Kinetics of the migratory insertion of olefin into rhodium-hydrogen bonds. Influence of electronic factors

1984 ◽  
Vol 89 (3) ◽  
pp. L53-L54 ◽  
Author(s):  
Jack Halpern ◽  
T. Okamoto
Keyword(s):  
Hydrogen Bonds ◽  
Migratory Insertion ◽  
Kinetics Of

scholarly journals Slow Dissolution Kinetics of Model Peptide Fibrils

2020 ◽  
Vol 21 (20) ◽  
pp. 7671
Author(s):  
Mona Koder Hamid ◽  
Axel Rüter ◽  
Stefan Kuczera ◽  
Ulf Olsson
Keyword(s):  
Hydrogen Bonds ◽  
Self Assembly ◽  
Amyloid Fibrils ◽  
Dissolution Kinetics ◽  
Titration Calorimetry ◽  
Model Peptide ◽  
Rate Limiting Step ◽  
Low Concentrations ◽  
Peptide Fibrils ◽  
Kinetics Of

Understanding the kinetics of peptide self-assembly is important because of the involvement of peptide amyloid fibrils in several neurodegenerative diseases. In this paper, we have studied the dissolution kinetics of self-assembled model peptide fibrils after a dilution quench. Due to the low concentrations involved, the experimental method of choice was isothermal titration calorimetry (ITC). We show that the dissolution is a strikingly slow and reaction-limited process, that can be timescale separated from other rapid processes associated with dilution in the ITC experiment. We argue that the rate-limiting step of dissolution involves the breaking up of inter-peptide β–sheet hydrogen bonds, replacing them with peptide–water hydrogen bonds. Complementary pH experiments revealed that the self-assembly involves partial deprotonation of the peptide molecules.

Enhancing the Catalysis of Oxygen Reduction Reaction via Tuning Interfacial Hydrogen Bonds

2020 ◽  
Author(s):  
Tao Wang ◽  
Yirui Zhang ◽  
Botao Huang ◽  
Bin Cai ◽  
Reshma Rao ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Hydrogen Bonds ◽  
Reduction Reaction ◽  
Protic Ionic Liquids ◽  
Proton Coupled Electron Transfer ◽  
Electrified Interface ◽  
Bond Interface ◽  
Orr Activity ◽  
Proton Activity ◽  
Kinetics Of

Abstract Proton activity at the electrified interface is central to the kinetics of proton-coupled electron transfer (PCET) reactions for making chemicals and fuels. Here we employed a library of protic ionic liquids in an interfacial layer on Pt and Au to alter local proton activity, where the intrinsic ORR activity was enhanced up to 5 times, exhibiting a volcano-shaped dependence on the pKa of the ionic liquid. The enhanced ORR activity was attributed to favorable proton transfer kinetics for strengthened hydrogen bonds between the ionic liquid to the ORR product with comparable pKa. This proposed mechanism was supported by in situ surface-enhanced Fourier-Transform Infrared Spectroscopy and our simulation of PCET kinetics based on computed proton vibrational wavefunction at the H-bond interface. These findings highlight opportunities in using non-covalent interactions of hydrogen bond structures and solvation environments at the electrified interface to tune the kinetics of ORR and beyond.

scholarly journals The inhibition effect of water on the purification of natural gas with nanoporous graphene membranes

2018 ◽  
Vol 9 ◽  
pp. 1906-1916 ◽  
Author(s):  
Krzysztof Nieszporek ◽  
Tomasz Pańczyk ◽  
Jolanta Nieszporek
Keyword(s):  
Natural Gas ◽  
Hydrogen Bonds ◽  
Membrane Separation ◽  
Extreme Case ◽  
Gas Permeation ◽  
Effect Of Water ◽  
Nanoporous Graphene ◽  
Analysis Of Stability ◽  
Dynamics Simulations ◽  
Kinetics Of

Molecular dynamics simulations are used to investigate the inhibiting effect of water on the natural gas separation with nanoporous graphene. The membrane separation process involves CH4 + N2 mixtures with and without the addition of water. The results show that water is able to form hydrogen bonds with nitrogen atoms located in a nanopore rim. This effect causes a decrease of separation selectivity as well as a reduction of gas permeation. In the extreme case, when the nanopore rim contains only nitrogen atoms, water agglomerates at the center of the nanopore and effectively closes down the permeation path. The conclusions are confirmed by the analysis of stability and kinetics of hydrogen bonds.

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