Low-temperature phase of Li2FeSiO4: crystal structure and a preliminary study of electrochemical behavior

A nearly single-phase of a low-temperature (LT) phase of Li(2)FeSiO(4) is prepared by a hydrothermal method at 150 °C. We report the detailed crystal structure of LT-Li(2)FeSiO(4) (S.G. Pmn2(1)) by applying Rietveld/MEM analysis to the synchrotron XRD pattern. LT-Li(2)FeSiO(4) shows 150 mA h g(-1) as the positive electrode materials of rechargeable batteries.     

Chain-growth polycondensation for well-defined aramide. Synthesis of unprecedented block copolymer containing aramide with low polydispersity

Poly(p-benzamide) with a defined molecular weight and a low polydispersity and a block copolymer containing this well-defined aramide was synthesized. Phenyl 4-aminobenzoate, which would yield poly(p-benzamide), did not polymerize under the conditions of chain-growth polycondensation. However, phenyl 4-(4-octyloxybenzylamino)benzoate (1b) polymerized at room temperature in the presence of base and phenyl 4-nitrobenzoate (2) as an initiator in a chain-growth polycondensation manner to give well-defined aromatic polyamides having the 4-octyloxybenzyl groups as a protecting group on nitrogen in an amide. It was confirmed by a model reaction that deprotection of this protecting group proceeded completely with trifluoroacetic acid (TFA) without breaking the amide linkage. The utility of this approach to poly(p-benzamide) with a low polydispersity was demonstrated by the synthesis of block copolymers. Thus, phenyl 4-(octylamino)benzoate (1a) polymerized in the presence of 2 and base, followed by addition of 1b and base to the reaction mixture of the prepolymer to yield the block copolymer of 1a and 1b with a controlled molecular weight and a low polydispersity. The block copolymer was treated with TFA, resulting in a soluble block copolymer of poly(N-octyl-p-benzamide) and poly(p-benzamide). The SEM images of the supramolecular assemblies of the block copolymer showed mum-sized bundles and aggregates of flake structures.     

Reductive carboxylation of alkyl halides with CO2 by use of photoinduced SmI2/Sm reduction system

Upon visible-light irradiation, reductive carboxylation of alkyl halides takes place by using a SmI₂/Sm mixed system under atmospheric CO₂ to afford the corresponding carboxylic acids in good to excellent yields.     

Stereoselective synthesis of tetrasubstituted (Z)-alkenes from aryl alkyl ketones utilizing the Horner-Wadsworth-Emmons reaction

Tetrasubstituted (Z)-alkenes were readily prepared through the Horner-Wadsworth-Emmons reactions of methyl 2-[bis(2,2,2-trifluoroethyl)phosphono]propionate with aryl alkyl ketones by employing Sn(OSO(2)CF(3))(2) and N-ethylpiperidine.     

Lewis acid promoted cyclization of enyne triesters and diesters

Reactions of enynes with three or two ester groups (1-4) in the presence of halogen-ligand Lewis acids gave cyclized products with halide incorporation (5-8) with high generality. The cyclization process was also analyzed in a theoretical study. Facile isomerization and dehydrohalogenation of five-membered products 5 and 8 by Al(2)O(3) or Et(3)N were also observed; this process introduces conjugated moieties into the products.     

New mu-opioid receptor agonists with phenoxyacetic acid moiety

New muq-opioid receptor (MOR) agonists containing 4-hydroxypiperidine, piperidine and piperazine moieties were synthesized and evaluated to find a peripheral opioid analgesic. Among the synthesized compounds, 12-[1-[3-(N,N-dimethylcarbamoyl)-3,3-diphenylpropyl]-4-hydroxypiperidin-4-yl]phenoxy]acetic acid (8: SS620) having phenoxyacetic acid and 4-hydroxypiperidine moieties showed the highest agonist potency on the MOR in an isolated guinea-pig ileum preparation, and it also had selectivity to the human MOR expressed in Chinese hamster ovary (CHO)-K1 cells compared with the same types of delta- and kappa-opioid receptors (DOR and KOR). In addition, compound 8 showed a 10 times more potent MOR agonist activity than loperamide. Furthermore, compound 8 showed a peripheral analgesic activity in vivo screening on rat.     

Effects of aluminum impurity on the structural relaxation in silica glass

To elucidate effects of Al impurity on the glass-forming process in silica glass, the structural relaxation in Al-containing silica glass, with alkali ions of only trace levels, was investigated by observing the fictive temperature. The fictive temperature was determined by infrared (IR) absorption analysis. Al, even at concentrations lower than 10 wtppm, increases the relaxation time and the activation energy of the -relaxation. It also suppresses the sub-relaxational process due to OH ions. These results indicated that Al should have other effects on structural relaxation than alkali–aluminate complex formation, as has been thought to be the cause for an increase in the -relaxation time and thus the viscosity of silica glass. Furthermore, the structural relaxation does not merely depend on the number of non-bridging oxygen atoms in the glass network.     

Hydrogen Intercalation in Potassium-C60

Abstract

Solid state ¹H NMR of (KH)₃C₆₀ was measured in the temperature range between ?80 and 60 °C. A doublet spectrum composed of main peak at ?7.0 ppm and shoulder peak at ～0 ppm was observed at room temperature. The negative chemical shift of the main peak indicates that hydrogen in (KH)₃C₆₀ exists as a hydride-like ion. The 60 °C spectrum became singlet at ?5.8 ppm due to motional narrowing.     

Solid State Intercalation of 4,4′-Bipyridine into the Interlayer Space of Montmorillonites

Abstract

Intercalation of 4,4′-bipyridine into the interlayer spaces of cobalt(II), nickel(II) and copper(II)-montmorillonites by solid-solid reactions was investigated. The successful intercalation of 4,4′-bipyridine and the complex formation in the interlayer spaces of montmorillonites was confirmed by powder XRD (the change in the basal spacings) as well as IR and the thermal analysis of the products.     

Degradation of aromatic compounds in ground-water, and methods of sample preservation

The degradation of acenaphthylene, acenaphthene, 2-methylnaphthalene, 2-methylindene, 3-methylindene and indene in water solutions was studied. These compounds at the 25-150 mug/l. level were almost totally degraded at ambient temperature within three days. The microbial population responsible for the degradation occurs naturally in ground-water taken from an aquifer in Ames, Iowa, which is contaminated with coal-tar products. These unidentified micro-organisms adapt readily to other waters when used as an inoculant for the degradation of aromatic compounds. The preservation of water to prevent such degradation was also investigated. Filtration through a 0.45-mum filter was found the most effective procedure for preserving the hydrocarbons in these waters.