Kyushu University · Materials Science
Professor Ryo Ohtani's research lab specializes in the design and functional control of coordination polymers, with a focus on spin-crossover materials, porous coordination networks, and stimuli-responsive frameworks. The lab investigates how guest molecules, metal oxidation states, and structural distortions influence magnetic, thermal, and optical properties, particularly in Hofmann-type and salen-based coordination polymers. A key research direction involves tuning physical properties such as spin transition temperatures and thermal expansion through chemical and structural engineering. The lab also explores applications in smart materials, sensors, and responsive devices via precise control of host-guest interactions and framework dynamics.
Figures are computed from collected data and may differ slightly.
Precise control of spin transition temperature (T(c)) is one of the most important challenges in molecular magnetism. A Hofmann-type porous coordination polymer {Fe(pz)[Pt(II)(CN)(4)]} (1; pz = pyrazine) exhibited cooperative spin transition near room temperature (T(c)(up) = 304 K and T(c)(down) = 284 K) and its iodine adduct {Fe(pz)[Pt(II/IV)(CN)(4)(I)]} (1-I), prepared by oxidative addition of iodine to the open metal sites of Pt(II), raised the T(c) by 100 K. DSC and microscopic Raman spectra
Abstract The host–guest composites of Hofmann‐type iron(II) spin‐transition (ST) porous coordination polymers incorporating guest molecules show guest‐dependent ST behavior in accordance with the respective guest species, which may be a gas, solvent, halogen, or organic molecule. The guest also works as a chemical stimulant to switch the spin state of the host between high and low spin at room temperature. In this review, we discuss guest properties including size, shape, flexibility, chemical p
Abstract Two 2D Hofmann‐type spin‐crossover coordination polymers, [Fe(stpy) 2 Pt(CN) 4 ] · 0.5MeOH (stpy = 4‐styrylpyridine; 1 ) and [Fe(pep) 2 Pt(CN) 4 ] {pep = 4‐(2‐phenylethyl)pyridine; 2 }, have been prepared by using long co‐ligands with different flexibilities. These compounds form 3D interdigitate structures based on 2D layers extended by Pt–CN–Fe linkages with different interlayer structures depending on the nature of the axial co‐ligand. The stpy co‐ligand forms one‐directional π–π net
Subarachnoid extension of the hematoma on CT strongly indicates a non-hypertensive cause, and more specifically, it suggests lobar ICH caused by vascular abnormalities.
The ability to tune physical properties is attractive for the development of new materials for myriad applications. Understanding and controlling the structural dynamics in complicated network structures like coordination polymers (CPs) is particularly challenging. We report a series of two-dimensional CPs [Mn(salen)]<sub>2</sub>[M(CN)<sub>4</sub>]· xH<sub>2</sub>O (M = Pt (1), PtI<sub>2</sub> (2), and MnN (3)) incorporating zigzag cyano-network layers that display composition-dependent anisotro
Zero in-plane thermal expansion (TE) in a two-dimensional (2D) coordination polymer is demonstrated. The combination of components that expand and those that shrink into zigzag layers results in no net area change in the 2D materials with temperature. Single crystals of [Mn(salen)]<sub>2</sub>[Mn(N)(CN)<sub>4</sub>(guest)] (salen = N,N'-ethylenebis(salicylideneaminato), guest = MeOH and MeCN) were prepared, and variable-temperature single-crystal X-ray structural analyses demonstrated that these
Metal node design is crucial for obtaining structurally diverse coordination polymers (CPs) and metal-organic frameworks with desirable properties; however, Fe<sup>II</sup> ions are exclusively six-coordinated. Herein, we present a cyanide-bridged three-dimensional (3D) CP, FePd(CN)<sub>4</sub> , bearing four-coordinate Fe<sup>II</sup> ions, which is synthesized by thermal treatment of a two-dimensional (2D) six-coordinate Fe<sup>II</sup> CP, Fe(H<sub>2</sub> O)<sub>2</sub> Pd(CN)<sub>4</sub> ⋅4
Recently, non-crystalline coordination materials have been shown to represent a versatile class of functional materials. However, such materials incorporating metal complex clusters have remained largely unexplored. Herein, we demonstrate that a luminescent tetranuclear ReV cluster melts at 489 K, with the cluster structure being maintained in the corresponding supercooled ionic liquid phase.
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