A versatile scaffold for facile synthesis of fluorescent cyano-substituted stilbenes

Here we report the facile derivatization of a cyano-substituted stilbene into higher π-extended analogues. The cyano-substituted stilbene, which serves as a synthetic scaffold, has a bromo group and a formyl group on its 4- and 4′-position of the phenylene rings and thus readily undergoes selective transformation into other functional groups using various simple organic reactions. The resultant π-conjugated molecules that contain a cyano-substituted stilbene skeleton exhibit fluorescence in solution and in the solid state.     

New aplysiatoxin derivatives from the Okinawan cyanobacterium Moorea producens

The marine cyanobacterium Moorea producens is a rich source of diverse compounds that possess a variety of biological activities. In the present study, eight new aplysiatoxin derivatives, namely 6, 8–13, and 15, along with aplysiatoxin (1), debromoaplysiatoxin (2), 3-methoxyaplysiatoxin (3), anhydroaplysiatoxin (4), anhydrodebromoaplysiatoxin (5), oscillatoxin B2 (7), and 30-methyloscillatoxin D (14) were isolated and identified from the Okinawan M. producens. In cytotoxicity and diatom growth inhibition tests, the fifteen compounds tested (1–15) showed moderate or no activity at a concentration of 10?μg/mL.     

Application of Protonic Acid-Doped Silica Gels to Electric Double-Layer Capacitors

Silica gels doped with several protonic acids such as HClO₄, H₂SO₄ and H₃PO₄ have been prepared by the sol-gel method and totally solid electric double-layer capacitors have been successfully fabricated using the highly proton-conductive silica gels as an electrolyte and activated carbon powder (ACP) hybridized with the silica gels as a polarizable electrode. It was found that the addition of HClO₄, which had the highest value of acid dissociation constant among these three acids, most effectively increased the proton conductivity of the resultant acid-doped silica gels. Tablets of the HClO₄-doped silica gels exhibited conductivities as high as 10^–5–10^–2 S cm^–1 at room temperature in dry N₂ atmosphere. One of the capacitors fabricated using the protonic acid-doped silica gels had a capacitance of 44 F/(gram of total ACP in the capacitor), which was comparable to those of conventional capacitors using liquid electrolytes.     

Ni‐Catalyzed [4+3+2] Cycloaddition of Ethyl Cyclopropylideneacetate and Dienynes: Scope and Mechanistic Insights

A detailed study of the Ni‐catalyzed [4+3+2] cycloaddition reaction between ethyl cyclopropylideneacetate and dienynes has been conducted, resulting in the development of a new method for the synthesis of compounds containing nine‐membered rings. We studied the reactivity of various dienynes, together with their substituent and conformational effects. The mechanism of the reaction was probed by examining the stoichiometric reactions of the Ni complexes and dienynes.     

Preparation of Titania Nanosheet-Precipitated Coatings on Glass Substrates by Treating SiO2-TiO2 Gel Films with Hot Water Under Vibrations

Titania nanosheet-precipitated coatings have been prepared by treating SiO₂-TiO₂ gel films on glass substrates with hot water at 90°C under vibration. Longitudinal vibrations at about 6 Hz during the treatment enhanced the formation of titania nanosheet. The titania nanosheet consisted of several layers with a spacing of about 0.6 nm and was identified as hydrated titania with a lepidocrocite-type structure. The morphology of the titania nanosheet-precipitated coatings is probably achieved by lowering of the concentration of hydrolyzed titania species at the surface due to rapid water flow driven by the vibrations. The coatings were transparent in the visible range and showed high photocatalytic activity and antifogging property.     

Sample enrichment by using monolithic precolumns in microcolumn liquid chromatography

An on-line sample enrichment system was designed using monolithic precolumns in microcolumn LC. The monolithic ODS capillary columns were prepared via in situ sol-gel processes. The enrichment efficiency of the monolithic columns was tested by using phthalates as the analytes. The relative standard deviations (n = 6) for the retention time, peak area and peak height were between 0.4 and 1.2%, 0.9 and 5.5% and 0.4 and 3.9%, respectively. The system was linear (R2 > 0.99) within the working sample concentration and sample volume ranges. Comparing to 0.2 microl injection with a typical sample injector, the theoretical plate number of a same separation column was increased by 3-6-fold when the precolumn unit was used for sample injection. The recoveries of the analytes were between 88 and 120%, and the sample volume that could be injected into the system was increased up to 5000-fold. The limits of detection were improved by more than 2000-fold and were between 0.21 and 0.87 ng ml(-1) even with a UV absorbance detector. This system was applied to the determination of phthalates contained in laboratory distilled water and tap water samples.     

Cloning, sequencing, and functional analysis of the biosynthetic gene cluster of macrolactam antibiotic vicenistatin in Streptomyces halstedii

Vicenistatin, an antitumor antibiotic isolated from Streptomyces halstedii, is a unique 20-membered macrocyclic lactam with a novel aminosugar vicenisamine. The vicenistatin biosynthetic gene cluster (vin) spanning approximately 64 kbp was cloned and sequenced. The cluster contains putative genes for the aglycon biosynthesis including four modular polyketide synthases (PKSs), glutamate mutase, acyl CoA-ligase, and AMP-ligase. Also found in the cluster are genes of NDP-hexose 4,6-dehydratase and aminotransferase for vicenisamine biosynthesis. For the functional confirmation of the cluster, a putative glycosyltransferase gene product, VinC, was heterologously expressed, and the vicenisamine transfer reaction to the aglycon was chemically proved. A unique feature of the vicenistatin PKS is that the loading module contains only an acyl carrier protein domain, in contrast to other known PKS-loading modules containing certain activation domains. Activation of the starter acyl group by separate polypeptides is postulated as well.     

A generalized technique for the encapsulation of nano‐sized NiO particles by styrene‐2‐hydroxyethyl methacrylate copolymer

Encapsulation of nickel oxide (NiO) particles is of great interest to the researchers as such modification produces remarkable improvement in properties and versatility in application potential. In this investigation, nanosized NiO particles were first prepared by calcination of nickel hydroxide precursor obtained using a simple liquid‐phase process. The produced NiO particles were stabilized with oleic acid and then treated with tetraethylorthosilicate to produce NiO/SiO₂ composite seed particles. Finally tri‐layered inorganic/organic composite particles were prepared by seeded copolymerization of styrene and 2‐hydroxyethyl methacrylate (HEMA) in the presence of NiO/SiO₂ composite seed particles. The produced composite particles named as NiO/SiO₂/P(S‐HEMA) were colloidally stable, and the obtained particles were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, X‐ray photoelectron spectroscopy and thermogravimetric analyses. Copyright © 2015 John Wiley & Sons, Ltd.     

Fe K‐Edge X‐ray Absorption Fine Structure Determination of γ‐Al2O3‐Supported Iron‐Oxide Species

The structure of FeO_x species supported on γ‐Al₂O₃ was investigated by using Fe K‐edge X‐ray absorption fine structure (XAFS) and X‐ray diffraction (XRD) measurements. The samples were prepared through the impregnation of iron nitrate on Al₂O₃ and co‐gelation of aluminum and iron sulfates. The dependence of the XRD patterns on Fe loading revealed the formation of α‐Fe₂O₃ particles at an Fe loading of above 10 wt %, whereas the formation of iron‐oxide crystals was not observed at Fe loadings of less than 9.0 wt %. The Fe K‐edge XAFS was characterized by a clear pre‐edge peak, which indicated that the Fe?O coordination structure deviates from central symmetry and that the degree of Fe?O?Fe bond formation is significantly lower than that in bulk samples at low Fe loading (<9.0 wt %). Fe K‐edge extended XAFS oscillations of the samples with low Fe loadings were explained by assuming an isolated iron‐oxide monomer on the γ‐Al₂O₃ surface.     

Anti-babesial compounds from Curcuma xanthorrhiza

Anti-babesial ingredients, (12R)- and (12S)-12,13-dihydro-12,13-dihydroxyxanthorrhizols, were isolated from Curcuma xanthorrhiza. The structures were established by the extensive NMR techniques. The assignments of (1)H NMR data of (12R)-12,13-dihydro-12,13-dihydroxyxanthorrhizol was revised, and (12S)-12,13-dihydro-12,13-dihydroxyxanthorrhizol was isolated as a pure form for the first time. The IC(50) of the active compounds were compared with that of commercial drug, diminazene aceturate (Ganaseg). IC(50) values of Ganaseg, (12R)-, and (12S)-12,13-dihydro-12,13-dihydroxyxanthorrhizols were 0.6 microg mL(-1), 8.3 microg mL(-1) and 11.6 microg mL(-1), respectively.