東北大学 · 材料科学
山下正博教授の研究室は、分子磁性と量子効果を核とした次世代ナノ材料の創出を目的としています。主にスピン・フラストレーションやハルダインギャップを示す磁性体、および単分子磁石(SMM)や鎖状磁性体(SCM)を用いた量子デコherence制御の研究が進められています。特に、光応答性リガンドやカーボンナノチューブへの封入を活用した、外部場で制御可能な分子スピンデバイスの構築を目指しています。
Figures are computed from collected data and may differ slightly.
Single-chain magnets (SCMs) are one-dimensional (1D) slow-relaxing magnetic chains with interesting fundamental properties and applications, such as information storage. The mechanism underlying the slow relaxation of SCMs is Glauber dynamics, in which R. J. Glauber proposed about 50 years ago that the 1D correlation of ferromagnetically coupled Ising spins causes very slow magnetic relaxation at a finite temperature. Since the first experimental observation of SCM dynamics of a cobalt(II)–organ
Practical implementation of highly coherent molecular spin qubits for challenging technological applications, such as quantum information processing or quantum sensing, requires precise organization of electronic qubit molecular components into extended frameworks. Realization of spatial control over qubit-qubit distances can be achieved by coordination chemistry approaches through an appropriate choice of the molecular building blocks. However, translating single qubit molecular building units
Lanthanide-based extended coordination frameworks showing photocontrolled single-molecule magnet (SMM) behavior were prepared by combining highly anisotropic Dy(III) and Ho(III) ions with the carboxylato-functionalized photochromic molecule 1,2-bis(5-carboxyl-2-methyl-3-thienyl)perfluorocyclopentene (H2 dae), which acts as a bridging ligand. As a result, two new compounds of the general formula [{Ln(III) 2 (dae)3 (DMSO)3 (MeOH)}⋅10 MeOH]n (M=Dy for 1 a and Ho for 2) and two additional pseudo-pol
Two assemblies composed of single-molecule magnets (SMMs) linked by photochromic ligands, [Cu(II)(2)Tb(III)(2)(L)(2)(NO(3))(2)(dae-o)(2)]·2(n-BuOH) (1) and {[Cu(II)Tb(III)(L)(n-BuOH)(0.5)](2)(dae-c)(3)}·5(DMF)·4(n-BuOH)·2(H(2)O) (2), were synthesized by reacting the SMM [Cu(II)Tb(III)(L)(NO(3))(3)] (H(2)L = 1,3-bis((3-methoxysalicylidene)amino)propane) and photochromic molecules, H(2)dae-o and H(2)dae-c, which are open- and closed-ring isomers of 1,2-bis(5-carboxyl-2-methyl-3-thienyl)perfluorope
Abstract My research target can be described as “Next Generation Multifunctional Nano-Science of Advanced Metal Complexes with Quantum Effect and Nonlinearity”. My work encompasses four important key areas: (1) inorganic-organic hybrid systems, (2) nano-size and nano-space, (3) bottom-up and self-assembly, and (4) nonlinearity and quantum effect. Among them, nonlinearity and quantum effect are the most important for nano-science of advanced metal complexes. I have been working on these two topic
DySc<sub>2</sub>N@C<sub>80</sub> is an endohedral metallofullerene showing single-molecule magnet (SMM) behavior. In this work, we encapsulated DySc<sub>2</sub>N@C<sub>80</sub>-SMMs into the internal one-dimensional nanospace of single-walled carbon nanotubes (SWCNTs). Using transmission electron microscopy, "peapod" structures were clearly observed. From magnetic field dependent measurements, DySc<sub>2</sub>N@C<sub>80</sub> showed stepwise hysteresis characteristic of SMMs even inside the SWCN
A neutral mononuclear Fe(III) complex [Fe(III) (H-5-Br-thsa-Me)(5-Br-thsa-Me)]⋅H2 O (1; H2 -5-Br-thsa-Me=5-bromosalicylaldehyde methylthiosemicarbazone) was prepared that exhibited a three-step spin-crossover (SCO) with symmetry breaking and a 14 K hysteresis loop owing to strong cooperativity. Two ordered intermediate states of 1 were observed, 4HS-2LS and 2HS-4LS, which exhibited reentrant phase-transition behavior. This study provides a new platform for examining multistability in SCO complex
Multifunctional molecular materials exhibiting electrical conductivity and single-molecule magnet (SMM) behaviour are particularly attractive for electronic devices and related applications owing to the interaction between electronic conduction and magnetization of unimolecular units. The preparation of such materials remains a challenge that has been pursued by a bi-component approach of combination of SMM cationic (or anionic) units with conducting networks made of partially oxidized (or reduc
Structures and magnetic characteristics of two three-coordinate erbium(iii) compounds with C<sub>3v</sub> geometry, tris(2,6-di-tert-butyl-p-cresolate)erbium, Er(dbpc)<sub>3</sub> (1) and tris(bis(trimethylsilyl)methyl)erbium, Er(btmsm)<sub>3</sub> (2), were determined. Both underwent temperature-dependent slow magnetic relaxation processes in the absence of an external magnetic field. As a result of the differences in the coordination environment, they exhibit different energy barriers and quan
Two-dimensional Dy(III) and Ho(III) homometal coordination polymers containing the photochromic ligand 1,2-bis(5-carboxyl-2-methyl-3-thienyl)perfluorocyclopentene (DTE) with the general formula [Ln2(DTE)3(bipyridine)2(H2O)2]n (Ln = Dy and Ho) were obtained, and the magnetic properties of their open (Dy-o and Ho-o) and closed forms (Dy-c and Ho-c) were investigated. The Dy complexes exhibited slow magnetic relaxation without an external dc field. The magnetic properties of the Dy complexes were i
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