Semiconducting tin oxide electrodes in molten sodium chloroaluminate at 175°C

Electrode behavior of Sb-doped poly-crystalline tin oxide electrodes has been investigated by means of current and differential capacity measurements in molten chloroaluminate melts (AlCl₃+NaCl) with different pCl values. The SnO₂ is stable in the melts consisting of near equimolar composition, being used as an indicator electrode possessing a polarizable potential region between chlorine evolution and its cathodic decomposition. The differential capacity is assigned to the space charge layer capacity of the electrode side and its potential dependence is explained by using the Mott-Schottky equation. It is found that the flat band potential does depend on pCl (=?log a_Cl^?) at a rate of 2(2.3kT/e) per pCl unit. This anomaly is attributed to the specific adsorption of Cl^? ions on the oxide electrode.     

Lipase-catalyzed synthesis and properties of poly[(12-hydroxydodecanoate)-co-(12-hydroxystearate)] directed towards novel green and sustainable elastomers

Novel green and sustainable elastomers having both good biodegradability and chemical recyclability properties were designed and synthesized using potentially biobased materials and lipase as an environmentally benign catalyst. High molecular weight poly[(12-hydroxydodecanoate)-co-(12-hydroxystearate)] [poly(12HD-co-12HS)] samples with varying monomer ratios were prepared by the polycondensation of 12-hydroxydodecanoic acid and methyl 12-hydroxystearate using immobilized lipase from Candida antarctica (IM-CA) in toluene in the presence of molecular sieves 4A at 90 degrees C. Although poly(12HD) is a highly crystalline polyester having a melting temperature (T(m)) of 87.6 degrees C and crystalline temperature (T(c)) of 64 degrees C, by the copolymerization of 12HD with 12HS, both the T(m) and T(c) of the copolymer decreased with increasing 12HS contents, and poly(12HD-co-12HS) containing more than 60 mol-% 12HS was a viscous liquid at room temperature. At the same time, the Young's modulus and hardness also decreased with increasing 12HS content, and poly(12HD-co-36 mol-% 12HS) exhibited an elastic behavior, having a hardness of 70 A using a durometer A. In addition, it showed an excellent biodegradability by activated sludge and chemical recyclability by lipase.     

Photoinduced Glycosylation Using a Diarylthiophene as an Organo Lewis Photoacid Catalyst

Here reports an photoinduced glycosylation of trichloroacetimidate donors and several alcohols using 3,11-dimethoxydinaphthothiophene as an organo Lewis photoacid catalyst upon long-wavelength UV-LED light (385 nm) irradiation. The reaction proceeded under mild reaction conditions smoothly to give the corresponding glycosides in good to high yields. In addition, the present glycosylation method was applicable to a wide range of trichloroacetimidate donors and acceptors. Furthermore, the dinaphthothiophene catalyst could be recovered and reused without any loss of efficiency. Moreover, this glycosylation method was applied successfully to the total synthesis of a biologically active natural product, cholesteryl 6-O-myristoyl-α-glucoside.     

Slow Magnetic Relaxation of Ni(III) Complexes toward Molecular Spin Qubits

Molecule-based magnetic materials are promising candidates for molecular spin qubits, which utilize spin relaxation behavior. Various kinds of transition metal complexes with S=1/2 have been reported to act as spin qubits with long spin-spin relaxation times (T₂). However, the spin qubit properties of low-spin Ni(III) complexes are not as well known since Ni(III) compounds are often unstable. We report here the slow magnetic relaxation behavior and T₂ values for three kinds of low-spin Ni(III) based complexes with S=1/2 under magnetically diluted conditions. [Ni(cyclam)X₂]Y (cyclam=1,4,8,11-tetraazacyclotetradecane) with octahedral structures and [Ni(mnt)₂]⁻ (mnt=maleonitriledithiolate) with a square-planar structure underwent slow magnetic relaxations in the presence of a dc magnetic bias field. From electron spin resonance (ESR) spectroscopy, the Ni(III) complexes exhibited observable T₂, indicating that Ni(III) complexes are promising candidates for use as molecule-based spin qubits.     

Capped Bimetallic and Trimetallic Nanoparticles for Catalysis and Information Technology

Summary: Polymer-capped metal nanoparticles can be recognized as a kind of macromolecule-metal nanoparticle complexes. Here the preparations of the capped bimetallic and trimetallic nanoparticles, in which each particle contains two and three elements of metal, respectively, are presented. They may have a random alloy, a core/shell, or other kinds of structure depending on the preparation method and the combination of elements. The core/shell structure is advantageous to electronically control the activity of metal catalysts. The triple core/shell structured trimetallic nanoparticles were found to have higher catalytic activity than the corresponding monometallic and bimetallic nanoparticles in three cases. Capped metal nanoparticles were also used as a dopant to liquid crystals. Liquid crystal displays, fabricated by metal nanoparticle-doped liquid crystals, showed faster response than those without dopants. Bimetalization could increase the long-term stability in the doped liquid crystal displays. Thus, metal nanoparticles can improve the electronic display system, which occupies an important position in information technology. In addition, SmCo₅ nanomagnets were successfully prepared by a chemical method, possibly providing a new building block for information technology. The prepared SmCo₅ nanoparticles have a coercivity of 1500 Oe at room temperature. The bimetallic nanoparticles may open a new field in super-high-density magnetic memories.     

Polymer-protected bimetallic clusters with various alloying structures

Colloidal dispersions of polymer-protected bimetallic cluster can be prepared by refluxing the alcoholic solutions of two kinds of metal ions in the presence of poly(N-vinyl-2-pyrrolidone). The bimetallic clusters thus prepared had higher activity as catalysts than the corresponding monometallic clusters. The structure of bimetallic clusters, analyzed by an Extended X-ray Absorption Fine Structure(EXAFS) technique as well as ultraviolet-visible(Uv-vis) absorption spectra, depends on the preparation method. Some of them have a special core-shell structure. The order of the tendency to be a core is estimated to be Au>Pt>Pd>Rh. This order could be explained by the redox potential of the corresponding metal ion and the coordination ability of the metal to polymer.     

Synthesis of Mannosylerythritol Lipid Analogues and their Self-Assembling Properties,Recovery Effects on Damaged Skin Cells,and Antibacterial Activity

Synthesis of three types of purpose-designed mannosylerythritol lipid (MEL)-D analogues with decanoyl groups, β-GlcEL-D, α-GlcEL-D, and α-MEL-D, was accomplished utilizing our boron-mediated aglycon delivery (BMAD) methods. Their self-assembling properties, recovery effects on damaged skin cells, and antibacterial activity were evaluated. It was revealed, for the first time, that α-GlcEL-D and α-MEL-D only generated giant vesicles, indicating that slight differences in the steric configuration of an erythritol moiety and fatty acyl chains affect the ability to form vesicles. Analogue α-MEL-D exhibited significant recovery effects on damaged skin cells. Furthermore, α-MEL-D exhibited antibacterial activity as high as that for MEL-D, indicating that α-MEL-D is a promising artificial sugar-based material candidate for enhancing the barrier function of the stratum corneum, superior to a known cosmetic ingredient, and possesses antibacterial activity.     

Total Synthesis of Aquayamycin

An efficient and practical total synthesis of aquayamycin has been accomplished. The highly oxidized and stereochemically complex tetracyclic ring system was constructed using three key reactions: 1) highly diastereoselective 1,2‐addition of C‐glycosyl naphthyllithium to a cyclic ketone, 2) indium‐mediated site‐selective allylation‐rearrangement sequence of naphthoquinone, and 3) diastereoselective intramolecular pinacol coupling. This synthetic strategy offers a novel and efficient pathway to prepare aquayamycin‐type angucycline antibiotics.