Electronic state on the surface in the strongly correlated electron systems

In order to clarify the tunneling spectroscopy in high-T_c cuprates, we study electronic state of the surface in the strongly correlated electron systems. First, we obtain Green's function of strongly correlated normal bulk system using the fluctuation exchange (FLEX) approximation. Next, we insert infinite potential into the bulk system and obtain Green's function of surface. We find that the density of states (DOS) in strongly correlated bulk systems are different from that on the surface, and the difference decreases as the magnitude of Coulomb interaction (U) increases.     

Conformational Changes and Redox Properties of Bimetallic Single Helicates of Hexapyrrole-α,ω-dicarbaldehydes

The hexapyrrole-α,ω-dicarbaldehydes 1 a and 1 b were metallated with Cu^II, Ni^II, and Pd^II to give bimetallic complexes where a pair of 3 N+O four-coordinate metal planes are helically distorted and the central 2,2′-bipyrrole subunit adopts a cis or trans conformation. X-ray crystallographic analysis of the bisCu complex revealed a closed form with a cis-2,2′-bipyrrole subunit and an open form with a trans-2,2′-bipyrrole subunit. The bisPd complexes took a closed form both in the solid state and in solution. They are regarded as single helicates of two turns and the energy barrier for the interchange between an M helix and a P helix was remarkably influenced by the bulky 3,3′-substituent of the central 2,2′-bipyrrole subunit. Although the bisNi complexes adopt a closed form in the solid state, they exist as a homohelical open C₂-symmetric form or a heterohelical open C_i-symmetric form in solution. A theoretical study suggested that the closed form of 1 a Pd was stabilized by the Pd–Pd interaction. Compound 1 a Pd was reversibly oxidized by one electron at 0.14 V versus ferrocene/ferrocenium (Fc/Fc⁺) and this oxidized species showed Vis/NIR absorption bands at λ=767 and 1408 nm.     

Synthesis and dynamic structure of multinuclear Rh complexes of porphyrinoids

Large porphyrinoids with three Rh(CO)2 groups at their dipyrrin units shows two-step metal transposition through the macrocycle in solution and the equilibrium between the C3v-isomer and the Cs-isomer depends on the solvent polarity.     

Copper-catalyzed addition reactions of aromatics and ketones to 2-aza-2,4-cyclopentadienone: facile and efficient transformation of carbonyl-ene-nitriles to 1H-pyrrolin-2(5H)-ones

Copper-catalyzed reactions of carbonyl-ene-nitriles with carbon nucleophiles, such as aromatics and ketones, afforded pyrrolin-2-ones (gamma-lactam) in excellent yield. The reaction mechanism involves addition reactions with a ketimine moiety of the 2-aza-2,4-cyclopentadienone intermediate, which is formed via hydration of a nitrile moiety followed by dehydrative cyclization.     

Sum frequency generation spectroscopic study of the condensation effect of cholesterol on a lipid monolayer

Sum frequency generation (SFG) spectra and surface pressure–molecular area (π–A) isotherms have been obtained for mixed cholesterol–DPPC monolayers with cholesterol mole fractions, x(chol.), from 0 to 1.0, at the air–water interface, under same conditions, at 22 °C. Analysis of the spectra indicated that incorporation of cholesterol into the monolayers at 3 mN m⁻¹ greatly increases the conformational and orientational order of the alkyl chains of DPPC, maximizing these properties at x(chol.)=0.4. Analysis also indicated that order in the mixed monolayers at 15 and 35 mN m⁻¹ is not affected by incorporation of cholesterol. The π–A isotherms measured at 3 mN m⁻¹ for the mixed monolayer with x(chol.)=0.4 have the largest negative deviation of the molecular area relative to those of ideal mixtures (the so-called “condensation effect” of cholesterol), indicating the most thermodynamically stable state. Comparison of results from SFG spectra and π–A isotherms explicitly proved that the condensation effect can be interpreted in terms of conformational and orientational ordering of the alkyl chains of DPPC.     

Alternative molecularly imprinted polymeric membranes from a tetrapeptide residue consisting of D- or L-amino acids

Alternative molecularly imprinted polymeric membranes were prepared from a polystyrene resin bearing tetrapeptides consisting of D -amino acids or L-amino acids. The membrane prepared from a DLDE derivative (H-Asp(OcHex)-Leu-Asp(OcHex)-Glu(OBzl) CH₂ ) consisting of D -amino acids and imprinted by Boc-D -Trp recognizes the D-isomer in preference to the corresponding L -isomer and vice versa. The amino acid preferentially adsorbed by the membrane was selectively permeated by applying electrodialysis.     

In situ observation of protein-adsorbed stearic acid monolayer by Brewster angle microscopy and fluorescence microscopy

A fluorescence probe, fluorescein isothiocyanate (FITC), was introduced to proteins, and the morphology of protein-adsorbed stearic acid monolayer was observed by fluorescence microscopy and Brewster angle microscopy (BAM) in order to analyze images. At a low protein concentration, the surface pressure increased as shown by a sigmoidal curve. A number of stripe patterns in the BAM images increased and the shapes became clear with increasing concentration of proteins. Simultaneously, the size of circular islands also became small, and finally disappeared. These results suggest that the very large stripe patterns in the BAM image show the assembly of both proteins and stearic acid molecules, and small circular islands show only the stearic acid molecules. © 1998 John Wiley & Sons, Ltd.     

Application of a novel photopolymer to a holographic head‐up display

A novel photopolymer for fabrication of high‐resolution volume holograms, which primarily are used on holographic optical elements such as head‐up display (HUD), is reported. This photopolymer consists of bisphenol‐type epoxy resin and radically polymerizable aliphatic monomer with diaryliodonium salt and 3‐ketocoumarin (KCD) as a complex initiator. The chemistry of imaging formation is based on the radical polymerization of the monomer initiated by a holographic exposure, following by the cationic polymerization of epoxy resin by UV‐exposure after post‐exposure baking. The yellowish color of hologram derived from KCD, the shape of peak of reconstructed light and the blue shift of wavelength of reconstructed light, were improved in order to satisfy the specifications for the combiner of HUD. A stand type holographic HUD system as an example of automotive display attached on the dashboard of an automobile is demonstrated. The display gives a high contrast image, and the combiner has good durability. Copyright © 1999 John Wiley & Sons, Ltd.     

Ruthenium-catalyzed [1,n]-metallotropic shift (n = 3, 5) of alkynyl carbene complex intermediates

The ruthenium-catalyzed isomerization of diynes and triynes involving propargyl carboxylate moieties affords dienynes and dienediynes, respectively. The [1,n]-metallotropic shift (n = 3, 5) (carbene walk) of in situ generated alkynyl carbene complexes has been proposed for the catalytic isomerization reaction.     

Highly reactive meso-like positions of dipyrihexaphyrin

The meso-like position of a pyridine-containing porphyrin analogue structurally related to amethyrin was found to be highly reactive to undergo addition of alcohols, amines and hydrogen cyanide at room temperature under neutral conditions.