C–H Bond Activation by Oxygen-Centered Radicals over Atomic Clusters DOI
Xunlei Ding, Xiao‐Nan Wu, Yan‐Xia Zhao

et al.

Accounts of Chemical Research, Journal Year: 2011, Volume and Issue: 45(3), P. 382 - 390

Published: Oct. 21, 2011

Saturated hydrocarbons, or alkanes, are major constituents of natural gas and oil. Directly transforming alkanes into more complex organic compounds is a value-adding process, but the task very difficult to achieve, especially at low temperature. Alkanes can react high temperature, these reactions (with oxygen, for example) control usually proceed carbon dioxide water, thermodynamically stable byproducts. Consequently, great deal research effort has been focused on generating studying chemical entities that able with efficiently activate C-H bonds lower temperatures, preferably room To identify low-temperature methods bond activation, researchers have investigated free radicals, is, species open-shell electronic structures. Oxygen-centered radicals typical naturally occur in atmospheric, chemical, biological systems. In this Account, we survey atomic clusters contain oxygen-centered (O(-•)), an emphasis radical generation reaction near Atomic intermediate state matter, situated between isolated atoms condensed-phase materials. containing O(-•) moiety generated promising results activation. After brief introduction experimental compositions focus two important factors dramatically influence The first factor spin. O(-•)-containing unpaired spin density distributions over oxygen atoms. We show nature distribution, such as localization delocalization within clusters, heavily influences reactivity second charge. be negatively charged, positively neutral overall. discuss how charge may Moreover, given state, cationic it demonstrated local distribution around centers also significantly change Through judicious synthetic choices, readily controllable physical quantities clusters. adjustment properties impact thus constituting consideration rational design catalysts practical alkane transformations.

Language: Английский

Spectroscopic Definition of the Copper Active Sites in Mordenite: Selective Methane Oxidation DOI

Pieter Vanelderen,

Benjamin E. R. Snyder, M.-H. Tsai

et al.

Journal of the American Chemical Society, Journal Year: 2015, Volume and Issue: 137(19), P. 6383 - 6392

Published: April 26, 2015

Two distinct [Cu-O-Cu](2+) sites with methane monooxygenase activity are identified in the zeolite Cu-MOR, emphasizing that this Cu-O-Cu active site geometry, having a ∠Cu-O-Cu ∼140°, is particularly formed and stabilized topologies. Whereas ZSM-5 similar located intersection of two 10 membered rings, Cu-MOR provides local structures, situated 8 ring windows side pockets. Despite their structural similarity, as ascertained by electronic absorption resonance Raman spectroscopy, clearly show different kinetic behaviors selective oxidation. This difference reactivity too large to be ascribed subtle differences ground states sites, indicating lattice tunes through second-sphere effects. The MOR therefore functionally analogous pocket metalloenzyme, demonstrating both its framework environment contribute direct transition metal ion-zeolites.

Language: Английский

Citations

283
Metal-catalyzed C H activation/functionalization: The fundamentals DOI

Fares Roudesly,

Julie Oble, Giovanni Poli

et al.

Journal of Molecular Catalysis A Chemical, Journal Year: 2016, Volume and Issue: 426, P. 275 - 296

Published: Sept. 9, 2016

Language: Английский

Citations

280
Activity and coke formation of nickel and nickel carbide in dry reforming: A deactivation scheme from density functional theory DOI
Ziyun Wang, Xiaoming Cao,

Jinghao Zhu

et al.

Journal of Catalysis, Journal Year: 2014, Volume and Issue: 311, P. 469 - 480

Published: Feb. 3, 2014

Language: Английский

Citations

275
The Drive to Life on Wet and Icy Worlds DOI
Michael J. Russell, Laura M. Barge, R. Bhartia

et al.

Astrobiology, Journal Year: 2014, Volume and Issue: 14(4), P. 308 - 343

Published: April 1, 2014

This paper presents a reformulation of the submarine alkaline hydrothermal theory for emergence life in response to recent experimental findings. The views life, like other self-organizing systems Universe, as an inevitable outcome particular disequilibria. In this case, disequilibria were two: (1) redox potential, between hydrogen plus methane with circuit-completing electron acceptors such nitrite, nitrate, ferric iron, and carbon dioxide, (2) pH gradient acidulous external ocean fluid. Both CO2 CH4 equally ultimate sources organic carbon, metal sulfides oxyhydroxides acted protoenzymatic catalysts. realization, now 50 years old, that membrane-spanning gradients, rather than intermediates, play vital role life's operations calls into question idea “prebiotic chemistry.” It informs our own suggestion experimentation should look kind nanoengines must have been precursors molecular motors—such pyrophosphate synthetase driven by these gradients—that make work. is putative free energy or converters, presumably constructed from minerals comprising earliest inorganic membranes, that, obstacles vectorial ionic flows, present themselves candidates future experiments. Key Words: Methanotrophy—Origin life. Astrobiology 14, 308–343. fixation material (autotrophy) prerequisite sets starting point biological evolution. (Fuchs, 2011) Further significant progress tightly membrane-bound H+-PPase family lead increased insight basic requirements transport protons through membranes its coupling phosphorylation. (Baltscheffsky et al., 1999)

Language: Английский

Citations

269
C–H Bond Activation by Oxygen-Centered Radicals over Atomic Clusters DOI
Xunlei Ding, Xiao‐Nan Wu, Yan‐Xia Zhao

et al.

Accounts of Chemical Research, Journal Year: 2011, Volume and Issue: 45(3), P. 382 - 390

Published: Oct. 21, 2011

Saturated hydrocarbons, or alkanes, are major constituents of natural gas and oil. Directly transforming alkanes into more complex organic compounds is a value-adding process, but the task very difficult to achieve, especially at low temperature. Alkanes can react high temperature, these reactions (with oxygen, for example) control usually proceed carbon dioxide water, thermodynamically stable byproducts. Consequently, great deal research effort has been focused on generating studying chemical entities that able with efficiently activate C-H bonds lower temperatures, preferably room To identify low-temperature methods bond activation, researchers have investigated free radicals, is, species open-shell electronic structures. Oxygen-centered radicals typical naturally occur in atmospheric, chemical, biological systems. In this Account, we survey atomic clusters contain oxygen-centered (O(-•)), an emphasis radical generation reaction near Atomic intermediate state matter, situated between isolated atoms condensed-phase materials. containing O(-•) moiety generated promising results activation. After brief introduction experimental compositions focus two important factors dramatically influence The first factor spin. O(-•)-containing unpaired spin density distributions over oxygen atoms. We show nature distribution, such as localization delocalization within clusters, heavily influences reactivity second charge. be negatively charged, positively neutral overall. discuss how charge may Moreover, given state, cationic it demonstrated local distribution around centers also significantly change Through judicious synthetic choices, readily controllable physical quantities clusters. adjustment properties impact thus constituting consideration rational design catalysts practical alkane transformations.

Language: Английский

Citations

263