Alkali-cation affinities of polyoxyethylene dodecylethers and helical conformations of their cationized molecules studied by electrospray mass spectrometry

Relative alkali-cation affinity of polyoxyethylene (POE) dodecylethers in gas phase was studied by electrospray ionization (ESI) mass spectrometry using dodecylether-poly-ethoxylate (C(12)EO:n, "n" denotes ethyleneoxide unit number) nonionic surfactants, and possible helical conformations of the cationized molecules were demonstrated. The alkali-cation affinity highly depended on the cation diameters. The mass spectra of C(12)EO:8 cationized by alkali-metal ions were dominated by potassiated molecules. The results indicated that the POE moiety could have specific affinity to K(+) ions based on a host-guest interaction between POE helix and potassium ions. This is very similar to the relationships between 18-crown-6 and K(+). The ESI mass spectra exhibited the multiply cationized C(12)EO:n in addition to the singly cationized molecules. The critical EO unit numbers necessary for producing the multiply-charged cationized molecules also depended on the cation diameters. In addition, the POE surfactants highly preferred alkali cations to proton. The results were strongly supported by molecular mechanics/dynamics calculations. A helical conformation of the POE moiety of C(12)EO:15 including two K(+) ions gave a potential minimum, while a lowest energy structure of the protonated molecule took irregular conformations due to the formation of local hydrogen bonds.     

Radical chain reactions using THP as a solvent

THP (tetrahydropyran) has been found to show an excellent stability towards autooxidation, compared with THF. Tributyltin hydride mediated radical cyclization, when conducted in THF as a solvent, suffers from competition of hydrogen abstraction from the solvent, whereas the use of THP resulted in the course to negligible degree. Tributyltin hydride, TTMSS, and hexanethiol mediated radical reactions were carried out successfully using THP as a solvent.     

Anisotropic self-organization of hybrid silica based xerogels containing bridged positively charged 1,4-diazoniabicycle[2.2.2]octane chloride group

Anisotropic self-organized hybrid silica based xerogels were obtained. The ordered structure was imposed by the double charged 1,4-diazoniabicycle[2.2.2]octane chloride group bonded in a bridged way. This was confirmed by the presence of well defined X-ray diffraction peaks corresponding to an interplanar distance with the same length estimated for the organic bridged groups. The material was characterized by elemental analysis using CHN technique and the chloride ion was analyzed by a potentiometric titration. (13)C and (29)Si CP MAS solid state NMR spectroscopy and thermogravimetric analysis were also performed. The material that can be obtained in the form of powders and transparent monoliths or films, is thermally stable up to 260 degrees C and the samples with high organic content presented birefringence properties.     

Preparation of 3-(4-chlorophenyl)-2-(2-aminothiazol-4-yl)-5-methoxybenzo[b]furan derivatives and their leukotriene B(4) inhibitory activity

A series of 3-(4-chlorophenyl)-2-(2-aminothiazol-4-yl)benzo[b]furan derivatives 6-10 were prepared and their leukotriene B(4) inhibitory activity was evaluated. We found that several compounds showed strong inhibition of calcium mobilization in CHO cells overexpressing human BLT(1) and BLT(2) receptors. Among them, 3-(4-chlorophenyl)-2-[5-formyl-2-[(dimethylamino)methyleneamino]thiazol-4-yl]-5-methoxybenzo[b]furan 9b showed the most potent and selective inhibition for the human BLT(2) receptor, and its IC(50) value was smaller than that of the selected positive control compound, ZK-158252.     

Crystal structures of Cr-based magnetic pyroxenes

Crystal structures of the Cr-based germanates: ACrGe₂O₆ (A = Li and Na) which show the specific magnetic properties, are solved using synchrotron powder-diffraction data at room temperature. Both compounds have isostructure which belongs to monoclinic C2/c with pyroxene-type structure. In both ACrGe₂O₆ structures, chromium atom forms the magnetic one-dimensional edge-shared CrO₆ chain. In the NaCrGe₂O₆ structure, the shortest Cr?Cr distance and Cr–O–Cr angle are both longer and wider compared to those in the LiCrGe₂O₆ structure. This behavior may give strong influence to the difference of their magnetic properties.