Nickel-catalyzed regioselective hydrocyanation of terminal alkynes by assistance of a tosyl group

Nickel-catalyzed regioselective hydrocyanation of terminal alkynes is described. A tosylamide functionality at the propargyl position was the most suitable group for controlling the regiochemistry for CCN bond formation as well as rate enhancement. A gram-scale synthesis was achieved by minimizing the catalyst loading to 2?mol%. The major HCN adduct could be transformed to the corresponding indoline through construction of a benzylic quaternary carbon under iron catalysis.     

Construction of a thermal conductivity measurement system for small single crystals of organic conductors

Journal of Thermal Analysis and Calorimetry - We newly constructed a thermal conductivity measurement system for single crystals of molecular compounds. This system enables us to measure the...     

Low-temperature heat capacity of heptacopper(II) complex [Cu7(μ3-Cl)2(μ3-OH)6-(d-pen-disulfide)3]

A single crystal calorimetry of a heptacopper(II) complex of [Cu₇(μ₃-Cl)₂(μ₃-OH)₆-(d-pen-disulfide)₃] which has a double-cubane structure supported by d-penicillaminedisulfides has been performed at low-temperature region below 8 K. This compound is a metal complex which contains seven Cu(II)s in a cluster unit. These Cu(II)s are magnetically coupled each other by strong intra-complex interactions. The heat capacities under magnetic fields exhibit Schottky type anomalies explained by the Zeeman splitting of the doublet ground state of the complex. The g-value of the ground state is evaluated as 1.86 from the systematic analysis of the Schottky peak under magnetic fields. The first excited state of the cluster seems to be separated at least by several Kelvins, which is consistent with the theoretical calculations and magnetic susceptibility results.     

Application of Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to Multi-Element Analysis of Human Organs

Abstract

Elemental concentrations of internal organs (cerebrum, cerebellum, heart, spleen, liver and kidney) of Japanese were measured with inductively coupled plasma mass spectrometry (ICP-MS). Sixty-one elements were determined simultaneously, and concentrations of some trace elements in human organs, on which information are scarcely available in the literature, were obtained. The analytical values obtained by ICP-MS and those by other methods were compared and fairly good agreement was found for Cd, Zn and Fe. Moderate agreement was found for Se and Hg, but discrepancy was observed for Mg and Na. Unacceptable values were obtained for some elements, such as Ti, Sc or Ge, probably due to polyatomic molecular interference.     

Determination of Quality Factor for Highly Overcoupled EPR Resonators

We reported determination of the loaded quality factor (Q) of highly overcoupled (dielectric, loop-gap, and cavity) resonators used in time-domain electron paramagnetic resonance. We introduced a microwave absorber into resonators and achieved critical-coupling. Due to the deep “Q-dip” of critical-coupling, we can easily determine the loaded Q as low as 10. The loaded Q of resonators with and without the microwave absorber was examined under various overcoupling conditions. We found that the radiation Q (Q _r) can be calculated from the loaded Q of the resonator that contains the microwave absorber. We proposed a simple model that represents the loaded Q of the overcoupled resonator in terms of two parameters, Q ₀ and Q _r. Q ₀ is the effective unloaded Q of the resonator determined for the critically coupled resonator without the microwave absorber and is independent of a degree of coupling. The model can be applied to overcoupling in which the coupling parameter (Q ₀/Q _r) is in the range of 1 to ca. 20.     

Liquid phase microextraction with in situ derivatization for measurement of bisphenol A in river water sample by gas chromatography-mass spectrometry

A new method that involves liquid phase microextraction (LPME) with in situ derivatization and gas chromatography-mass spectrometry (GC-MS) is described for the determination of trace amounts of bisphenol A (BPA) in river water samples. The LPME conditions, such as the type of extraction solvent and the extraction time, are investigated. Then, the extract is directly injected into GC-MS. The detection limit and the quantification limit of BPA in river water sample are 2 and 10pgml(-1) (ppt), respectively. The calibration curve for BPA is linear with a correlation coefficient of >0.999 in the range of 10-10,000pgml(-1). The average recoveries of BPA in river water samples spiked with 100 and 1000pgml(-1) BPA are 104.1 (RSD: 8.9%) and 98.3 (RSD: 3.2%), respectively, with correction using the added surrogate standard, bisphenol A-(13)C(12). This simple, accurate, sensitive and selective analytical method may be applicable to the determination of trace amounts of BPA in liquid samples.     

Structural analysis of alanine tripeptide with antiparallel and parallel beta-sheet structures in relation to the analysis of mixed beta-sheet structures in Samia cynthia ricini silk protein fiber using solid-state NMR spectroscopy

The structural analysis of natural protein fibers with mixed parallel and antiparallel beta-sheet structures by solid-state NMR is reported. To obtain NMR parameters that can characterize these beta-sheet structures, (13)C solid-state NMR experiments were performed on two alanine tripeptide samples: one with 100% parallel beta-sheet structure and the other with 100% antiparallel beta-sheet structure. All (13)C resonances of the tripeptides could be assigned by a comparison of the methyl (13)C resonances of Ala(3) with different [3-(13)C]Ala labeling schemes and also by a series of RFDR (radio frequency driven recoupling) spectra observed by changing mixing times. Two (13)C resonances observed for each Ala residue could be assigned to two nonequivalent molecules per unit cell. Differences in the (13)C chemical shifts and (13)C spin-lattice relaxation times (T(1)) were observed between the two beta-sheet structures. Especially, about 3 times longer T(1) values were obtained for parallel beta-sheet structure as compared to those of antiparallel beta-sheet structure, which could be explicable by the difference in the hydrogen-bond networks of both structures. This very large difference in T(1) becomes a good measure to differentiate between parallel or antiparallel beta-sheet structures. These differences in the NMR parameters found for the tripeptides may be applied to assign the parallel and antiparallel beta-sheet (13)C resonances in the asymmetric and broad methyl spectra of [3-(13)C]Ala silk protein fiber of a wild silkworm, Samia cynthia ricini.     

Detection of coloured tracks of heavy ion particles using photographic colour film

A photographic colour film, which was exposed to heavy ions, reveals a coloured dye image of the ion tracks. Since the colour film consists of several layers and different colours appear on each layer, three-dimensional information on the tracks in the layers can be obtained by the colour image. Previously, we have reported the method for which the tracks in different colours represented differences of track depth and we also discussed the disadvantages of using commercial colour films. Here we present the procedure for a self-made photographic coating and the development formula which can overcome the disadvantages.     

Characterization of collagen model peptides containing 4-fluoroproline; (4(S)-fluoroproline-pro-gly)10 forms a triple helix,but (4(R)-fluoroproline-pro-gly)10 does not

Collagen model peptide (Pro-Pro-Gly)10 has a triple helical structure and undergoes a thermal transition to a single random coil structure. The transition temperature of the analogous model peptides depends largely on amino acid substitution. Substitution of Pro by 4-hydroxyproline (Hyp) or 4-fluoroproline (fPro) has especially attracted attention because the position of substitution and chirality of the hydroxyl group or fluorine atom affect the transition temperatures. Here, we demonstrated that (4(S)-fPro-Pro-Gly)10 takes a triple helical structure, but (4(R)-fPro-Pro-Gly)10 exists in a single chain structure. This is not consistent with the case of Hyp substitution in our previous report where both (4(S)-Hyp-Pro-Gly)10 and (4(R)-Hyp-Pro-Gly)10 are in a single random coil state.