Synthesis and optical resolution of aminophosphines with axially chiral C(aryl)-N(amine) bonds for use as ligands in asymmetric catalysis

N-Aryl indoline-type aminophosphines 1a-c were obtained in good yields by a nucleophilic aromatic substitution (S(N)Ar) reaction followed by silane reduction. Aminophosphine 1d was also prepared from 2,3-difluorobenzaldehyde (4) via dimethylhydrazone. Optical resolution of C(aryl)-N(amine) bond atropisomers was achieved using (S)-(+)-di-mu-chlorobis[2-[(dimethylamino)ethyl]phenyl-C(2),N]dipalladium(II) ((S)-10). The determination of absolute configuration and the investigation of the rotation barrier for C(aryl)-N(amine) bond axial stability of an aminophosphine 1 are described. Finally, the ability of the chiral phosphine ligand 1 is demonstrated in a catalytic asymmetric reaction, such as a palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate (up to 95% ee).     

Sliding behavior of water droplets on flat polymer surface

Flat films of methyl methacrylate-fluoroalkyl methacrylate copolymers were prepared, and their hydrophobicity was investigated. It was revealed that the F concentration directly affects the static hydrophobicity on the flat polymer surface in a systematic manner. Furthermore, the sliding behavior of a water droplet on these surfaces depends on the static hydrophobicity; the sliding motion changes from constant velocity to constant acceleration with an increase in the water contact angle.     

PLA2 inhibitory activity of marine sesterterpenoids cladocorans, their diastereomers and analogues

Inhibition of secretory phospholipase A(2) (sPLA(2)) by cladocorans A and B and their diastereomers almost equaled that of manoalide.     

New iridoid glucosides from the aerial parts of Verbena brasiliensis

Two new iridoid glucosides, verbenabraside A (1) and verbenabraside B (2), were isolated from the aerial parts of Verbena brasiliensis VELL., along with six known iridoid glucosides, gelsemiol 3-O-beta-D-glucoside (3), verbraside (4), 9-hydroxysemperoside (5), griselinoside (6), aralidioside (7), and 6alpha-hydroxyforsythide dimethyl ester (8), three known phenylethanoid glycosides, 2-phenylethyl O-beta-D-xylopyranosyl-(1-->2)-beta-D-glucopyranoside (9), acteoside (10), and leucosceptoside A (11), two known lignan glucosides, dihydroxymethyl-bis(3,5-dimethoxy-4-hydroxyphenyl) tetrahydrofuran-9 (or 9')-O-beta-glucopyranoside (12) and (+)-lyoniresinol 3alpha-O-beta-D-glucopyranoside (13), a known methyl salicylate glucoside, methyl 2-O-beta-D-glucopyranosylbenzoate (14), and two known sterols, beta-sitosterol 3-O-beta-D-glucopyranoside (15) and beta-sitosterol (16). Their chemical structures were determined on the basis of spectroscopic data. Compound 1 exhibited stronger scavenging effect on the stable free radical 1,1-diphenyl-2-picrylhydrazyl than that of alpha-tocopherol.     

Multiple-relaxation-time lattice Boltzmann model for the convection and anisotropic diffusion equation

A lattice Boltzmann model with a multiple-relaxation-time (MRT) collision operator for the convection–diffusion equation is presented. The model uses seven discrete velocities in three dimensions (D3Q7 model). The off-diagonal components of the relaxation-time matrix, which originate from the rotation of the principal axes, enable us to take into account full anisotropy of diffusion. An asymptotic analysis of the model equation with boundary rules for the Dirichlet and Neumann-type (specified flux) conditions is carried out to show that the model is first- and second-order accurate in time and space, respectively. The results of the analysis are verified by several numerical examples. It is also shown numerically that the error of the MRT model is less sensitive to the variation of the relaxation-time coefficients than that of the classical BGK model. In addition, an alternative treatment for the Neumann-type boundary condition that improves the accuracy on a curved boundary is presented along with a numerical example of a spherical boundary.     

Fragment molecular orbital study of the electronic excitations in the photosynthetic reaction center of Blastochloris viridis

All electron calculations were performed on the photosynthetic reaction center of Blastochloris viridis, using the fragment molecular orbital (FMO) method. The protein complex of 20,581 atoms and 77,754 electrons was divided into 1398 fragments, and the two‐body expansion of FMO/6‐31G* was applied to calculate the ground state. The excited electronic states of the embedded electron transfer system were separately calculated by the configuration interaction singles approach with the multilayer FMO method. Despite the structural symmetry of the system, asymmetric excitation energies were observed, especially on the bacteriopheophytin molecules. The asymmetry was attributed to electrostatic interaction with the surrounding proteins, in which the cytoplasmic side plays a major role. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010     

Effect of spin contamination error on surface catalytic reaction: NO reduction by core-shell catalysts

ABSTRACT

The effects of spin contamination errors on the activation barriers of catalytic NO reduction by TiO₂/Ag and ZrO₂/Cu core-shell catalyst models were investigated using an approximate spin projection method and an unrestricted density functional theory calculation with the plane-wave basis set. The estimated barrier of the TiO₂/Ag system increased (0.03?eV), whereas that of the ZrO₂/Cu system decreased (0.04?eV) after the correction of the spin contamination error. This difference in the estimated barriers of the two systems can be attributed to the difference in their surface structures. The error obtained for the TiO₂/Ag system was larger than that obtained for the gas phase, i.e. the spin contamination error was induced by the molecule/surface interaction. Moreover, the error correction also changed the rate-determining step of ZrO₂/Cu. These results demonstrate the importance of the correction of spin contamination errors for the detailed investigation of catalytic reactions.     

Spatial structure,regression to steady states based on a coupled random walk process

Based on a simple model of coupled random walks, coupled Fokker-Planck equations are derived. It is shown that their steady state solutions exhibit spatial structures. The condition for regressive solutions, the stability condition are expressed in terms of jumping probabilities.On leave of absence from Tohoku University, Department of Applied Science, Faculty of Engineering, Sendai 980 Japan