[ArN]Mo(N)(O-t-Bu), which contains the conformationally rigid pyridine-based diamido ligand, [2,6-(ArNCH)NCH] (Ar = 2,6-diisopropylphenyl), can be prepared from H[ArN], butyllithium, and (t-BuO)Mo(N). [ArN]Mo(N)(O-t-Bu) serves as a catalyst or precursor for the catalytic reduction of molecular nitrogen to ammonia in diethyl ether between -78 and 22 °C in a batchwise manner with CoCp* as the electron source and PhNHOTf as the proton source. Up to ∼10 equiv of ammonia can be formed per Mo with a maximum efficiency in electrons of ∼43%.

We observed fast proton conduction in a material consisting of packed acids, the “packed-acid mechanism” resulting from acid–acid interactions.

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SummaryThe specific growth rate of Chlorella vulgaris in the presence of glucose (mixotroph) was always larger than that in autotroph when the light intensity was less than 10 klux. However, Scenedesmus acutus behaved differently, i.e., when the light intensity was more than 6 klux, the specific growth rate in mixotroph became smaller than that in autotroph. Cellular contents of chlorophyll a and 6 in Scenedesmus acutus that deteriorated more markedly in

Available methods to analyze proton conduction mechanisms cannot distinguish between two proton-conduction processes derived from the Grotthuss mechanism. The two mechanistic variations involve structural diffusion, for which water movement is indispensable, and the recently proposed "packed-acid mechanism," which involves the conduction of protons without the movement of water and is typically observed in materials consisting of highly concentrated (packed) acids. The latter mechanism could improve proton conductivity under low humidity conditions, which is desirable for polymer electrolyte fuel cells. We proposed a method with which to confirm quantitatively the packed-acid mechanism by combining (2)H and (17)O solid-state magic-angle-spinning nuclear magnetic resonance (MAS-NMR) measurement and (1)H pulsed-field gradient (PFG)-NMR analysis. In particular, the measurements were performed below the water-freezing temperature to prevent water movement, as confirmed by the (17)O-MAS-NMR spectra. Even without water movement, the high mobility of protons through short- and long-range proton conduction was observed by using (2)H-MAS-NMR and (1)H-PFG-NMR techniques, respectively, in the composite of zirconium sulfophenylphosphonate and sulfonated poly(arylene ether sulfone) (ZrSPP-SPES), which is a material composed of highly concentrated acids. Such behavior contrasts with that of a material conducting protons through structural diffusion or vehicle mechanisms (SPES), in which the peaks in both (2)H and (17)O NMR spectra diminished below water-freezing temperature. The activation energies of short-range proton movement are calculated to be 2.1 and 5.1 kJ/mol for ZrSPP-SPES and SPES, respectively, which indicate that proton conduction in ZrSPP-SPES is facilitated by the packed-acid mechanism. Furthermore, on the basis of the mean-square displacement using the diffusivity coefficient below water-freezing temperature, it was demonstrated that long-range proton movement, of the order of 1.3 μm, can take place in the packed-acid mechanism in ZrSPP-SPES.

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A novel ethylene-forming enzyme that catalyses the formation of ethylene from 2-oxoglutarate was purified from a cell-free extract of Pseuhmonas syringa pv. phaseolicola PK2. It was purified about 2800-fold with an overall yield of 53 % to a single band of protein after SDS-PAGE. The purified enzyme had a specific activity of 660 nmol ethylene min-l (mg protein)-l. The molecular mass of the enzyme was approximately 36 kDa by gel filtration and 42 kDa. by SDS-PAGE. The isoelectric point and optimum pH were 5.9 and ca. 74k7.5, respectively. There was no homology between the N-terminal amino acid sequence of the ethylene-forming enzyme of Ps. syringa pv. phaseolicola PK2 and the sequence of the ethylene-forming enzyme of the fungus Penicillium digitarturn I F 0 9372. However, the two enzymes have the following properties in commop. The presence of 2-oxoglutarate, L-arginine, Fe2+ and oxygen is essential for the enzymic reaction. The enzymes are highly specific for 2-oxoglutarate as substrate and L-arginine as cofactor. EDTA, Tiron, DTNB [5,5'-dithio-bis(2-nititrobenzoate)] and hydrogen peroxide are all effective inhibitors.