A new synthesis of p-nitrocalix[6]arene

p-Nitrocalix[6]arene which possibly serves as a potential intermediate to derive functionalized calixarenes was synthesized for the first time.     

Electrochemical and photosensitized redox reactions of a prussian blue film layered on a WO3/[Ru(bpy)3]2+/polymer hybrid film.

A hybrid film of WO(3)/tris(2,2'-bipyridine)ruthenium(II) ([Ru(bpy)(3)](2+))/poly(sodium 4-styrenesulfonate) (PSS) (denoted as a WRP hybrid film) was prepared as a base layer on an indium tin oxide electrode substrate by cathodic electrodeposition from a colloidal ternary solution containing peroxotungstic acid, [Ru(bpy)(3)](2+), and PSS. Prussian blue, Fe(III) (4)[Fe(II)(CN)(6)](3) (Fe(II)-Fe(III)) was cathodically electrodeposited on the WRP hybrid film from a Berlin brown (Fe(III)-Fe(III)) colloidal solution to give a WRP/Fe(II)-Fe(III) bilayer film. Spectrocyclic voltammetry measurement of the WRP/Fe(II)-Fe(III) bilayer film reveals that Prussian white (Fe(II)-Fe(II)) is oxidized to Fe(II)-Fe(III) by electrogenerated Ru(III), and Fe(II)-Fe(III) is re-reduced to Fe(II)-Fe(II) by electrogenerated H(x)WO(3). Visible-light irradiation of the WRP hybrid film generates a small photocurrent (approximately 8 nA cm(-2)) at 0.4 V of an applied potential, whereas irradiation of the WRP/Fe(II)-Fe(II) bilayer film (Fe(II)-Fe(III) is electrochemically reduced to the Fe(II)-Fe(II) state) significantly generates a steady photoanodic current of 2.0-1.1 microA cm(-2) under the same conditions, thus demonstrating that the photoanodic current is produced by the layered Fe(II)-Fe(II) film. The photoaction spectrum of the bilayer film reveals that the photoanodic current is based on the photoexcitation of [Ru(bpy)(3)](2+). The photogeneration of Fe(II)-Fe(III) from Fe(II)-Fe(II) is shown by the absorption spectral change of the bilayer film on irradiation. These results corroborate the notion that Fe(II)-Fe(II) is oxidized by photogenerated Ru(III) to generate Fe(II)-Fe(III). However, the rate of photogeneration of Fe(II)-Fe(III) is slow, which could be ascribed to the fast back electron transfer (ET) from WO(3) to Ru(III), comparable with the forward ET from Fe(II)-Fe(II) to Ru(III). The fast back ET could be a crucial problem for the [Ru(bpy)(3)](2+)-sensitized reaction in the hybrid film.     

Isolation, structure, and synthesis of dolastatin C, a new depsipeptide from the sea hare Dolabella auricularia

Dolastain C (1), a new depsipeptide exhibiting weak cytotoxicity, has been isolated from the Japanese sea hare Dolabella auricularia. The structure of 1 was elucidated by spectroscopic analysis and chemical degradation. The synthesis of 1 was carried out to confirm the structure unambiguously.     

Citrinadin A, a novel pentacyclic alkaloid from marine-derived fungus Penicillium citrinum

[structure: see text] A novel pentacyclic alkaloid, citrinadin A (1), was isolated from the cultured broth of the fungus Penicillium citrinum, which was separated from a marine red alga, and the structure was elucidated by spectroscopic data. The relative stereochemistry of the pentacyclic core was assigned on the basis of NOESY data and (1)H-(1)H coupling constants, and the presence of an N,N-dimethyl-L-valine residue in 1 was determined by chiral HPLC analysis of the hydrolysate.     

Cationic grafting from carbon black. VIII. Cationic ring-opening polymerization and copolymerization of oxepane initiated by acylium perchlorate groups on carbon black

The cationic ring-opening polymerization of oxepane was found to be initiated by carbon black having acylium perchlorate (CO⁺CIO) groups, which were introduced by the reaction of acyl chloride groups with silver perchlorate. It was confirmed that polyoxepane, i.e., poly(oxyhexamethylene), was propagated from CO⁺CIO groups on carbon black and effectively grafted on the surface. The rate of the polymerization and the percentage of grafting of poly(oxyhexamethylene) remarkably increased by the addition of epichlorohydrin (ECH) as a promoter: the percentage of grafting in the presence of ECH increased to about 100% with an increase in conversion. Furthermore, CO⁺CIO groups on carbon black have an ability to initiate the cationic ring-opening copolymerization of oxepane with ECH to give poly(oxepane-co-ECH) with various composition. The ring-opening copolymerization of oxepane with phthalic anhydride was also initiated by CO⁺CIO groups to give polyether ester, i.e., poly(hexamethylene phthalate) containing poly(oxyhexamethylene) sequence. In the copolymerization, polyether or polyether ester was effectively grafted from carbon black based on the propagation of these polymers from CO⁺CIO groups.     

Effects of heating rate (1–300° h−1) on the non-isothermal thermogravimetry of CuSO4 · 5 H2O

The course of the reaction CuSO₄ · 5 H₂O ? CuSO₄ · H₂O + 4 H₂O was studied by non-isothermal thermogravimetry with various heating rates ranging from 1 to 300° h^?. The measurements were made either in static air, in a dry nitrogen stream, or in water vapor at a reduced pressure (9 mm Hg). In static air, the shape of the TG curve changed drastically at a heating rate of 13 to 15° h^?, and this change was explained by considering the nature of the plateaus and inflections present. In a dry nitrogen stream, the dehydration is made much easier at slow heating rates and occurs almost in one step at 2° h^?; in water vapor at 9 mm Hg, on the other hand, a very distinct two-step curve is obtained at 1° h^?. This can reasonably be compared with the phase diagram of copper sulfate.     

Radical polymerization of methyl methacrylate initiated by an enolizable ketone–carbon black system

The polymerization of methyl methacrylate (MMA) initiated by an enolizable ketone (R₁? CO? CH₂? CO? R₂)-carbon black system was investigated. Although enolizable ketone itself could not do so, the polymerization of MMA was initiated by enolizable ketone in the presence of carbon black. In addition, a chloranil-enolizable ketone system was able to initiate the polymerization of MMA. It was found that the enol form of the ketone and quinonic oxygen groups on the carbon black surface played an important role in the initiation system; namely, it was considered that the polymerization was begun by the ketone radical (R₁? CO? CH? CO? R₂) formed by a one-electron transfer reaction from enolate ion to quinonic oxygen groups. The effect of solvent on the process was also studied. The rate of the polymerization increased, depending on the solvent used, in the following order: benzene < 1,4-dioxane < dimethyl sulfoxide < N,N-dimethylformamide < N-methyl-2-pyrrolidone. Furthermore, it became apparent that during the polymerization poly(methyl methacrylate) was grafted onto the carbon black surface (grafting ratio was ca. 40% when benzene was used as solvent) and the carbon black obtained gave a stable colloidal dispersion in organic solvent.     

Positive and negative magnetodielectric effects in A-site ordered (BiMn3)Mn4O12 perovskite

A-site ordered perovskite (BiMn3)Mn4O12 was synthesized through a high-pressure synthesis route at 5 GPa and found to exhibit two magnetic transitions and to show either a positive or a negative magnetodielectric effect depending on the temperature range/magnetic state.     

Catalytic asymmetric synthesis of 2,2-disubstituted terminal epoxides via dimethyloxosulfonium methylide addition to ketones

Catalytic asymmetric Corey-Chaykovsky epoxidation of ketones with dimethyloxosulfonium methylide 2 using an LLB 1a + Ar3P O complex proceeded smoothly at room temperature, and 2,2-disubstituted terminal epoxides were obtained in high enantioselectivity (91-97%) and yield (>88-99%) from a broad range of methyl ketones with 1-5 mol % catalyst loading. The use of achiral additive Ar3P O 5i was important to achieve high enantioselectivity.     

Affinity-based elimination of aromatic VOCs by highly crystalline multi-walled carbon nanotubes

Carbon nanotubes (CNTs) are capable of adsorbing pollutant chemicals. Their adsorptive capacities and adsorbing mechanisms, however, are not fully understood. As-grown CNTs often contain both crystalline and amorphous carbon, and the ratio of carbon types can affect adsorption. In this study, highly crystalline multi-walled carbon nanotubes (HC-MWCNTs) were used as the adsorbent for volatile organic compounds (VOCs) in contaminated air samples. Air containing 23 added VOCs (1,1-dichloroethylene, dichloromethane, trans-1,2-dichloroethylene, cis-1,2-dichloroethylene, chloroform, 1,1,1-trichloroethane, carbon tetrachloride, 1,2-dichloroethane, benzene, trichloroethylene, 1,2-dichloropropane, bromodichloromethane, cis-1,3-dichloropropene, toluene, trans-1,3-dichloropropene, 1,1,2-trichloroethane, tetrachloroethylene, dibromochloromethane, m-xylene, p-xylene, o-xylene, bromoform, and p-dichlorobenzene) was used for model samples. Adsorptive experiments were carried out by passing the air samples through a cartridge packed with HC-MWCNTs. Initial results showing high selectivity and high affinity for adsorbing aromatic VOCs (benzene, toluene, m-xylene, p-xylene, o-xylene, and p-dichlorobenzene) have provided new insight into the adsorption mechanisms. Data suggest that the HC-MWCNTs, unlike conventional carbon materials, adsorb aromatic compounds according to Fukui's frontier theory, which is based on the interactions between the HOMO and LUMO of the aromatic VOCs and those of the HC-MWCNTs.