Boosted Activity of Cobalt Catalysts for Ammonia Synthesis with BaAl2O4-xHy Electrides.

Electrides are promising support materials to promote transition metal catalysts for ammonia synthesis due to their strong electron-donating ability. Cobalt (Co) is an alternative non-noble metal catalyst to ruthenium in ammonia synthesis; however, it is difficult to achieve acceptable activity at low temperatures due to the weak Co-N interaction. Here, we report a novel oxyhydride electride, BaAl2O4-xHy, that can significantly promote ammonia synthesis over Co (500 mmol gCo-1 h-1 at 340 °C and 0.90 MPa) with a very low activation energy (49.6 kJ mol-1; 260-360 °C), which outperforms the state-of-the-art Co-based catalysts, being comparable to the latest Ru catalyst at 300 °C. BaAl2O4-xHy with a stuffed tridymite structure has interstitial cage sites where anionic electrons are accommodated. The surface of BaAl2O4-xHy with very low work functions (1.7-2.6 eV) can donate electrons strongly to Co, which largely facilitates N2 reduction into ammonia with the aid of the lattice H- ions. The stuffed tridymite structure of BaAl2O4-xHy with a three-dimensional AlO4-based tetrahedral framework has great chemical stability and protects the accommodated electrons and H- ions from oxidation, leading to robustness toward the ambient atmosphere and good reusability, which is a significant advantage over the reported hydride-based catalysts.

Anomalous Cu phase observed at HIP bonded Fe-Cu interface.

Hot isostatic pressing (HIP) processes are widely used for removing inner defects, densifying sintered components, consolidating particles and powders, and interfacial diffusion bonding. However, microscopic views of the phenomena have not been fully understood. X-ray absorption fine structure (XAFS) experiments were performed to study the interfacial region of the HIP bonded Fe-Cu sample. XAFS analyses clearly show that the bond distance around Cu is extraordinarily short compared with the bulk fcc Cu. The Cu species in the Fe-Cu HIP bonded sample takes a bcc structure even in the Cu-rich phase at room temperature. This anomalous bcc phase of Cu may derive from the HIP diffusion bonding process, which is performed below the melting points of both the elements. Cu atoms can diffuse into Fe with the bcc structure and settle in the bcc sites.

Approach to Chemically Durable Nickel and Cobalt Lanthanum-Nitride-Based Catalysts for Ammonia Synthesis.

Metal nitride complexes have recently been proposed as an efficient noble-metal-free catalyst for ammonia synthesis utilizing a dual active site concept. However, their high sensitivity to air and moisture has restricted potential applications. We report that their chemical sensitivity can be improved by introducing Al into the LaN lattice, thereby forming La-Al metallic bonds (La-Al-N). The catalytic activity and mechanism of the resulting TM/La-Al-N (TM=Ni, Co) are comparable to the previously reported TM/LaN catalyst. Notably, the catalytic activity did not degrade after exposure to air and moisture. Kinetic analysis and isotopic experiment showed that La-Al-N is responsible for N2 absorption and activation despite substantial Al being introduced into its lattice because the local coordination of the lattice N remained largely unchanged. These findings show the effectiveness of metallic bond formation, which can support the chemical stability of rare-earth nitrides with retention of catalytic functionality.

Preparation of Isodehydrodigallic Acid Using Ullmann Condensation.

Isodehydrodigallic acid, which is an important component of several ellagitannin compounds, was easily synthesized using a classical Ullmann condensation reaction.

Synthesis of Chloro-Substituted 6H-Dibenzo[b,d]pyran-6-one Natural Products, Graphislactone G, and Palmariols A and B.

A palladium-mediated intramolecular aryl-aryl coupling reaction was applied to the total synthesis of the bioactive natural products, graphislactone G (1), and palmariols A (2) and B (3), which possess an unusual chloro-subsutituent on the 6H-dibenzo[b,d]pyran-6-one skeleton. Based on the transition state model of the coupling reaction, the mechanistic aspect for the regioselectivity of the aryl-aryl coupling reaction is also discussed.

Anti-cancer potential of natural products containing (6H-dibenzo[b,d]pyran-6-one) framework using docking tools.

To explore complex biological and chemical systems, pharmaceutical research has effectively included several molecular modeling tools into a range of drug development initiatives. Molecular docking methods are widely employed in current drug design to investigate ligand conformations within macromolecular targets' binding sites. This method also estimates the ligand-receptor binding free energy by assessing critical phenomena involved in the intermolecular recognition process. In an attempt, several natural products have been synthesized in our laboratory. All the synthesized compounds containing (6H-Dibenzo[b,d]pyran-6-one) framework were subjected to molecular docking studies for the inhibition of CYP1B1 and BCL2 proteins using Auto Dock Vina software and the interacting amino acid residues were visualized using Discovery Studio, to look into the binding modalities that might influence their anticancer properties. The in silico molecular docking study outcomes showed that all the synthesized compounds having optimum binding energy and have a decent affinity to the active pocket, thus, they may be considered as a respectable inhibitor of CYP1B1 and BCL2 proteins.

A surface sensitive hard X-ray spectroscopic method applied to observe the surface layer reduction reaction of Co oxide to Co metal.

A simple and easy surface sensitive spectroscopic method using hard X-rays has been developed and applied to observe the surface oxide reduction reaction. The method named TREXS, Total REflection X-ray Spectroscopy, records the total reflection of incident X-rays at sample surfaces. The surface reduction reaction of Co oxide (Co3O4) to Co metal was successfully observed by in situ TREXS measurements with a surface sensitivity of ∼2 nm. The in situ TREXS measurements were performed under H2 flow of N2 balanced atmospheric pressure with increasing temperature. This method, in situ TREXS, will be a suitable and powerful tool to observe a variety of surface chemical reactions and consequently to understand catalytic processes under realistic operating conditions.

Low-Temperature Synthesis of Perovskite Oxynitride-Hydrides as Ammonia Synthesis Catalysts.

Mixed anionic materials such as oxyhydrides and oxynitrides have recently attracted significant attention due to their unique properties, such as fast hydride ion conduction, enhanced ferroelectrics, and catalytic activity. However, high temperature (≥800 °C) and/or complicated processes are required for the synthesis of these compounds. Here we report that a novel perovskite oxynitride-hydride, BaCeO3-xNyHz, can be directly synthesized by the reaction of CeO2 with Ba(NH2)2 at low temperatures (300-600 °C). BaCeO3-xNyHz, with and without transition metal nanoparticles, functions as an efficient catalyst for ammonia synthesis through the lattice N3- and H- ion-mediated Mars-van Krevelen mechanism, while ammonia synthesis occurs over conventional catalysts through a Langmuir-Hinshelwood mechanism with high energy barriers (85-121 kJ mol-1). As a consequence, the unique reaction mechanism leads to enhancement of the activity of BaCeO3-based catalysts by a factor of 8-218 and lowers the activation energy (46-62 kJ mol-1) for ammonia synthesis. Furthermore, isotopic experiments reveal that this catalyst shifts the rate-determining step for ammonia synthesis from N2 dissociation to N-H bond formation.

Porous Molecular Conductor: Electrochemical Fabrication of Through-Space Conduction Pathways among Linear Coordination Polymers.

The first porous molecular conductor (PMC), which exhibits porosity, a through-space conduction pathway and rich charge carriers (electrons), was prepared through electrocrystallization from Cd2+ and N, N'-di(4-pyridyl)-1,4,5,8-naphthalenetetracarboxdiimide (NDI-py). [Cd(NDI-py)(OH2)4](NO3)1.3±0.1· nDMA (PMC-1) was assembled by π-π stacking among one-dimensional (1D) linear coordination polymers. The NDI cores were partially reduced into radical anions to form conductive π-stacked columns, yielding (1.0-3.3) × 10-3 S cm-1 at room temperature. Moreover, the electrical conductivity was significantly enhanced by removing the solvent molecules from PMC-1, indicating that PMCs are promising as molecule-responsive conductive materials.

Idea of thin-film beam splitters for two-colour beamlines.

The idea to split soft X-ray and hard X-ray beams on the same axis into different directions is presented. A thin-film beam splitter can serve this purpose. Performances of thin-film beam splitters made of carbon and aluminium were examined. The idea of thin-film beam splitters expands possibilities in the design of two-colour beamlines.

Hyaluronan-Binding Protein Involved in Hyaluronan Depolymerization Is Up-Regulated and Involved in Hyaluronan Degradation in Human Osteoarthritic Cartilage.

Hyaluronan (HA)-binding protein involved in HA depolymerization (HYBID), also called cell migration-inducing protein (CEMIP; alias KIAA1199), plays a key role in the degradation of HA in skin and arthritic synovial fibroblasts, but its functions in osteoarthritic (OA) cartilage remain elusive. Here, we investigated the expression and roles of HYBID in human OA cartilage. HYBID was highly expressed by chondrocytes in the HA-depleted area of OA cartilage, and HYBID immunoreactivity was correlated with Mankin score, the histopathologic severity of OA lesions of cartilage. Real-time quantitative PCR indicated that HYBID expression was significantly higher in OA cartilage than in control cartilage. In addition, OA chondrocytes exhibited HA-degrading activity, which was abolished by knock-down of HYBID by siRNAs. Although OA chondrocytes also expressed certain levels of hyaluronidases 1 and 2 and CD44, knock-down of these molecules exhibited negligible effects on HA degradation. Double immunostaining of HYBID and clathrin heavy chain revealed that HYBID was localized in the clathrin-coated vesicles, and HA was endocytosed within the vesicles of OA chondrocytes. Among eight factors including cytokines and growth factors examined, only tumor necrosis factor α stimulated OA chondrocytes to overexpress HYBID. These data are the first to demonstrate that HYBID is up-regulated in OA cartilage, and suggest that tumor necrosis factor α-stimulated HYBID plays a role in HA degradation in OA cartilage.

Formation of the CuII -Phenoxyl Radical by Reaction of O2 with a CuII -Phenolate Complex via the CuI -Phenoxyl Radical.

Reaction of Cu(ClO4 )2 ⋅6 H2 O with a tripodal 2N2O ligand, H2 Me2 NL, having a p-(dimethylamino)phenol moiety, in CH2 Cl2 /MeOH (1:1 v/v) under basic conditions under an inert gas atmosphere gave [Cu(Me2 NL)(H2 O)] (1). The same reaction carried out under aerobic conditions gave [Cu(Me2 NL)(MeOH)]ClO4 (2), which could be obtained also from the isolated complex 1 by reaction with O2 in CH2 Cl2 /MeOH. The X-ray crystal structures of 1 and 2 revealed similar square-pyramidal structures, but 2 showed the (dimethylamino)phenoxyl radical features. Complex 1 exhibits characteristic CuII EPR signals of the d x 2 - y 2 ground state in CH2 Cl2 /MeOH at 77 K, whereas 2 is EPR-silent. The EPR and X-ray absorption fine structure (XAFS) results suggest that 2 is assigned to the CuII -(dimethylamino)phenoxyl radical. However, complex 1 showed different features in the absence of MeOH. The EPR spectrum of the CH2 Cl2 solution of 1 exhibits distortion from the d x 2 - y 2 ground state and a temperature-dependent equilibrium between the CuII -(dimethylamino)phenolate and the CuI -(dimethylamino)phenoxyl radical. From these results, CuII -phenoxyl radical complex 2 is concluded to be formed by the reaction of 1 with O2 via the CuI -phenoxyl radical species.

π-π Stacking Interaction in an Oxidized CuII -Salen Complex with a Side-Chain Indole Ring: An Approach to the Function of the Tryptophan in the Active Site of Galactose Oxidase.

In order to gain new insights into the effect of the π-π stacking interaction of the indole ring with the CuII -phenoxyl radical as seen in the active form of galactose oxidase, we have prepared a CuII complex of a methoxy-substituted salen-type ligand, containing a pendent indole ring on the dinitrogen chelate backbone, and characterized its one-electron-oxidized forms. The X-ray crystal structures of the oxidized CuII complex exhibited the π-π stacking interaction of the indole ring mainly with one of the two phenolate moieties. The phenolate moiety in close contact with the indole moiety showed the characteristic phenoxyl radical structural features, indicating that the indole ring favors the π-π stacking interaction with the phenoxyl radical. The UV/Vis/NIR spectra of the oxidized CuII complex with the pendent indole ring was significantly different from those of the complex without the side-chain indole ring, and the absorption and CD spectra exhibited a solvent dependence, which is in line with the phenoxyl radical-indole stacking interaction in solution. The other physicochemical results and theoretical calculations strongly support that the indole ring, as an electron donor, stabilizes the phenoxyl radical by the π-π stacking interaction.

In situ TREXS Observation of Surface Reduction Reaction of NiO Film with ∼2 nm Surface Sensitivity.

X-ray absorption fine structure (XAFS) spectroscopy is one of the most widely used methods at synchrotron radiation facilities. XAFS gives us information on chemical states and local structures. Fundamentally, XAFS is bulk sensitive, not surface sensitive. If a surface sensitive XAFS method was available, surface chemical reactions can be observed under realistic conditions. Here, we report the development and present status of a type of surface sensitive x-ray spectroscopy, which is named total reflection x-ray spectroscopy, TREXS.

An XAFS study of Cs adsorption by the precipitation bands of Mn-Fe-based Prussian blue analogues spontaneously formed in agarose gel.

The adsorption of Cs+ ions by the precipitation bands of a Mn-Fe based Prussian blue analogue (Mn-Fe PBA) that form spontaneously in agarose gel was investigated by X-ray absorption fine structure spectroscopy coupled with scanning electron microscopy (SEM) and X-ray fluorescence (XRF) distribution analysis. Two gel samples were prepared by contacting a gel containing 0.05 M [Fe(CN)6]3- and 2.3 mass% agarose with a 0.50 M MnSO4 solution, into one of which a 0.10 M CsCl solution was introduced. The SEM images and the XRF intensity distributions reveal that Mn-Fe PBA forms cubic crystallites (approx. 3 × 3 × 3 µm in size) in the gels that trap Cs+ ions with considerably high affinity. Cs L3-edge and Mn K-edge X-ray absorption near-edge structure (XANES) spectra, which were analyzed with the aid of FEFF simulations, strongly suggest that Cs adsorption occurs at relatively large defect sites close to the sub-cube faces in the PBA. This suggestion is supported by Cs L3-edge extended X-ray absorption fine structure spectroscopy, which suggested that the first and second coordination shells around the Cs+ ions are at a Cs-O distance of 0.35 ± 0.02 nm and a Cs-N distance of 0.43 ± 0.01 nm, respectively, with coordination numbers of 1.5 ± 0.5 and 3.0 ± 0.5. The Mn K-edge XANES data also suggest that H2O molecules, which initially occupy many cubic centers in the Mn-Fe PBAs, are mostly displaced during Cs adsorption. These findings provide valuable insight toward fully understanding Cs adsorption by Mn-Fe PBA.

The challenge of constructing an international XAFS database.

The present state of XAFS databases, particularly in Japan, and proposals for future directions are presented. International collaboration is important for enlarging the database for further development of XAFS spectroscopy.

A call for a round robin study of XAFS stability and platform dependence at synchrotron beamlines on well defined samples.

Round robin studies have been used across fields of science for quality control testing and to investigate laboratory dependencies and cross-platform inconsistencies as well as to drive forward the improvement of understanding of experimental systems, systematic effects and theoretical limitations. Here, following the Q2XAFS Workshop and Satellite to IUCr Congress 2017 on `Data Acquisition, Treatment, Storage - quality assurance in XAFS spectroscopy', a mechanism is suggested for a suitable study across XAFS (X-ray absorption fine-structure) beamlines and facilities, to enable each beamline to cross-calibrate, provide representative test data, and to enable collaborative cross-facility activities to be more productive.

Improving the quality of XAFS data.

Following the Q2XAFS Workshop and Satellite to IUCr Congress 2017 on `Data Acquisition, Treatment, Storage - quality assurance in XAFS spectroscopy', a summary is given of the discussion on different aspects of a XAFS experiment that affect data quality. Some pertinent problems ranging from sources and minimization of noise to harmonic contamination and uncompensated monochromator glitches were addressed. Also, an overview is given of the major limitations and pitfalls of a selection of related methods, such as photon-out spectroscopies and energy-dispersive XAFS, and of increasingly common applications, namely studies at high pressure, and time-resolved investigations of catalysts in operando. Advice on how to avoid or deal with these problems and a few good practice recommendations are reported, including how to correctly report results.

Large Oblate Hemispheroidal Ruthenium Particles Supported on Calcium Amide as Efficient Catalysts for Ammonia Decomposition.

Ammonia decomposition is an important technology for extracting hydrogen from ammonia toward the realization of a hydrogen economy. Herein, it is reported that large oblate hemispheroidal Ru particles on Ca(NH2 )2 function as efficient catalysts for ammonia decomposition. The turnover frequency of Ru/Ca(NH2 )2 increased by two orders of magnitude when the Ru particle size was increased from 1.5 to 8.4 nm. More than 90 % ammonia decomposition was achieved over Ru/Ca(NH2 )2 with large oblate hemispheroidal Ru particles at 360 °C, which is comparable to that of alkali-promoted Ru catalysts with small Ru particle sizes. XAFS analyses revealed that Ru particles are immobilized on Ca(NH2 )2 by Ru-N bonds formed at the metal/support interface, which lead to oblate hemispheroidal Ru particles. Such a strong metal-support interaction in Ru/Ca(NH2 )2 is also substantiated by DFT calculations. The high activity of Ru/Ca(NH2 )2 with large Ru particles primarily originates from the shape and appropriate size of the Ru particles with a high density of active sites rather than the electron-donating ability of Ca(NH2 )2 .

SOX4, an epithelial-mesenchymal transition inducer, transactivates ADAM28 gene expression and co-localizes with ADAM28 at the invasive front of human breast and lung carcinomas.

ADAM28 (a disintegrin and metalloproteinase 28) is abundantly expressed by carcinoma cells in the human breast and non-small cell lung carcinomas, and plays a role in carcinoma cell growth and metastasis. Although Src is an inducer of ADAM28 gene expression through the PI3K/AKT/mTOR and MEK/ERK pathways, direct transcriptional regulators for ADAM28 gene expression remain unknown. In this study, we performed the luciferase reporter assay and found that SOX4 (SRY-related HMG-box 4), an inducer of epithelial-mesenchymal transition (EMT), is a transcriptional activator for the ADAM28 gene. This activation required the SOX4-binding consensus sequence at the 5'-untranslated region of the mouse and human ADAM28 genes. Forced expression of SOX4 promoted the ADAM28 gene expression and migration in human breast and lung carcinoma cell lines. In the human breast and lung carcinoma tissues, ADAM28 and SOX4 were co-expressed at the invasive front of carcinoma cell nests. Our data demonstrate that SOX4 transactivates ADAM28 gene expression through direct binding to the ADAM28 promoter region and suggest the possibility that ADAM28 plays a role in invasion through SOX4-mediated EMT in the human breast and lung carcinomas.