Collision-induced dissociation (CID) of guanine radical cation in the gas phase: an experimental and computational study

A combined experimental and theoretical study is presented on the collision-induced dissociation of 9-methylguanine–1-methylcytosine base-pair radical cation ([9MG·1MC]˙+) and its monohydrate ([9MG·1MC]˙+·H2O) with Xe and Ar gases.

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Hydrogen atom transfer in the radical cations of tryptophan-containing peptides AW and WA studied by mass spectrometry, infrared multiple-photon dissociation spectroscopy, and theoretical calculations

European Journal of Mass Spectrometry ◽

10.1177/1469066718802547 ◽

2018 ◽

Vol 25 (1) ◽

pp. 112-121 ◽

Cited By ~ 3

Author(s):

Andrii Piatkivskyi ◽

Justin Kai-Chi Lau ◽

Giel Berden ◽

Jos Oomens ◽

Alan C Hopkinson ◽

...

Keyword(s):

Hydrogen Atom ◽

Gas Phase ◽

Radical Cation ◽

Density Functional ◽

Theoretical Calculations ◽

Radical Cations ◽

Hydrogen Atom Transfer ◽

Collision Induced Dissociation ◽

Infrared Multiple Photon Dissociation ◽

Nitrogen Radical

Two types of radical cations of tryptophan—the π-radical cation and the protonated tryptophan-N radical—have been studied in dipeptides AW and WA. The π-radical cation produced by removal of an electron during collision-induced dissociation of a ternary Cu(II) complex was only observed for the AW peptide. In the case of WA, only the ion corresponding to the loss of ammonia, [WA–NH3] •+, was observed from the copper complex. Both protonated tryptophan-N radicals were produced by N-nitrosylation of the neutral peptides followed by transfer to the gas phase via electrospray ionization and subsequent collision-induced dissociation. The regiospecifically formed N• species were characterized by infrared multiple-photon dissociation spectroscopy which revealed that the WA tryptophan-N• radical remains the nitrogen radical, while the AW nitrogen radical rearranges into the π-radical cation. These findings are supported by the density functional theory calculations that suggest a relatively high barrier for the radical rearrangement (N• to π) in WA (156.3 kJ mol−1) and a very low barrier in AW (6.1 kJ mol−1). The facile hydrogen atom migration in the AW system is also supported by the collision-induced dissociation of the tryptophan-N radical species that produces fragments characteristic of the tryptophan π-radical cation. Gas-phase ion–molecule reactions with n-propyl thiol have also been used to differentiate between the π-radical cations (react by hydrogen abstraction) and the tryptophan-N• species (unreactive) of AW.

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Gas-phase structure and reactivity of the keto tautomer of the deoxyguanosine radical cation

Physical Chemistry Chemical Physics ◽

10.1039/c5cp01573a ◽

2015 ◽

Vol 17 (39) ◽

pp. 25837-25844 ◽

Cited By ~ 10

Author(s):

Linda Feketeová ◽

Bun Chan ◽

George N. Khairallah ◽

Vincent Steinmetz ◽

Philippe Maître ◽

...

Keyword(s):

Ir Spectroscopy ◽

Computational Chemistry ◽

Gas Phase ◽

Radical Cation ◽

Phase Structure ◽

Collision Induced Dissociation ◽

Ion Molecule Reactions ◽

Gas Phase Structure

Gas-phase IR spectroscopy, ion–molecule reactions, collision-induced dissociation and computational chemistry in combination form a powerful tool to gain insights into the structure of one-electron oxidised guanine in DNA and its resultant chemistry.

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Collision-induced dissociation of singly and doubly charged CuII–cytidine complexes in the gas phase: an experimental and computational study

RSC Advances ◽

10.1039/c2ra01293f ◽

2012 ◽

Vol 2 (6) ◽

pp. 2568 ◽

Cited By ~ 5

Author(s):

Shuqin Zhang ◽

Li Xu ◽

Junguo Dong ◽

Ping Cheng ◽

Zhen Zhou ◽

...

Keyword(s):

Gas Phase ◽

Computational Study ◽

Collision Induced Dissociation ◽

Doubly Charged

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Explaining the magnetism of gold

10.26434/chemrxiv.5393944.v1 ◽

2017 ◽

Author(s):

Robson de Farias

Keyword(s):

Gas Phase ◽

Computational Study ◽

Formation Enthalpy ◽

Gold Atom ◽

Orbital Energy ◽

Knudsen Effusion ◽

Energy Diagram ◽

Unpaired Electrons ◽

The Difference ◽

Good Agreement

In the present work, a computational study is performed in order to clarify the possible magnetic nature of gold. For such purpose, gas phase Au2 (zero charge) is modelled, in order to calculate its gas phase formation enthalpy. The calculated values were compared with the experimental value obtained by means of Knudsen effusion mass spectrometric studies [5]. Based on the obtained formation enthalpy values for Au2, the compound with two unpaired electrons is the most probable one. The calculated ionization energy of modelled Au2 with two unpaired electrons is 8.94 eV and with zero unpaired electrons, 11.42 eV. The difference (11.42-8.94 = 2.48 eV = 239.29 kJmol-1), is in very good agreement with the experimental value of 226.2 ± 0.5 kJmol-1 to the Au-Au bond7. So, as expected, in the specie with none unpaired electrons, the two 6s1 (one of each gold atom) are paired, forming a chemical bond with bond order 1. On the other hand, in Au2 with two unpaired electrons, the s-d hybridization prevails, because the relativistic contributions. A molecular orbital energy diagram for gas phase Au2 is proposed, explaining its paramagnetism (and, by extension, the paramagnetism of gold clusters and nanoparticles).

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2-Deoxyribose Radicals in the Gas Phase and Aqueous Solution. Transient Intermediates of Hydrogen Atom Abstraction from 2-Deoxyribofuranose

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20051769 ◽

2005 ◽

Vol 70 (11) ◽

pp. 1769-1786 ◽

Cited By ~ 4

Author(s):

Luc A. Vannier ◽

Chunxiang Yao ◽

František Tureček

Keyword(s):

Aqueous Solution ◽

Hydrogen Atom ◽

Gas Phase ◽

Computational Study ◽

Hydrogen Atom Abstraction ◽

Oh Radical ◽

Free Energies ◽

Intramolecular Hydrogen ◽

Solvation Free Energies ◽

Transient Intermediates

A computational study at correlated levels of theory is reported to address the structures and energetics of transient radicals produced by hydrogen atom abstraction from C-1, C-2, C-3, C-4, C-5, O-1, O-3, and O-5 positions in 2-deoxyribofuranose in the gas phase and in aqueous solution. In general, the carbon-centered radicals are found to be thermodynamically and kinetically more stable than the oxygen-centered ones. The most stable gas-phase radical, 2-deoxyribofuranos-5-yl (5), is produced by H-atom abstraction from C-5 and stabilized by an intramolecular hydrogen bond between the O-5 hydroxy group and O-1. The order of radical stabilities is altered in aqueous solution due to different solvation free energies. These prefer conformers that lack intramolecular hydrogen bonds and expose O-H bonds to the solvent. Carbon-centered deoxyribose radicals can undergo competitive dissociations by loss of H atoms, OH radical, or by ring cleavages that all require threshold dissociation or transition state energies >100 kJ mol-1. This points to largely non-specific dissociations of 2-deoxyribose radicals when produced by exothermic hydrogen atom abstraction from the saccharide molecule. Oxygen-centered 2-deoxyribose radicals show only marginal thermodynamic and kinetic stability and are expected to readily fragment upon formation.

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A vibrational spectroscopic and computational study of the structures of protonated imidacloprid and its fragmentation products in the gas phase

Physical Chemistry Chemical Physics ◽

10.1039/d0cp06069k ◽

2021 ◽

Vol 23 (5) ◽

pp. 3377-3388

Author(s):

Kelsey J. Menard ◽

Jonathan Martens ◽

Travis D. Fridgen

Keyword(s):

Computational Chemistry ◽

Gas Phase ◽

Vibrational Spectroscopy ◽

Computational Study ◽

Unimolecular Decomposition ◽

Decomposition Products

Vibrational spectroscopy and computational chemistry studies were combined with the aim of elucidating the structures of protonated imidacloprid (pIMI), and its unimolecular decomposition products.

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