An efficient chemoenzymatic route to dihydroxyacetone phosphate from glycidol for the in situ aldolase-mediated synthesis of monosaccharides

We report a new two-step procedure that uses inexpensive rac-glycidol to obtain valuable dihydroxyacetone phosphate (DHAP), a building block for the synthesis of monosaccharide analogues.     

Analysis of Fluorescence Lifetime of Protochlorophyllide and Chlorophyllide in Isolated Etioplast Membranes Measured from Multifrequency Cross-correlation Phase Fluorometry

The fluorescence decays of protochlorophyllide (Pchlide) and of chlorophyllide (Chlide) in wheat etioplast membranes were analyzed using a multiexponential fluorescence decay model. Using different excitation wavelengths from 430 to 470 nm, we found that a triple-exponential model at 14°C and a double-exponential model at — 170°C were adequate to describe the Pchlide fluorescence decay. We discuss the origin of the three fluorescence lifetime components at 14°C on the basis of the dependence of their fractional intensities on the excitation wavelength and by correlating the fractional intensities with integrated fluorescence intensities of different Pchlide forms in steady-state fluorescence spectra. The fluorescence decay of the main Pchlide form, photoactive Pchlide-F657, is shown to have a complex character with a fast component of 0.25 ns and a slower component of about 2 ns. Two lifetime components of 2 ns and 5.5–6.0 ns are ascribed to the second photoactive form, Pchlide-F645, and to nonphotoactive Pchlide forms, respectively. In etioplast membranes preilluminated by a short saturating light pulse, we found a single 5.0 ns component for Chlide-F688 (the Chlide-NADPH: protochlorophyllide oxidoreductase [PORJ-NADP⁺complex) and an additional 1.6 ns component when the formation of Chlide-F696 (the Chlide-POR-NADPH complex) was promoted by exogenous NADPH. From the fluorescence lifetime results we evaluated the quantum yield of the primary photoreaction by Chlide-F696 as being 70%.     

Ionic IPNs as novel candidates for highly conductive solid polymer electrolytes

Five ionic imidazolium based monomers, namely 1‐vinyl‐3‐ethylimidazolium bis(trifluoromethylsulfonyl)imide (ILM1), 1‐vinyl‐3‐(diethoxyphosphinyl)‐propylimidazolium bis(trifluoromethylsulfonyl)imide (ILM2), 1‐[2‐(2‐methyl‐acryloyloxy)‐propyl]‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (ILM3), 1‐[2‐(2‐methyl‐acryloyloxy)‐undecyl]‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (ILM4), 1‐vinyl‐3‐ethylimidazolium dicyanamide (ILM5) were prepared and used for the synthesis of linear polymeric ionic liquids (PILs), crosslinked networks with polyethyleneglycol dimethacrylate (PEGDM) and interpenetrating polymer networks (IPNs) based on polybutadiene (PB). The ionic conductivities of IPNs prepared using an in situ strategy were found to depend on the ILM nature, T_g and the ratio of the other components. Novel ionic IPNs are characterized by increased flexibility, small swelling ability in ionic liquids (ILs) along with high conductivity and preservation of mechanical stability even in a swollen state. The maximum conductivity for a pure IPN was equal to 3.6 × 10^?5 S/cm at 20 °C while for IPN swollen in [1‐Me‐3‐Etim] (CN)₂N σ reached 8.5 × 10^?3 S/cm at 20 °C or 1.4 × 10^?2 S/cm at 50 °C. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4245–4266, 2009     

Zinc(0)/dimethylformamide-mediated synthesis of symmetrical carboxylic anhydrides from acid chlorides

The high yielding synthesis of symmetrical carboxylic anhydrides from acid chlorides mediated by zinc dust in the presence of dimethylformamide is presented. A mechanism involving the reductive insertion of zinc(0) into the C-Cl bond of a Vilsmeier-type iminium intermediate as the crucial step is also proposed.     

Nickel(II) and copper(II) complexes of 5-aryl-2-phenyl-6H-pyrazolo-[1,5-c]pyrimidine-7-thiones

Ni^II and Cu^II complexes of 5-aryl-2-phenyl-6H-pyrazolo-[1,5-C]pyrimidine-7-thiones were prepared and characterized by elemental analysis, i.r, u.v.-vis. spectra, molar conductivities and magnetic measurements. Spectral and magnetic data suggest a square-planar structure for nickle(II) complexes. TMC 2636     

Structure and dynamics of oxide melts and glasses: A view from multinuclear and high temperature NMR

From a presentation of the various nuclear magnetic resonance (NMR) experiments that allows to characterize the local structure and dynamics of oxide glasses and melts, we show that it becomes possible to evidence not only the details of the coordination state of the constituting atoms but also the nature of polyatomic molecular motifs extending over several chemical bonds.     

Studies on pyrrolidinones: Some attempts to improve the synthesis of methyl n‐(3,4,4′,5‐tetramethoxybenzhydryl)pyroglutamate (hei 81) by using n‐acyl iminium salts methodologies

Some ways to use the N‐acyl iminium salt methodologies to synthesize a new inhibitor of tubulin polymerization, methyl N‐(3,4,4′,5‐tetramethoxybenzhydryl)pyroglutamate (HEI 81) were studied. The most interesting reactions utilize a new pyroglutamic lactone (3‐(3,4,5‐trimethoxyphenyl)dihydropy‐rrolo[1,2‐c]oxazole‐1,5‐dione).