Efficient synthesis of 2,4-disubstituted 1,2,4-benzothiadiazin-3-one 1,1-dioxides on solid support

The first solid-phase synthesis of 1,2,4-benzothiadiazin-3-one 1,1-dioxides has been developed. Synthesis of the title compounds was achieved by the reduction of 2-nitrobenzenesulfonamides, followed by cyclization with carbonyldiimidazole. Because 1,2,4-benzothiadiazin-3-one 1,1-dioxides have been known to possess various bioactivities, this method is useful from the viewpoint of new drug discovery. In addition to the excellent purity of the title compounds, a large number of compounds can be synthesized with this method, because this synthesis includes four diversity points.     

Charge‐discharge properties of composites of polypyrrole and vanadium oxide powder

Composite of polypyrrole and crystalline V₂O₅ powder was prepared by chemical oxidation of pyrrole with use of V₂O₅ powder itself as an oxidizing agent. The V₂O₅ content was changed from 0 to 94 wt% by changing the amount of V₂O₅ dispersed in the preparation bath. The pellet electrodes could be prepared by pressing the composite powder alone even if amount of polypyrrole in the composite was only 6 wt%. The resulting pellet electrode exhibited good charge‐discharge performance as a positive electrode of Li rechargeable battery in an electrolyte solution as well as in a quasi‐solid cell fabricated by using a gel electrolyte sheet of poly(methyl methacrylate).     

Deoxyfluorination of alcohols using N,N-diethyl-α,α-difluoro-(m-methylbenzyl)amine

Deoxyfluorination of alcohols was carried out using N,N-diethyl-α,α-difluoro-(m-methylbenzyl)amine (DFMBA). Primary alcohols were effectively converted to fluorides under microwave irradiation or conventional heating. Deoxyfluorination of an anomeric hydroxy group in sugars by DFMBA proceeded at below room temperature and glycosyl fluorides could be obtained in good yields. The deoxyfluorination reaction chemoselectively proceeded and various protecting groups on the sugar can survive under the reaction conditions.     

Synthesis of nonplanar bipyridyls bridged by disilane and disiloxane and their phosphorescent copper complexes

Disilane- and disiloxane-bridged bipyridyls ( DSBPy and DSOBPy ) were prepared and their optical properties were investigated in comparison with those of previously reported monosilane- and monogermane-bridged counterparts. The UV–visible absorption and photoluminescence bands of DSBPy and DSOBPy were blue-shifted as a result of elongation of the bridging units from monosilane and monogermane to disilane and disiloxane, likely due to the enhanced twisting of the bipyridyl units. Phosphorescent complexes DSBPy–Cu and DSOBPy–Cu were prepared by the interaction of DSBPy and DSOBPy with Cu₂I₂(PPh₃)₂. X-ray diffraction studies of their single-crystal structures revealed polymeric structures composed of repeat units of DSBPy or DSOBPy and [Cu^II(PPh₃)]₂. Organic light-emitting diodes with the ITO/PEDOT:PSS/ DSBPy–Cu or DSOBPy–Cu :PCTSQ/TAZ/Al structure were fabricated to examine the applications of the complexes as electroluminescent materials. The devices emitted yellow light with emission maxima at approximately 600 nm, and maximal luminance reached 120 and 190 cd m⁻² for devices based on DSBPy–Cu and DSOBPy–Cu , respectively. The performance of the DSOBPy–Cu -based device was improved by using TAZ as the dopant of the emissive layer, and luminance was increased to 390 cd m⁻².     

Effect of crystallite size on the thermal phase change and porous properties of boehmite

The effect of crystallite size on the thermal phase change and porous properties of boehmite was investigated using boehmites with crystallite sizes of 2.9 to 24.4 nm and boehmite gels prepared by precipitation and hydrothermal methods. The dehydroxylation temperature of boehmite increases, its phase transition temperature from gamma- to theta-Al(2)O(3) decreases and the theta- to alpha-Al(2)O(3) transition temperature increases as the crystallite size of the boehmite increases. Boehmite with a crystallite size of approximately 5 nm shows the highest specific surface area and greatest thermal stability. This boehmite contains pores of about 2-3 nm radius, suggested to be responsible for the superior porous properties and thermal stability.     

Ultrasensitive CE for heavy metal ions using the variations in the chemical structures formed from new octadentate fluorescent probes and cationic polymers

Novel fluorescent probes have been developed for the ultratrace detection of heavy metal ions by capillary electrophoresis using laser-induced fluorescence detection. Based on a molecular design, the probes are composed of an octadentate chelating moiety, a macrocyclic DOTA (tetraazacyclododecanetetraacetic acid) and an acyclic DTPA (diethylenetriaminepentaacetic acid) frame, a spacer and a fluorophore (fluorescein). These were chosen on the basis of their ability to form kinetically inert and highly emissive complexes, and to prevent a quenching effect even with heavy and paramagnetic metal ions. Addition of a cationic polymer, polybrene, in the separation buffer provided high resolution and simultaneous detection of Ca(2+), Mg(2+), Cu(2+), Zn(2+), Ni(2+), Co(2+), Mn(2+), Cd(2+) and Pb(2+). The direct fluorescence detection of these metal ions with high sensitivity at lower ppt levels, typically 2-7 × 10(-11) M (potentially sub-ppt), was successfully achieved. While separation of anionic compounds using a counter cation ("Ion Association (IA)" mode) is typically controlled by the ion association equilibrium constants, K(ass), it was found that differences in the mobilities, μ(ep(IAC)), of the ion association complexes formed between the probe complexes and counter cations are the driving forces for separation in this new method. This suggests that each of the polybrene-probe complexes has different chemical structures among metal ions, which were able to be determined by CD spectra in this investigation. This novel separation mode was termed the "Ion Association Complex (IAC)" mode, distinct from the IA mode.     

Control of the Dynamic Motion of a Gel Actuator Driven by the Belousov‐Zhabotinsky Reaction

A novel self‐oscillating gel actuator with gradient structure, which generates a pendulum motion by fixing one edge of the gel without external stimuli was achieved. The gel was synthesized by copolymerizing the ruthenium catalyst for the Belousov‐Zhabotinsky reaction with N‐isopropylacrylamide and 2‐acrylamido‐2‐methylpropane sulfonic acid. Furthermore, we clarified that the period and amplitude for the self‐oscillating behavior of the gel actuator are controllable by changing the composition, temperature, and size of the gel. The maximum amplitude of the novel gel actuator is about a 100 times larger than that of the conventional self‐oscillating gel system.

     

Cobalt oxide supported gold nanoparticles as a stable and readily-prepared precursor for the in situ generation of cobalt carbonyl like species

A treatment of cobalt oxide supported gold nanoparticles (Au/Co₃O₄) under syngas atmosphere effectively generated a cobalt carbonyl-like active species in the reaction vessel. The preparation of Au/Co₃O₄ was quite simple and the in situ generated cobalt species could be used as a stable and easy handling alternative for dicobalt octacarbonyl without bothersome purification prior to use. The reactions, which are sensitive to the purity of the dicobalt octacarbonyl, such as the alkoxycarbonylation of epoxides and the Pauson-Khand reaction, smoothly progressed with Au/Co₃O₄.     

Beta-1,3-glucan polysaccharide (schizophyllan) acting as a one-dimensional host for creating supramolecular dye assemblies

We have demonstrated that one-dimensional supramolecular dye assemblies with a uniform diameter can be created by utilizing schizophyllan (SPG) as a one-dimensional host. In the supramolecular nanofibers, the dye molecules are assembled into the different aggregation modes depending on the preparation procedures. The findings establish that SPG is useful for creating the supramolecular nanofibers, where temporal superstructures can be stabilized by the SPG-specific helical higher-order structure. [structure: see text].