Phosphoester hydrolysis by cerium(IV)-thiacalix[4]arene complexes and its application to immunoassay

Thiacalix[4]arenetetrasulfonate was treated with Ce(IV) in water at pH 9.5 to give novel phosphoester-hydrolyzing complexes. The dinuclear Ce(IV) complex promoted the hydrolysis of p-nitrophenyl phosphate with a turnover frequency of 6.8 h⁻¹ at 50 °C, showing fourfold higher activity than the mononuclear complex. The dinuclear complex was readily immobilized onto an antibody by simply mixing them in water, hence its phosphatase-like activity was applied to the color-developing reaction in immunoassay. The model assay using an antibody labeled with the dinuclear complex allowed the detection of as little as 10 ng mL⁻¹ of a tumor marker, Bence–Jones protein, in a 96-well microtiter plate format. Analysis of urine for Bence–Jones protein was performed by the proposed method.     

Infrared spectroscopy of hydrogen-bonded 2-fluoropyridine-water clusters in supersonic jets

The hydrogen-bonded clusters of 2-fluoropyridine with water were studied experimentally in a supersonic free jet and analyzed with molecular orbital calculations. The IR spectra of 2-fluoropyridine-(H2O)(n) (n = 1 to 3) clusters were observed with a fluorescence detected infrared depletion (FDIR) technique in the OH and CH stretching vibrational regions. The frequencies of OH stretching vibrations show that water molecules bond to the nitrogen atom of 2-fluoropyridine in the clusters. The hydrogen-bond formation between aromatic CH and O was evidenced in the 1:2 and 1:3 clusters from the experimental and calculated results. The overtone vibrations of the OH bending mode in hydrogen-bonded water molecules appear in the IR spectra, and these frequencies become higher with the increase of the number of water molecules in the clusters. The band structure of the IR spectra in the CH stretching region changes depending on the number of coordinating water molecules.     

High-throughput and high-resolution two dimensional mapping of pI and m/z using a microchip in a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer

We have developed a high-throughput, two-dimensional-mapping (isoelectric point [pI], mass-to-charge ratio [m/z]) method by combining a capillary isoelectric focusing chip sealed with removable resin tape and a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer. Sample proteins are separated in a meandering channel on the chip and immediately frozen. The tape is then removed and the proteins are freeze-dried. The freeze-drying maintains the separation state of the proteins and prevents movement of the sample solution, which can reduce pI resolution. A matrix solution is then applied and mass spectrometry is carried out by laser irradiation. The whole process takes less than 70 min, more than 10 times faster than with two-dimensional, polyacrylamide gel electrophoresis.     

Stereoselective synthesis of a fragment of mycobacterial arabinan

Strategies for the stereoselective synthesis of mycobacterial arabinan were explored. Arabinofuranosyl donors with various protective groups were screened in terms of suitability for beta-(1,2-cis)-selective glycosylation. The protective group was found to affect the stereoselectivity of arabinofuranosylation. Beta-selectivity was drastically enhanced by using donors protected with 3,5-TIDPS, possibly due to conformational constraints on the furanose ring. Synthesis of heptaarabinofuranoside was then performed to demonstrate the practicality of this methodology. [reaction: see text].     

Development of ambient sampling chemi/chemical ion source with dielectric barrier discharge

The development of a new configuration of chemical ionization (CI)‐based ion source is presented. The ambient air containing the gaseous sample is sniffed into an enclosed ionization chamber which is of sub‐ambient pressure, and is subsequently mixed with metastable species in front of the ion inlet of the mass spectrometer. Metastable helium atoms (He*) are used in this study as the primary ionizing agents and are generated from a dielectric barrier discharge (DBD) source. The DBD is powered by an AC high‐voltage supply and the configuration of the electrodes is in such a way that the generated plasma is confined within the discharge tube and is not extended into the ionization chamber. The construction of the ion source is simple, and volatile compounds released from the bulky sample can also be analyzed directly by approaching the sample to the sampling nozzle. When combined with heated nitrogen or other desorption methods, its application can also be extended to non‐volatile compounds, and the consumption for helium can be kept minimum solely for maintaining the stable discharge and gas phase ionization. Applications to non‐proximate sample analysis, direct determination of active ingredients in drug tablets and the detection of trace explosive such as hexamethylene triperoxide diamine are demonstrated. Copyright © 2010 John Wiley & Sons, Ltd.     

Charge-transfer phase transition and zero thermal expansion in caesium manganese hexacyanoferrates

A series of caesium manganese hexacyanoferrates is prepared; Cs(I)(1.78)Mn(II)[Fe(II)(CN)6]0.78[Fe(III)(CN)6](0.22) (1), Cs(I)(1.57)Mn(II)[Fe(II)(CN)6]0.57[Fe(III)(CN)6](0.43) (2), Cs(I)(1.51)Mn(II)[Fe(II)(CN)6]0.51[Fe(III)(CN)6](0.49) (3), and Cs(I)(0.94)Mn(II)[Fe(II)(CN)6]0.21[Fe(III)(CN)6](0.70).0.8H2O (4). 1-3 show charge-transfer phase transitions between the high-temperature (HT) and low-temperature (LT) phases with transition temperatures (T(1/2 downward arrow), T(1/2 upward arrow)) of (207 K, 225 K) (1), (190 K, 231 K) (2), and (175 K, 233 K) (3) at a cooling and warming rates of 0.5 K min(-1). Variable temperature IR spectra indicate that the valence states of the LT phases of 1-3 are Cs(I)(1.78)Mn(II)(0.78)Mn(III)(0.22)[Fe(II)(CN)6], Cs(I)(1.57)Mn(II)(0.57)Mn(III)(0.43)[Fe(II)(CN)6], and Cs(I)(1.51)Mn(II)(0.51)Mn(III)(0.49) [Fe(II)(CN)6], respectively. The XRD measurements for 1-3 show that crystal structures of the HT and LT phases are cubic structures (Fm3[combining macron]m), but the lattice constants decrease from the HT phase to the LT phase; a = 10.5446(17) --> 10.4280(7) A (1), 10.5589(17) --> 10.3421(24) A (2), and 10.5627(11) --> 10.3268(23) A (3). The magnetization vs. temperature curves and the magnetization vs. external magnetic field curves show that the LT phases are ferromagnetic with Curie temperatures of 4.3 (1), 5.0 (2), and 5.6 K (3). At a cooling rate of -0.5 K min(-1), 4 does not show the charge-transfer phase transition, but does show a behavior of zero thermal expansion with a thermal expansivity of +0.2 x 10(-6) K(-1) throughout the temperature range 300 and 20 K.     

Roles of adriamycin and adriamycin dimer in antitumor activity of the polymeric micelle carrier system

Adriamycin (ADR) dimer was prepared and its antitumor activity was evaluated with mouse colon adenocarcinoma 26 (C 26). As compared with original ADR, the dimer did not show significant antitumor activity, either in vitro or in vivo. Furthermore, polymeric micelles containing varied ratios of the dimer to the original ADR were prepared. Polymeric micelles with a higher dimer/ADR ratio (9.7) showed significant antitumor activity, but the effective dose shifted higher. Effective doses were found to largely depend on the concentration of the original ADR, rather than that of the dimer at the tumor sites. Therefore, it was presumed that the original ADR played a major role in antitumor activity, and the dimer played a supplementary role to contribute selective delivery of ADR to the tumor sites.     

Mercuric triflate-(TMU)3-catalyzed cyclization of omega-arylalkyne leading to dihydronaphthalenes

[reaction: see text] Efficient arylyne cyclization catalyzed by the Hg(OTf)(2)-(TMU)(3) complex has been developed. The reaction was carried out at ambient temperature in acetonitrile, and the catalytic cycle reaches up to 1000 turnovers.     

Reheating decomposition process as chemical recycling for rigid polyurethane foam

We have found that a reheating process for the products in the chemical recycling of rigid polyurethane foam by an extruder with diethanolamine as a decomposing agent is effective for improving the product stability. The product with stable viscosity was obtained by the reheating process at 175-200 °C for 2 h, regardless of the extruding condition. An amine adduct, which is an intermediate, was found to be the cause of instability of the discharged product from the extruder. At the initial stage of reheating, the intermediate decomposed, releasing toluenediamine, which promoted further decomposition of the discharged products. We have succeeded in controlling the quality of the recycled products.     

Light-induced formation of curved needle texture by circularly polarized light irradiation on a discotic liquid crystal containing a racemic chromium complex

We have found that the discotic nematic liquid crystal, hexakis(4-nonylphenylethynyl)benzene (HNEB), doped with the racemic chromium complex Cr(Ocacac)₃, shows a novel straight-needle texture with hexagonal columnar alignments, changing to a curved-needle texture under irradiation of circularly polarized light (CPL). This novel phenomenon is specific to the mixture of HNEB and Cr(Ocacac)₃. The formation of curved needles means that chiroselective photoinversion of racemic Cr(Ocacac)₃ by CPL irradiation induces a needle direction change in a discotic liquid crystal. The change in chirality of Cr(Ocacac)₃ in HNEB induced by CPL irradiation, and the resulting nano-segregation of its enantiomers during cooling from the isotropic to mesophase of HNEB, are considered to influence changes in the alignment of columns and/or small domains of column aggregates in the discotic liquid crystal.