Topological insulator as an efficient catalyst for oxidative carbonylation of amines.

Topological materials have received much attention because of their robust topological surface states, which can be potentially applied in electronics and catalysis. Here, we show that the topological insulator bismuth selenide functions as an efficient catalyst for the oxidative carbonylation of amines with carbon monoxide and dioxygen to synthesize urea derivatives. For example, the carbonylation of butylamine can be completed over bismuth selenide nanoparticle catalyst in 4 hours at 20°C with a yield of 99%, whereas most noble metal-based catalysts do not function at such a low temperature.

Single-Molecule Identification of Nucleotides Using a Quantum Computer.

Genomic information is essential for human health. Due to its large volume, genomic information can be potentially computed using quantum computers, which are rapidly developing. Genome analysis using quantum computers can accelerate the development of personalized medicine, innovative drugs, and novel diagnostics based on genomic information.

Collective bending motion of a two-dimensionally correlated bowl-stacked columnar liquid crystalline assembly under a shear force.

Stacked teacups inspired the idea that columnar assemblies of stacked bowl-shaped molecules may exhibit a unique dynamic behavior, unlike usual assemblies of planar disc- and rod-shaped molecules. On the basis of the molecular design concept for creating higher-order discotic liquid crystals, found in our group, we synthesized a sumanene derivative with octyloxycarbonyl side chains. This molecule forms an ordered hexagonal columnar mesophase, but unexpectedly, the columnar assembly is very soft, similar to sugar syrup.

Room-Temperature Fast H Conduction in Oxygen-Substituted Lanthanum Hydride.

The hydride ion (H) is a unique anionic species that exhibits high reactivity and chemical energy. H conductors are key materials to utilize advantages of H for applications, such as chemical reactors and energy storage systems. However, low H conductivity at room temperature (RT) in current H conductors limit their applications.

Electronic Correlation Strength of Inorganic Electrides from First Principles.

Strongly correlated electron systems, generally recognized as d- and f-electron systems, have attracted attention as a platform for the emergence of exotic properties such as high-Tc superconductivity. However, correlated electron behaviors have been recently observed in a group of novel materials, electrides, in which s-electrons are confined in subnanometer-sized spaces. Here, we present a trend of electronic correlation of electrides by evaluating the electronic correlation strength obtained from model parameters characterizing effective Hamiltonians of 19 electrides from first principles.

Control of dominant conduction orbitals by peripheral substituents in paddle-wheel diruthenium alkynyl molecular junctions.

Control of charge carriers that transport through the molecular junctions is essential for thermoelectric materials. In general, the charge carrier depends on the dominant conduction orbitals and is dominantly determined by the terminal anchor groups. The present study discloses the synthesis, physical properties in solution, and single-molecule conductance of paddle-wheel diruthenium complexes having diarylformamidinato supporting ligands (DArF: -R-CH-NCHN-CH-R-) and two axial thioanisylethynyl conducting anchor groups, revealing unique substituent effects with respect to the conduction orbitals.

Single-molecule junctions of multinuclear organometallic wires: long-range carrier transport brought about by metal-metal interaction.

Here, we report multinuclear organometallic molecular wires having (2,5-diethynylthiophene)diyl-Ru(dppe) repeating units. Despite the molecular dimensions of 2-4 nm the multinuclear wires show high conductance (up to 10 to 10 ) at the single-molecule level with small attenuation factors () as revealed by STM-break junction measurements. The high performance can be attributed to the efficient energy alignment between the Fermi level of the metal electrodes and the HOMO levels of the multinuclear molecular wires as revealed by DFT-NEGF calculations.

Organometallic Molecular Wires with Thioacetylene Backbones, trans-{RS-(C≡C) } Ru(phosphine) : High Conductance through Non-Aromatic Bridging Linkers.

In this work, the design, synthesis, and single-molecule conductance of ethynyl- and butadiynyl-ruthenium molecular wires with thioether anchor groups [RS=n-C H S, p-tert-Bu-C H S), trans-{RS-(C≡C) } Ru(dppe) (n=1 (1 ), 2 (2 ); dppe: 1,2-bis(diphenylphosphino)ethane) and trans-(n-C H S-C≡C) Ru{P(OMe) } 3 ] are reported. Scanning tunneling microscope break-junction study has revealed conductance of the organometallic molecular wires with the thioacetylene backbones higher than that of the related organometallic wires having arylethynylruthenium linkages with the sulfur anchor groups, trans-{p-MeS-C H -(C≡C) } Ru(phosphine) 4 (n=1, 2) and trans-(Th-C≡C) Ru(phosphine) 5 (Th=3-thienyl). It should be noted that the molecular junctions constructed from the butadiynyl wire 2 , trans-{Au-RS-(C≡C) } Ru(dppe) (Au: gold metal electrode), show conductance comparable to that of the covalently linked polyynyl wire with the similar molecular length, trans-{Au-(C≡C) } Ru(dppe) 6 .

Single-Molecule Junction of a Cationic Rh(III) Polyyne Molecular Wire.

Single-molecule conductance studies on metal-containing inorganic and organometallic molecular wires are relatively less explored compared to those on organic molecular wires. Furthermore, conductance and transmission profiles of the metal-containing wires insensitive to the metal centers often hinder rational design for high performance wires. Here, synthesis and single-molecule conductance measurements of the bis(butadiynyl)rhodium wires with tetracarbene ligands and are reported as rare examples for Rh(III) diacetylide molecular wires.

Vacancy-enabled N activation for ammonia synthesis on an Ni-loaded catalyst.

Ammonia (NH) is pivotal to the fertilizer industry and one of the most commonly produced chemicals. The direct use of atmospheric nitrogen (N) had been challenging, owing to its large bond energy (945 kilojoules per mole), until the development of the Haber-Bosch process. Subsequently, many strategies have been explored to reduce the activation barrier of the N≡N bond and make the process more efficient.

The role of lattice vibration in the terahertz region for proton conduction in 2D metal-organic frameworks.

We studied the relationship between proton conductivity and the terahertz-regime vibrations of two-dimensional MOFs. The results of spectroscopy studies clarified the essential role played by the collective motions in the terahertz region in 2D layers for efficient H conduction. calculations suggested the collective motion to be predominantly determined by the valence electronic structure, depending on the identity of the metal ion.

Palladium-bearing intermetallic electride as an efficient and stable catalyst for Suzuki cross-coupling reactions.

Suzuki cross-coupling reactions catalyzed by palladium are powerful tools for the synthesis of functional organic compounds. Excellent catalytic activity and stability require negatively charged Pd species and the avoidance of metal leaching or clustering in a heterogeneous system. Here we report a Pd-based electride material, YPd, in which active Pd atoms are incorporated in a lattice together with Y.

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, BaCeONH, can be directly synthesized by the reaction of CeO with Ba(NH) at low temperatures (300-600 °C).

Discovery of hexagonal ternary phase TiInB and its evolution to layered boride TiB.

MAX phases are a large family of compounds that have been limited, so far, to carbides and nitrides. Here we report the prediction of a compound, TiInB, a stable boron-based ternary phase in the Ti-In-B system, using a computational structure search strategy. This predicted TiInB compound is successfully synthesized using a solid-state reaction route and its space group is confirmed as P[Formula: see text]m2 (No.

Triptycene Tripods for the Formation of Highly Uniform and Densely Packed Self-Assembled Monolayers with Controlled Molecular Orientation.

When employing self-assembled monolayers (SAMs) for tuning surface and interface properties, organic molecules that enable strong binding to the substrate, large-area structural uniformity, precise alignment of functional groups, and control of their density are highly desirable. To achieve these goals, tripod systems bearing multiple bonding sites have been developed as an alternative to conventional monodentate systems. Bonding of all three sites has, however, hardly been achieved, with the consequence that structural uniformity and orientational order in tripodal SAMs are usually quite poor.

Controlling stacking order and charge transport in π-stacks of aromatic molecules based on surface assembly.

Here, we report a facile procedure based on surface self-assembly for controlling the π-π stacking order and relevant rectified charge transport properties in stacks of aromatic molecules on a single-molecule scale. A high rectification ratio of 10 was achieved and the rectification direction was uniquely determined by the controlled stacking order of the aromatic molecules on the graphene layers of HOPG.

"Doping" of Polyyne with an Organometallic Fragment Leads to Highly Conductive Metallapolyyne Molecular Wire.

Exploration of highly conductive molecules is essential to achieve single-molecule electronic devices. The present paper describes the results on single-molecule conductance study of polyyne wires doped with the organometallic Ru(dppe) fragment, X-(C≡C) -Ru(dppe)-(C≡C) -X. The metallapolyyne wires end-capped with the gold fragments (X = AuL) are subjected to single-molecule conductance measurements with the STM break junction technique, which reveal the high conductance (10-10 G; n = 2-4) with the low attenuation factor (0.

Dopant driven tuning of the hydrogen oxidation mechanism at the pore/nickel/zirconia triple phase boundary.

The effects of cation dopants in zirconia on the H2 oxidation mechanism at the pore/nickel/zirconia triple phase boundary (TPB) were theoretically examined. Y, Sc, Al, Ce, and Ca were considered as dopants, and on-boundary, O-migration, and H-migration reaction mechanisms were examined. Based on density functional theory calculations, Y as a dopant favored the on-boundary mechanism with water molecule formation within the immediate proximity of the TPB.

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(NH ) function as efficient catalysts for ammonia decomposition. The turnover frequency of Ru/Ca(NH ) increased by two orders of magnitude when the Ru particle size was increased from 1.

Self-organized Ruthenium-Barium Core-Shell Nanoparticles on a Mesoporous Calcium Amide Matrix for Efficient Low-Temperature Ammonia Synthesis.

A low-temperature ammonia synthesis process is required for on-site synthesis. Barium-doped calcium amide (Ba-Ca(NH ) ) enhances the efficacy of ammonia synthesis mediated by Ru and Co by 2 orders of magnitude more than that of a conventional Ru catalyst at temperatures below 300 °C. Furthermore, the presented catalysts are superior to the wüstite-based Fe catalyst, which is known as a highly active industrial catalyst at low temperatures and pressures.

Copper-Based Intermetallic Electride Catalyst for Chemoselective Hydrogenation Reactions.

The development of transition metal intermetallic compounds, in which active sites are incorporated in lattice frameworks, has great potential for modulating the local structure and the electronic properties of active sites, and enhancing the catalytic activity and stability. Here we report that a new copper-based intermetallic electride catalyst, LaCuSi, in which Cu sites activated by anionic electrons with low work function are atomically dispersed in the lattice framework and affords selective hydrogenation of nitroarenes with above 40-times higher turnover frequencies (TOFs up to 5084 h) than well-studied metal-loaded catalysts. Kinetic analysis utilizing isotope effect reveals that the cleavage of the H-H bond is the rate-determining step.

Exploration of Stable Strontium Phosphide-Based Electrides: Theoretical Structure Prediction and Experimental Validation.

Inspired by the successful synthesis of alkaline-earth-metals-based electrides [CaAlO](e) (C12A7:e) and [CaN]:e and high-throughput database screening results, we explore the potential for new electrides to emerge in the Sr-P system through a research approach combining ab initio evolutionary structure searches and experimental validation. Through employing an extensive evolutionary structure search and first-principles calculations, we first predict the new structures of a series of strontium phosphides: SrP, SrP, SrP and SrP. Of these structures, we identify SrP and SrP as being potential electrides with quasi-one-dimensional (1D) and zero-dimensional (0D) character, respectively.

Triphosphasumanene Trisulfide: High Out-of-Plane Anisotropy and Janus-Type π-Surfaces.

A triphosphasumanene trisulfide was designed and synthesized as an out-of-plane anisotropic π-conjugated molecule. Incorporating three anisotropic phosphine sulfide moieties into a sumanene skeleton induced a cumulative anisotropy with a large dipole moment (12.0 D), which is aligned in perpendicular direction with respect to the π-framework and more than twice as large as those of conventional out-of-plane anisotropic molecules.

A Stable, Soluble, and Crystalline Supramolecular System with a Triplet Ground State.

A supramolecular complex was constructed by encapsulation of a O molecule inside an open-cage C derivative. Its single-crystal X-ray diffraction analysis revealed the presence of the O at the center of the fullerene cage. The CV measurements suggested that unprecedented dehydrogenation was promoted by the encapsulated O after two-electron reduction.