Chameleonic layered metal-organic frameworks with variable charge-ordered states triggered by temperature and guest molecules.

Molecular materials whose electronic states are multiply varied depending on external stimuli are among the most promising targets for the development of multiply accessible molecular switches. Here, we report a honeycomb layer composed of tetraoxolene-bridged iron (Fe) subunits whose charge-ordered states are multiply variable thermal treatments and solvation/desolvation with the crystallinity intact. The compound is (NPr)[Fe(ClAn)] (; NPr = tetra--propylammonium; ClAn = 2,5-dichloro-3,6-dihydroxo-1,4-benzoquinonate), which possesses three charge-ordered states: a low-temperature (LT) phase [(Fe)(ClAn)(ClAn˙)]; an intermediate (IM) phase [(Fe)(ClAn)(ClAn)]; and a high-temperature (HT) phase [(Fe)(ClAn)] that varies according to temperature.

Biomimetic catechol-based adhesive polymers for dispersion of polytetrafluoroethylene (PTFE) nanoparticles in an aqueous medium.

Biomimetic synthetic functional materials are valuable for a large number of practical applications with improved or tunable performance. In this paper, we present a series of mussel-inspired biomimetic catechol-containing copolymers synthesized from dopamine methacrylamide (DMA) and 2-(2-ethoxyethoxy)ethyl acrylate (EEA) and abbreviated as poly(PDMA-PEEA). The successfully synthesized adhesive polymers allow adhering polytetrafluoroethylene (PTFE) and were used for coating PTFE particles in organic solvent and re-dispersion in an aqueous medium.

Magnetic field induced uniaxial alignment of the lyotropic liquid-crystalline PMMA-grafted FeO nanoplates with controllable interparticle interaction.

Magnetite (FeO) nanoplates with a hexagonal platelet shape were synthesized by two steps: hydrothermal synthesis of iron(iii) oxide (α-FeO) nanoplates followed by wet chemical reduction of the α-FeO nanoplates. Then, poly(methyl methacrylate) (PMMA) chains were grafted onto the surface of the hexagonal FeO nanoplates (F) surface-initiated atom transfer radical polymerization (SI-ATRP), which ensures dispersion stability in organic solvents and ionic liquids. After mixing with 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([Emim][NTf ]), a representative ionic liquid, the resulting PMMA-modified F were found to show good lyotropic liquid-crystalline (LC) behaviour in [Emim][NTf ] and to exhibit a fast response to the application of an external magnetic field.

Weak Intermolecular CH···N Hydrogen Bonding: Determination of CH-N Hydrogen-Bond Mediated Couplings by Solid-State NMR Spectroscopy and First-Principles Calculations.

Weak hydrogen bonds are increasingly hypothesized to play key roles in a wide range of chemistry from catalysis to gelation to polymer structure. Here, N/C spin-echo magic-angle spinning (MAS) solid-state nuclear magnetic resonance (NMR) experiments are applied to "view" intermolecular CH···N hydrogen bonding in two selectively labeled organic compounds, 4-[N] cyano-4'-[C] ethynylbiphenyl () and [N,C]-2,4,6-triethynyl-1,3,5-triazine (). The synthesis of , is reported here for the first time via a multistep procedure, where the key element is the reaction of [N]-2,4,6-trichloro-1,3,5-triazine () with [C]-[(trimethylsilyl)ethynyl]zinc chloride () to afford its immediate precursor [N,C]-2,4,6-tris[(trimethylsilyl)ethynyl]-1,3,5-triazine ().

Synthesis, Crystal Structure, and Luminescence Properties of a White-Light-Emitting Nitride Phosphor, CaEuAlSiN.

Colorless transparent single crystals of a new europium-doped calcium aluminum silicon nitride, CaEuAlSiN, were synthesized by heating a mixture of binary nitrides (CaN, EuN, AlN, SiN, and MgN) at 2150 °C under a nitrogen gas pressure of 0.85 MPa. The X-ray diffraction reflections from a single crystal were indexed with orthorhombic cell parameters = 11.

Rapid room-temperature synthesis of ultrasmall cubic Mg-Mn spinel cathode materials for rechargeable Mg-ion batteries.

Reducing the particle size of cathode materials is effective to improve the rate capability of Mg-ion batteries. In this study, ultrasmall cubic Mg-Mn spinel oxide nanoparticles approximately 5 nm in size were successfully synthesized an alcohol reduction process within 30 min at room temperature. Though the particles aggregated to form large secondary particles, the aggregation could be suppressed by covering the particles with graphene.

Rapid synthesis of defective and composition-controlled metal chalcogenide nanosheets by supercritical hydrothermal processing.

This study presents a simple one-pot synthesis method to achieve few-layered and defective Mo(S,Se) and (Mo,W)S by using supercritical water with organic reducing agents from simple and less-toxic precursors. This synthesis process is expected to be suitable for preparing other various kinds of TMD solid solutions.

Self-assembled microrings of Au nanoparticle and Au nanorod clusters formed at the equators of Janus particles.

A method for fabricating polymer Janus particles with microring structures at their equators has been developed. This method allows gold nanoparticles and nanorods to be aligned and densely packed along the microrings.

Single crystal growth and structure analysis of type-I (Na/Sr)-(Ga/Si) quaternary clathrates.

Single crystals of (Na/Sr)-(Ga/Si) quaternary type-I clathrates, Na Sr Ga Si , were synthesized by evaporating Na from a mixture of Na-Sr-Ga-Si-Sn in a 6 : 0.5 : 1 : 2 : 1 molar ratio at 773 K for 12 h in an Ar atmosphere. Electron-probe microanalysis and single-crystal X-ray diffraction revealed that three crystals from the same product were Na Sr Ga Si with and values of 7.

In Situ Atomic-Scale Observation of Kinetic Pathways of Sublimation in Silver Nanoparticles.

Uncovering kinetics of sublimation atomically is critical to understanding both natural phenomena and advanced manufacturing technologies. Here, direct in situ atomic-scale observations to understand the effects of size, surface, and defects in the sublimation process of supported silver nanoparticles upon heating within an aberration-corrected transmission electron microscopy are conducted. Atomic-scale evidence to sublimation and atomic rearrangement in small Ag nanoparticles during heating is provided, and it is demonstrated that the sublimation-induced stable surfaces in the particles with a size smaller than ≈30 nm are {111} and {100} planes.

Nuclear Magnetic Resonance Spectroscopy as a Dynamical Structural Probe of Hydrogen under High Pressure.

An unambiguous crystallographic structure solution for the observed phases II-VI of high pressure hydrogen does not exist due to the failure of standard structural probes at extreme pressure. In this work we propose that nuclear magnetic resonance spectroscopy provides a complementary structural probe for high pressure hydrogen. We show that the best structural models available for phases II, III, and IV of high pressure hydrogen exhibit markedly distinct nuclear magnetic resonance spectra which could therefore be used to discriminate amongst them.

Atomic-scale investigation of the heterogeneous structure and ionic distribution in an ionic liquid using scanning transmission electron microscopy.

Ionic liquids show characteristic properties derived from them being composed of only molecular ions, and have recently been used as solvents for chemical reactions and as electrolytes for electrochemical devices. The liquid structures, , ionic distributions, form when solutes are dissolved in ionic liquids and fundamentally affect the reactions and transfer efficiency in such solutions. In this study, we directly observe the liquid structure in a solution of the long-chain ionic liquid 1-octyl-3-methylimidazolium bromide (Cmim Br) and barium stearate (Ba(CHCOO)) using the annular dark-field method of scanning transmission electron microscopy (ADF-STEM).

A Picture of Disorder in Hydrous Wadsleyite-Under the Combined Microscope of Solid-State NMR Spectroscopy and Ab Initio Random Structure Searching.

The Earth's transition zone, at depths of 410-660 km, while being composed of nominally anhydrous magnesium silicate minerals, may be subject to significant hydration. Little is known about the mechanism of hydration, despite the vital role this plays in the physical and chemical properties of the mantle, leading to a need for improved structural characterization. Here we present an ab initio random structure searching (AIRSS) investigation of semihydrous (1.

Na-Ga-Si type-I clathrate single crystals grown Na evaporation using Na-Ga and Na-Ga-Sn fluxes.

Single crystals of a Na-Ga-Si clathrate, NaGaSi, of size 2.9 mm were grown the evaporation of Na from a Na-Ga-Si melt with the molar ratio of Na : Ga : Si = 4 : 1 : 2 at 773 K for 21 h under an Ar atmosphere. The crystal structure was analyzed using X-ray diffraction with the model of the type-I clathrate (cubic, = 10.

A promising visible light-driven photocatalytic activity of conjugated polymer nanocrystals.

Conjugated polymers have recently emerged as a new class of photocatalysts. However, many conjugated polymer photocatalysts are not as effective as inorganic materials due to the limited electronic properties of their LUMO and HOMO and low long-term stability caused by the degradation of the conjugated backbone. In the present study, we have demonstrated, for the first time, the superior Visible (Vis) light-driven photocatalytic activity of conjugated polymer nanocrystals (NCs) of polydiacetylene (PDA) derivatives, namely, p-DCHD NCs for the photodegradation of Rhodamine B (RhB) compared with that of the state-of-the-art P25 TiO nanoparticles (NPs).

Preconception dysmenorrhea as a risk factor for psychological distress in pregnancy: The Japan Environment and Children's Study.

Background: Dysmenorrhea influences emotional distress as well as physical suffering in young non-pregnant women. The aim of this study was to assess the potential association between preconception dysmenorrhea and the development of psychological distress during pregnancy.

Methods: This study was a part of the Japan Environment and Children's Study (JECS), a nationwide birth cohort study conducted between 2011 and 2014 in Japan.

Expansion of the photoresponse window of a BiVO photocatalyst by doping with chromium(vi).

Doping of Cr into BiVO was examined in this study. A new absorption band with a 1.84 eV energy threshold appeared with Cr-doping.

Complex Low Energy Tetrahedral Polymorphs of Group IV Elements from First Principles.

The energy landscape of carbon is exceedingly complex, hosting diverse and important metastable phases, including diamond, fullerenes, nanotubes, and graphene. Searching for structures, especially those with large unit cells, in this landscape is challenging. Here we use a combined stochastic search strategy employing two algorithms (ab initio random structure search and random sampling strategy combined with space group and graph theory) to apply connectivity constraints to unit cells containing up to 100 carbon atoms.

Viscosity measurement of Xanthan-Poly(vinyl alcohol) mixture and its effect on the mechanical properties of the hydrogel for 3D modeling.

Biomodels made of poly(vinyl alcohol) (PVA) are demanded because they can represent the geometries and mechanical properties of human tissues realistically. Injecting and molding, commonly used in three-dimensional (3D) modeling, help to represent the blood vessels accurately. However, these techniques sometimes require higher pressures than the upper pressure limit of the dispensers for pouring in high viscosity materials; the material viscosity should therefore be lower.

A Trinuclear Iron(III) Complex of a Triple Noninnocent Ligand for Spin-Structured Molecular Conductors.

N,N',N'',N''',N'''',N'''''-(Triphenylene-2,3,6,7,10,11-hexayl)hexapicolinamide (H hptp), a triangular ligand containing three noninnocent coordination sites, and its trinuclear iron(III) complex (PPh ) [Fe (hptp) (CN) ] were prepared. In this complex, three low-spin Fe ions are coordinated by the triangular hptp bridging ligand at its apices. Cyclic voltammetry of (PPh ) [Fe (hptp) (CN) ] in PhCN solution showed one reductive wave for 3 Fe /3 Fe and three oxidative waves for the hptp ligand.

Structural Basis for the Inhibition of Cyclin G-Associated Kinase by Gefitinib.

Gefitinib is the molecular target drug for advanced non-small-cell lung cancer. The primary target of gefitinib is the positive mutation of epidermal growth factor receptor, but it also inhibits cyclin G-associated kinase (GAK). To reveal the molecular bases of GAK and gefitinib binding, structure analyses were conducted and determined two forms of the gefitinib-bound nanobody⋅GAK kinase domain complex structures.

Helium-Iron Compounds at Terapascal Pressures.

We investigate the binary phase diagram of helium and iron using first-principles calculations. We find that helium, which is a noble gas and inert at ambient conditions, forms stable crystalline compounds with iron at terapascal pressures. A FeHe compound becomes stable above 4 TPa, and a FeHe_{2} compound above 12 TPa.

Structure and Metallicity of Phase V of Hydrogen.

A new phase V of hydrogen was recently claimed in experiments above 325 GPa and 300 K. Because of the extremely small sample size at such record pressures the measurements were limited to Raman spectroscopy. The experimental data on increase of pressure show decreasing Raman activity and darkening of the sample, which suggests band gap closure and impending molecular dissociation, but no definite conclusions could be reached.

Synthesis of Bare Iron Nanoparticles from Ferrocene Hexane Solution by Femtosecond Laser Pulses.

Iron-based nanoparticles (FeNPs) have unique and attractive properties such as superparamagnetism, biocompatibility, and catalytic activity. Although the synthesis of precious metal NPs from a metal in liquid and/or metal salt solution by a pulsed laser has been investigated, comparably little effort has been devoted to examine the production of FeNPs. Here we report the synthesis of carbon-shell free spherical NPs of iron oxide (magnetite) from ferrocene hexane solution by femtosecond near infrared laser pulses.

Tubular and lamellar hydrogen-bonding molecular assemblies of isophthalic acid derivatives bearing a -CONHC H chain.

Isophthalic acid derivatives (CnIP), bearing alkylamide chains (-CONHC H: = 6, 10, 14, and 18) at the 5-position that can participate in hydrogen bonding, were prepared and evaluated for their hydrogen-bonding molecular assembly structures for organogelation and liquid crystal formation. The hydrogen-bonding carboxylic acid (-COOH) groups form a ring-shaped (CnIP) hexamer or a one-dimensional (1D) zig-zag (CnIP) chain. Although neither organogelation nor liquid crystal formation was observed in the isophthalic acid derivative bearing an alkoxy (-OCH) chain, C14IP and C18IP derivatives could form both organogel and liquid crystal states through intermolecular N-H⋯O = amide-type hydrogen-bonding interactions.