29 results match your criteria: "Kyoto University Yoshida Honmachi[Affiliation]"

We created different amorphous structures of a coordination polymer by applying mechanical shear forces. One-dimensional Cu(TfN)(bip) (1, TfN = bis(trifluoromethanesulfonyl)imide, bip = 1,3-bis(1-imidazolyl)propane) melted at 245 °C and underwent a glass transition at -10 °C by a static cooling process. 1 formed another amorphous state with a distinct glass transition point of 70 °C under oscillatory shear stress.

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Systematic design and functionalisation of amorphous zirconium metal-organic frameworks.

Chem Sci

October 2024

Centre for Membrane Separations, Adsorption, Catalysis, and Spectroscopy (cMACS), KU Leuven Celestijnenlaan 200F 3001 Leuven Belgium

Controlling the structure and functionality of crystalline metal-organic frameworks (MOFs) using molecular building units and post-synthetic functionalisation presents challenges when extending this approach to their amorphous counterparts (aMOFs). Here, we present a new bottom-up approach for synthesising a series of Zr-based aMOFs, which involves linking metal-organic clusters with specific ligands to regulate local connectivity. In addition, we overcome the limitations of post-synthetic modifications in amorphous systems, demonstrating that homogeneous functionalisation is achievable even without regular internal voids.

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A cyano-bridged coordination polymer, K{Co [Fe(CN)]} {(K)Co-Fe}, reported as a highly active heterogeneous catalyst for water oxidation was solubilised by a conventional counter-cation exchange of K with MeN ions to provide the homogeneous catalyst of (MeN){Co [Fe(CN)]} {(MeN)Co-Fe}. (MeN)Co-Fe exhibited enhanced catalytic activity for photocatalytic water oxidation using [Ru(2,2'-bipyridine)] and SO as a photosensitiser and a sacrificial electron acceptor, respectively, in terms of the initial reaction rate (1.26 μmol min), which is about twice that of (K)Co-Fe (0.

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The authors previously proposed that 5-hydroxymethylfurfural (5-HMF) can be produced from the reducing ends of cellulose as a key intermediate during carbonization. The present work investigated the mechanisms by which furan and benzene rings are formed in cellulose char based on carbonization at 280 °C using C-labeled 5-HMF together with C-labeled glucose (as a model for the cellulose reducing ends). Glycerol was added to the 5-HMF to prevent the formation of stable glassy polymers.

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Utilization of cell wall components of woody biomass has attracted attention as alternatives for fossil fuels towards a sustainable society. A semi-flow hydrothermal treatment was used to fractionate the beech () wood into cellulose-rich residues and lignin-rich precipitates. The enzymatic saccharification of the cellulose component in the residue was enhanced significantly because the preferential delignification from the secondary wall increased enzyme accessibility.

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Functional metal-organic liquids.

Chem Sci

May 2024

Department of Chemistry, Graduate School of Science, Kyoto University Kitashirakawa-Oiwake-cho, Sakyo-ku Kyoto 606-8502 Japan

For decades, the study of coordination polymers (CPs) and metal-organic frameworks (MOFs) has been limited primarily to their behavior as crystalline solids. In recent years, there has been increasing evidence that they can undergo reversible crystal-to-liquid transitions. However, their "liquid" states have primarily been considered intermediate states, and their diverse properties and applications of the liquid itself have been overlooked.

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Nanocrystal (NC) superlattices (SLs) have been widely studied as a new class of functional mesoscopic materials with collective physical properties. The arrangement of NCs in SLs governs the collective properties of SLs, and thus investigations of phenomena that can change the assembly of NC constituents are important. In this study, we investigated the dynamic evolution of NC arrangements in three-dimensional (3D) SLs, specifically the morphological transformation of NC constituents during the direct liquid-phase synthesis of 3D NC SLs.

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Article Synopsis
  • Some endosymbionts cause male killing, where infected females produce few or no male offspring due to unknown mechanisms.
  • In this research, a specific 76 kbp prophage region linked to male-killing was identified in a moth, revealing genes that affect male and female offspring development.
  • The study showed that certain gene expressions led to high male mortality rates, while combinations of these genes highlighted complex interactions in male lethality, shedding light on the evolution of male-killing among insects and the role of bacteriophages in this process.
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The detection of vertical and lateral forces at the nanoscale by atomic force microscopy (AFM) reveals various mechanical properties on surfaces. The qPlus sensor is a widely used force sensor, which is built from a quartz tuning fork (QTF) and a sharpened metal probe, capable of high-resolution imaging in viscous liquids such as lubricant oils. Although a simultaneous detection technique of vertical and lateral forces by using a qPlus sensor is required in the field of nanotribology, it has still been difficult because the torsional oscillations of QTFs cannot be detected.

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In order to improve the solubility of sulfuric acid lignin (SL) in ,-dimethylformamide (DMF), dry ball milling with excess amounts of additives such as l-tartaric acid was performed. Although the ball-milled SL without any additives was not soluble in DMF, when the SL was ball milled with an excessive amount of l-tartaric acid (the concentration of SL to be 0.1%), the dispersion and solubility of SL in DMF detected by the dynamic light scattering was greatly improved.

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The structure of the melt state of one-dimensional (1D) coordination polymer crystal Cu(isopropylimidazolate) (melting temperature = 143 °C) was characterized by DSC, variable temperature PXRD, solid-state NMR (SSNMR), viscoelastic measurements, XAS, and DFT-AIMD calculations. These analyses suggested "coordination polymer-forming liquid" formation with preserved coordination bonds above . Variable chain configurations and moderate cohesive interaction in adjacent chains are the keys to the rarely observed polymer-forming liquid.

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Biomedical imaging using cell labeling is an important technique to visualize cell dynamics in the body. To label cells, thiol-organosilica nanoparticles (thiol-OS) containing fluorescein (thiol-OS/Flu) and rhodamine B (thiol-OS/Rho) were surface-functionalized with polyethyleneimine (PEI) (OS/Flu-PEI and OS/Rho-PEI) with 4 molecular weights (MWs). We hypothesized PEI structures such as brush, bent brush, bent lie-down, and coiled types on the surface depending on MWs based on dynamic light scattering and thermal gravimetric analyses.

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Stable Oligomer Formation from Lignin by Pyrolysis of Softwood in an Aprotic Solvent with a Hydrogen Donor.

ChemistryOpen

September 2022

Department of Socio-Environmental Energy Science, Graduate School of Energy Science, Kyoto University Yoshida-honmachi, Sakyo-ku, Kyoto, 606-8501, Japan.

Pyrolysis of Japanese cedar wood in diphenoxybenzene (an aprotic solvent) with a hydrogen donor was investigated between 270-380 °C. Under these conditions, re-condensation via radical and quinone methide intermediates was efficiently suppressed and a thermally stable oligomer was obtained. The oligomer was stable even after the treatment time was extended.

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Article Synopsis
  • * The study highlights how thermodynamic issues and the size of side groups affect the PUs' morphology and overall properties.
  • * Increased 1,2-vinyl content results in better phase mixing and smaller microdomains, which leads to more complex pathways for gas molecules, ultimately reducing gas permeability in the membranes.
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We synthesized luminescent coordination polymer glasses composed of d metal cyanides and triphenylphosphine through melt-quenching and mechanical milling protocols. Synchrotron X-ray total scattering measurements and solid-state NMR revealed their one-dimensional chain structures and high structural dynamics. Thermodynamic and photoluminescence properties were tunable by the combination of heterometallic ions (Ag, Au, and Cu) in the structures.

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Proton-conductive coordination polymer glass for solid-state anhydrous proton batteries.

Chem Sci

March 2021

Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University Katsura, Nishikyo-ku Kyoto 615-8510 Japan

Designing solid-state electrolytes for proton batteries at moderate temperatures is challenging as most solid-state proton conductors suffer from poor moldability and thermal stability. Crystal-glass transformation of coordination polymers (CPs) and metal-organic frameworks (MOFs) melt-quenching offers diverse accessibility to unique properties as well as processing abilities. Here, we synthesized a glassy-state CP, [Zn(HPO)(HO)](1,2,3-benzotriazole), that exhibited a low melting temperature (114 °C) and a high anhydrous single-ion proton conductivity (8.

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Hydrogen bond donor solvents such as aromatic solvents inhibit the secondary degradation of cellulose-derived primary pyrolysis products. In a previous study, we found that the formation of solid carbonized products was completely inhibited during cellulose pyrolysis in aromatic solvents, with 5-hydroxymethylfurfural (5-HMF) recovered in certain yields instead. This indicated that 5-HMF is an intermediate in cellulose carbonization.

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To evaluate rhombohedral Y(SO) as a new potential material for low-temperature thermochemical energy storage, its thermal behavior, phase changes, and hydration/dehydration reaction mechanisms are investigated. Rhombohedral Y(SO) exhibits reversible hydration/dehydration below 130 °C with relatively small thermal hysteresis (less than 50 °C). The reactions proceed two reaction steps in approximately 0.

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High proton conducting electrolytes with mechanical moldability are a key material for energy devices. We propose an approach for creating a coordination polymer (CP) glass from a protic ionic liquid for a solid-state anhydrous proton conductor. A protic ionic liquid (dema)(HPO), with components which also act as bridging ligands, was applied to construct a CP glass (dema)[Zn(HPO)(HPO)].

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This is the first study of cellulose carbonization in the interior of cell walls. Cotton cellulose was pyrolyzed under nitrogen or in aromatic solvents (benzophenone, diphenyl sulfide, and 1,3-diphenoxybenzene) at 280 °C, and cross sections of the cell walls were examined using ultraviolet (UV) microscopy. After pyrolysis under nitrogen, UV absorption caused by carbonization appeared inside the cell walls.

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We studied the relationship between proton conductivity and the terahertz-regime vibrations of two-dimensional MOFs. The results of spectroscopy studies clarified the essential role played by the collective motions in the terahertz region in 2D layers for efficient H conduction. calculations suggested the collective motion to be predominantly determined by the valence electronic structure, depending on the identity of the metal ion.

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Sodium ion batteries have been developed using ionic liquids as electrolytes. Sodium is superior to lithium as a raw material for mass production of large-scale batteries for energy storage due to its abundance and even distribution across the earth. Ionic liquids are non-volatile and non-flammable, which improved the safety of the batteries remarkably.

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Iron is an essential transition metal species for all living organisms and plays various physiologically important roles on the basis of its redox activity; accordingly, the disruption of iron homeostasis triggers oxidative stress and cellular damage. Therefore, cells have developed sophisticated iron-uptake machinery to acquire iron while protecting cells from uncontrolled oxidative damage during the uptake process. To examine the detailed mechanism of iron uptake while controlling the redox status, it is necessary to develop useful methods with redox state selectivity, sensitivity, and organelle specificity to monitor labile iron, which is weakly bound to subcellular ligands.

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The influences of working memory representations on long-range regression in text reading: an eye-tracking study.

Front Hum Neurosci

October 2014

Department of Cognitive Psychology in Education, Graduate School of Education, Kyoto University Yoshida-Honmachi, Sakyo-ku, Kyoto, Japan.

The present study investigated the relationship between verbal and visuospatial working memory (WM) capacity and long-range regression (i.e., word relocation) processes in reading.

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