Showing papers by "Osamu Sato published in 2016"
TL;DR: Recent advances in the development of stimuli-responsive, switchable crystalline compounds - referred to here as dynamic molecular crystals - are discussed and how different approaches can serve to prepare functional materials are suggested.
Abstract: The development of molecular materials whose physical properties can be controlled by external stimuli - such as light, electric field, temperature, and pressure - has recently attracted much attention owing to their potential applications in molecular devices. There are a number of ways to alter the physical properties of crystalline materials. These include the modulation of the spin and redox states of the crystal's components, or the incorporation within the crystalline lattice of tunable molecules that exhibit stimuli-induced changes in their molecular structure. A switching behaviour can also be induced by changing the molecular orientation of the crystal's components, even in cases where the overall molecular structure is not affected. Controlling intermolecular interactions within a molecular material is also an effective tool to modulate its physical properties. This Review discusses recent advances in the development of such stimuli-responsive, switchable crystalline compounds - referred to here as dynamic molecular crystals - and suggests how different approaches can serve to prepare functional materials.
581 citations
TL;DR: A significant increase in the phase transition temperature of the deuterated analogue suggests that the proton plays an important role in the ferroelectric phase transition.
Abstract: A pure organic single crystal, [H2dabco]·[2CB]2 ([H2dabco]2+ = diprotonated 1,4-diazabicyclo[2.2.2]octane, 2CB– = 2-chlorobenzoate), which undergoes a ferroelectric-to-paraelectric phase transition above room temperature (∼323 K upon heating), was prepared and characterized. This ferroelectric crystal possesses a distinctive supramolecular architecture composed of discrete H-bonded trimeric units (two 2CB– anions bridged by one [H2dabco]2+ cation through N–H···O hydrogen bond interactions). In the paraelectric phase, the [H2dabco]2+ cation is rotationally disordered and lies at the symmetric center of the trimer. Upon cooling, it is frozen in an ordered state and deviates toward a 2CB– anion at one end along the H-bond. The collective displacement of the cations leads to a polarization of the single crystal along the crystallographic c axis, which is confirmed by the temperature dependence of the second harmonic generation and spontaneous polarization. A significant increase in the phase transition temper...
75 citations
TL;DR: Interestingly, the lanthanide metallogrid complex (2) exhibits magnetic hysteresis loop even up to 16 K at a given field sweep rate of 500 Oe/s, and both magnetic dilution and application of a moderate magnetic field suppress ground-state quantum tunneling of magnetization.
Abstract: Structural assembly and reversible transformation between a metallogrid Dy4 SMM (2) and its fragment Dy2 (1) were established in the different solvent media. The zero-field magnetization relaxation was slowed for dysprosium metallogrid (2) with relaxation barrier of Ueff = 61.3 K when compared to Dy2 (1). Both magnetic dilution and application of a moderate magnetic field suppress ground-state quantum tunneling of magnetization and result in an enhanced Ueff of 119.9 and 96.7 K for 2, respectively. Interestingly, the lanthanide metallogrid complex (2) exhibits magnetic hysteresis loop even up to 16 K at a given field sweep rate of 500 Oe/s.
70 citations
TL;DR: A neutral mononuclear Fe(III) complex was prepared that exhibited a three-step spin-crossover (SCO) with symmetry breaking and a 14 K hysteresis loop owing to strong cooperativity, providing a new platform for examining multistability in SCO complexes.
Abstract: A neutral mononuclear FeIII complex [FeIII(H-5-Br-thsa-Me)(5-Br-thsa-Me)]⋅H2O (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 complexes.
55 citations
TL;DR: A mixed-valence Fe(II) /Fe(III) cyanide-bridged coordination polymer, {[Fe(Tp)(CN)3 ]2 Fe(bpe)⋅5 H2 O}n, which demonstrates a thermally induced charge-transfer phase transition, is described.
Abstract: Heterometallic Prussian blue analogues are known to exhibit thermally induced charge transfer, resulting in switching of optical and magnetic properties. However, charge-transfer phase transitions have not been reported for the simplest FeFe cyanide-bridged systems. A mixed-valence Fe(II) /Fe(III) cyanide-bridged coordination polymer, {[Fe(Tp)(CN)3 ]2 Fe(bpe)⋅5 H2 O}n , which demonstrates a thermally induced charge-transfer phase transition, is described. As a result of the charge transfer during this phase transition, the high-spin state of the whole system does not change to a low-spin state. This result is in contrast to FeCo cyanide-bridged systems that exhibit charge-transfer-induced spin transitions.
50 citations
TL;DR: It is demonstrated that the structural transition between an empty orthorhombic phase and an empty tetragonal phase in a flexible porous dodecatuple intercatenated supramolecular organic framework can be controlled cooperatively through guest incorporation and thermal treatment, thus inducing empty shape-memory nanopores.
Abstract: Flexible porous materials generally switch their structures in response to guest removal or incorporation. However, the design of porous materials with empty shape-switchable pores remains a formidable challenge. Here, we demonstrate that the structural transition between an empty orthorhombic phase and an empty tetragonal phase in a flexible porous dodecatuple intercatenated supramolecular organic framework can be controlled cooperatively through guest incorporation and thermal treatment, thus inducing empty shape-memory nanopores. Moreover, the empty orthorhombic phase was observed to exhibit superior thermoelasticity, and the molecular-scale structural mobility could be transmitted to a macroscopic crystal shape change. The driving force of the shape-memory behaviour was elucidated in terms of potential energy. These two interconvertible empty phases with different pore shapes, that is, the orthorhombic phase with rectangular pores and the tetragonal phase with square pores, completely reject or weakly adsorb N2 at 77 K, respectively.
48 citations
TL;DR: A synthetic and crystal engineering strategy is devised that enables the selective synthesis of a [CrCo] heterometallic dinuclear complex with a polar crystal structure, wherein polarization changes stem from intramolecular charge transfer between Co and the ligand.
Abstract: The polarization switching mechanism is used in various devices such as pyroelectric sensors and memory devices. The change in polarization mostly occurs by ion displacement. The development of materials whose polarization switches via electron transfer in order to enhance operation speed is a challenge. We devised a synthetic and crystal engineering strategy that enables the selective synthesis of a [CrCo] heterometallic dinuclear complex with a polar crystal structure, wherein polarization changes stem from intramolecular charge transfer between Co and the ligand. Polarization can be modulated both by visible-light irradiation and temperature change. The introduction of chiral ligands was paramount to the successful polarization switching in the valence tautomeric compound. Mixing Cr and Co complexes with enantiopure chiral ligands resulted in the selective formation of only pseudosymmetric [CrCo] heterometallic complexes. Furthermore, the left-handed chiral ligands preferentially interacted with their ...
41 citations
TL;DR: X-ray structure analysis showed that the coexistence of hydrogen bond and cation-π interactions, as well as alkali metal coordination bonds, to give 2D coordination polymer structure, contrary to previous reports of broad thermal hysteresis induced by coordination bonds of Fe(II) spin crossover coordination polymers (with 1D/3D structures).
Abstract: The anionic Fe(III) complex exhibiting cooperative spin transition with a wide thermal hysteresis near room temperature, K[Fe(5-Brthsa)2 ] (5-Brthsa-H2 =5-bromosalicylaldehyde thiosemicarbazone), is reported. The hysteresis (Δ=69 K in the first cycle) shows a one-step transition in heating mode and a two-step transition in cooling mode. X-ray structure analysis showed that the coexistence of hydrogen bond and cation-π interactions, as well as alkali metal coordination bonds, to give 2D coordination polymer structure. This result is contrary to previous reports of broad thermal hysteresis induced by coordination bonds of Fe(II) spin crossover coordination polymers (with 1D/3D structures), and by strong intermolecular interactions in the molecular packing through π-π stacking or hydrogen-bond networks. As a consequence, the importance, or the very good suitability of alkali metal-based coordination bonds and cation-π interactions for communicating cooperative interactions in spin-crossover (SCO) compounds must be reconsidered.
30 citations
TL;DR: A self-assembled cobalt molecular grid of a pyrazine-bridged bis-tridentate ligand (L(R), where R = H (1), CH3 (2), and Br (3), was prepared and structurally characterized and the magnetic behavior from essentially high-spin Co(II) in 3 versus completely diamagnetic Co(III) in 1 to Co( II) spin-crossover in 2 can be achieved.
Abstract: A self-assembled cobalt molecular grid of a pyrazine-bridged bis-tridentate ligand (LR), where R = H (1), CH3 (2), and Br (3), was prepared and structurally characterized. Depending on the electronic effects of the substituents on the ligand, the redox of the metal center was systematically modulated, and the magnetic behavior from essentially high-spin CoII in 3 versus completely diamagnetic CoIII in 1 to CoII spin-crossover in 2 can be achieved.
28 citations
TL;DR: This study demonstrates how an intra-carboxyl proton shuttle can be generated in a molecular assembly akin to a rack-and-pinion cascade via a thermally induced single-crystal-to-single- Crystal phase transition.
Abstract: Proton transport via dynamic molecules is ubiquitous in chemistry and biology. However, its use as a switching mechanism for properties in functional molecular assemblies is far less common. In this study, we demonstrate how an intra-carboxyl proton shuttle can be generated in a molecular assembly akin to a rack-and-pinion cascade via a thermally induced single-crystal-to-single-crystal phase transition. In a triply interpenetrated supramolecular organic framework (SOF), a 4,4′-azopyridine (azpy) molecule connects to two biphenyl-3,3′,5,5′-tetracarboxylic acid (H4BPTC) molecules to form a functional molecular system with switchable mechanical properties. A temperature change reversibly triggers a molecular movement akin to a rack-and-pinion cascade, which mainly involves 1) an intra-carboxyl proton shuttle coupled with tilting of the azo molecules and azo pedal motion and 2) H4BPTC translation. Moreover, both the molecular motions are collective, and being propagated across the entire framework, leading to a macroscopic crystal expansion and contraction.
26 citations
TL;DR: Two polymorphic structures have been well determined in a valence tautomeric (VT) dinuclear cobalt complex and showed distinct thermal- and photomagnetic behavior, and are ideal for studying the "pure" intermolecular factors to VT transitions.
Abstract: Two polymorphic structures have been well determined in a valence tautomeric (VT) dinuclear cobalt complex. These polymorphs showdistinct thermal and photo magnetic behaviors, and are thus, ideal for studyingthe "pure" intermolecular factors to VT transitions. In polymorph 1A, the VT cations are arranged head-to-waist with their neighbors and exhibit weak pai-pai interactions, resulting in a gradual and incomplete thermal VT transition. In contrast, the cations in polymorph 1B are arranged head-to-tail and exhibit relatively strong pai-pai interactions, leading to an abrupt and complete thermal VT transition with adjustable hysteresis loop at around room temperature. The VT process for both polymorphs can be induced by light, but the light-excited state of 1B*2H2O has a higher thermal relaxation temperature than that of 1A*3H2O.
TL;DR: In this work, spin crossover iron(ii) complexes [Fe(Liq)2](BF4)2·(CH3CH2)2O (1-Et2O) and [Fe([BF4]2]2·3H2O(1-3H 2O) were prepared and structurally and magnetically analysed and the single-crystal-to-single-Crystal (SCSC) solvation transformation and the influence on the crystal structures
Abstract: The recent upsurge in molecular magnetism reflects its application in the areas of sensors and molecular switches. Thermal hysteresis is crucial to the molecular bistability and information storage, a wide hysteresis near room temperature is expected to be of practical sense for the molecular compound. In this work, spin crossover iron(II) complexes [Fe(Liq)2](BF4)2·(CH3CH2)2O (1-Et2O) and [Fe(Liq)2](BF4)2·3H2O (1-3H2O) were prepared and structurally and magnetically analysed. The single-crystal-to-single-crystal (SCSC) solvation transformation and the influence on the crystal structures and magnetic hysteresis were investigated in an etherification–hydration cycle. At room temperature, X-ray diffraction experiments indicated a transformation from one crystal (1-Et2O, P21212) to another crystal (1-3H2O, P212121) upon humidity exposure and reversible recovery of its crystallinity upon exposure to ether vapor. The etherified phase 1-Et2O exhibits room temperature spin crossover (T1/2 = 305 K) but negligible thermal hysteresis, however the hydrated phase 1-3H2O exhibits the apparent hysteresis loop (T1/2↑ = 346 K, T1/2↓ = 326 K) which expands to room temperature. This effect is associated with the change of intermolecular cooperativity in the etherification–hydration recyclability.
TL;DR: In this article, a nuclear iron carbonyl complex with an elongated unsupported Fe-Fe bond was synthesized by the reaction between Fe2(CO)9 and phosphinyl radical.
Abstract: Dinuclear iron carbonyl complex 2, which contains an elongated unsupported Fe–Fe bond, was synthesized by the reaction between Fe2(CO)9 and phosphinyl radical 1. Thermal Fe–Fe bond homolysis led to the generation of a four-coordinate carbonyl-based iron-centered radical, 3, which is stabilized by π-donation. Complex 3 exhibited high reactivity toward organic radicals to form diamagnetic five-coordinate Fe(II) complexes.
01 Jan 2016
TL;DR: In this paper, the authors synthesize Fe(II) compounds consisting of 2-Acetylpyridine isonicotinoylhydrazone and dicarboxylic acids.
Abstract: We synthesized new Fe(II) compounds consisting of [Fe(L)2] (HL: 2-Acetylpyridine isonicotinoylhydrazone) and dicarboxylic acids. Single crystal analysis shows that short hydrogen bonds are formed between [Fe(L)2] and dicarboxylic acids. The hydrogen bonding interactions between metal complexes and dicarboxylic acids are complemented by π-π interactions, forming two-dimensional network structures. Magnetic properties show that the Fe(II) compounds exhibit gradual spin crossover behavior around room temperature and a T1/2 value is dependent on the halogen substituent on the dicarboxylic acids.
TL;DR: The water-dependent CTIST behaviour of Na0.46Co[Fe(CN)6]0.78(H2O)1.31 together with its single crystal X-ray structural analysis, for the first time, is reported.
Abstract: Cobalt–iron Prussian blue analogues are magnetic functional compounds that exhibit charge-transfer-induced spin transition (CTIST), however, the role of guest species such as water in influencing the magnetic behaviour has remained unclear. Here, we report the water-dependent CTIST behaviour of Na0.46Co[Fe(CN)6]0.78(H2O)1.31 together with its single crystal X-ray structural analysis, for the first time.
TL;DR: In this article, the aromatic hydrogenation of 4-propylphenol to cis-and trans-4propylcyclohexanols was performed over a charcoal-supported palladium catalyst (Pd/C) in water-ethanol cosolvent.
Abstract: The aromatic hydrogenation of 4-propylphenol to 4-propylcyclohexanone, cis- and trans-4-propylcyclohexanols proceeded over a charcoal-supported palladium catalyst (Pd/C) in water–ethanol cosolvent ...
TL;DR: The introduction of alkali-metal coordination bonds and cation-π interactions into spin-crossover metal centers gives rise to strong cooperativity, yielding molecular bistability at room temperature.
Abstract: Spin Crossover S. Kang, O. Sato et al. report a novel approach for introducing cooperativity by intermolecular interactions into spin-crossover complexes so that they can exhibit a cooperative spin transition with a large thermal hysteresis loop at room temperature. The introduction of alkali-metal coordination bonds and cation-π interactions into spin-crossover metal centers gives rise to strong cooperativity, yielding molecular bistability at room temperature. For more details, read the Full Paper by O. Sato et al. on page 532 ff.
TL;DR: It’s time to get used to the idea that you can’t predict the future with certainty when it comes to the weather.
Abstract: 受付:2015年3月10日,採用:2015年12月26日 連絡先 佐藤 理 〒060-0001 北海道札幌市中央区北1条西6丁目 KKR札幌医療センター斗南病院外科 現病歴:2010年12月に当科にてS状結腸癌に対 し腹腔鏡下S状結腸切除,D3郭清を施行した. tub1,pT3(SS),ly1,v2,pN0,M0,pStage II にて当院内科で術後補助化学療法としてFOLFOX 療法(folinic acid,fluorouracil,oxaliplatin)8 コース,FUFOL療法(fluorouracil,folinic acid) 4コースを施行した.2012年4月の造影CTでB7 肝内胆管の拡張を認め,同8月の造影CTでは拡張 の増強と内部に腫瘤性病変を認めたため,精査加 療目的にて当科紹介となった. 入院時現症:身長161cm,体重53.5kg,腹部は 平坦,軟. 入院時検査所見:CA19-9 5.0U/mlであり,今回 の経過観察中に上昇を認めなかった. 腹部CT所見:2012年4月の術後補助化学療法後 のCTでB7肝内胆管の軽度拡張を認めたが,明ら かな腫瘍性病変は指摘できなかった.しかしその 後も胆管拡張の増強傾向を認め,同年8月の造影 CTでB7肝内胆管内に鋳型の腫瘍性病変を認めた (Fig. 1). 内容要旨
Patent•
17 Mar 2016
TL;DR: In this paper, a method for synthesizing 5-hydroxymethylfurfural by one-pot reaction by using cellulose and/or a cellulose-containing material as raw materials, and without using a harmful catalyst or organic solvent is presented.
Abstract: PROBLEM TO BE SOLVED: To provide a method for synthesizing 5-hydroxymethylfurfural by one pot (single stage) reaction by using cellulose and/or a cellulose-containing material as raw materials, and without using a harmful catalyst or organic solvent.SOLUTION: Calcium phosphate is used as a catalyst, and preferably, cellulose and/or a cellulose-containing material which are raw materials are subjected beforehand to crushing/grinding treatment independently or in the mixed state with the catalyst, and then the catalyst and the cellulose or the cellulose-containing material which is the raw material are subjected to a heating treatment in a water solvent, to thereby obtain 5-hydroxymethylfurfural.SELECTED DRAWING: Figure 1
TL;DR: In this article, Dimensional X (DXCT) is introduced as a new dimension for CT and CT装 (Dimensional X Expandable CT Expandable Expandable Bundle) is used.
Abstract: 医療用の断層撮影装置として 1970 年代に実用化された X線 CT装置は,人体のみならず物体の内部を非破壊で観 察できるという特長から,現在では工業製品の非破壊検査 に広く応用されている.さらに,内部形状などを克明に抽 出できる能力から,物体内部の幾何学的な測定への応用が 開始されてきている.一方,測定技術の側面から見ると, 三次元測定技術は,接触式プローブを使った接触式・離散 点測定から光を使った非接触式・面測定へと進んできた. そして,X線 CT装置を使った測定が新たな内外同時計測 を可能とする測定手段として,受け入れられつつある.X 線 CT装置が万能の測定装置として使えるのではないかと いう期待もあり,近年,X線 CT装置による幾何学測定が 注目を浴びつつある.既にいくつかのメーカは,測定精度 を保証することができる Dimensional X 線 CT 装置 (DXCT)と呼ばれる製品を販売している.DXCT が従 来の観察用の X 線 CT 装置と区別される点は,測定値が 長さの国家標準にトレーサブルであり,かつ精度が保証さ れた測定を可能としている点である. DXCT を検定された測定機として利用できるようにす るため,ドイツでは 2007 年頃から官民が一体となり, DXCT の寸法測定精度評価法に関する VDI/VDE ガイド ラインを作成してきた.日本でも,2009 年頃から産総研 が DXCT に関する研究に着手し,トレーサビリティを確 保するための技術的な研究を手がけるかたわら,国内公設 試験所を中心に持ち回り試験を実施すると同時に,産業用 X線 CT 装置の用語規格(JIS B 7442:2013)を制定する といった活動を行ってきた. 2.DXCTの精度評価法標準化