Tohoku University · Materials Science
Professor Takashi Takeda's research lab specializes in the design and synthesis of functional molecular materials with unique stimuli-responsive behaviors, particularly focusing on mechanically and thermally responsive crystals, supramolecular assemblies, and advanced electrode materials. Key research directions include the development of thermosalient molecular crystals that exhibit crystal-jumping upon thermal stimulation, the formation of chiral π-stacked supramolecules with tunable optical properties, and the exploration of novel oxide materials—such as ruthenium pyrochlores and perovskites—for solid oxide fuel cell applications. The lab also investigates ultralong chemical bonds and their conformational expandability, aiming to create smart materials for sensing and actuation. These interdisciplinary efforts bridge molecular chemistry, solid-state physics, and materials science to advance next-generation responsive and energy materials.
Figures are computed from collected data and may differ slightly.
There is a limited number of reports on mechanically responsive molecular crystals, including thermo-responsive and light-responsive crystals. Rigid ordered molecular crystals with a close-packing structure are less able to accept distortion, which hampers the development of such molecular crystals. The thermosalient effect, or "crystal jumping", refers to a thermo-responsive system that converts heat into mechanical force by thermally induced phase transition. While they have recently attracted
The absorption and fluorescence spectra of chiral alkylamide-substituted pyrene derivatives (R-1 and S-1) in the solution phase were consistent with the formation of N–H···O═ hydrogen-bonded helical π-stacked one-dimensional (1D) supramolecules (R-1)n and (S-1)n in methylcyclohexane (MCH), toluene, chloroform (CHCl3), and tetrahydrofuran (THF); the π-stacked structures and aggregation number (n) were governed by the concentration (c) and solvent polarity. The aggregation of (R-1)n and (S-1)n in
The ruthenium pyrochlores, , and ruthenium perovskites, were characterized as new electrode materials for solid oxide fuel cells. The electrical conductivity, cathodic polarization, thermal expansion, and reactivity with yttria‐stabilized zirconia were examined. The pyrochlores showed low cathodic overpotential even at 800°C, metallic behavior with high electrical conductivity, and no reaction with yttria‐stabilized zirconia at 900°C. The thermal expansion coefficient of the bismuth pyrochlore w
Ethylacridone (1 b) and dicyanomethylenated acridones 2 a,b,d showed crystal-jumping activity upon heating. This is the first example of thermosalient behavior in a simple aromatic ketone and its derivatives. A systematic investigation of the jumping behavior of derivatives with different alkyl chains by variable-temperature X-ray crystal-structure analyses revealed the mechanism of this phenomenon. Anisotropic dissociation of π stacking in a dimer was important for inducing crystal jumping in 1
A sequential Sonogashira cross-coupling/Pd-mediated oxidative homocoupling strategy affords two-dimensional dehydrobenzoannulene trefoils containing different sizes of the central annulenic ring system. Use of these conditions instead of Cu-mediated homocoupling conditions yields a structural isomer possessing a triphenylene ([6]annulene) core. Noticeable differences in the absorption and emission spectra are observed depending upon the core unit.
Abstract Over the past few decades, many studies have been conducted on ultralong C–C bonds (bond length greater than 1.7 Å). This highlight review discusses the molecular design of ultralong C–C bonds and their bonding properties, especially their “expandability.” In particular, the ultralong C–C bonds in tetraarylpyracene derivatives can change in length by adopting a slightly different conformation in the crystalline state. This expandability of ultralong C–C bonds could be due to the smaller
Abstract There is a limited number of reports on mechanically responsive molecular crystals, including thermo‐responsive and light‐responsive crystals. Rigid ordered molecular crystals with a close‐packing structure are less able to accept distortion, which hampers the development of such molecular crystals. The thermosalient effect, or “crystal jumping”, refers to a thermo‐responsive system that converts heat into mechanical force by thermally induced phase transition. While they have recently
We herein report a thermoresponsive amphipathic fluorescent organic liquid, tetraethylene glycol (TEG) ester-substituted tetraphenylethylene (TPE), 1, as a new class of functional organic material. AIE fluorescence of 1 could be modulated by controlling the temperature. The introduction of hydrophilic PEG chains induced the formation of a uniform fluorescent colloidal supramolecular structure in H2O. This colloidal structure of 1 also showed temperature-dependent fluorescence due to its motility
Molecular structures of dicyanomethylenated quinacridone (1) as a solid and in solution were examined on the basis of single-crystal X-ray structural analysis, temperature-dependent (1)H NMR in CD2Cl2, and theoretical calculations. Crystal 1 had a curved, butterfly-shaped molecular structure. Thermally activated flipping between the curved, butterfly-shaped structure and an armchair structure occurred in solution. Electrochemical reduction triggered a dynamic change from the curved, butterfly-sh
Alkylamide-substituted [1]benzothieno[3,2-<i>b</i>][1]benzothiophene (<b>BTBT</b>) derivative of <b>BTBT</b>-NHCOC<sub>14</sub>H<sub>29</sub> (<b>1</b>), which has ferroelectric N-H···O= hydrogen-bonding network of alkylamide group and two-dimensional (2D) electric structure of <b>BTBT</b> π-cores, was prepared to design the external electric field-responsive organic semiconductors. The short-chain derivative of <b>BTBT-</b>NHCOC<sub>3</sub>H<sub>7</sub> (<b>1'</b>) revealed the coexistence of a
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