Structural Basis for Polymer Packing and Solvation Properties of the Organogermanium Crystalline Polymer Propagermanium and Its Derivatives

Of organogermanium compounds known to have an immunostimulatory action, propagermanium [PGe; 3-oxygermylpropionic acid polymer, (C3 H5 GeO3.5 )n] is the only one used as a pharmaceutical agent, to treat the hepatitis B virus in Japan. However, because of lack of information about its structure, PGe has been confused with a polymeric solid, repagermanium (RGe, Ge-132, poly-trans-[(2-carboxyethyl) germasesquioxane], (C18 H30 Ge6 O21 )n), which has the same essential formula as PGe. To clarify this issue, the structure of PGe was analyzed using X-ray diffraction (XRD). PGe has a polymeric ladder-shaped structure of a concatenated eight-membered ring composed of Ge-O bonds, which is clearly distinguished from the infinite sheet structure in RGe. Moreover, we observed temperature or moisture-dependent transformations among these compounds using powder XRD. For instance, PGe was easily dissolved in water, and transformed to RGe by exposure to water vapor, but transformed into another straight-chain structure when exposed to aqueous solution. As a result of these findings, PGe was indicated to have labile polymer packing against RGe. These characteristics of PGe may affect pharmaceutical properties such as respective stability and solubility, which indicate its unique impact on physiological activity.

Translation of the assembling trajectory by preorganisation: a study of the magnetic properties of 1D polymeric unpaired electrons immobilised on a discrete nanoscopic scaffold

A nitronyl nitroxide (NN)-appended hexabenzocoronene (HBC(NN)), when allowed to coassemble with bis(hexafluoroacetylacetonato)cobalt(II), forms a coaxial nanotubular architecture featuring NN-Co(II) coordinated copolymer chains immobilised on the outer and inner nanotube surfaces. Upon lowering the temperature, this nanotube has enhanced magnetic susceptibility below 10 K.

All-in-all-out magnetic domains: x-ray diffraction imaging and magnetic field control

Long-range noncollinear all-in-all-out magnetic order has been directly observed for the first time in real space in the pyrochlore Cd_{2}Os_{2}O_{7} using resonant magnetic microdiffraction at the Os L_{3} edge. Two different antiferromagnetic domains related by time-reversal symmetry could be distinguished and have been mapped within the same single crystal. The two types of domains are akin to magnetic twins and were expected-yet unobserved so far-in the all-in-all-out model. Even though the magnetic domains are antiferromagnetic, we show that their distribution can be controlled using a magnetic field-cooling procedure.

Systematic studies on side-chain structures of phthalocyaninato-polysiloxanes: Polymerization and self-assembling behaviors

A series of dihydroxysilicon phthalocyanines having soluble side chains were synthesized and their bulk-state polymerization capability was investigated. Detailed spectroscopic study of the obtained phthalocyaninato-polysiloxanes revealed that strong electron donating ability and small steric hindrance of the peripheral substituents are the dominant factors to afford high-molecular weight polymers. The polymers show the behaviors of columnar liquid crystal (LC), which is clarified by the presence of clear X-ray diffraction patterns with a hexagonal lattice and birefringent textures in polarized optical microscopy. Because of the siloxane covalent bonds through central silicon atoms, phthalocyaninato-polysiloxanes accommodate one-dimensional phthalocyanine arrays with strong π-electronic couplings, thus exhibiting colmnar LC property even for the derivatives carrying short peripheral chains and leading to the relatively higher density of π-electron systems in the materials. This tendency is different from typical discotic small molecules that require optimum side chain structures for LC formation.

Preparation of solid–solution type Fe–Co nanoalloys by synchronous deposition of Fe and Co using dual arc plasma guns

We succeeded in the efficient preparation of well-dispersed Fe–Co nanoalloys (NAs) using the arc plasma deposition method.

Evaluation of the intrinsic charge carrier transporting properties of linear- and bent-shaped π-extended benzo-fused thieno[3,2-b]thiophenes

The local-scale hole mobilities of two isomeric linear- and bent-shaped π-extended thienoacenes were investigated using flash-photolysis and field-induced time-resolved microwave conductivity (FP- and FI-TRMC) techniques.

2,6-Diphenyl- and -distyryl-capped 3,7-dialkoxybenzo[1,2-b:4,5-b']dithiophenes and their dithieno-annulated higher homologs: structural phase transition with enhanced charge carrier mobility

Synthesis of the title benzo[1,2-b:4,5-b']dithiophenes was achieved using 2-ethylhexyl 3,7-dihydroxybenzo[1,2-b:4,5-b']dithiophene-2,6-dicarboxylate as the common starting material. The effect of the introduction of phenyl and styryl groups as well as thieno-annulation to the benzo[1,2-b:4,5-b']dithiophene core on π-conjugation was estimated by means of absorption and emission spectrometry and cyclic voltammetry. The phase behaviours of the compounds were also observed by differential scanning calorimetry and the dithieno-annulated higher homologs were found to show a solid-solid (crystalline-crystalline) phase transition. Then, intrinsic charge carrier mobilities in the π-systems were measured by the flash-photolysis time-resolved microwave conductivity (FP-TRMC) method and the values were in the range of 0.04-0.17 cm(2) V(-1) s(-1). Remarkably, the thieno-annulated and phenyl-capped derivative showed a temperature/phase-dependent hole mobility profile with 3-fold increment in the second crystalline phase above 100 °C.

Fasudil, a rho kinase inhibitor, limits motor neuron loss in experimental models of amyotrophic lateral sclerosis

BACKGROUND AND PURPOSE

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder with no effective treatment. Fasudil hydrochloride (fasudil), a potent rho kinase (ROCK) inhibitor, is useful for the treatment of ischaemic diseases. In previous reports, fasudil improved pathology in mouse models of Alzheimer's disease and spinal muscular atrophy, but there is no evidence in that it can affect ALS. We therefore investigated its effects on experimental models of ALS.

EXPERIMENTAL APPROACH

In mice motor neuron (NSC34) cells, the neuroprotective effect of hydroxyfasudil (M3), an active metabolite of fasudil, and its mechanism were evaluated. Moreover, the effects of fasudil, 30 and 100 mg·kg(-1), administered via drinking water to mutant superoxide dismutase 1 (SOD1(G93A)) mice were tested by measuring motor performance, survival time and histological changes, and its mechanism investigated.

KEY RESULTS

M3 prevented motor neuron cell death induced by SOD1(G93A). Furthermore, M3 suppressed both the increase in ROCK activity and phosphorylated phosphatase and tensin homologue deleted on chromosome 10 (PTEN), and the reduction in phosphorylated Akt induced by SOD1(G93A). These effects of M3 were attenuated by treatment with a PI3K inhibitor (LY294002). Moreover, fasudil slowed disease progression, increased survival time and reduced motor neuron loss, in SOD1(G93A) mice. Fasudil also attenuated the increase in ROCK activity and PTEN, and the reduction in Akt in SOD1(G93A) mice.

CONCLUSIONS AND IMPLICATIONS

These findings indicate that fasudil may be effective at suppressing motor neuron degeneration and symptom progression in ALS. Hence, fasudil may have potential as a therapeutic agent for ALS treatment.

Japanese Science & Technology with Crystallography

Divers Japanese Science and Technology has advanced together with the progress of crystallography in biology, chemistry, physics, materials science, metallurgy, electronics, engineering, geoscience, etc. Based on the highly scientific and crystallographic technology, Japan has been a great contributor in developing of high-end X-ray generator, electron microscope as well as large scale Photon Science facilities, such as Photon Factory (SR), SPring-8 (SR), J-PARC (Neutron) and SACLA (XFEL). Under such background, we promote IYCr2014 with the partnership of 36 academic societies in the field of pure and applied sciences. In the last half-century, developments in crystallography have also helped thriving manufacturing sectors such as the semiconductor, the iron and steel, the pharmaceuticals, the electronics, the textile, and the chemical industries. Some of the recent impressive outcomes in Japan are fundamental findings of photosynthesis [1] and pristine asteroid [2]. Crystallography in Japan keeps promoting our nationwide projects grappling with global problems such as environment and food, and will contribute to realize a sustainable society.

Nanoporous Structural Science Developed by the MEM/Rietveld Method

Wide-spread functionalization research of Metal Organic Frameworks(MOFs) has brought rapid increase in variety of materials since the beginning of structural study in nanoporous of MOFs were made by SR(Synchrotron Radiation) powder diffraction using the MEM(Maximum Entropy Method)/Rietveld Method(Kitaura et al, 2002). The MEM/Rietveld method has successfully applied to refine the structural position of absorbed molecules and to investigate a bonding nature between the molecules and MOF's pore walls. Noise-resistance electron density mapping with incomplete data set was a key advantage of MEM to visualize unmodeled feature of molecules in nanoporous. Since then, the charge density studies by the MEM/Rietveld Method have uncovered various ordering structure of absorbed molecules into nanoporous more and more(Takata, 2008). Those findings ignited trends to design the nanoporous as the space to be functionalized. Recently, the MEM/Rietveld method has been further developed as the method to map an electrostatic potential and electric field(Tanaka 2006). This technique is making a progress in structural science of MOFs since the visualized electrostatic potential in the nanoporous ought to provide information of interplay between the molecule and the pore walls. The talk will present the recent progress and challenges of the MEM/Rietveld method to the structural science of the MOFs.

Direct Visualization of Energy-transferred Excited State in Eu Complex

Highly luminescent lanthanide (Ln) complexes have attracted much attention because Ln3+ions show long-lived ff-emissions with narrow band shape. Their unique photo-optical properties are promising for the design of light-emitting materials and sensing devices. Although the ff-emissions are essentially weak because of Laporte forbidden, chelate ligands is effective to strengthen the intramolecular energy transfer from photo-excited organic ligands to Ln3+ions. The direct evidence of energy transfer from ligands to Ln3+and details of excited state, however, are still veiled. Here, we report direct visualization of energy-transferred excited state in Eu complex with a hexadentate ligand (L) consisting of two bipyridine moieties bridged by an ethylendiamine unit, [Eu3+(L)(NO3)2](PF6) (Eu(L))[1] by Maximum Entropy Method (MEM) charge density[2] and electrostatic potential analysis[3] based on SR X-ray diffraction. First, we confirmed that the electron numbers of Eu and ligand L in the excited state are the same as those in the ground state, which is a direct evidence of energy transfer instead of charge transfer. Next, we observed charge re-distribution in the Eu ion and the ligand L. The electrostatic potential distributions calculated using MEM charge density give an experimental evidence for the existence of polarization of ligand L both in the ground and photo-excited states. The orientation polarization in the ground state changed during pumping at 315 nm, and the charge re-distribution are qualitatively consistent with a theoretical prediction. This characteristic luminescence behavior based on the energy relaxation process have not been detected by fundamental crystal structural analysis. We have succeeded in visualization of subtle but important change due to energy transfer in the mononuclear Europium complex with hexadentate ligand at the first time.

In situ synchrotron powder diffraction for an ionic conductor transition

In situ synchrotron X-ray powder diffraction can be one of the most powerful probes to investigate the structure evolution by a chemical reaction thanks to simultaneity of data collection. It is not, however, with ease to produce a homogeneous chemical reaction in the limited spaces, which is essential to see an atomic-scale structure evolution. We have developed an in situ capillary cell for both high-temperature H2reduction and precise humidity control at the SPring-8 BL44B2. We successfully applied this in situ system to an electronic conductor LaSr3Fe3O10, which is transformed into an ionic conductor by the two-step chemical treatments [1]. LaSr3Fe3O10has a triple-layer structure with a FeO6octahedral unit. One triple layer is bonded with another layer through van der Waals interaction. Structure refinements with in situ synchrotron powder diffraction data revealed that the H2reduction at 613 K produced in-plane oxygen vacancies, which resulted in suppression of the interlayer interaction. We found from charge density studies and Raman spectroscopy measurements that the following humidification intercalated H2O and OH-into the interlayer and intralayer, respectively. That means that H2O plays a role for suppression of three-dimensional electronic conductivity, stabilizing the intercalation structure. On the other hand, the OH-ions behave as carriers for ionic conductivity, maintaining the charge neutrality in the intralayer. Finally we determined the composition of the ionic conductor to be LaSr3Fe3O8.0(OH)1.2·2H2O, which indicates a transformation of LaSr3Fe3O10into an OH-ionic conductor. In the presentation, I will discuss the OH-ionic conduction channel based on electrostatic potentials obtained from charge densities.

Instrumentation of SAXS for the Analysis of Heterogeneous Structure in Polymer

Polymer materials have hierarchal structure in the very wide range of scale. It is well known that the property is dependent on the hierarchical structure. In order to improve the performance of the materials, clarifying the hierarchical structure in a wide range and the feed back to the manufacturing process are important. However, it is difficult to clarify the hierarchical heterogeneous structure of polymer materials using only single method. Therefore the combination of microbeam small- and wide- angle X-ray scattering (SAXS/WAXS) is useful for evaluation of the hierarchical heterogeneous structural of polymer materials. The BL03XU, in alias, FSBL, in SPring-8 was constructed by consortium of industrial and academic groups and has been used from 20101),2). Structure characterization of advanced materials in the industrial field has been carried out using microbeam SAXS/WAXS method. In addition to the description of the SAXS/WAXS measurement system at BL03XU, we will report on the local structural evaluation of carbon fiber (CF). A hierarchal heterogeneous structure of CFs was visualized in the space resolution of 1 μm using a microbeam and an X-ray imaging technique. The image contrasts were identified by the difference in peak positions corresponding to the void size, the peak width corresponding to the crystallite size, and intensities corresponding to the amount of crystallites and voids. The X-ray scattering images of high-modulus CF are shown in a figure. Nanometer-size voids estimated by SAXS are abundant in the center of a fiber, on the other hand, the crystallite is abundant in the vicinity of a surface was revealed. It is suggested that the voids were generated near the center of the fiber to relax the strain during the crystallization process from the surface during the graphitization of fibers. We succeeded in visualizing the distribution of voids and crystallite of a few nanometers, which cannot be observed by an X-ray transmission imaging method.

Structural Basis for Emergence of Superionic Conductivity by an Ion Exchange

Various superionic conductors have been examined in terms of the application to electrolytes for solid fuel cells [1]. Recently we demonstrated by impedance measurements that a simple two-step chemical reaction transformed an electronic conductor NaxCoO2into a superionic one. In the present study, we performed in situ synchrotron X-ray diffraction experiments to investigate a structural mechanism for the superionic conductivity driven by the chemical treatment of the layered oxide NaxCoO2. We developed a temperature- and humidity-controllable capillary cell under hydrogen and helium gas flow to install in the Debye-Scherrer camera at BL44B2 of SPring-8. This cell allows us to explore a structural transformation process by reduction and humidification treatments. Structural identifications and refinements with in situ diffraction data proved that Co vacancies formed by a CoO separation suppressed the electronic conductivity. Meanwhile it turned out from charge estimation in the Na layers that the superionic conductor transition originated from an ion exchange of H3O+for Na+, which was confirmed by Raman spectroscopy measurements. In addition, charge densities clearly visualized the H3O+ions disordering around the Na original sites, suggesting that the H3O+behave as a carrier source. Finally it was found from electrostatic potentials that the disordering H3O+sites were coupled through shallow potential barriers to trace a honeycomb-like ion pathway. In the presentation, I will discuss what a carrier is for the superionic-conductive phase from different viewpoints such as activation energies, concentration cell tests, and molecular dynamics simulations using the experimental structure information.

Japanese Crystallography in Culture and Art

"We can find many seeds of crystallography in Japanese culture. Most of the family crests have symmetry elements such as rotation axes and mirror symmetry elements. Sekka-zue, a picture book of 86 kinds of crystals of snow, was made by Toshitura Doi, who is a feudal lord in Edo-period and he observed snow using a microscope in nineteenth century. In recent years, people enjoy to make crystal structures, polyhedrons, carbon nanotube, quasicrystal etc. by origami, the art of folding paper [1]. In the field of science, the Japanese crystallography has contributed to explore culture and art. An excellent example is unveiling the original color of Japanese painting "Red and White Plum Blossoms" by Korin Ogata [2]. Prof. Izumi Nakai (Tokyo University of Science) developed an X-ray fluorescence analyzer and an X-ray powder diffractometer designated to the investigation of cultural and art works and had succeeded in reproducing the silver-colored waves through computer graphics after X-ray analyses of crystals on the painting. The scientific approach by Prof. Nakai et al. unveiled the mystery of cultural heritage of ancient near east, ancient Egypt etc. and is being to contribute to insight into the history of human culture. [1] An event to enjoy making crystals by origami is under contemplation. [2] The symposium ""Crystallography which revives heritages"" was held on February 16, 2014 at Atami in Japan."