Linear free energy correlations in mass spectrometry

Harrison, Alex G.

doi:10.1002/(sici)1096-9888(199906)34:6<577::aid-jms829>3.0.co;2-z

Cited by 41 publications

(28 citation statements)

References 69 publications

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“…Its first application in gas phase was conducted by McLafferty in 1959 [46], who found out that the logarithm of the ratio of the fragment ion to the precursor ion increases linearly with the increase in the substituent constants. From then on, Hammett plots have been extensively employed in the study of gas-phase chemistry [47][48][49][50] owing to its intuitive presentation of the substituent effect on the direct cleavage as well as on competitive fragmentation pathways. To get a more direct understanding on the relationship between substituents and competitive pathways, the logarithm of the intensity ratios of these two competitive product ions are usually utilized to plot with the substituent constants [31,37,50,51].…”

Section: Resultsmentioning

confidence: 98%

Gas-Phase Intramolecular Cyclization of Argentinated N-Allylbenzamides

Sun

Chai

Jin

et al. 2015

J. Am. Soc. Mass Spectrom.

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Abstract. The fragmentations of argentinated N-allylbenzamides have been exhaustively studied through collision-induced dissociation and through deuterium labeling. The intriguing elimination of AgOH is certified as the consequence of intramolecular cyclization between terminal olefin and carbonyl carbon following proton transfer to carbonyl oxygen, rather than simple enolization of amide. Linear free energy correlations and density functional theory (DFT) calculations were performed to understand the competitive relationship between AgOH loss and AgH loss, which results from the 1,2-elimination of α-hydrogen (to the amido nitrogen) with the silver.

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Section: Resultsmentioning

confidence: 98%

Gas-Phase Intramolecular Cyclization of Argentinated N-Allylbenzamides

Sun

Chai

Jin

et al. 2015

J. Am. Soc. Mass Spectrom.

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“…Analysis of the product ion spectra of the related peptides and rationalizing the observed fragmentation tendencies led to improved fragmentation mechanisms of peptides [3,5,8,9]. Often, a linear free energy relationships [59] could be established from the observed fragmentation tendencies. The product ion spectra of protonated Ala-Ala-Xxx-ProAla (Xxx includes Ala, Ser, Leu, Val, Phe, and Trp) are presented in Figure. 1 and Figures S1, S2, S3, S4 and S5.…”

Section: Protonation Energetics and Fragmentation Pathways Of Protonamentioning

confidence: 99%

Towards Understanding the Tandem Mass Spectra of Protonated Oligopeptides. 2: The Proline Effect in Collision-Induced Dissociation of Protonated Ala-Ala-Xxx-Pro-Ala (Xxx = Ala, Ser, Leu, Val, Phe, and Trp)

Bleiholder

Suhai

Harrison

et al. 2011

J. Am. Soc. Mass Spectrom.

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The product ion spectra of proline-containing peptides are commonly dominated by y n ions generated by cleavage at the N-terminal side of proline residues. This proline effect is investigated in the current work by collision-induced dissociation (CID) of protonated Ala-AlaXxx-Pro-Ala (Xxx includes Ala, Ser, Leu, Val, Phe, and Trp) in an electrospray/quadrupole/timeof-flight (QqTOF) mass spectrometer and by quantum chemical calculations on protonated AlaAla-Ala-Pro-Ala. The CID spectra of all investigated peptides show a dominant y 2 ion (Pro-Ala sequence). Our computational results show that the proline effect mainly arises from the particularly low threshold energy for the amide bond cleavage N-terminal to the proline residue, and from the high proton affinity of the proline-containing C-terminal fragment produced by this cleavage. These theoretical results are qualitatively supported by the experimentally observed y 2 /b 3 abundance ratios for protonated Ala-Ala-Xxx-Pro-Ala (Xxx = Ala, Ser, Leu, Val, Phe, and Trp). In the post-cleavage phase of fragmentation the N-terminal oxazolone fragment with the Ala-Ala-Xxx sequence and Pro-Ala compete for the ionizing proton for these peptides. As the proton affinity of the oxazolone fragment increases, the y 2 /b 3 abundance ratio decreases.

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“…Figure 8 shows the correlation between (k · [CH 3 CN]) and the Brown σ + parameters [8]. The correlation is not perfect, and this can be explained by the fact that σ + parameters have been tabulated for typical reactions occurring in solution [9]. For example, an inversion between m-CN and p-CN benzyl ions has also been found for the gas-phase ionization potential of the corresponding benzyl radicals [10].…”

Section: Kinetics Of Ch 3 Cn Addition Monitored In the Trapmentioning

confidence: 99%

“…The electron withdrawing character of the substituent can been quantified in solution by the Hammett σ empirical parameter [7]. In the following we will use the values σ + given by Brown et al [8], as these are better suited for positive charge stabilization [9].…”

Section: Introductionmentioning

confidence: 99%

Kinetics of solvent addition on electrosprayed ions in an electrospray source and in a quadrupole ion trap

Gabelica

Lemaire

Laprévôte

et al. 2001

International Journal of Mass Spectrometry

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:Benzylpyridinium cations readily fragment in the electrospray source by loss of pyridine to give benzyl cations (M -79). The full-scan spectra obtained with some instruments also show, in addition, an m/z (M -38) peak corresponding to the addition of acetonitrile, being present in the solvent mixture, on the benzyl cations. Here we report that the addition reaction can occur in the source region of ES-MS instruments, and in a quadrupole ion trap. The kinetics of acetonitrile addition was monitored in an ion trap, acetonitrile being provided by leakage from the source, through the heated capillary. For benzyl ions with different substituents, the addition kinetics has been found positively correlated with the Brown parameter σ + of the benzyl radical, and therefore with the effective charge density on the α-carbon atom of the benzyl ion. This is consistent with the Langevin or ADO theory of ion-molecule reaction kinetics.Introduction :

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Linear free energy correlations in mass spectrometry

Cited by 41 publications

References 69 publications

Gas-Phase Intramolecular Cyclization of Argentinated N-Allylbenzamides

Gas-Phase Intramolecular Cyclization of Argentinated N-Allylbenzamides

Towards Understanding the Tandem Mass Spectra of Protonated Oligopeptides. 2: The Proline Effect in Collision-Induced Dissociation of Protonated Ala-Ala-Xxx-Pro-Ala (Xxx = Ala, Ser, Leu, Val, Phe, and Trp)

Kinetics of solvent addition on electrosprayed ions in an electrospray source and in a quadrupole ion trap

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