorCorresponding author
    Cellulose is one of the main components of plant cell walls, abundant on earth, and is a non-edible material that can be acquired at a low cost. Furthermore, there has been increasing interest in its use in environmentally friendly, carbon-neutral, sustainable materials. It is expected that the applications of cellulose will expand with the development of a simple processing method. Previously, it was demonstrated that cellulose can be dissolved in a non-heated, short-duration process using an aqueous pyrrolidinium hydroxide solution. In this study, we dissolved cellulose in aqueous N-butyl-N-methylpyrrolidinium hydroxide solution ([C4mpyr][OH]/H2O) and investigated the cellulose regeneration process based on changes in solubility upon application of CO2 gas. We investigated the effect of transformation of the anion chemical structure on cellulose solubility by flowing CO2 gas into [C4mpyr][OH]/H2O and conducted pH, FT-IR, and 13C NMR measurements. We observed that the changes in anion structure allowed for the modulation of cellulose solubility in [C4mpyr][OH]/H2O, thus establishing a simple and safe cellulose regeneration process. This regeneration process was also applied to enable the production of cellulose hydrogels. The hydrogel formed using this approach was revealed to be of a higher mechanical strength than that of an analogous hydrogel produced using the same dissolution solvent with addition of a cross-linker. The ability to produce cellulose-based hydrogels of different mechanical properties is expected to expand the possible applications.
  • 藤田正博
    液晶, 27(4) 240-244, Oct, 2023  InvitedCorresponding author
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