Co-generation of palladium nanoparticles and phosphate supported on metal-organic frameworks as hydrogenation catalysts.

In this study, we demonstrated the direct synthesis of sodium dihydrogen phosphate (PA) containing palladium nanoparticles (PdNPs) supported on a metal-organic framework (MOF). The resulting composite containing PA molecules coexisting with PdNPs demonstrated improved hydrogenation catalytic performance compared to the composites without PA.

Direct generation of polypyrrole-coated palladium nanoparticles inside a metal-organic framework for a semihydrogenation catalyst.

Herein, the direct synthesis of polypyrrole (PPy)-coated palladium nanoparticles (PdNPs) inside a metal-organic framework (MIL-101) was successfully demonstrated. Owing to the PPy coating of PdNPs, the resulting composites exhibited higher semihydrogenation capability (selectivity: up to 96%) than the analog composite without PPy coating.

Cooperative catalysis in a metal-organic framework via post-synthetic immobilisation.

Herein, we generated a series of cooperative catalysts via post-synthetic immobilisation of a Co(salen) complex in a metal-organic framework (MOF). By tuning the amount of Co(salen) in the MOF, the cooperative catalytic activities can be successfully optimised.

Rational and site-selective formation of coordination polymers consisting of d10 coinage metal ions with thiolate ligands using a metal ion-doped polymer substrate.

Here, we report an interfacial approach for fabricating coordination polymers (CPs) consisting of d10 coinage metal ions with thiolate ligands on a polymer substrate. It was found that CPs were selectively formed on the polymer substrate, resulting in the formation of CP-based thin films. In addition, utilizing a mixed metal ion-doped polymer substrate leads to the formation of mixed-metal CP-based films.

Controlling Interfacial Ion-Transport Kinetics Using Polyelectrolyte Membranes for Additive- and Effluent-free, High-Performance Electrodeposition.

The development of high-performance, environmentally friendly electrodeposition processes is critical for emerging coating technologies because current technologies use highly complex baths containing metal salts, supporting electrolytes, and various kinds of organic additives, which are problematic from both environmental and cost perspectives. Here, we show that a 200 µm-thin polyelectrolyte membrane sandwiched between electrodes effectively concentrates metal ions through interfacial penetration, which increases the conductance between the electrodes to 0.30 S and realizes solid-state electrodeposition that produces no mist, sludge, or even waste effluent. Both, experimental results and theoretical calculations, reveal that electrodeposition is controlled by ion penetration at the solution/polyelectrolyte interface, providing an intrinsically different ion-transport mechanism to that of conventional diffusion-controlled electrodeposition. The setup, which includes 0.50 mol L-1 copper sulfate and no additives, delivers a maximum current density of 300 mA cm-2, which is nearly fivefold higher than that of a current commercial plating bath containing organic additives.

Controlled syntheses of Ag nanoparticles inside MOFs by using amine-borans as vapour phase reductants.

Controlled synthesis of Ag nanoparticles inside porous materials is difficult because of their high mobilities during the reactions. Herein, by using a series of amine-boranes as vapour phase reductants, we succeeded in synthesizing Ag nanoparticles in a controlled manner inside MOFs.

Formation of Metal-Organic Frameworks on a Metal Ion-Doped Polymer Substrate: In-Depth Time-Course Analysis Using Scanning Electron Microscopy.

The growth of metal-organic frameworks (MOFs) on a metal ion-doped polymer as a precursor and support substrate was investigated based on mechanistic and kinetic analyses. The studies were performed by varying the reaction temperature and the concentrations of the organic ligand and nucleation-promoted additive. Using the NH2-MIL-53(Al) framework as a model system, a systematic study of the mechanism of formation of tetragonal- and rod-shaped NH2-MIL-53(Al) crystals on the substrate was performed. The nucleation rate in the early stage of the reaction is a major factor in determining the surface morphology of the resultant NH2-MIL-53(Al) crystal films, as confirmed by changing the concentration of organic ligands and by employing pyridine additives. These results provide a fundamental understanding of the influence of the nucleation rate on the ability to control the morphology and structure of MOF crystal films.

Preparation of Ni nanoparticles by liquid-phase reduction to fabricate metal nanoparticle-polyimide composite films.

Nickel-nanoparticle-containing polyimide composite films were prepared by liquid-phase reduction of Ni2+ ions with potassium borohydride (KBH4). The nanoparticles were amorphous with diameters of approximately 10-20 nm, depending on the KBH4 concentration and reduction temperature. At high KBH4 concentrations, the nanoparticles appeared to contain various nickel boride species. The number of nanoparticles and Ni content both increased upon repeated adsorption/reduction of Ni2+ ions, where the particle growth was inhibited by the rigid polymer chain and the formation of smaller particles was favored.

An anionic phthalocyanine decreases NRAS expression by breaking down its RNA G-quadruplex.

Aberrant activation of RAS signalling pathways contributes to aggressive phenotypes of cancer cells. The RAS-targeted therapies for cancer, therefore, have been recognised to be effective; however, current developments on targeting RAS have not advanced due to structural features of the RAS protein. Here, we show that expression of NRAS, a major isoform of RAS, can be controlled by photo-irradiation with an anionic phthalocyanine, ZnAPC, targeting NRAS mRNA. In vitro experiments reveal that ZnAPC binds to a G-quadruplex-forming oligonucleotide derived from the 5'-untranslated region of NRAS mRNA even in the presence of excess double-stranded RNA, which is abundant in cells, resulting in selective cleavage of the target RNA's G-quadruplex upon photo-irradiation. In line with these results, upon photo-irradiation, ZnAPC decreases NRAS mRNA and NRAS expression and thus viability of cancer cells. These results indicate that ZnAPC may be a prominent photosensitiser for a molecularly targeted photodynamic therapy for cancer.

Unusual Colorimetric Change for Alkane Solvents with a Porous Coordination Framework.

Alkane-selective colorimetric change from white to pink was observed with the simple system consisting of UiO-66 and 7-azaindole. The colorimetric change was strongly enhanced with increasing amounts of defects inside the UiO-66 framework, which indicates that interaction between the defects and 7-azaindole plays a pivotal role for this phenomenon.

Highly Sensitive Plasmonic Optical Sensors Based on Gold Core-Satellite Nanostructures Immobilized on Glass Substrates.

Fabrication of discrete nanostructures consisting of noble metal nanoparticles immobilized on substrates is challenging because of structural complexity but important for chip-based plasmonic sensor technology. Here we report optical sensing capabilities of core-satellite nanostructures made of gold nanoparticles immobilized on glass substrate, which were fabricated by combining stepwise interconnection of gold nanoparticles through dithiol linkers and surface treatment using vacuum ultraviolet light. The nanostructures exhibit large changes in coupled plasmon resonance peak upon surrounding refractive index, with sensitibity of ca. 350 nm RIU(-1), thus providing highly sensitive optical sensors for determining the surrounding refractive index and detecting organic vapors.

Morphology Control of Metal-Organic Frameworks Based on Paddle-Wheel Units on Ion-Doped Polymer Substrate Using an Interfacial Growth Approach.

A three-dimensional metal-organic framework (MOF) consisting of pillared square-grid nets based on paddle-wheel units was synthesized by interfacial self-assembly of the frameworks on a metal-ion-doped polymer substrate. Although this type of Cu-based MOF is typically synthesized by a two-step solvothermal method, the utilization of a metal-ion-doped polymer substrate as a metal source for the framework allowed for the one-pot growth of MOF crystals on the substrate. The morphology of the obtained MOF crystals could be controlled from tetragonal to elongated tetragonal with different aspect ratios by changing the concentrations of the dicarboxylate layer ligands and diamine pillar ligands. The present approach provides a new route for the design and synthesis of MOF crystals and thin films for future applications such as gas membranes, catalysts, and electronic devices.

Metal nanocrystal/metal-organic framework core/shell nanostructure from selective self-assembly induced by localization of metal ion precursors on nanocrystal surface.

Metal nanocrystal/metal-organic framework core/shell nanostructures have been constructed using metal ion-trapped nanocrystals as scaffolds through a selective self-assembly of framework components on the nanocrystal surfaces. The resulting nanostructures exhibit unique catalytic activity toward nitrophenol analogs.

Electroless nickel plating on polymer particles.

Near-monodisperse, micrometer-sized polypyrrole-palladium (PPy-Pd) nanocomposite-coated polystyrene (PS) particles have been coated with Ni overlayers by electroless plating in aqueous media. Good control of the Ni loading was achieved for 1.0 µm diameter PPy-Pd nanocomposite-coated PS particles and particles of up to 20 µm in diameter could also be efficiently coated with the Ni. Laser diffraction particle size analysis studies of dilute aqueous suspensions indicated that an additional water-soluble colloidal stabilizer, poly(N-vinyl pyrrolidone), in the electroless plating reaction media was crucial to obtain colloidally stable Ni-coated composite particles. Elemental microanalysis indicated that the Ni loading could be controlled between 61 and 78 wt% for the 1.0 µm-sized particles. Scanning/transmission electron microscopy studies revealed that the particle surface had a flaked morphology after Ni coating. Spherical capsules were obtained after extraction of the PS component from the Ni-coated composite particles, which indicated that the shell became rigid after Ni coating. X-ray diffraction confirmed the production of elemental Ni and X-ray photoelectron spectroscopy studies indicated the existence of elemental Ni on the surface of the composite particles.

All-inorganic water-dispersible silicon quantum dots: highly efficient near-infrared luminescence in a wide pH range.

We report a novel method to prepare silicon quantum dots (Si-QDs) having excellent stability in water without organic-ligands by simultaneously doping phosphorus and boron. The codoped Si-QDs in water exhibit bright size-tunable luminescence in a biological window. The luminescence of codoped Si-QDs is very stable under continuous photoexcitation in water.

A facile template synthesis of asymmetric gold silica heteronanoparticles.

Silica hemispheres containing gold nanoparticle cores have been synthesized via immobilization of gold nanoparticles on a substrate and site-selective growth of silica followed by removal of the hemispherical particles. The structure of these asymmetric heteronanoparticles allows selective etching or overgrowth of the core gold seeds, which results in the respective formation of hemispherical capsules or gold homodimers.

Fabrication of silver patterns on polyimide films based on solid-phase electrochemical constructive lithography using ion-exchangeable precursor layers.

We report a fully additive-based electrochemical approach to the site-selective deposition of silver on a polyimide substrate. Using a cathode coated with ion-doped precursor polyimide layers, patterns of metal masks used as anodes were successfully reproduced at the cathode-precursor interface through electrochemical and ion-exchange reactions, which resulted in the generation of silver patterns on the polyimide films after subsequent annealing and removal from the substrate. Excellent interfacial adhesion was achieved through metal nanostructures consisting of interconnecting silver nanoparticles at the metal-polymer interface, which are electrochemically grown "in" the precursor layer. This approach is a resist- and etch-free process and thus provides an effective methodology toward lower-cost and high-throughput microfabrication.

Controlled self-assembly of metal-organic frameworks on metal nanoparticles for efficient synthesis of hybrid nanostructures.

We report a novel approach for synthesizing inorganic nanoparticle/metal-organic frameworks (MOFs) heterostructured nanocomposites by self-assembly of MOFs on nanoparticles. This approach involves the synthesis of Au nanoparticles and preferential growth of [Cu(3)(btc)(2)](n) frameworks consisting of Cu(2+) ions and benzene-1,3,5-tricarboxylate (btc) on nanoparticles. Aggregates consisting of 11-mercaptoundecanoic acid (MUA)-stabilized Au nanoparticles linked by Cu(2+) ions were necessary for preferential self-assembly of [Cu(3)(btc)(2)](n) frameworks on the aggregates, resulting in the formation of Au nanoparticles/[Cu(3)(btc)(2)](n) nanocomposites. The present approach was confirmed to be applicable for other hybrids consisting of Au nanoparticles and tetragonal [Cu(2)(ndc)(2)(dabco)](n) frameworks.

Fabrication of copper damascene patterns on polyimide using direct metallization on trench templates generated by imprint lithography.

Facile imprint and wet chemical processes were used to fabricate copper damascene patterns on polyimide substrate. Poly(amic acid) substrate with trench structures as template has been successfully prepared by imprint lithography using a poly(dimethylsiloxane) mold. The doped Ni(2+) ions into a template through ion-exchange reaction were reduced by an aqueous NaBH(4) solution, resulting in the formation of a nickel thin layer along the surface structure of the template. The resulting nickel films can act as catalyst for subsequent electrodeposition of copper. After electrodeposition, a polishing process was carried out for removing excess deposited copper films, followed by imidization of the substrate. The resulting damascene structured copper films exhibited fine and good adhesion with the polyimide substrate, and they could be utilized for good application in the fields of minute copper circuit patterns on insulating substrates.

Synthesis and characterization of polypyrrole-palladium nanocomposite-coated latex particles and their use as a catalyst for Suzuki coupling reaction in aqueous media.

Polypyrrole-palladium (PPy-Pd) nanocomposite was deposited in situ from aqueous solution onto micrometer-sized polystyrene (PS) latex particles. The PS seed particles and resulting composite particles were extensively characterized with respect to particle size and size distribution, morphology, surface/bulk chemical compositions, and conductivity. PPy-Pd nanocomposite loading onto the PS seed latex particles was systematically controlled over a wide range (10-60 wt %) by changing the weight ratio of the PS latex and PPy-Pd nanocomposite. Pd loading was also controlled between 6 and 33 wt %. The conductivity of pressed pellets increased with the PPy-Pd nanocomposite loading and four-point probe measurements indicated conductivities ranging from 3.0 x 10(-1) to 7.9 x 10(-6) S cm(-1). Hollow capsule and broken egg-shell morphologies were observed by scanning/transmission electron microscopy after extraction of the PS component from the composite particles, which confirmed a PS core and PPy-Pd nanocomposite shell morphology. X-ray diffraction confirmed that the production of elemental Pd and X-ray photoelectron spectroscopy indicated the existence of elemental Pd on the surface of the composite particles. Transmission electron microscopy confirmed that nanometer-sized Pd particles were distributed in the shell. The nanocomposite particles functioned as an efficient catalyst for Suzuki-type coupling reactions in aqueous media for the formation of carbon-carbon bonds.