Palladium(II)‐Catalyzed Dehydroboration via Generation of Boron Enolates

The Pd^II‐catalyzed dehydroboration of boron enolates generated from ketones and 9‐iodo‐9‐borabicyclo[3.3.1]nonane was achieved, providing a synthetically versatile protocol from ketones to α,β‐unsaturated ketones. The Pd^II compound employed in this reaction worked catalytically in the presence of Cu(OAc)₂. The high trans‐selectivity of the olefinic moiety was observed. Aryl halide moieties (‐Br and ‐Cl) remained intact for this reaction in spite of the presence of a Pd species. An ester substrate could also be applied when a stoichiometric amount of Pd^II was used. The crossover reactions using boron and silyl enolates revealed that the oxidation reaction is much faster than the Saegusa‐Ito reaction.     

Microchip reversed-phase liquid chromatography with packed column and electrochemical flow cell using polystyrene/poly(dimethylsiloxane)

A microchip pressure-driven liquid chromatography (LC) with a packed column and an electrochemical flow cell has been developed by using polystyrene (PS) and poly(dimethylsiloxane) (PDMS). The cylindrical separation column with packed octadecyl silica particles was fabricated in the PS substrate. The three electrode system (working, reference, and counter electrode) for amperometric detection was fabricated onto the PS substrate, using the Au deposition, photolithography, and chemical etching. The detector flow cell was formed by sealing the electrode system with a PDMS chip containing a channel. In this flow cell, the effect of working electrode width (in the direction of flow) on chromatographic parameters, such as peak width and peak resolution were studied in electrode width ranging 50-5,000 microm. The effect of electrode width on sensitivity (current intensity, current density, and S/N ratio) was also examined. The sensitivity was discussed by simulating the concentration profile generated around the working electrode. The effects of the column packing size and the column size on the separation efficiency were examined. In this study, a good separation of three catechins was successfully achieved and the detection limits for (+)-catechin, epicatechin, and epigallocatechin gallate were 350, 450, and 160 nM, respectively.     

Development of pyrrole-imidazole polyamide for specific regulation of human aurora kinase-A and -B gene expression

Pyrrole-imidazole polyamide (PIP) is a nuclease-resistant novel compound that inhibits gene expression through binding to the minor groove of DNA. Human aurora kinase-A (AURKA) and -B (AURKB) are important regulators in mitosis during the cell cycle. In this study, two specific PIPs (PIP-A and PIP-B) targeting AURKA and AURKB promoter regions were designed and synthesized, and their biological effects were investigated by several in vitro assays. PIP-A and PIP-B significantly inhibited the promoter activities, mRNA expression, and protein levels of AURKA and AURKB, respectively, in a concentration-dependent manner. Moreover, 1:1 combination treatment with both PIPs demonstrated prominent antiproliferative synergy (CI value [ED(50)] = 0.256) to HeLa cells as a result of inducing apoptosis-mediated severe catastrophe of cell-cycle progression. The novel synthesized PIP-A and PIP-B are potent and specific gene-silencing agents for AURKA and AURKB.     

Solid-State Structures and Photoluminescence of Lamellar Architectures of Cu(I) and Ag(I) Paddlewheel Clusters with Hydrogen-Bonded Polar Guests

Two hexanuclear paddlewheel-like clusters appending six carboxylic-acid pendants have been isolated with the inclusion of polar solvent guests: [Cu₆(Hmna)₆]·7DMF (1·7DMF) and [Ag₆(Hmna)₆]·8DMSO (2·8DMSO), where H₂mna = 2-mercaptonicotininc acid, DMF = N,N’-dimethylformamide, and DMSO = dimethyl sulfoxide. The solvated clusters, together with their fully desolvated forms 1 and 2, have been characterized by FTIR, UV–Vis diffuse reflectance spectroscopy, TG-DTA analysis, and DFT calculations. Crystal structures of two solvated clusters 1·7DMF and 2·8DMSO have been unambiguously determined by single-crystal X-ray diffraction analysis. Six carboxylic groups appended on the clusters trap solvent guests, DMF or DMSO, through H-bonds. As a result, alternately stacked lamellar architectures comprising of a paddlewheel cluster layer and H-bonded solvent layer are formed. Upon UV illumination (λ_ex = 365 nm), the solvated hexasilver(I) cluster 2·8DMSO gives intense greenish-yellow photoluminescence in the solid state (λ_PL = 545 nm, Φ_PL = 0.17 at 298 K), whereas the solvated hexacopper(I) cluster 1·7DMF displays PL in the near-IR region (λ_PL = 765 nm, Φ_PL = 0.38 at 298 K). Upon complete desolvation, a substantial bleach in the PL intensity (Φ_PL < 0.01) is observed. The desorption–sorption response was studied by the solid-state PL spectroscopy. Non-covalent interactions in the crystal including intermolecular H-bonds, CH⋯π interactions, and π⋯π stack were found to play decisive roles in the creation of the lamellar architectures, small-molecule trap-and-release behavior, and guest-induced luminescence enhancement.     

Anti-Obesity Effects of Matoa (Pometia pinnata) Fruit Peel Powder in High-Fat Diet-Fed Rats

Fruit peels, pericarps, or rinds are rich in phenolic/polyphenolic compounds with antioxidant properties and potentially beneficial effects against obesity and obesity-related non-communicable diseases. This study investigated the anti-obesity effects of matoa (Pometia pinnata) and salak (Salacca zalacca) fruit peel. Neither matoa peel powder (MPP) nor salak peel powder (SPP) affected the body weight, visceral fat weight, or serum glucose or lipid levels of Sprague–Dawley rats when included as 1% (w/w) of a high-fat diet (HFD). However, MPP significantly decreased the hepatic lipid level. MPP at a dose of 3% (w/w) of the HFD decreased body weight, visceral fat, and serum triglyceride levels as well as the hepatic lipid content. The inhibitory effect of MPP on hepatic lipid accumulation was not enhanced when its concentration was increased from 1% to 3% of the HFD. The anti-obesity effect of matoa was partly explained by the inhibitory effect of the matoa peel extract on fatty acid-induced secretion of ApoB-48 protein, a marker of intestinal chylomicrons, in differentiated Caco-2 cell monolayers. We identified hederagenin saponins that are abundant in MPP as potential anti-obesity substances. These results will contribute towards the development of functional foods with anti-obesity effects using the matoa fruit peel.     

A smooth‐particle mesh Ewald method for DL_POLY molecular dynamics simulation package on the Fujitsu VPP700

An N⋅ log (N) smooth‐particle mesh Ewald method has been incorporated into the DL_POLY molecular dynamics simulation package. The performance of the new code has been tested on a Fujitsu VPP700 for several DL_POLY‐specific benchmark systems. The new method is highly vectorizable, and makes use of the extremely efficient Fast Fourier Transforms on the Fujitsu vector machine. In calculations of the coulombic forces in periodic systems requiring large reciprocal space vectors, the new code was found to be considerably faster than the conventional Ewald method. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 1187–1191, 2000     

Ab initio MO study of the chlorophyll dimer in the photosynthetic reaction center. I. A theoretical treatment of the electrostatic field created by the surrounding proteins

The charge separation occurring in the photosynthetic reaction center is the primary subject in order to understand the whole photosynthetic process. In this article, the electronic structures of the chlorophyll dimer, in which photoexcitation occurs, are investigated by using the ab initio molecular orbital scheme and pseudocharges and dipoles method which takes into account the electrostatic effect of the surrounding proteins, pigments, and aqueous solvent. As a first step, the ionization potentials of BCmp, BCIp, and the dimer of Rhodopseudomonas viridis are computed to study the characteristic of each molecule toward the elucidation of the primary charge separation. It has been found, from the present calculations, that BCmp and BClp constituting the dimer are not equivalent in their electronic ground states, since the electron could be removed more easily from BCmp than from BClp for two reasons: (1) the distorted molecular plane of Cmp, and (2) the effects of the surrounding electrostatic potentials to BCmp and BCIp. This tendency is further strengthened by the polarization of the environment, when, to the ab initio MO calculation, the contribution from the induced dipoles of the neighboring atoms in the proteins and other chromophores is included. From the present application, induced electric dipoles are found to be important to describe the molecular electronic structures affected by proteins. © 1997 John Wiley & Sons, Inc.     

Cationic polymerization behavior of seven-membered cyclic sulfite

Cationic ring-opening polymerization behavior of a seven-membered cyclic sulfite ( 1 ) was examined. 1 was prepared by the reaction of 1,4-butanediol with SOCl₂ in 58% yield. The cationic polymerization of 1 was carried out at 0, 25, 60, or 100°C with trifluoromethanesulfonic acid (TfOH), methyl trifluoromethanesulfonate (TfOMe), BF₃ · OEt₂, SnCl₄, methyl p-toluenesulfonate (TsOMe), or MeI as an initiator in bulk under a nitrogen atmosphere to afford the polymer with M̄_n 1000–10,400. The order of activities of the initiators for 1 was as follows, TfOH ≅ TfOMe > SnCl₄ > BF₃ · OEt₂ > TsOMe ≅ MeI. The polymerization of 1 with TfOMe afforded a poly(sulfite) below 25°C, but afforded a polymer containing an ether unit at 60°C, which was formed by a desulfoxylation. The higher the activity of the initiator was, the more easily the desulfoxylation occurred. We expected volume expansion on polymerization because cyclic sulfites have large dipole moment values, but it turned out that 1 showed 4.34% shrinkage on polymerization. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3673–3682, 1997     

A novel redox system consisting of π-conjugated polymers and transition metals

Coordination of π-conjugated polymers to transition metals constructs a novel redox system due to interchangeable various oxidation states of the polymers, which permits transition metals to interact with each other through a π-conjugate chain. The redox characteristics were found to depend on the electronic interaction with metals and the doping. A combination of copper(II) or iron(III) chloride and polyanilines afforded the complex catalysts with the higher oxidation capability for dehydrogenative oxidation. A catalytic system was also realized in the transition-metal-induced oxidation reaction, in which π-conjugated polymers serve as redox-active ligands participating in the reversible redox cycle. The Wacker oxidation of terminal olefins proceeded catalytically in the presence of a catalytic amount of polyaniline or polypyrrole derivative under oxygen.