Reactions of simple and peptidic alpha-carboxylate radical anions with dioxygen in the gas phase

Ly, Tony; Kirk, Benjamin B.; Hettiarachchi, Pramesh I.; Poad, Berwyck L. J.; Trevitt, Adam J.; Silva, Gabriel da; Blanksby, Stephen J.

doi:10.1039/c1cp20784a

Cited by 48 publications

(51 citation statements)

References 36 publications

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“…In studies where site specific radicals are generated by laser photolysis of iodinated ion precursors, [38][39][40]43,[57][58][59] this band is very well-matched to the 4 th harmonic (266 nm) of the commercially available Nd:YAG laser.…”

Section: Resultsmentioning

confidence: 99%

UV Photodissociation Action Spectroscopy of Haloanilinium Ions in a Linear Quadrupole Ion Trap Mass Spectrometer

Hansen

Kirk

Blanksby

et al. 2013

J. Am. Soc. Mass Spectrom.

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. (2013). UV photodissociation action spectroscopy of haloanilinium ions in a linear quadrupole ion trap mass spectrometer. Journal of the American Society for Mass Spectrometry, 24 (6), 932-940. UV photodissociation action spectroscopy of haloanilinium ions in a linear quadrupole ion trap mass spectrometer Abstract UV-vis photodissociation action spectroscopy is becoming increasingly prevalent because of advances in, and commercial availability of, ion trapping technologies and tunable laser sources. This study outlines in detail an instrumental arrangement, combining a commercial ion-trap mass spectrometer and tunable nanosecond pulsed laser source, for performing fully automated photodissociation action spectroscopy on gas-phase ions. The components of the instrumentation are outlined, including the optical and electronic interfacing, in addition to the control software for automating the experiment and performing online analysis of the spectra. To demonstrate the utility of this ensemble, the photodissociation action spectra of 4-chloroanilinium, 4-bromoanilinium, and 4-iodoanilinium cations are presented and discussed. Multiple photoproducts are detected in each case and the photoproduct yields are followed as a function of laser wavelength. It is shown that the wavelength-dependent partitioning of the halide loss, H loss, and NH3 loss channels can be broadly rationalized in terms of the relative carbon-halide bond dissociation energies and processes of energy redistribution. The photodissociation action spectrum of (phenyl)Ag2 + is compared with a literature spectrum as a further benchmark. AbstractUV-Vis photodissociation action spectroscopy is becoming increasingly prevalent due to advances in, and commercial availability of, ion trapping technologies and tunable laser sources. This study outlines in detail an instrumental arrangement, combining a commercial ion-trap mass spectrometer and tunable nanosecond pulsed laser source, for performing fully automated photodissociation action spectroscopy on gas-phase ions. The components of the instrumentation are outlined, including the optical and electronic interfacing, in addition to the control software for automating the experiment and performing online analysis of the spectra. To demonstrate the utility of this ensemble, the photodissociation action spectra of 4-chloroanilinium, 4-bromoanilinium and 4-iodoanilinium cations are presented and discussed. Multiple photoproducts are detected in each case and the photoproduct yields are followed as a function of laser wavelength. It is shown that the wavelength-dependent partitioning of the halide loss, H loss and NH 3 loss channels can be broadly rationalized in terms of the relative carbon-halide bond dissociation energies and processes of energy redistribution. The photodissociation action spectrum of (phenyl)Ag 2 + is compared to a literature spectrum as a further benchmark.3

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Section: Resultsmentioning

confidence: 99%

UV Photodissociation Action Spectroscopy of Haloanilinium Ions in a Linear Quadrupole Ion Trap Mass Spectrometer

Hansen

Kirk

Blanksby

et al. 2013

J. Am. Soc. Mass Spectrom.

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“…37,38 Briefly, a 10 mm aperture was milled into the removable backplate of the vacuum chamber. A 2.75 inch quartz viewport was mounted over the aperture with a CF flange.…”

Section: Photodissociation (Pd)mentioning

confidence: 99%

Hydroxyl radical formation in the gas phase oxidation of distonic 2-methylphenyl radical cations

Prendergast

Cooper

Kirk

et al. 2013

Phys. Chem. Chem. Phys.

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The reactions of distonic 4-(N,N,N-trimethylammonium)-2-methylphenyl and 5-(N,N,Ntrimethylammonium)-2-methylphenyl radical cations (m/z 149) with O 2 are studied in the gas phase using ion-trap mass spectrometry. Photodissociation (PD) of halogenated precursors gives rise to the target distonic charge-tagged methylphenyl radical whereas collision-induced dissociation (CID) is found to produce unreactive radical ions. The PD generated distonic radicals, however, react rapidly with O2 to form [M + O2]•+ and [M + O2 -OH]•+ ions, detected at m/z 181 and m/z 164, respectively. Quantum chemical calculations using G3SX(MP3) and M06-2X theories are deployed to examine key decomposition pathways of the 5-(N,N,N-trimethylammonium)-2-methylphenylperoxyl radical and rationalise the observed product ions. The prevailing product mechanism involves a 1,5-H shift in the peroxyl radical forming a QOOH-type intermediate that subsequently eliminates •OH to yield charge-tagged 2-quinone methide. Our study suggests that the analogous process should occur for the neutral methylphenyl + O2 reaction, thus serving as a plausible source of •OH radicals in combustion environments. The prevailing product mechanism involves a 1,5-H shift in the peroxyl radical forming a QOOH-type intermediate that subsequently eliminates OH to yield charge-tagged 2-quinone methide. Our study suggests that the analogous process should occur for the neutral methylphenyl + O 2 reaction, thus serving as a plausible source of OH radicals in combustion environments.

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“…Modifications to the mass spectrometer to perform UV photodissociation (UVPD) in the trap have been described in detail elsewhere, 29 and similar experimental configurations have been reported previously. 24,30 Briefly, a quartz viewport is fitted to the backplate of the LTQ vacuum manifold to allow transmission of a UV laser pulse.…”

Section: Mass Spectrometrymentioning

confidence: 99%

Ultraviolet Action Spectroscopy of Iodine Labeled Peptides and Proteins in the Gas Phase

et al. 2012

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Structural investigations of large biomolecules in the gas phase are challenging. Herein, it is reported that action spectroscopy taking advantage of facile carbon-iodine bond dissociation can be used to examine the structures of large molecules, including whole proteins. Iodotyrosine serves as the active chromophore, which yields distinctive spectra depending on the solvation of the side chain by the remainder of the molecule. Isolation of the chromophore yields a double featured peak at 290 nm, which becomes a single peak with increasing solvation. Deprotonation of the side chain also leads to reduced apparent intensity and broadening of the action spectrum. The method can be successfully applied to both negatively and positively charged ions in various charge states, although electron detachment becomes a competitive channel for multiply charged anions. In all other cases, loss of iodine is by far the dominant channel which leads to high sensitivity and simple data analysis. The action spectra for iodotyrosine, the iodinated peptides KGYDAKA, DAYLDAG, and the small protein ubiquitin are reported in various charge states. * to whom correspondence should be addressed: ryan.julian@ucr.edu, adamt@uow.edu.au RECEIVED DATE (to be automatically inserted after your manuscript is accepted if required according to the journal that you are submitting your paper to) 2 Abstract. Structural investigations of large biomolecules in the gas phase are challenging. Herein, it is reported that action spectroscopy taking advantage of facile carbon-iodine bond dissociation can be used to examine the structures of large molecules, including whole proteins. Iodotyrosine serves as the active chromophore, which yields distinctive spectra depending on the solvation of the side chain by the remainder of the molecule. Isolation of the chromophore yields a double featured peak at ~290 nm, which becomes a single peak with increasing solvation. Deprotonation of the side chain also leads to reduced apparent intensity and broadening of the action spectrum. The method can be successfully applied to both negatively and positively charged ions in various charge states, although electron detachment becomes a competitive channel for multiply charged anions. In all other cases, loss of iodine is by far the dominant channel which leads to high sensitivity and simple data analysis. The action spectra for iodotyrosine, the iodinated peptides KGYDAKA, DAYLDAG, and the small protein ubiquitin are reported in various charge states.

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Reactions of simple and peptidic alpha-carboxylate radical anions with dioxygen in the gas phase

Cited by 48 publications

References 36 publications

UV Photodissociation Action Spectroscopy of Haloanilinium Ions in a Linear Quadrupole Ion Trap Mass Spectrometer

UV Photodissociation Action Spectroscopy of Haloanilinium Ions in a Linear Quadrupole Ion Trap Mass Spectrometer

Hydroxyl radical formation in the gas phase oxidation of distonic 2-methylphenyl radical cations

Ultraviolet Action Spectroscopy of Iodine Labeled Peptides and Proteins in the Gas Phase

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