Aquatic Functional Materials

Takashi Kato (A01) and co-workers have successfully synthesized biomineral-based aquatic colloidal liquid crystals composed of fluoroapatite/polymer hybrids. They exhibited photonic functions displaying bright structural colors. The liquid crystals immobilized in polymer networks showed mechanochromic properties.
Advanced Materials, 2404396, Early View, (2024).
Press Release: Head Office of UTokyo, Dept of Engineering of UTokyo
News and Highlights: Nikkei, Mynabi news, BIGLOBE news, OPTLONICS, JST  (Chinese)

Motomu Tanaka (A03), Masaki Nakahata (A03), Yuka Ikemoto (A02) and Takashi Nakamura (A01) have developed polymeric materials inspired by plant proteins that selectively capture and neutralize heavy metal ions such as cadmium. Through international collaboration with Heidelberg University (Germany), they succeeded in the hyperconfinement of the bio-inspired polymer and dramatically improved the selective ion trapping capacity. They demonstrated that this system enables to improve the aquatic environment by removing harmful heavy metal ions in simulated industry wastewater down to the drinkable level.
Nat. Commun., 15, 5824-1/10 (2024).
Online release: Jul. 11, 2024
Press release: Osaka University, Kyoto University
Nihon Keizai Shimbun, Springer Nature Research Communities, EurekAlert!, Asia Research News, ScienMag, Phys.org, Nanowerk, Bioengineer.org, Smart Water Magazine, AZoMaterials, Chem Europe, Mirage News, Technology Networks, Water Online, Innovazione.

Tomoko Fujino (A01) and her colleague have developed single-crystalline oligomers models of doped polyethylenedioxythiophene (PEDOT). This study achieved a room temperature conductivity 1,000,000 times higher than that of the dimer salt in a charge transfer salt of a tetramer with a mixed sequence, realizing a metallic state at room temperature and above. The key to high conductivity was the pathway created by the water and acetone included in the single crystal. The excess anions incorporated into this pathway caused the band filling rate to deviate from the half-filled state.
J. Am. Chem. Soc. 2023, 145 (28), 15152–15161.
Press release: The Univ. of Tokyo, JST, IMS

Takashi Kato (A01) and Motomu Tanaka (A03) have fabricated a new composite electronic material by functionalizing the surface of GaN semiconductor with a supramolecular liquid-crystal membrane possessing a unique anion selectivity under international collaboration with University of Bremen (Germany). By analyzing the electric signals obtained by chronoamperometry, they unraveled the mechanism of selective transport of large, divalent sulfate ions through the nano-porous membrane compared to small, monovalent chloride ions. J. Phys. Chem. B, 2024, 128, 4537−4543.
DOI: 10.1021/acs.jpcb.4c00047
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On line release: April 29, 2024.

Takashi Kato (A01), Yoshihisa Harada (A02) and coworkers have examined hydrogen-boned structures of water molecules in the hydroxy-group-functionalized one-dimensional nanochannels (diameter: ca 1.5 nm) of liquid-crystalline (LC) nanostructured membranes with soft X-ray emission spectroscopy. Unlike the case of the ionic LC nanochannels (Ref: Kato and Harada, Angew. Chem. Int. Ed., 59, 23461-23465 (2020)), the water molecules confined in the LC nanochannels covered with hydroxy groups exhibit hydrogen-bonded structures close to those of bulk liquid water. These findings provide new insight of the separation mechanisms and new approaches to novel function designs of LC membranes.
J. Phys. Chem. Lett., 15, 454-460 (2024).

Motomu Tanaka (A03), Yoshinori Takashima (A03) and Masaki Nakahata (A03) have developed the hydrogel membranes whose stiffness can be switched on demand by changing the degree of hydration. Under international collaboration with Heidelberg University Hospital (Germany), they found that human stem cells feel the substrate elasticity beyond a certain threshold. Moreover, stem cells change their biological function when the stiffness was switched too frequently.
Adv. Healthcare Mater. 13, 2302607 (2024).
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Online release: Dec. 20, 2023

Hayato Tsuji(A01), Masaki Nakahata (A03), Mafumi Hishida (A02), Hideki Seto (A02) and coworkers have observed aggregation behavior of hydrophobic fluorescent molecule in water-tetrahydrofuran (THF) mixed solvent. They have observed that water and THF molecules form varieties of micro-mesoscopic scale structures, where hydrophobic molecules are distributed to form aggregation. They have also elucidated that the aggregation state of the solute and the size of the aggregate accordingly change upon changing the mixing ratio of water and THF, which significantly affects the fluorescence properties of the solution.
J. Phys. Chem. Lett., 14, 11235-11241 (2023).
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Press Release: Kanagawa University, Osaka University, Tokyo University of Science, KEK, J-PARC、JAEA

Yoshinori Takashima (A03), Yuta Nishina (A01), Go Matsuba (A03), Yuka Ikemoto (A02) , and coworkers fabricated the stress-strain sensors using the composites between stretchable polymers and carbon-filler. The composites detected applied stress-strain through resistance changes.
ACS Polymers Au, 3, 394-405 (2023).
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Yoshinori Takashima　(A03), Hitoshi Washizu　(A02), Tsuyoshi Minami　(A01), and co-workers prepared gas sensors based on supramolecular polymers with reversible crosslinks and carbon materials. The gas sensors selectively detected ammonia compounds through the molecular recognition of cyclodextrins.
ACS Appl. Mater. Interfaces, 15, 39777-39785 (2023).

Masahiko Imashimizu (A02), Mafumi Hishida (A02) and co-workers have successfully observed that externally applied sub-THz electromagnetic fields perturb the rapid collective dynamics in protein-water systems. They further verified the relevance of this observation with THz and NMR spectroscopies. They found that a protein hydration change, which usually takes a long time, is significantly accelerated by the sub-THz irradiation.
Nat. Commun., 14, 2825 (2023),
Editors’ Highlights.
Press Release: AIST, Tokyo University of Science

Tomoko Fujino (A01), Rie Makiura (A01) and coworkers developed single-component, ambipolar semiconductors, stable even in air containing water and oxygen. These materials are solution-processible and highly crystalline, even in thin film forms, exhibiting excellent ambipolar charge-transport properties with high carrier mobility of up to 10^–2 cm²V^–1s^–1 and large on/off ratios of up to 105. They are inert to water and oxygen and stable even after several months of exposure to air.
J. Am. Chem. Soc., 145, 2127-2134 (2023),
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Press Release: ISSP, The University of Tokyo News and Highlights: Nikkan Kogyo Shimbun

Katsuya Teshima (A02) and co-workers synthesized layered double hydroxides with high crystallinity, cation state, porosity, and unique particle shape. They demonstrated that a 24% reduction in the packing density of interlayer ions effectively promotes a two-dimensional hydrogen-bonded structure in water around nitrate ions, increasing the storage capacity of nitrate ions by 300%, while minimizing changes in the layered structure.
Nat. Commun., 13, 6448-1/9 (2022).
Press Release: Shinshi University

Takeshi Serizawa (A01), Go Watanabe (A02), Masaru Tanaka (A03) and co-workers systematically revealed the relationship between hydration states and protein nonadsorption/adsorption properties for cellulose-based molecular assemblies.
Colloids Surf. B: Biointerfaces, 220, 112898-1/9 (2022).

Yuka Ikemoto (A02), Hajime Torii (A02), Yoshihisa Harada (A02), Masaru Tanaka (A03), Hitoshi Washizu (A02) and coworkers showed that the OH stretching frequency of water is controlled by the electric field perceived by the H atoms and is well correlated with the water arrangement at the polymer interface by theoretical calculations compared with infrared absorption spectra of different biocompatible polymers under humidification.
J. Phys. Chem. B., 126, 4143-4145 (2022).

Mitsuo Hara (A01), Yoshihisa Fujii (A03) and co-workers synthesized water-soluble polysiloxanes containing alkylamine hydrochloride side chains. The resulting polysiloxanes exhibit changes in mechanical properties due to intra- and inter-molecular ionic aggregation and high ordering of the main chain structure induced by humidity.
Macromolecules, 55, 4313-4319 (2022).

Masaru Tanaka (A03), Yoshihisa Harada (A02), Yuka Ikemoto (A02) and coworkers showed by atomic force microscopy, quartz crystal microbalance, and soft X-ray emission spectroscopy that water on polymers causes phase separation and water in tetrahedral coordination coexisting with water adsorbed on C=O groups in low-density regions provides a scaffold for intermediate water formation, contributing to blood compatibility.
Langmuir, 38, 1090-1098 (2022).
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Yoshifumi Hashikawa (A01) and co-workers observed quantum rotational excitations of a water molecule using H₂O@C₆₀ single-molecule transistors and revealed that an ortho-para conversion of the encapsulated water molecule occurs within a minute, probably due to interaction between the valence electrons of H₂O molecule and the conduction electrons of ₆₀.
Nano Lett., 21, 10346-10353 (2021).
Press release: Kyoto Univ., UTokyo, Tohoku Univ.
News and Highlights: Nikkei Shimbun, Nikkan Kogyo Shimbun, EurekAlert!

Rie Makiura (A01) and co-workers successfully fabricated uniaxially oriented MOF nanosheets that show high electric conductivity using a simple method of dropping a solution onto the surface of water.
ACS Appl. Mater. Interfaces, 13, 54570-54578 (2021).
Press release: Osaka Pref. Univ.
News and Highlights: Nikkei Shimbun, Nikkan Kogyo Shimbn,
Mynavi news, EurekAlert!, AsiaResearchNews、AZONANO, ScienceDaily, Phys.org、Mirage.News, Nanowerk

Koji Harano (A01), Motomu Tanaka (A03) and their co-workers synthesized a 3-nm-thick nanofilm with large-area uniformity over tens of cm², which is composed of a fullerene double layer holding a water layer between them. The film can be transferred onto a variety of substrates including gold comb electrodes, and shows high proton conductivity through hydrogen-bonded network of the water layer inside.
Adv. Mater., 34, 2106465-1/10 (2022).

Hitoshi Washizu (A02), Takashi Kato (A01), Go Watanabe (A02) and co-workers performed large-scale molecular dynamics simulations of self-assembled ionic liquid crystalline membranes and reproduced the nanochannel structure obtained by X-ray diffraction. Hydrogen-bond analysis of water showed that the one-dimensional ionic nanochannel structure is suited for dissolution and diffusion of water in the nanochannel.
Sci. Adv., 7, eabf0669-1/14 (2021).
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Press Release: Univ. of Hyogo, Hyogo Prefectural Board of Education, Osaka Univ., Kitasato Univ., Dept. Eng., UTokyo
News and Highlights: Nikkei Shimbun

Chie Kojima (A03) synthesized PEGylated dendrimers with high and low PEG density as a model of drug carrier, and investigated their hydration states and biodistribution, collaborating with Shigeaki Morita (A02) and Masaru Tanaka (A03). They suggested a relationship between the hydration states and the tumor accumulation (blood circulation) property.
Mater. Sci. Eng. C, 126, 112159-1/7 (2021).

Takashi Kato (A01), Jiro Kumaki (A02) and their coworkers have developed a 2D thermotropic smectic liquid-crystalline (LC) membrane with gemini-type nanostructure composed of cationic imidazolium moieties showing over 99.99997% virus rejection ability and improved water permeation.
ACS Appl. Mater. Interfaces, 13, 20598-20605 (2021).

Youfeng Yue (A03) and co-workers fabricated ultra-high water content 1D photonic hydrogels exhibiting a large electro-optical response in the entire wavelength range from visible to near-infrared region due to ionic diffusion, which maintain electrically printed patterns underwater for a long time. These full-color properties are expected to pave the way for next-generation reflective displays for underwater applications.
Adv. Opt. Mater., 9, 2002198-1/9 (2021).

Collaboration by Takashi Kato (A01) and Yoshihisa Harada (A02) has revealed that water treatment membranes based on liquid crystalline polymers recognize the hydrogen-bonded structure of water surrounding ions to allow selective ion permeation.
Angew. Chem. Int. Ed., 59, 23461-23465 (2020).
Press release: Dept. Eng., UTokyo, ISSP, UTokyo
News and Highlights: Nikkei, Nature Reviews Chemistry (Research Highlight)

Youhei Takeda (A01) and co-workers developed porous molecular crystals that show reversible color change in response to humidity. In collaboration with Yuka Ikemoto (A02) they revealed that the color change is due to changes in the molecular structure and nature of the pores in the crystals depending on humidity.
Commun. Chem., 3, 118-1/8 (2020).
Press release: Osaka Univ., JASRI
News and Highlights: Optronics, ScienceDaily、Phys.org., EurekAlert!