scholarly journals A DFT study of the role of water in the rhodium-catalyzed hydrogenation of acetone

2016 ◽  
Vol 52 (96) ◽  
pp. 13881-13884 ◽  
Author(s):  
Victor Polo ◽  
Richard R. Schrock ◽  
Luis A. Oro
Keyword(s):  
Reductive Elimination ◽  
Dft Study ◽  
Water Molecules ◽  
Acetone Hydrogenation

Acetone hydrogenation by [RhH2(PR3)2S2]+ catalysts involves hydride migration to the ketone and subsequent reductive elimination assisted by two water molecules.

C−C Reductive Elimination in Palladium Complexes, and the Role of Coupling Additives. A DFT Study Supported by Experiment

2009 ◽  
Vol 131 (10) ◽  
pp. 3650-3657 ◽  
Author(s):  
Martín Pérez-Rodríguez ◽  
Ataualpa A. C. Braga ◽  
Max Garcia-Melchor ◽  
Mónica H. Pérez-Temprano ◽  
Juan A. Casares ◽  
...  
Keyword(s):  
Reductive Elimination ◽  
Palladium Complexes ◽  
Dft Study

scholarly journals Critical computational analysis illuminates the reductive-elimination mechanism that activates nitrogenase for N2reduction

2018 ◽  
Vol 115 (45) ◽  
pp. E10521-E10530 ◽  
Author(s):  
Simone Raugei ◽  
Lance C. Seefeldt ◽  
Brian M. Hoffman
Keyword(s):  
Electrostatic Interactions ◽  
Density Functional ◽  
Computational Analysis ◽  
Reductive Elimination ◽  
Water Molecules ◽  
Computational Investigation ◽  
Functional Theory ◽  
Elimination Mechanism ◽  
Femo Cofactor

Recent spectroscopic, kinetic, photophysical, and thermodynamic measurements show activation of nitrogenase for N2→ 2NH3reduction involves the reductive elimination (re) of H2from two [Fe–H–Fe] bridging hydrides bound to the catalytic [7Fe–9S–Mo–C–homocitrate] FeMo-cofactor (FeMo-co). These studies rationalize the Lowe–Thorneley kinetic scheme’s proposal of mechanistically obligatory formation of one H2for each N2reduced. They also provide an overall framework for understanding the mechanism of nitrogen fixation by nitrogenase. However, they directly pose fundamental questions addressed computationally here. We here report an extensive computational investigation of the structure and energetics of possible nitrogenase intermediates using structural models for the active site with a broad range in complexity, while evaluating a diverse set of density functional theory flavors. (i) This shows that to prevent spurious disruption of FeMo-co having accumulated 4[e−/H+] it is necessary to include: all residues (and water molecules) interacting directly with FeMo-co via specific H-bond interactions; nonspecific local electrostatic interactions; and steric confinement. (ii) These calculations indicate an important role of sulfide hemilability in the overall conversion ofE0to a diazene-level intermediate. (iii) Perhaps most importantly, they explain (iiia) how the enzyme mechanistically couples exothermic H2formation to endothermic cleavage of the N≡N triple bond in a nearly thermoneutralre/oxidative-addition equilibrium, (iiib) while preventing the “futile” generation of two H2without N2reduction: hydrideregenerates an H2complex, but H2is only lost when displaced by N2, to form an end-on N2complex that proceeds to a diazene-level intermediate.

scholarly journals Substrate wettability guided oriented self assembly of Janus particles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Meneka Banik ◽  
Shaili Sett ◽  
Chirodeep Bakli ◽  
Arup Kumar Raychaudhuri ◽  
Suman Chakraborty ◽  
...  
Keyword(s):  
Self Assembly ◽  
Janus Particles ◽  
Water Molecules ◽  
Functional Coatings ◽  
Hexagonal Close Packed ◽  
Local Densities ◽  
Inhomogeneous Properties ◽  
Metal Polymer ◽  
Specific Orientation

AbstractSelf-assembly of Janus particles with spatial inhomogeneous properties is of fundamental importance in diverse areas of sciences and has been extensively observed as a favorably functionalized fluidic interface or in a dilute solution. Interestingly, the unique and non-trivial role of surface wettability on oriented self-assembly of Janus particles has remained largely unexplored. Here, the exclusive role of substrate wettability in directing the orientation of amphiphilic metal-polymer Bifacial spherical Janus particles, obtained by topo-selective metal deposition on colloidal Polymestyere (PS) particles, is explored by drop casting a dilute dispersion of the Janus colloids. While all particles orient with their polymeric (hydrophobic) and metallic (hydrophilic) sides facing upwards on hydrophilic and hydrophobic substrates respectively, they exhibit random orientation on a neutral substrate. The substrate wettability guided orientation of the Janus particles is captured using molecular dynamic simulation, which highlights that the arrangement of water molecules and their local densities near the substrate guide the specific orientation. Finally, it is shown that by spin coating it becomes possible to create a hexagonal close-packed array of the Janus colloids with specific orientation on differential wettability substrates. The results reported here open up new possibilities of substrate-wettability driven functional coatings of Janus particles, which has hitherto remained unexplored.

A first-principles study of the atomic layer deposition of ZnO on carboxyl functionalized carbon nanotubes: the role of water molecules

2021 ◽  
Vol 23 (5) ◽  
pp. 3467-3478
Author(s):  
J. I. Paez-Ornelas ◽  
H. N. Fernández-Escamilla ◽  
H. A. Borbón-Nuñez ◽  
H. Tiznado ◽  
Noboru Takeuchi ◽  
...  
Keyword(s):  
First Principles ◽  
Ligand Exchange ◽  
Functional Group ◽  
Atomic Layer ◽  
High Reactivity ◽  
Water Molecules ◽  
Exchange Reactions ◽  
Layer Deposition ◽  
The Right

Atomic description of ALD in systems that combine large surface area and high reactivity is key for selecting the right functional group to enhance the ligand-exchange reactions.

scholarly journals The role of the water molecules in novel superconductor, Na0.35CoO2·1.3H2O

2004 ◽  
Vol 412-414 ◽  
pp. 182-186 ◽  
Author(s):  
H. Sakurai ◽  
K. Takada ◽  
F. Izumi ◽  
R.A. Dilanian ◽  
T. Sasaki ◽  
...  
Keyword(s):  
Water Molecules

The dielectric β relaxation of polybenzoxazole: The role of water molecules

1977 ◽  
Vol 15 (6) ◽  
pp. 1121-1126 ◽  
Author(s):  
S. De Petris ◽  
V. Frosini ◽  
E. A. Nicol
Keyword(s):  
Water Molecules ◽  
Β Relaxation
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