Investigation of doubly charged organic cations by electrospray ion cyclotron resonance mass spectrometry

Katritzky, Alan R.; Shipkova, Petia; Burton, Richard D. E.; Allin, Steven M.; Watson, Clifford H.; Eyler, John R.

doi:10.1002/jms.1190301110

Cited by 12 publications

(12 citation statements)

References 24 publications

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“…This was puzzling, since it had been shown earlier that ESI, as a soft ionisation technique, is an excellent method for transferring intact pyridinium ions into the gas phase. 11 Evidently, during the ESI process, the sample molecules are decomposed, with the formation of [A -H] + ions (Scheme 2).…”

Section: Esi Spectramentioning

confidence: 99%

Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Study of Mesomeric Heterocyclic Betainium Ions

Mäkinen

Vainiotalo

Schmidt

2000

Eur J Mass Spectrom (Chichester)

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Mesomeric heterocyclic betainium ions derived from 4-aminopyrimidine-2,6-bis(pyridinium) salts, were examined in the gas phase by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with electrospray ionisation. The purpose of the study was to clarify the general gas-phase properties and reactions of these novel ions. Collision-induced dissociation (CID) was used to investigate fragment ion formation and fragmentation pathways. The ions have an unusual tripolar structure with one negative and two positive charges that are in cross-conjugation within a common-electron system. Resonance stabilisation within the ions makes them relatively unreactive in ion-molecule reactions under the conditions in the FT-ICR cell. CID spectra showed that the charged pyridinium groups are easily lost as neutral pyridine. Otherwise the fragmentation depends on the substituent on the aniline moiety.

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Section: Esi Spectramentioning

confidence: 99%

Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Study of Mesomeric Heterocyclic Betainium Ions

Mäkinen

Vainiotalo

Schmidt

2000

Eur J Mass Spectrom (Chichester)

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“…1 Indeed, they are fundamental in gas-phase ion chemistry and in mass spectrometry in spite of their short lifetime. [2][3][4] They also play important roles in photochemical processes, 5,6 as well as in astrochemistry and the chemistry of the atmospheres. [7][8][9][10] It has also been postulated that they may have played some role in the origin of life, [11][12][13][14][15] since doubly charged metal ions may have induced the precipitation of nucleic acid molecules.…”

Section: Introductionmentioning

confidence: 99%

A RRKM study and a DFT assessment on gas-phase fragmentation of formamide–M2+ (M = Ca, Sr)

Martín-Sómer

Gaigeot

Yáñez

et al. 2014

Phys. Chem. Chem. Phys.

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A kinetic study of the unimolecular reactivity of formamide-M(2+) (M = Ca, Sr) systems was carried out by means of RRKM statistical theory using high-level DFT. The results predict M(2+), [M(NH2)](+) and [HCO](+) as the main products, together with an intermediate that could eventually evolve to produce [M(NH3)](2+) and CO, for high values of internal energy. In this framework, we also evaluated the influence of the external rotational energy on the reaction rate constants. In order to find a method to perform reliable electronic structure calculations for formamide-M(2+) (M = Ca, Sr) at a relatively low computational cost, an assessment of different methods was performed. In the first assessment twenty-one functionals, belonging to different DFT categories, and an MP2 wave function method using a small basis set were evaluated. CCSD(T)/cc-pWCVTZ single point calculations were used as reference. A second assessment has been performed on geometries and energies. We found BLYP/6-31G(d) and G96LYP/6-31+G(d,p) as the best performing methods, for formamide-Ca(2+) and formamide-Sr(2+), respectively. Furthermore, a detailed assessment was done on RRKM reactivity and G96LYP/6-31G(d) provided results in agreement with higher level calculations. The combination of geometrical, energetics and kinetics (RRKM) criteria to evaluate DFT functionals is rather unusual and provides an original assessment procedure. Overall, we suggest using G96LYP as the best performing functional with a small basis set for both systems.

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“…Diquaternary ammonium ions have been used for a variety of biochemical applications, such as herbicides (diquat, paraquat), anti-hypertensive drugs (hexamethonium), and muscle relaxants (decamethonium, succinylcholine, curare alkaloids). Mass spectrometry has been successfully applied to the characterization of such ions using a variety of desorption ionization and spray techniques [1][2][3][4][5][6][7]. For example, Hercules et al [1] used laser desorption to ionize a variety of diquaternary ammonium salts.…”

Section: Introductionmentioning

confidence: 99%

“…Eyler et al [5] recently reported the use of ESI with Fourier transform mass spectrometry (FTMS) [8] to study the dissociation and reactivity of doubly charged pyridinium cations. For these experiments, FTMS has the advantage of long ion storage times and extensive capabilities for tandem MS and MS n .…”

Section: Introductionmentioning

confidence: 99%

On the dissociation and conformation of gas-phase methonium ions

Gross¹,

Williams²

1996

International Journal of Mass Spectrometry and Ion Processes

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The dissociation pathways of both doubly and singly charged methonium ions, (CH(3))(3)N(+) -(CH(2))(n)-(+)N(CH(3))(3)·X(-) (n = 6,10; X = Br, I, and OAc), are measured using blackbody infrared radiative dissociation (BIRD) and SORI-CAD in a Fourier transform mass spectrometer. SORI-CAD of the doubly charged decamethonium ions results primarily in the formation of even electron ions by hydrogen rearrangements. In contrast, homolytic bond cleavage to form two odd electron ions is highly favored in the hexamethonium ion, presumably due to increased Coulomb repulsion in this ion. For BIRD of the singly charged salts, ions are mass selected and dissociated by heating the vacuum chamber to elevated temperatures. Under the low pressure conditions of our experiment, energy is transferred from the chamber walls to the ions by the absorption of blackbody radiation. From the temperature dependence of the unimolecular rate constants for dissociation, Arrhenius activation energies in the zero-pressure limit are obtained. The primary dissociation pathways correspond to counterion substitution reactions which result in loss of N(CH(3))(3) and CH(3)X. For hexamethonium and decamethonium with X = Br or I, the branching ratios for these pathways differ dramatically; the ratio of loss of N(CH(3))(3) and CH(3)Br is 3.8 and 0.4 for hexamethonium and decamethonium bromide, respectively. The hexamethonium acetate salt has a branching ratio of 0.1. The Arrhenius activation energies for hexamethonium (Br or I) and decamethonium (Br or I) are 0.9 and 1.0 eV, respectively. This value for hexamethonium acetate is 0.6 eV. Molecular dynamics simulations and Monte Carlo conformation searching are used to obtain the lowest energy structures of hexamethonium and decamethonium bromide. These calculations indicate that the methonium ion folds around the counterion to form a cyclic salt-bridge structure in which both quaternary nitrogens interact with the oppositely charged counterion. The significantly different branching ratios observed for these ions is attributed to the large change in orientation of the counterion with respect to the ammonium centers as the number of methylene groups in these ions increases. Similar ion conformational differences appear to explain the fragmentation for the OAc counter ion as well.

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Investigation of doubly charged organic cations by electrospray ion cyclotron resonance mass spectrometry

Cited by 12 publications

References 24 publications

Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Study of Mesomeric Heterocyclic Betainium Ions

Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Study of Mesomeric Heterocyclic Betainium Ions

A RRKM study and a DFT assessment on gas-phase fragmentation of formamide–M2+ (M = Ca, Sr)

On the dissociation and conformation of gas-phase methonium ions

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