Fragmentation patterns of 4(5)‐nitroimidazole and 1‐methyl‐5‐nitroimidazole—The effect of the methylation

Itälä, Eero; Tanzer, Katrin; Granroth, Sari; Kooser, Kuno; Denifl, Stephan; Kukk, E.

doi:10.1002/jms.3979

Cited by 14 publications

(19 citation statements)

References 23 publications

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“…However, such an estimate based on the present data is unreliable, because it would be affected by the kinetic energy distribution of the involved fragments, which in turn affects the detection efficiency. photoioni-photoion coincidence (PEPIPICO) experiments (Itälä et al, 2017) reported that the dominant contribution in the fragmentation of doubly/multiply charged 4(5)NIM ions just above the C K-edge corresponds to the release of NO + , while NO2+ is either hardly produced or has a large probability to fragment, consistent with our observations.…”

Section: Resultssupporting

confidence: 90%

“…Passing through core excitations and ionizations the fragmentation mechanisms could be different from the ones identified in the valence region, mainly due to the possibility for multiply-charged ion formations. However, the PEPIPICO experiments of (Itälä et al, 2017) in 4(5)NIM at 317 eV photon energy (i.e., still well below the N K edge) do not display any significant signal for ion pairs including m/z fragments heavier than 46. Therefore, we deduced that double ionization events are not the major channels for the production of heavier fragments in 2NIM too.…”

Section: Resultsmentioning

confidence: 94%

“…The photoionization and photofragmentation properties of nitroimidazole isomers, including 2NIM, have already been investigated in the valence region for the neutral (Bolognesi et al, 2016; Cartoni et al, 2018) and protonated (Feketeová et al, 2015b) molecule. The 4(5)NIM isomers have also been studied by XPS and NEXAFS (Feketeová et al, 2015a) as well as by ion-ion coincidence experiments (PIPICO) (Itälä et al, 2017). Sections 2 and 3 describe the experimental and theoretical methods, while section 4 is devoted to the description and discussion of the XPS, NEXAFS, and mass spectrometry measurements.…”

Section: Introductionmentioning

confidence: 99%

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Core Shell Investigation of 2-nitroimidazole

et al. 2019

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Tunability and selectivity of synchrotron radiation have been used to study the excitation and ionization of 2-nitroimidazole at the C, N, and O K-edges. The combination of a set of different measurements (X-ray photoelectron spectroscopy, near-edge photoabsorption spectroscopy, Resonant Auger electron spectroscopy, and mass spectrometry) and computational modeling have successfully disclosed local effects due to the chemical environment on both excitation/ionization and fragmentation of the molecule.

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Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

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Core Shell Investigation of 2-nitroimidazole

et al. 2019

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“…Although the detailed mechanisms by which radiosensitisation operates are still unknown, it is believed that radiosensitisers are chemical compounds subject to redox reactions inside the hypoxic cells [4], and in case of nitroimidazoles, the ring facilitates reduction through reactive anion radicals' formation [5][6][7]. Nitroimidazole radiosensitisers have been thoroughly investigated by experimental methods on low-energy electron interactions [8][9][10][11][12] and together with nimorazole probed by electrospray ionization mass spectrometry [13][14][15]. While associative electron attachment may contribute to NIMO's radiosensitising effect, within the biological environment, electron transfer processes (redox reactions) may prevail and so these may seem more appropriate to describe the underlying molecular mechanisms of such chemical compounds and their role as radiosensitisers.…”

Section: Introductionmentioning

confidence: 99%

Bound Electron Enhanced Radiosensitisation of Nimorazole upon Charge Transfer

et al. 2022

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This novel work reports nimorazole (NIMO) radiosensitizer reduction upon electron transfer in collisions with neutral potassium (K) atoms in the lab frame energy range of 10–400 eV. The negative ions formed in this energy range were time-of-flight mass analyzed and branching ratios were obtained. Assignment of different anions showed that more than 80% was due to the formation of the non-dissociated parent anion NIMO•− at 226 u and nitrogen dioxide anion NO2− at 46 u. The rich fragmentation pattern revealed that significant collision induced the decomposition of the 4-nitroimidazole ring, as well as other complex internal reactions within the temporary negative ion formed after electron transfer to neutral NIMO. Other fragment anions were only responsible for less than 20% of the total ion yield. Additional information on the electronic state spectroscopy of nimorazole was obtained by recording a K+ energy loss spectrum in the forward scattering direction (θ ≈ 0°), allowing us to determine the most accessible electronic states within the temporary negative ion. Quantum chemical calculations on the electronic structure of NIMO in the presence of a potassium atom were performed to help assign the most significant lowest unoccupied molecular orbitals participating in the collision process. Electron transfer was shown to be a relevant process for nimorazole radiosensitisation through efficient and prevalent non-dissociated parent anion formation.

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“…Decomposition products upon photon excitation were reported in [31] with nitric oxide (NO) and nitrogen dioxide (NO 2 ) as the main fragments. A recent photofragmentation study of doubly charged, core excited 4(5)-nitromindazole (4(5)-NI) showed that methylation at the N1 position (see Scheme 1) suppresses efficiently the NO and NO + production [32]. The first mass spectra of electrosprayed nitroimidazolic compounds, like nimorazole, were recorded by Feketeová et al [33, 34].…”

Section: Introductionmentioning

confidence: 99%

Electron Ionization of Imidazole and Its Derivative 2-Nitroimidazole

Meißner

Feketeová

Ribar

et al. 2019

J. Am. Soc. Mass Spectrom.

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Imidazole (IMI) is a basic building block of many biologically important compounds. Thus, its electron ionization properties are of major interest and essential for the comparison with other molecular targets containing its elemental structure. 2-Nitroimidazole (2NI) contains the imidazole ring together with nitrogen dioxide bound to the C2 position, making it a radiosensitizing compound in hypoxic tumors. In the present study, we investigated electron ionization of IMI and 2NI and determined the mass spectra, the ionization energies, and appearance energies of the most abundant fragment cations. The experiments were complemented by quantum chemical calculations on the thermodynamic thresholds and potential energy surfaces, with particular attention to the calculated transition states for the most important dissociation reactions. In the case of IMI, substantially lower threshold values (up to ~ 1.5 eV) were obtained in the present work compared to the only available previous electron ionization study. Closer agreement was found with recent photon ionization values, albeit the general trend of slightly higher values for the case of electron ionization. The only exception for imidazole was found in the molecular cation at m/z 40 which is tentatively assigned to the quasi-linear HCCNH+/ HCNCH+. Electron ionization of 2NI leads to analogous fragment cations as in imidazole, yet different dissociation pathways must be operative due to the presence of the NO2 group. Regarding the potential radiosensitization properties of 2NI, electron ionization is characterized by dominant parent cation formation and release of the neutral NO radical. Electronic supplementary materialThe online version of this article (10.1007/s13361-019-02337-w) contains supplementary material, which is available to authorized users.

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Fragmentation patterns of 4(5)‐nitroimidazole and 1‐methyl‐5‐nitroimidazole—The effect of the methylation

Cited by 14 publications

References 23 publications

Core Shell Investigation of 2-nitroimidazole

Core Shell Investigation of 2-nitroimidazole

Bound Electron Enhanced Radiosensitisation of Nimorazole upon Charge Transfer

Electron Ionization of Imidazole and Its Derivative 2-Nitroimidazole

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