Methacrylic acid and methyl methacrylate oligomers adsorbed to porous isotactic poly(methyl methacrylate) ultrathin films and mechanistic studies of living template polymerization

Methacrylic acid (MAA), methyl methacrylate (MMA), methacrylamide, and oligomers of MAA and MMA were selected as a model of active radical species in living template polymerization using stereocomplex formation. The adsorption behaviors of the aforementioned model compounds were examined toward porous isotactic‐(it‐) poly(methyl methacrylate) (PMMA) ultrathin films on a quartz crystal microbalance, which was prepared by the extracting of syndiotactic‐(st‐) poly(methacrylic acid) (PMAA) from it‐PMMA/st‐PMAA stereocomplexes. The apparent predominant adsorption of oligomers to monomers was observed in both PMAA and PMMA oligomers, suggesting that the mechanism of template polymerization follows the pick up mechanism. Although vinyl monomers were not incorporated into the porous it‐PMMA ultrathin film, both PMMA and PMAA oligomers were adsorbed at the initial stages. However, adsorbed amounts were limited to about 5 and 15% at 0.1 mol L^?1, respectively, which are much smaller values than corresponding st‐polymers. The results imply that radical coupling reaction is prevented during template polymerization to support the resulting living polymerization. ATR‐IR spectral patterns of oligomer complexes and it‐PMMA slightly changed in both cases, suggesting complex formation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5879–5886, 2008     

Self-assembly and subsequent accumulation of lipid nanotubes at oil/water interfaces.

We utilized oil/water interfaces as a new field to produce lipid nanotubes (LNTs), which are formed by the self-assembly of lipid molecules, and possess hollow nanometer-wide cylindrical structures. Compared to the self-assembling field in bulk water, oil/water interfaces produced shorter lipids nanotubes less than 10 microm long more efficiently. In addition, we found that the oil/water interface accumulates lipid nanotubes spontaneously. This methodology is favorable to fabricate LNTs as new nano-fluidic devices, or sensors that require accumulation and alignment in two dimensions.     

Regulated interaction between polypeptide chain elongation factor-1 complex with the 26S proteasome during <Emphasis Type="Italic">Xenopus</Emphasis> oocyte maturation

Background  

During Xenopusoocyte maturation, the amount of a 48 kDa protein detected in the 26S proteasome fraction (p48) decreased markedly during oocyte maturation to the low levels seen in unfertilized eggs. The results indicate that the interaction of at least one protein with the 26S proteasome changes during oocyte maturation and early development. An alteration in proteasome function may be important for the regulation of developmental events, such as the rapid cell cycle, in the early embryo. In this study, we identified p48.     

Measurements of the solubilities of derivatized amino acids in supercritical carbon dioxide

The solubilities of phenylalanine and tyrosine in supercritical carbon dioxide (SCCO₂) were measured after derivatization as the N-acetyl amino acid ethyl ester, N-carbobenzoxy amino acid and N-acetyl amino acid. Using an SCCO₂ flow system, a measuring method of the saturated solubilities of the derivatized amino acids was established in which the contact height of the extraction cell, i.e. a packed column, is increased till the concentration of a derivatized amino acid at the exit of the cell reaches a plateau. The solubilities of N-acetyl phenylalanine ethyl ester (APEE) exceeded 0.001 mole fraction, which is higher than those of caffeine produced in industrial SCCO₂ processes. A possible way of separating the amino acid mixtures using polarity differences in different amino acid side chains was demonstrated using the solubility data of the N-acetyl-amino acid ethyl esters in SCCO₂, as the solubilities of APEE are higher than those of N-acetyl tyrosine ethyl ester by two orders of magnitude.     

Properties and cage lactone synthesis of diels-alder adducts from 2-pyrones

New cage lactones were synthesized by the photocyclization of the tricyclodienolactones 1a, 1b, 2 which were available from the Diels-Alder reactions of 2-pyrones with p-benzoquinones or norbornadiene. Retro-Diels-Alder reactions of cross-adducts between 2-pyrone-mono-adducts and p-benzoquinone were also described.     

Vibrational spectroscopic study on the phase transition of water in nanospaces and at interfaces

Phase transition of water confined in nanospaces with charged inner-surfaces was investigated by vibrational spectroscopy. Aerosol sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles give a series of spherical nanospaces with controlled inner-radius (R_w) with nanometer-scale precision. Successive spectroscopic measurements of the confined water with decreasing temperature revealed that the water freezes to metastable cubic ice (I_c) coexisting with super-cooled water or unstable amorphous ice at the R_w ranging from 1.0 to 2.0 nm. When R_w exceeded 2.0 nm, stable hexagonal ice (I_h) dominated. The drastic change of the dominant ice structure with the increase of 1 nm in R_w shows that the thickness of water layers affected by the inner surface can be estimated to be ~1 nm, where three or four layers of water hydrated to the surface. It is worth noting that the clear phase transition behavior of the confined water vanishes at R_w = 1.2 nm and that the gradual formation of I_c and coexistence of super-cooled water or glassy state of water are detected. The range of the effective interaction between interfacial water and the charged inner surfaces and the mechanism of the extremely slow phase transition were also discussed.     

Nickel (o)-catalyzed Cycloaddition of Ethoxyethyne with Carbon Dioxide to 4,5-diethoxy-α-pyrone

Ni(O)-phosphine(L) complexes (L=tri-n-alkylphosphines and bis(diphenylphosphino)butane) catalyzed the cycloaddition of ethoxyethyne and carbon dioxide to afford 4,5-diethoxy-α-pyrone regioselectively.     

Electron-enhanced Raman scattering: a history of its discovery and spectroscopic applications to solution and interfacial chemistry

Raman scattering spectroscopy can be used to distinguish highly similar molecules and obtain useful information on local physical and chemical environments at their functional group levels. However, obtaining a high-quality Raman spectrum requires high-power excitation and a long acquisition time owing to the inherently small Raman scattering cross section, which is problematic in the analyses of living cells and real-time environmental monitoring. Herein, a new Raman enhancement technique, electron-enhanced Raman scattering (EERS), is described in which artificially generated electrons affect the polarizability of target molecular systems and enhance their inherent Raman cross sections. The EERS technique stands in contrast to the well-known SERS technique, which requires roughened metal surfaces. The history of EERS and its spectroscopic applications to aqueous solutions are presented.     

Preparation of novel aluminohydride complexes of ruthenium(II)

Treatment of (η⁵-C₅Me₅)RuCl₂(PR₃) (1) with LiAlH₄ in diethyl ether gives the ruthenium(II) tetrahydroaluminate complexes, (η⁵-C₅Me₅)Ru(AlH₄)(PR₃) (2) (R₃ = Me₃, Et₃, ⁱPr₃, Ph₂Me, Ph₃), which can be quantitatively converted to the trihydriodurthenium(IV) complexes (η⁵-C₅Me₅)RuH₃(PR₃) (4), via protonolysis either by reaction with ethanol or by filtration through alumina. Low-temperature ¹H NMR studies suggest the fluxionality of complexes 2 in solution at ambient temperature.