Ion-molecule reactions of distonic radical cations

Stirk, Krista M.; Kiminkinen, L. K. Marjatta; Kenttämaa, Hilkka I.

doi:10.1021/cr00015a008

Cited by 271 publications

(180 citation statements)

References 33 publications

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“…Formation of site-specific peptide sulfinyl radical ion from radical attack of an inter-chain disulfide peptide. The radical reactions allowed the formation of peptide sulfinyl radical ions independent of ion polarity and charge state ions in Figure 3 contained a significant fraction of the 13 C isotope from m/z 603.3 ions, which was much less when the inter-chain linked peptide was used (inset of Figure 3). CID of m/z 603.3 showed a dominant 18 Da loss (data not shown), which was very different from CID of the sulfinyl radical ions at m/z 604.3.…”

Section: Radical Attack Of Free Cysteine Residuementioning

confidence: 99%

“…Mass spectrometry (MS) has been utilized to analyze the stable reaction products of biomolecules after exposure to radical attack in solution [10][11][12]. The distonic ion approach pioneered by Kenttämaa and co-workers allows exploration of radical attack on biomolecules via gas-phase ion/molecule reactions [13]. In those studies, distonic ions (ions with separated charge and radical site) were used as surrogates of radicals to react with neutral amino acids or dipeptides, and several classes of reaction channels were identified [14,15].…”

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confidence: 99%

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Gas-Phase Peptide Sulfinyl Radical Ions: Formation and Unimolecular Dissociation

Tan

Xia

2012

J. Am. Soc. Mass Spectrom.

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A variety of peptide sulfinyl radical (RSO•) ions with a well-defined radical site at the cysteine side chain were formed at atmospheric pressure (AP), sampled into a mass spectrometer, and investigated via collision-induced dissociation (CID). The radical ion formation was based on AP reactions between oxidative radicals and peptide ions containing single inter-chain disulfide bond or free thiol group generated from nanoelectrospray ionization (nanoESI). The radical induced reactions allowed large flexibility in forming peptide radical ions independent of ion polarity (protonated or deprotonated) or charge state (singly or multiply charged). More than 20 peptide sulfinyl radical ions in either positive or negative ion mode were subjected to low energy collisional activation on a triple-quadrupole/linear ion trap mass spectrometer. The competition between radical-and charge-directed fragmentation pathways was largely affected by the presence of mobile protons. For peptide sulfinyl radical ions with reduced proton mobility (i.e., singly protonated, containing basic amino acid residues), loss of 62 Da (CH 2 SO), a radicalinitiated dissociation channel, was dominant. For systems with mobile protons, this channel was suppressed, while charge-directed amide bond cleavages were preferred. The polarity of charge was found to significantly alter the radical-initiated dissociation channels, which might be related to the difference in stability of the product ions in different ion charge polarities.

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Section: Radical Attack Of Free Cysteine Residuementioning

confidence: 99%

mentioning

confidence: 99%

Gas-Phase Peptide Sulfinyl Radical Ions: Formation and Unimolecular Dissociation

Tan

Xia

2012

J. Am. Soc. Mass Spectrom.

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“…However, in the case of odd numbered C,+ the positive charge and the radical electron are likely to reside in separate orthogonal MO typical of distonic ions [18]. Conceivably, the ion/ molecule reactions of these two types of carbon radical cations should be different [19]. The exact electronic configurations of monocyclic C, + ions have to be substantiated by high level ab-initio calculations and preferably by high resolution spectroscopy of carbon cluster ions.…”

Section: Product Ionsmentioning

confidence: 99%

Gas-phase reactions of carbon cluster ions with isomeric chloropropenes

Sun

Grützmacher

Lifshitz

1994

International Journal of Mass Spectrometry and Ion Processes

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Gas-phase ion/molecule reactions of carbon cluster ions (CA', n = 10-20) with allylchloride (AC) and 2-chloropropene (CP) were investigated by Fourier transform ion cyclotron resonance spectrometry (FT-ICR). The carbon cluster ions CA+ were generated by electron impact ionization of perchloroarenes and subsequent elimination of all Cl substituents from the molecular ion giving rise to monocyclic CA'. Clear pseudo-first-order reactions were observed for the carbon cluster ions C;;' thus formed without any sign of isomeric clusters of different reactivity. An exception is Ci:, for which a small amount of unreactive ions was observed. The reactions of Ci' with AC and CP at low operating pressure (1.2 x 1O-8-8.O x IO-'mbar) yield product ions C n+3H: by loss of Cl from an intermediate adduct. Rate constants for the reactions with CP are always distinctly larger than with AC in spite of the smaller dissociation energy of the C-Cl bond in AC. Exceptionally large reaction efficiencies are found for Ci: and Ci:, corroborating the high reactivity of cyclic anti-aromatic CA+ with n = 4r + 1. The nature of the reaction products depends on the number of carbon atoms in CA+. Secondary reactions of primary product ions C n+3H: were observed only for reactions of odd numbered Cit and Ciq. Further, on collision induced dissociation (CID) the product ions from even CA' yield exclusively C3H$, while product ions from odd Cl: generate several fragment ions by loss of H and of Ct2_4jH2. A reaction model explaining these observations is proposed.

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“…In their ion cyclotron resonance (ICR) study Pakarinen et al (6,7) found compelling evidence from characteristic ion-molecule reactions that ionized acetol rearranges to the 0 -H . 0 species CH,C=O..-H...O=CH,'+, 4. It was further proposed that ion 4 undergoes a hydrogen shift prior to the loss of HC=O' as follows:…”

Section: Introductionmentioning

confidence: 99%

Proton and electron transfers in O•H•O and C•H•O hydrogen-bridged ions: their role in the dissociation chemistry of ionized acetol, CH₃C(=O)CH₂OH^•+

Ruttink¹,

Burgers²,

Terlouw³

1996

Can. J. Chem.

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Low-energy acetol ions CH,C(=O)CH,OH'+, 1, dissociate to CH3C(H)OH+ and HC=O by a double hydrogen transfer (DHT), a common reaction among oxygen-containing radical cations. Recent experimental work has shown that the isotopologue CH,C(=O)CH,OD'+ specifically loses HC=U to produce CH,C(D)OH+. This finding refutes an earlier postulated attractive mechanism based on the behaviour of 1 in ion-molecule reactions. Using ab initio MO calculations (at the CEPA//RHF/DZP level of theory complemented with valence bond (VB) methods), a low-energy pathway was traced that may explain all of the available experimental observations. It is shown that the unimolecular chemistry of 1 can be understood in terms of two proton transfers, taking place in intermediate 0 . H -0 and C.H.0 bonded hydrogen-bridged radical cations. The two protons originate from the same moiety and a charge transfer complex is therefore implicated and shown to be involved. These concepts of proton and charge transfer may well be more generally applicable and they do correctly predict the unimolecular chemistry of ionized acetoin, CH,C(=O)CH(CH,)OH'+ and related a-ketols. Key words: ab initio calculations, hydrogen-bridged ions.Resume : Les ions acttol de basse tnergie, CH,(C=O)CH,OH'+, 1, se dissocient en CH,C(H)OH+ et en HC=O' par un double transfert d'hydrogkne (DTH), une reaction courante des cations radicaux contenant de l'oxygkne. Des travaux exptrimentaux rtcents ont montrk que l'isotopologue, CH,(C=O)CH,OD'+ perd specifiquement du HC=O pour fournir du CH,C(D)OH+. Cette observation refute un mecanisme attrayant propost anttrieurement et qui Ctait bast sur le comportement du compost 1 dans les rtactions ion-moltcule. Utilisant des calculs d'OM ab initio (au niveau CEPA//RHF/DZP de la thtorie avec un compltment des mtthodes de liaisons de valence), on a pu tracer une voie rtactionnelle de basse Cnergie qui peut expliquer toutes les donntes exptrimentales disponibles. I1 a t t t montrt que le chimie unimoltculaire du compost 1 peut se comprendre en termes de deux transferts de protons qui se produisent par l'intermtdiaire de cations radicaux de liasions hydrogknes ponttes 0 -H . 0 et C.H.0. Les deux protons ont leur origine dans la m&me partie de la moltcule; il y a donc un complexe de transfert de charge d'impliquer et on I'a dtmontrt. I1 est fort possible que ces concepts de transferts de protons et de charges puissent s'appliquer d'une faqon gtntrale et ils permettent de prtdire correctement la chimie unimoltculaire de l'actto'ine ioniste, CH,(C=O)CHCH,OH'+ et des a-cttols apparentis. tions." So begins Professor R.F.W. Bader an influential review article entitled "A quantum chemical theory of molecular structure and its applications" (1). One of the purposes of the present commemorative paper is to show that nowadays state-of-the-art ab initio molecular orbital (MO) calculations can indeed predict experimental observables and that they can indeed lead to a deeper understanding of the underlying phenomena. In this paper we deal with gas-phas...

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Ion-molecule reactions of distonic radical cations

Cited by 271 publications

References 33 publications

Gas-Phase Peptide Sulfinyl Radical Ions: Formation and Unimolecular Dissociation

Gas-Phase Peptide Sulfinyl Radical Ions: Formation and Unimolecular Dissociation

Gas-phase reactions of carbon cluster ions with isomeric chloropropenes

Proton and electron transfers in O•H•O and C•H•O hydrogen-bridged ions: their role in the dissociation chemistry of ionized acetol, CH₃C(=O)CH₂OH^•+

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Ion-molecule reactions of distonic radical cations

Cited by 271 publications

References 33 publications

Gas-Phase Peptide Sulfinyl Radical Ions: Formation and Unimolecular Dissociation

Gas-Phase Peptide Sulfinyl Radical Ions: Formation and Unimolecular Dissociation

Gas-phase reactions of carbon cluster ions with isomeric chloropropenes

Proton and electron transfers in O•H•O and C•H•O hydrogen-bridged ions: their role in the dissociation chemistry of ionized acetol, CH3C(=O)CH2OH•+

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Proton and electron transfers in O•H•O and C•H•O hydrogen-bridged ions: their role in the dissociation chemistry of ionized acetol, CH₃C(=O)CH₂OH^•+