Structure of the jet-cooled 1-naphthol dimer studied by IR dip spectroscopy: cooperation between the pi-pi interaction and the hydrogen bonding

The structure of a jet-cooled 1-naphthol (1-NpOH) dimer was investigated by using resonant-enhanced two-photon ionization (R2PI) and ion-detected infrared (IR) dip spectroscopy. A geometrical optimization and a frequency calculation in (1-NpOH)2 were also performed at the MP2/cc-pVDZ level. Stable isomers in the MP2/cc-pVDZ calculation were classified into a structure dominated only by the pi-pi interaction and structures formed by cooperation between the pi-pi interaction and hydrogen bonding. On the basis of a comparison between the observed and calculated IR spectra, the geometry of (1-NpOH)2 was concluded to be a pi-pi stacking structure supported by hydrogen bonding.     

Ruthenium-catalyzed oxidative cyanation of tertiary amines with molecular oxygen or hydrogen peroxide and sodium cyanide: sp3 C-H bond activation and carbon-carbon bond formation

Ruthenium-catalyzed oxidative cyanation of tertiary amines with molecular oxygen in the presence of sodium cyanide and acetic acid gives the corresponding alpha-aminonitriles, which are highly useful intermediates for organic synthesis. The reaction is the first demonstration of direct sp(3) C-H bond activation alpha to nitrogen followed by carbon-carbon bond formation under aerobic oxidation conditions. The catalytic oxidation seems to proceed by (i) alpha-C-H activation of tertiary amines by the ruthenium catalyst to give an iminium ion/ruthenium hydride intermediate, (ii) reaction with molecular oxygen to give an iminium ion/ruthenium hydroperoxide, (iii) reaction with HCN to give the alpha-aminonitrile product, H2O2, and Ru species, (iv) generation of oxoruthenium species from the reaction of Ru species with H2O2, and (v) reaction of oxoruthenium species with tertiary amines to give alpha-aminonitriles. On the basis of the last two pathways, a new type of ruthenium-catalyzed oxidative cyanation of tertiary amines with H2O2 to give alpha-aminonitriles was established. The alpha-aminonitriles thus obtained can be readily converted to alpha-amino acids, diamines, and various nitrogen-containing heterocyclic compounds.     

Recent advances in calorimetry and thermal analysis: Collected papers from the 8th international and 10th Japan–China joint symposium on calorimetry and thermal analysis (CATS-2017)

Journal of Thermal Analysis and Calorimetry -     

The measurement of various molecules of pyrolysis gas of coal by using VUV-SPI-TOFMS

We developed and tested a system that combines a vacuum ultraviolet single photon ionization time-of-flight mass spectrometer (VUV-SPI-TOFMS) with a Fourier transform-infrared (FT-IR) spectrometer and used it for the simultaneous detection of the various compounds generated during the pyrolysis of coal. We characterized the performance of the system, including its limits of detection and time resolution. We also determined the various compounds that could be detected using the system. The instrument exhibited a laboratory-determined detection limit that was in the parts per billion volume (ppbv) range and a detection time of 10 s for most of the aromatic compounds generated during the pyrolysis process. In addition, using this system, it was possible to determine the correlation between the pyrolysis temperature and the various compounds generated from different types of coals during the pyrolysis process.     

Direct Fabrication of Surface Relief Holographic Diffusers in Azobenzene Polymer Films

We propose a direct fabrication of light diffusers using azobenzene polymer films. Holographic recordings of surface relief diffusers are formed on the polymer film by exposure to an Nd:YAG laser (532 nm) through source diffusion materials. No post-treatment is needed, and it can be erased by heating or irradiating uniform laser beam. Diffusion pattern can be controlled by the polarization of the laser. Transmittance of over 88% is obtained at the wavelength of 633 nm.     

Global existence of small analytic solutions to schrodinger equations with quadratic nonlinearity

We study the nonlinear Schriidinger equations     

Enzymatic Precision Polymerization for Synthesis of Glycosaminoglycans and Their Derivatives

Hyaluronidase (HAase)-catalyzed polymerization was performed to provide synthetic hyaluronan (HA), chondroitin (Ch) and their derivatives. The 2-methyl oxazoline derivatives derived from their repeating disaccharides of N-acetylhyalobiuronate ( 1a ) and N-acetylchondrosine ( 3a ) were effectively polymerized by the enzyme, giving rise to synthetic HA and synthetic Ch in good yields through regio-selective and stereo-controlled ring-opening polyaddition. The oxazoline derivatives of 2-ethyl ( 1b , 3b ), 2-n-propyl ( 1c , 3c ), 2-isopropyl ( 1d , 3d ), 2-phenyl ( 1e , 3e ), 2-vinyl ( 1f , 3f ) and 2-isopropenyl ( 1g ) were synthesized and subjected to the enzymatic reaction. Monomers 1b , 1c , 1f , 3b and 3f were polymerized to corresponding polysaccharides 2b , 2c , 2f , 4b and 4f , all of which are unnatural glycosaminoglycans. Compounds 1d , 3c and 3d were also catalyzed by the enzyme, affording oligomers of 2d , 4c and 4d were produced in trace amounts. Monomers 1e , 1g and 3e were not catalyzed by HAase.     

Design and synthesis of a dimeric derivative of RK-682 with increased inhibitory activity against VHR, a dual-specificity ERK phosphatase: implications for the molecular mechanism of the inhibition

BACKGROUND: VHR is a dual-specificity phosphatase, which dephosphorylates activated ERK1/2 and weakens the ERK signaling cascade in mammalian cells. A selective inhibitor is expected to be useful for revealing the physiological function of VHR. RESULTS: First, we investigated the molecular mechanism of VHR inhibition by a known natural product, RK-682. Kinetic analysis indicated that inhibition was competitive toward the substrate, and two molecules of RK-682 were required to inhibit one molecule of VHR. Based on the structure-activity relationships for VHR inhibition by RK-682 derivatives, we constructed a binding model using molecular dynamics calculation. Based on this model, we designed and synthesized a novel dimeric derivative. As expected, the dimeric derivative showed increased inhibition of VHR, supporting our proposed mechanism of VHR inhibition by RK-682. CONCLUSION: We have developed a novel inhibitor of VHR based on the results of kinetic analysis and docking simulation.