Two new glycosides from the whole plants of Glechoma hederacea L

Two new glycosides, 7S,7'S,8R,8'R-icariol A(2)-9-O-beta-D-glucopyranoside (1) and 4-allyl-2-hydroxyphenyl 1-O-beta-D-apiosyl-(1-->6)-beta-D-glucopyranoside (2), were isolated from the dried whole plants of Glechoma hederacea L. (Labiatae) together with four known compounds, cistanoside E (3), dihydrodehydrodiconiferyl alcohol 4-O-beta-D-glucopyranoside (4), apigenin 7-O-beta-D-glucuronopyranoside (5) and luteolin 7-O-beta-D-glucopyranoside (6). The structures of the new compounds were elucidated on the basis of chemical and spectral analysis.     

New entry for synthesis of N-acylhydrazones, pyridazinones, and 1,3,4-oxadiazin-6-ones from alpha-amino acid esters

Versatile electrophiles N-acylhydrazones are synthesized via diazotization, reduction, and acylation of alpha-amino acid esters. Reduction of diazo esters with L-selectride or tributylphosphine affords the corresponding hydrazones in good yields. Both reducing agents give anti-hydrazones as the major product although the reactivity of each reductant is slightly different. The resulting hydrazones are acylated to give N-acylhydrazones, which are subjected to further reactions to give 1,3,4-oxadiazin-6-ones that serve as useful synthetic intermediates for the Diels-Alder reaction.     

Analysis of the thermal properties of a liquid 1-butanol polymer composed during a plasma-induced reaction

This paper investigates the mechanisms of thermosetting and simultaneous hydrogen desorption of liquid 1-butanol polymer composed during a plasma-induced reaction. A transparent liquid 1-butanol polymer consisting of partially dissociated 1-butanol, oxygen, and nitrogen gradually gains viscosity at less than 50 degrees C and transforms to a solid between 100 and 150 degrees C. This polymer also traps at least 0.225 mass % hydrogen during its composition and thermally desorbs the hydrogen between 26 and 150 degrees C. Electron probe microanalyses (EPMA) and FTIR analyses indicate that 11 wt % nitrogen fixed from the air is the principal component in the formation of stable 3-D bridge structures and the resultant thermosetting of the polymer. Thermal-desorption analysis and electrical resistivity measurements also support the theory that some hydrogen is electrically trapped as quasi-stable ions around negatively polarized OH and/or C=O bonds in the polymer, contributing to both electrical conductivity and the desorption of hydrogen.     

Variation of characteristics of pentaoxyethylene decyl C10E5 and hexaoxyethylene tetradecyl C14E6 ether micelles with uptake of n-octanol

Wormlike micelles of the surfactant pentaoxyethylene decyl C10E5 and hexaoxyethylene tetradecyl C14E6 ethers were characterized by static (SLS) and dynamic light scattering (DLS) experiments to examine effects of uptake of n-octanol on the micellar characteristics. The SLS results have been successfully analyzed by the light scattering theory for micelle solutions to yield the molar mass Mw(c) as a function of concentration c along with the cross-sectional diameter d of the micelle. The apparent hydrodynamic radius RH,app(c) determined by DLS as a function of c has also been successfully analyzed by a fuzzy cylinder theory which takes into account the hydrodynamic and direct collision interactions among micelles, providing us with the values of the stiffness parameter lambda(-1). It has been found that the micellar length Lw increases with increasing surfactant weight fraction ws and increasing n-octanol content wo in the micelles or with raising temperature T. The values of d and lambda(-1) are found to increase with increasing wo, whereas the spacing s between hydrophilic tails of adjacent surfactant molecules on the micellar surface decreases with increasing wo. Comparison with our previous results for the C10E5 and C14E6 micelles containing n-dodecanol has revealed the salient features in change of the micellar characteristics with uptake of n-alcohols as follows: (i) The Lw values increase more significantly for the C14E6 micelles containing n-dodecanol than those containing n-octanol, whereas Lw of the C10E5 micelles increases by including n-dodecanol and n-octanol without a significant difference for the two alcohols. (ii) The values of d and lambda(-1) of the C10E5 and C14E6 micelles increase with uptake of n-octanol and n-dodecanol into the micelles. They are larger for the C10E5 micelles than for the C14E6 micelles, and their increase with alcohol content is less significant for the C14E6 micelles in comparison with the C10E5 micelles. (iii) The s values of the C10E5 and C14E6 micelles decrease with uptake of n-octanol and n-dodecanol into the micelles. They are somewhat larger in the latter micelles than in the former. (iv) The variation in d, s, and lambda(-1) with uptake of n-alcohol occurs with no difference in the effects for the two alcohols n-octanol and n-dodecanol.     

Rh-catalyzed [4 + 2] carbocyclization of vinylarylaldehydes with alkenes and alkynes leading to substituted tetralones and 1-naphthols

Regio-, diastereo-, and enantioselective intermolecular [4 + 2] carbocyclizations of vinylarylaldehydes with alkenes and alkynes leading to substituted tetralones and 1-naphthols have been developed by using a cationic rhodium(I)/dppb or dppp complex as a catalyst.     

Implantation of a glass capillary-based enzyme electrode in mouse hippocampal slices for monitoring of <Emphasis Type="SmallCaps">L</Emphasis>-glutamate release

A glass capillary-based enzyme electrode (tip size ≈10 μm) was implanted in the target neuronal region, i.e., dentate gyrus (DG) or cornu ammonis 1 (CA1), of acute brain slices at a depth of ≈10 μm from the slice surface in order to allow the monitoring of chemical stimulant-induced changes in L-glutamate levels. First, the sampling behavior of a glass capillary in a slice was investigated by visualizing the transport of a fluorescence dye. Then, the electrode was applied to real-time monitoring of L-glutamate release in acute hippocampal slices stimulated by surface application of a stimulant solution. The extracellular application of KCl (0.10 M) increased the glutamate levels in the DG and CA1 regions, respectively. The enhancement of L-glutamate concentration at DG was much larger than at CA1. The application of tetraethylammonium chloride (TEA) (25 mM) enhanced the L-glutamate level in the DG region and the enhanced level did not return to the initial value before TEA application even when washed with an artificial cerebrospinal fluid (ACSF). The usefulness of a surface-implanted capillary electrode for monitoring L-glutamate release in acute brain slices is discussed.     

Cell dynamics simulation of droplet and bridge formation within striped nanocapillaries

The kinetics of droplet and bridge formation within striped nanocapillaries is studied when the wetting film grows via interface-limited growth. The phenomenological time-dependent Ginzburg-Landau (TDGL)-type model with thermal noise is used and numerically solved using the cell dynamics method. The model is two-dimensional and consists of undersaturated vapor confined within a nanocapillary made of two infinitely wide flat substrates. The surface of the substrate is chemically heterogeneous with a single stripe of lyophilic domain that exerts long-range attractive potential to the vapor molecule. The dynamics of nucleation and subsequent growth of droplet and bridge can be simulated and visualized. In particular, the evolution of the morphology from droplet or bump to bridge is clearly identified. The crucial role played by the substrate potential on the morphology of bridge of nanoscopic size is clarified. Nearly temperature-independent evolution of capillary condensation is predicted when the interface-limited growth dominates. In addition, it is shown that the dynamics of capillary condensation follows the scenario of capillary condensation proposed by Everett and Haynes three decades ago.     

Synthesis and positive‐imaging photosensitivity of soluble polyimides having pendant carboxyl groups

Polyimides having pendant carboxyl groups were prepared by a direct one‐pot polycondensation of 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) with 3,5‐diaminobenzoic acid (DABz) and bis[4‐(3‐aminophenoxy)phenyl]sulfone (m‐BAPS) in the presence of a γ‐valerolactone/pyridine catalyst system using N‐methyl‐2‐pyrrolidone (NMP)/toluene mixture as a solvent at 180 °C. The obtained polyimides were soluble in dipolar aprotic solvents such as dimethylformamide, dimethyl sulfoxide, and NMP as well as in tetrahydrofuran and aqueous basic solution. The solubility of the polyimides was dependent on the diamine composition. Photosensitve polyimide (PSPI) systems composed of the polyimides and diazonaphthoquinone compound as a photosensitive material gave positive‐tone behavior by UV irradiation, followed by development with aqueous tetramethylammonium hydroxide (TMAH) solution. The scanning electron microscopic photograph of the resulting image showed 10‐μm line/space resolution with about 15 μm of film thickness. The PSPIs baked at 350 °C for a short time had excellent thermal resistance comparable to the original polyimides. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 934–946, 2001     

Photoinduced hydrogen production using a multilayered molecular assembly composed of zinc tetraphenylporphine and Nafion® membrane

A photoinduced proton reduction to produce H₂ was found to take place in the system using zinc tetraphenylporphine (ZnTPP) incorporated into a Nafion® membrane coated on a platinum electrode (denoted as Pt/Nf[ZnTPP]). When visible light (λ > 390 nm) was irradiated on the Pt/Nf[ZnTPP] system, a photocurrent was generated under applied potentials below −0.10 (v. Ag/AgCl). The action spectrum for the photocurrent agreed with the absorption spectrum of the Nf[ZnTPP] membrane, showing that the present photochemical process is induced on light absorption by the ZnTPP. By measuring the emission decay of ZnTPP under the photoelectrochemical conditions, it was exhibited that the emission from the singlet excited ZnTPP is quenched by the cathodic potentials. The amount of the H₂ produced increased with the cathodic potentials. These results indicated that, in the photochemical primary process, a reductive quenching takes place by electron injection from the Pt electrode to the singlet excited ZnTPP forming ZnTPP^.–, subsequently leading to the H₂ formation by a bimolecular catalysis of the ZnTPP. Copyright © 2000 John Wiley & Sons, Ltd.     

Microsphere synthesis by dispersion copolymerization of methyl methacrylate with poly(acrylic acid) macromonomers: pH effect on microsphere formation

The pH effect on microsphere formation in the dispersion copolymerization of methyl methacrylate with vinylbenzyl-terminated poly(acrylic acid) (PAA) macromonomers is studied. The diameter of poly(methyl methacrylate) (PMMA) microspheres is minimum around pH = 8. Dynamic light scattering data indicate that the shell thickness of PAA-grafted chains shows a maximum around this pH. The degree of expansion of PAA chains drastically affects the particle size of PMMA microspheres during the dispersion copolymerization.