The real-time dynamics of hydrogen-atom-transfer processes under collisionless conditions are studied using femtosecond depletion techniques. The experiments focus on the methyl salicylate system, which exhibits ultrafast hydrogen motion between two oxygen atoms due to molecular tautomerization, loosely referred to as intramolecular “proton” transfer. To test for tunneling and mass effects on t...

Redox-inactive metal ions play pivotal roles in regulating the reactivities of high-valent metal-oxo species in a variety of enzymatic and chemical reactions. A mononuclear non-heme Mn(IV)-oxo complex bearing a pentadentate N5 ligand has been synthesized and used in the synthesis of a Mn(IV)-oxo complex binding scandium ions. The Mn(IV)-oxo complexes were characterized with various spectroscopi...

Hydrogen atom transfer reactions between the substrate and coenzyme are key mechanistic features of all adenosylcobalamin-dependent enzymes. For one of these enzymes, glutamate mutase, we have investigated whether hydrogen tunneling makes a significant contribution to the mechanism by examining the temperature dependence of the deuterium kinetic isotope effect associated with the transfer of a ...

cellulose was modified by polystyrene (ps) and polyacrylonitrile (pan) via free radical and living radical polymerization, and then cellulose was used as the matrix in the preparation of polymer/clay nanocomposite, through a solution intercalation method. for this purpose, first, the graft polymerization of styrene (st) onto cellulose fibers was performed by using suspension polymerization and ...

The dicarboxylate radical -OOC--CH--CH(OH)COO- was generated in an N2O-saturated fumarate solution by high energy ionizing radiation. When NADH was present in the solution, product analysis indicated a stoichiometry of 2 molecules of the radical reacted with 1 NADH molecule to form 2 malate and 1 enzymatically active NAD+ molecules. In a similar experiment using tritium label on position A of N...

Glutamate mutase is one of a group of adenosylcobalamin-dependent enzymes that use free radicals to catalyse unusual and chemically difficult rearrangements involving 1,2-migrations of hydrogen atoms. A key mechanistic feature of these enzymes is the transfer of the migrating hydrogen atom between substrate, coenzyme and product. The present review summarizes recent experiments from my laborato...

Density functional theory calculations have been performed to investigate the detailed mechanism of the carbonyl hydrogenation catalyzed by the first well-defined bifunctional iron catalyst. The catalytic reaction proceeds by hydrogen transfer and dihydrogen activation. The hydrogen transfer reaction occurs via the bifunctional mechanism in which the two hydrogen atoms attached on the Fe and O ...

the b3lyp/6-31++g** density functional calculations were used to obtain minimum geometries and interaction energies between the molecular hydrogen and nanostructures of fullerenes, c20 (cage), c20 (bowl), c19si (bowl, penta), c19si (bowl, hexa). the h2 molecule is set as adsorbed in the distance of 3å at vertical position from surface above the pentagonal and hexagonal sites of nanostructures. ...

Hydrogen-transfer processes are expected to show appreciable quantum mechanical behavior. Intensive investigations of enzymes under their physiological conditions show this to be true in practically every example investigated. Initially, tunneling was treated either as a tunneling correction [cf. Bell, The Tunnel Effect in Chemistry, Chapman & Hall, New York, (l980)], or as corner-cutting [Truh...