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Hydrogen atom abstraction

About: Hydrogen atom abstraction is a research topic. Over the lifetime, 7059 publications have been published within this topic receiving 151781 citations.


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Journal ArticleDOI
TL;DR: A multiscale and hybrid quantum mechanical-molecular mechanical simulation is employed to study the interaction of OH radicals with a guanine-deoxyribose-phosphate DNA molecular unit in the presence of water, where all of the water molecules and the deoxyribosing fragment are treated with the simplistic classical molecular mechanical scheme.
Abstract: Understanding the damage of DNA bases from hydrogen abstraction by free OH radicals is of particular importance to understanding the indirect effect of ionizing radiation. Previous studies address the problem with truncated DNA bases as ab initio quantum simulations required to study such electronic-spin-dependent processes are computationally expensive. Here, for the first time, we employ a multiscale and hybrid quantum mechanical–molecular mechanical simulation to study the interaction of OH radicals with a guanine-deoxyribose-phosphate DNA molecular unit in the presence of water, where all of the water molecules and the deoxyribose-phosphate fragment are treated with the simplistic classical molecular mechanical scheme. Our result illustrates that the presence of water strongly alters the hydrogen-abstraction reaction as the hydrogen bonding of OH radicals with water restricts the relative orientation of the OH radicals with respect to the DNA base (here, guanine). This results in an angular anisotropy...

44 citations

Journal ArticleDOI
TL;DR: Molecular dynamics simulations of the reaction of dimethyldioxirane (DMDO) with isobutane find the time gap between C-H bond-breaking and C-O bond formation ranges from 30 to 150 fs, close to the <200 fs lifetime of radical pairs from DMDO hydroxylation of trans-1-phenyl-2-ethylcyclopropane measured by Newcomb.
Abstract: We report molecular dynamics simulations of the reaction of dimethyldioxirane (DMDO) with isobutane. The reaction involves hydrogen atom abstraction in the transition state, and trajectories branch to the oxygen rebound pathway, which gives tert-butanol and acetone, or a separated radical pair. In the gas phase, only 10% of the reactive trajectories undergo the oxygen rebound pathway, but this increases to 90% in simulations in an implicit acetone solvent (SMD) because the oxygen rebound becomes barrierless in solution. Short-lived diradical species were observed in the oxygen rebound trajectories. The time gap between C–H bond-breaking and C–O bond formation ranges from 30 to 150 fs, close to the <200 fs lifetime of radical pairs from DMDO hydroxylation of trans-1-phenyl-2-ethylcyclopropane measured by Newcomb.

44 citations

Journal ArticleDOI
TL;DR: Quantum chemistry computations used to investigate hydrogen-atom abstraction by chlorine atom from protonated and N-acetylated amino acids show a peculiar stability for amino acids and peptides and their derivatives with respect to radical degradation.
Abstract: Quantum chemistry computations have been used to investigate hydrogen-atom abstraction by chlorine atom from protonated and N-acetylated amino acids. The results are consistent with the decreased reactivity at the backbone α-carbon and adjacent side-chain positions that is observed experimentally. The individual effects of NH3+, COOH, and NHAc substituents have been examined and reveal important insights. The NH3+ group in isolation is found to be deactivating at the α-position, while the acetamido group is activating. For the COOH group, polar effects lead to a contrathermodynamic deactivation of the thermodynamically most favorable α-abstraction. In the N-acetylamino acid, the α-position is deactivated by the combined inductive effect of the substituents and the presence of an early transition structure, again overriding the greater thermodynamic stability of the α-centered radical product. Deactivation of the α-, β-, and γ-positions results in a peculiar stability for amino acids and peptides and their...

44 citations

Patent
02 Mar 2012
TL;DR: A compound represented by the general formula below has high thermal stability and has excellent characteristics as a charge transport material as mentioned in this paper, however, it is not suitable for use as a fuel.
Abstract: A compound represented by the general formula below has high thermal stability and has excellent characteristics as a charge transport material. (Ar1 denotes a single bond, a benzene ring or the like; X1 denotes a linking group linked via an oxygen atom, a sulfur atom, a carbon atom, a nitrogen atom, a phosphorus atom or a silicon atom; one of L1 and L2 or L3 and L4 bond together to form a linking group linked via an oxygen atom, a sulfur atom, a carbon atom, a nitrogen atom, a phosphorus atom or a silicon atom and the other of L1 and L2 or L3 and L4 are hydrogen atoms or substituent groups; Y1 denotes a linking group linked via a nitrogen atom, a boron atom or a phosphorus atom; R1, R2, R5 to R7 and R10 to R12 are hydrogen atoms or substituent groups, and n1 is an integer of 2 or higher.)

44 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202382
2022142
2021120
2020121
2019104
2018124