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The mechanism of H2O2 dismutation catalyzed by the dibenzotetraaza[14]annulene-Fe(III) complex ([Fe(C24H22N4O4)]+) which was recently reported (Paschke, J.; Kirsch, M.; Korth, H. G.; de Groot, H.; Sustmann, R. J. Am. Chem. Soc. 2001, 123, 11099) has been investigated by density functional theory using the B3LYP hybrid functional. The quartet potential energy profile of the catalytic reaction has been explored. In the whole catalytic cycle, the rate-determining step is found to be the O-O bond homolytic cleavage, without the assistance of solvent molecules in the second coordination shell. The calculated free energy barrier for this step is 10.8 kcal/mol, which is in reasonable agreement with the experimental facts. The calculations also show that the hydroxyl and hydroperoxyl radicals may be generated in the reaction processes, but they can be efficiently quenched in strongly exothermic steps. This study provides a satisfactory explanation to the observed efficiency of the H2O2 dismutation catalyzed by this complex. [ABSTRACT FROM AUTHOR]

The microbial fuel cell (MFC), being an environment-friendly technology for wastewater treatment, is limited by low efficiency and high cost. Power output based on capital cost had been greatly increased in our previous work by introducing a novel activated carbon (AC) air-cathode (ACAC). The catalysis behavior of this ACAC was studied here based on catalysis kinetics and pore analysis of both carbon powders and catalyst layers (CLs). Plain AC (AC1#), ultracapacitor AC (AC2#), and non-AC (XC-72) powders were used as catalysts. The electron transfer number (n) of oxygen reduction reaction (ORR) with CLs increased by 5–23% compared to those n values of corresponding carbon powders before being rolled to CLs with PTFE, while the n value of Pt/C decreased by 38% when it was brushed with Nafion as the CL, indicating that rolling procedure with PTFE binder substantially increased the catalytic activity of carbon catalysts. Two–four times larger in micropore area of AC powders than non-AC powder resulted in 1.3–1.9 times increase in power density of MFCs. In addition, more uniform distribution of microporosity was found in AC1# than in AC2#, which could be the reason for the 25% increase in power density of ACAC1# (1355 ± 26 mW·m–2) compared to 1086 ± 8 mW·m–2 of ACAC2#. [ABSTRACT FROM AUTHOR]

Explores the catalytic mechanism of the p21-activated protein kinase (PAK). Role of PAK in diverse cellular processes; Kinetic analysis of PAK2 in phosphorylation of protein substrate, myelin basic protein.

The article explores the construction of a multifunctional 3D ferroelectric and nonlinear optical (NLO)-active porous metal-organic frameworks (MOFs). It says that MOFs can be applied in host-guest molecular interactions, catalysis, gas storage, and separation. It provides a framework with chiral tetrahedral secondary building units (SBUs) made by various connections of carboxylate groups to zinc units to form a noncentrosymmetric complex with occupying ferroelectric and NLO properties.

Novel C-C bond cleavage of secondary alcohols through Rh(III)-catalyzed β-carbon elimination directed by a pyridinyl group is reported. A five-membered rhodacycle is proposed as a key intermediate, which undergoes further alkenylation with various olefins. This novel transformation shows high efficiency along with excellent selectivity in mild conditions. A wide range of functionalities are compatible. This study offers a new strategy to carry out C-C bond activation. [ABSTRACT FROM AUTHOR]

A catalytic hydrovinylation of N-acetylenamines with ethylene is reported. This new hydrovinylation reaction is catalyzed by a ruthenium hydride complex, RuHCl(CO)(PCy3)2, providing a series of N-acetylamines with a quaternary carbon center with up to 99% yield. [ABSTRACT FROM AUTHOR]