Gas-Phase Formation of Radical Cations of Monomers and Dimers of Guanosine by Collision-Induced Dissociation of Cu(II)−Guanosine Complexes

2007 ◽  
Vol 111 (37) ◽  
pp. 11075-11082 ◽  
Author(s):  
Ping Cheng ◽  
Diethard K. Bohme
Keyword(s):  
Gas Phase ◽  
Phase Formation ◽  
Radical Cations ◽  
Collision Induced Dissociation

Gas-phase formation and reactions of radical cations of guanosine, deoxyguanosine and their homodimers and heterodimers

2011 ◽  
Vol 304 (2-3) ◽  
pp. 74-82 ◽  
Author(s):  
Linda Feketeová ◽  
Elizabeth Yuriev ◽  
John D. Orbell ◽  
George N. Khairallah ◽  
Richard A.J. O’Hair
Keyword(s):  
Gas Phase ◽  
Phase Formation ◽  
Radical Cations

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

2018 ◽  
Vol 25 (1) ◽  
pp. 112-121 ◽  
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.

Reactivity Trends in the Gas Phase Addition of Acetylene to N-protonated Aryl Radical Cations

2020 ◽  
Author(s):  
Oisin Shiels ◽  
P. D. Kelly ◽  
Cameron C. Bright ◽  
Berwyck L. J. Poad ◽  
Stephen Blanksby ◽  
...  
Keyword(s):  
Gas Phase ◽  
Ion Trap ◽  
Radical Cations ◽  
Rate Coefficients ◽  
Similar Process ◽  
Ion Molecule Reactions ◽  
Aromatic Radicals ◽  
Polycyclic Aromatic ◽  
Gas Phase Ion ◽  
Type Radical

<div> <div> <div> <p>A key step in gas-phase polycyclic aromatic hydrocarbon (PAH) formation involves the addition of acetylene (or other alkyne) to σ-type aromatic radicals, with successive additions yielding more complex PAHs. A similar process can happen for N- containing aromatics. In cold diffuse environments, such as the interstellar medium, rates of radical addition may be enhanced when the σ-type radical is charged. This paper investigates the gas-phase ion-molecule reactions of acetylene with nine aromatic distonic σ-type radical cations derived from pyridinium (Pyr), anilinium (Anl) and benzonitrilium (Bzn) ions. Three isomers are studied in each case (radical sites at the ortho, meta and para positions). Using a room temperature ion trap, second-order rate coefficients, product branching ratios and reaction efficiencies are reported. </p> </div> </div> </div>

On the trustability of semi-empirical methods to the calculation of gas phase formation enthalpies of inorganic compounds containing heavy metals: tin borates

2017 ◽  
Author(s):  
Robson de Farias
Keyword(s):  
Heavy Metals ◽  
Gas Phase ◽  
Phase Formation ◽  
Inorganic Compounds ◽  
Formation Enthalpy ◽  
Computational Time ◽  
Gas Formation ◽  
Formation Enthalpies ◽  
Knudsen Effusion Mass Spectrometry ◽  
Semi Empirical

<p>In the present work, are calculated the gas formation enthalpies (SE; PM3 and PM6) for tin borates: SnB<sub>2</sub>O<sub>4</sub><sup> </sup>and Sn<sub>2</sub>B<sub>2</sub>O<sub>5</sub>. The calculated values are compared with experimental ones, obtained by Knudsen effusion mass spectrometry [3]. It is shown that SE methods, besides their lower computational time consuming can, indeed, provide reliable gas phase formation enthalpy values for inorganic compounds containing heavy metals.</p>

scholarly journals Gas-Phase Formation and Isomerization Reactions of Cyanoacetaldehyde, a Prebiotic Molecule of Astrochemical Interest

2021 ◽  
Author(s):  
Bernardo Ballotta ◽  
Surajit Nandi ◽  
Vincenzo Barone ◽  
Sergio Rampino
Keyword(s):  
Gas Phase ◽  
Phase Formation ◽  
Prebiotic Molecule

Gas-Phase Formation of the Gomberg-Bachmann Magnesium Ketyl

2008 ◽  
Vol 47 (47) ◽  
pp. 9118-9121 ◽  
Author(s):  
Charlene C. L. Thum ◽  
George N. Khairallah ◽  
Richard A. J. O'Hair
Keyword(s):  
Gas Phase ◽  
Phase Formation

Gas-Phase Formation of C5H6 Isomers via the Crossed Molecular Beam Reaction of the Methylidyne Radical (CH; X2Π) with 1,2-Butadiene (CH3CHCCH2; X1A′)

2021 ◽  
Author(s):  
Chao He ◽  
Anatoliy A. Nikolayev ◽  
Long Zhao ◽  
Aaron M. Thomas ◽  
Srinivas Doddipatla ◽  
...  
Keyword(s):  
Gas Phase ◽  
Phase Formation ◽  
Molecular Beam ◽  
Crossed Molecular Beam
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