Isomer Selectivity in Low‐Energy Electron Attachment to Nitroimidazoles

Ribar, Anita; Fink, Klaus; Probst, Michael; Huber, S.; Feketeová, Linda; Denifl, Stephan

doi:10.1002/chem.201702644

Cited by 28 publications

(29 citation statements)

References 49 publications

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“…Although the BR for (M−NO) − is not shown here, the threshold in the case of 4(5)NI (19.8 eV) is much higher than in 2NI (5.7 eV). These results are consistent with the three DEA resonances found below 3 eV [11,32] where 2NI shows an enhancement in the fragmentation pattern as compared with 4(5)NI. These two reactions are quite important within the biological environment further to low-energy electron transfer collisions.…”

Section: (M-no)and (M-oh) -Formationsupporting

confidence: 90%

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Electron Transfer Induced Decomposition in Potassium–Nitroimidazoles Collisions: An Experimental and Theoretical Work

Mendes

Garcı́a

Bacchus‐Montabonel

et al. 2019

IJMS

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Electron transfer induced decomposition mechanism of nitroimidazole and a selection of analogue molecules in collisions with neutral potassium (K) atoms from 10 to 1000 eV have been thoroughly investigated. In this laboratory collision regime, the formation of negative ions was time-of-flight mass analyzed and the fragmentation patterns and branching ratios have been obtained. The most abundant anions have been assigned to the parent molecule and the nitrogen oxide anion (NO2–) and the electron transfer mechanisms are comprehensively discussed. This work focuses on the analysis of all fragment anions produced and it is complementary of our recent work on selective hydrogen loss from the transient negative ions produced in these collisions. Ab initio theoretical calculations were performed for 4-nitroimidazole (4NI), 2-nitroimidazole (2NI), 1-methyl-4- (Me4NI) and 1-methyl-5-nitroimidazole (Me5NI), and imidazole (IMI) in the presence of a potassium atom and provided a strong basis for the assignment of the lowest unoccupied molecular orbitals accessed in the collision process.

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Section: (M-no)and (M-oh) -Formationsupporting

confidence: 90%

“…According to the BR results (see Figures 5-7), the CN − threshold of formation is 9 eV for all molecules except for 4(5)NI, which is below 2.4 eV. This agrees well with DEA experiments where resonances near 0 and 4 eV for 4(5)NI and 2NI, and around 4 eV in the case of methylated molecules [11,32] were observed.…”

Section: Cn − Formationsupporting

confidence: 87%

Electron Transfer Induced Decomposition in Potassium–Nitroimidazoles Collisions: An Experimental and Theoretical Work

Mendes

Garcı́a

Bacchus‐Montabonel

et al. 2019

IJMS

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“…As is obvious from Figure 4a, this reaction is already operative at threshold (zero electron energy) and additionally within the weak resonances at around 0.25 and 1 eV. We note that the loss of a water molecule upon DEA turned out to be an isomer selective process for NIs [40]. The DEA reaction with formation of H 2 O was only abundant for the 2-NI isomer, while for the 4-NI molecule this channel was very weak.…”

Section: Resultsmentioning

confidence: 88%

Reactions in the Radiosensitizer Misonidazole Induced by Low-Energy (0–10 eV) Electrons

Meißner

Feketeová

Illenberger

et al. 2019

IJMS

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Misonidazole (MISO) was considered as radiosensitizer for the treatment of hypoxic tumors. A prerequisite for entering a hypoxic cell is reduction of the drug, which may occur in the early physical-chemical stage of radiation damage. Here we study electron attachment to MISO and find that it very effectively captures low energy electrons to form the non-decomposed molecular anion. This associative attachment (AA) process is exclusively operative within a very narrow resonance right at threshold (zero electron energy). In addition, a variety of negatively charged fragments are observed in the electron energy range 0–10 eV arising from dissociative electron attachment (DEA) processes. The observed DEA reactions include single bond cleavages (formation of NO2−), multiple bond cleavages (excision of CN−) as well as complex reactions associated with rearrangement in the transitory anion and formation of new molecules (loss of a neutral H2O unit). While any of these AA and DEA processes represent a reduction of the MISO molecule, the radicals formed in the course of the DEA reactions may play an important role in the action of MISO as radiosensitizer inside the hypoxic cell. The present results may thus reveal details of the molecular description of the action of MISO in hypoxic cells.

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“…In order to achieve a more comprehensive knowledge about the DEA process, a set of theoretical calculations was performed at the M06-2X 25 /aug-cc-pVTZ 26,27 level of theory, which has proven to give comparable results to the G4 28 extrapolation scheme. 29 However, the latter method is much more computationally demanding. In particular, the thermodynamic thresholds of various DEA reactions as well as the AEA of the neutral OTfU and of the observed anions were calculated.…”

Section: Computationalmentioning

confidence: 99%

Low-energy electron-induced decomposition of 5-trifluoromethanesulfonyl-uracil: A potential radiosensitizer

Ameixa

Arthur‐Baidoo

Meißner

et al. 2018

The Journal of Chemical Physics

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5-trifluoromethanesulfonyl-uracil (OTfU), a recently proposed radiosensitizer, is decomposed in the gas-phase by attachment of low-energy electrons. OTfU is a derivative of uracil with a triflate (OTf) group at the C 5-position, which substantially increases its ability to undergo effective electron-induced dissociation. We report a rich assortment of fragments formed upon dissociative electron attachment (DEA), mostly by simple bond cleavages (e.g., dehydrogenation or formation of OTf −). The most favorable DEA channel corresponds to the formation of the triflate anion alongside with the reactive uracil-5-yl radical through the cleavage of the O-C 5 bond, particularly at about 0 eV. Unlike for halouracils, the parent anion was not detected in our experiments. The experimental findings are accounted by a comprehensive theoretical study carried out at the M06-2X/aug-cc-pVTZ level. The latter comprises the thermodynamic thresholds for the formation of the observed anions calculated under the experimental conditions (383.15 K and 3 × 10 −11 atm). The energy-resolved ion yield of the dehydrogenated parent anion, (OTfU-H) − , is discussed in terms of vibrational Feshbach resonances arising from the coupling between the dipole bound state and vibrational levels of the transient negative ion. We also report the mass spectrum of the cations obtained through ionization of OTfU by electrons with a kinetic energy of 70 eV. The current study endorses OTfU as a potential radiosensitizer agent with possible applications in radio-chemotherapy.

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Isomer Selectivity in Low‐Energy Electron Attachment to Nitroimidazoles

Cited by 28 publications

References 49 publications

Electron Transfer Induced Decomposition in Potassium–Nitroimidazoles Collisions: An Experimental and Theoretical Work

Electron Transfer Induced Decomposition in Potassium–Nitroimidazoles Collisions: An Experimental and Theoretical Work

Reactions in the Radiosensitizer Misonidazole Induced by Low-Energy (0–10 eV) Electrons

Low-energy electron-induced decomposition of 5-trifluoromethanesulfonyl-uracil: A potential radiosensitizer

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