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Ameixa J, Arthur-Baidoo E, Pereira-da-Silva J, Ončák M, Ruivo J, Varella MDN, Ferreira da Silva F, Denifl S. Parent anion radical formation in coenzyme Q 0: Breaking ubiquinone family rules. Comput Struct Biotechnol J 2022; 21:346-353. [PMID: 36582437 PMCID: PMC9792397 DOI: 10.1016/j.csbj.2022.12.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/06/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022] Open
Abstract
We report electron attachment (EA) measurements for the parent anion radical formation from coenzyme Q0 (CoQ0) at low electron energies (<2 eV) along with quantum chemical calculations. CoQ0 may be considered a prototype for the electron withdrawing properties of the larger CoQ n molecules, in particular ubiquinone (CoQ10), an electron carrier in aerobic cell respiration. Herein, we show that the mechanisms for the parent anion radical formation of CoQ0 and CoQ n (n = 1,2,4) are remarkably distinct. Reported EA data for CoQ1, CoQ2, CoQ4 and para-benzoquinone indicated stabilization of the parent anion radicals around 1.2-1.4 eV. In contrast, we observe for the yield of the parent anion radical of CoQ0 a sharp peak at ∼ 0 eV, a shoulder at 0.07 eV and a peak around 0.49 eV. Although the mechanisms for the latter feature remain unclear, our calculations suggest that a dipole bound state (DBS) would account for the lower energy signals. Additionally, the isoprenoid side chains in CoQ n (n = 1,2,4) molecules seem to influence the DBS formation for these compounds. In contrast, the side chains enhance the parent anion radical stabilization around 1.4 eV. The absence of parent anion radical formation around 1.4 eV for CoQ0 can be attributed to the short auto-ionization lifetimes. The present results shed light on the underappreciated role played by the side chains in the stabilization of the parent anion radical. The isoprenoid tails should be viewed as co-responsible for the electron-accepting properties of ubiquinone, not mere spectators of electron transfer reactions.
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Affiliation(s)
- J. Ameixa
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria,CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal,Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - E. Arthur-Baidoo
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria,Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - J. Pereira-da-Silva
- CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - M. Ončák
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - J.C. Ruivo
- Institute of Physics, University of São Paulo, Rua do Matão 1731, 05508-090 São Paulo, Brazil
| | - M.T. do N. Varella
- Institute of Physics, University of São Paulo, Rua do Matão 1731, 05508-090 São Paulo, Brazil,Corresponding authors at: Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria (S. Denifl).
| | - F. Ferreira da Silva
- CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal,Corresponding authors at: Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria (S. Denifl).
| | - S. Denifl
- Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria,Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria,Corresponding authors at: Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria (S. Denifl).
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Ziegler P, Pelc A, Arthur-Baidoo E, Ameixa J, Ončák M, Denifl S. Negative ion formation and fragmentation upon dissociative electron attachment to the nicotinamide molecule. RSC Adv 2021; 11:32425-32434. [PMID: 35495526 PMCID: PMC9041917 DOI: 10.1039/d1ra06083j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 09/13/2021] [Indexed: 12/20/2022] Open
Abstract
Nicotinamide (C6H6N2O) is a biologically relevant molecule. This compound has several important roles related to the anabolic and metabolic processes that take place in living organisms. It is also used as a radiosensitizer in tumor therapy. As a result of the interaction of high-energy radiation with matter, low-energy electrons are also released, which can also interact with other molecules, forming several types of ions. In the present investigation, dissociative electron attachment to C6H6N2O has been studied in a crossed electron-molecular beams experiment in the electron energy range of about 0-15 eV. In the experiment, six anionic species were detected: C6H5N2O-, C5H4N-, NCO-, O-/NH2 -, and CN-, with NCO- being the most prominent anion. We also provide detailed computational results regarding the energetic thresholds and pathways of the respective dissociative electron attachment (DEA) channels. The experimental results are compared with the theoretical ones and on this basis, the possible DEA reactions for the formation of anions at a given resonance energy were assigned as well as the generation of neutrals fragments such as pyridine and its several derivatives and radicals are predicted. The pyridine ring seems to stay intact during the DEA process.
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Affiliation(s)
- Patrick Ziegler
- Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstrasse 25 6020 Innsbruck Austria
| | - Andrzej Pelc
- Maria Curie-Skłodowska University, Department of Biophysics, Mass Spectrometry Laboratory Pl. M. C.-Skłodowskiej 1 20-031 Lublin Poland
| | - Eugene Arthur-Baidoo
- Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstrasse 25 6020 Innsbruck Austria
| | - Joao Ameixa
- Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstrasse 25 6020 Innsbruck Austria .,Centre of Physics and Technological Research, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa 2829-516 Caparica Portugal
| | - Milan Ončák
- Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstrasse 25 6020 Innsbruck Austria
| | - Stephan Denifl
- Institute for Ion Physics and Applied Physics, University of Innsbruck Technikerstrasse 25 6020 Innsbruck Austria
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Arthur-Baidoo E, Ameixa J, Ončák M, Denifl S. Ring-Selective Fragmentation in the Tirapazamine Molecule upon Low-Energy Electron Attachment. Int J Mol Sci 2021; 22:ijms22063159. [PMID: 33808887 PMCID: PMC8003736 DOI: 10.3390/ijms22063159] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/15/2021] [Accepted: 03/16/2021] [Indexed: 01/08/2023] Open
Abstract
We investigate dissociative electron attachment to tirapazamine through a crossed electron-molecule beam experiment and quantum chemical calculations. After the electron is attached and the resulting anion reaches the first excited state, D1, we suggest a fast transition into the ground electronic state through a conical intersection with a distorted triazine ring that almost coincides with the minimum in the D1 state. Through analysis of all observed dissociative pathways producing heavier ions (90-161 u), we consider the predissociation of an OH radical with possible roaming mechanism to be the common first step. This destabilizes the triazine ring and leads to dissociation of highly stable nitrogen-containing species. The benzene ring is not altered during the process. Dissociation of small anionic fragments (NO2-, CN2-, CN-, NH2-, O-) cannot be conclusively linked to the OH predissociation mechanism; however, they again do not require dissociation of the benzene ring.
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Affiliation(s)
- Eugene Arthur-Baidoo
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria; (E.A.-B.); (J.A.)
- Center for Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria
| | - Joao Ameixa
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria; (E.A.-B.); (J.A.)
- Center for Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria
- Atomic and Molecular Collisions Laboratory, Department of Physics, CEFITEC, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - Milan Ončák
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria; (E.A.-B.); (J.A.)
- Correspondence: (M.O.); (S.D.)
| | - Stephan Denifl
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria; (E.A.-B.); (J.A.)
- Center for Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstrasse 25/3, 6020 Innsbruck, Austria
- Correspondence: (M.O.); (S.D.)
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Ameixa J, Arthur-Baidoo E, Pereira-da-Silva J, Ryszka M, Carmichael I, Cornetta LM, do N Varella MT, Ferreira da Silva F, Ptasińska S, Denifl S. Formation of resonances and anionic fragments upon electron attachment to benzaldehyde. Phys Chem Chem Phys 2020; 22:8171-8181. [PMID: 32249870 DOI: 10.1039/d0cp00029a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Benzaldehyde is a simple aromatic aldehyde and has a wide range of applications in the food, pharmaceutical, and chemical industries. The positive electron affinity of this compound suggests that low-energy electrons can be easily trapped by neutral benzaldehyde. In the present study, we investigated the formation of negative ions following electron attachment to benzaldehyde in the gas-phase. Calculations on elastic electron scattering from benzaldehyde indicate a π* valence bound state of the anion at -0.48 eV and three π* shape resonances (0.78, 2.48 and 5.51 eV). The excited state spectrum of the neutral benzaldehyde is also reported to complement our findings. Using mass spectrometry, we observed the formation of the intact anionic benzaldehyde at ∼0 eV. We ascribe the detection of the benzaldehyde anion to stabilization of the π* valence bound state upon dissociative electron attachment to a benzaldehyde dimer. In addition, we report the cross sections for nine fragment anions formed through electron attachment to benzaldehyde. Investigations carried out with partially deuterated benzaldehyde show that the hydrogen loss is site-selective with respect to the incident electron energy. In addition, we propose several dissociation pathways, backed up by quantum chemical calculations on their thermodynamic thresholds. The threshold calculations also support that the resonances formed at higher energies lead to fragment anions observable by mass spectrometry, whereas the resonances at low electron energies decay only by electron autodetachment.
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Affiliation(s)
- J Ameixa
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria. and Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
| | - E Arthur-Baidoo
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria.
| | - J Pereira-da-Silva
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
| | - M Ryszka
- Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - I Carmichael
- Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - L M Cornetta
- Instituto de Física, Universidade de São Paulo, Rua do Matão 1731, 05508-090 São Paulo, Brazil
| | - M T do N Varella
- Instituto de Física, Universidade de São Paulo, Rua do Matão 1731, 05508-090 São Paulo, Brazil
| | - F Ferreira da Silva
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
| | - S Ptasińska
- Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556, USA and Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
| | - S Denifl
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria.
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Tiefenthaler L, Ameixa J, Martini P, Albertini S, Ballauf L, Zankl M, Goulart M, Laimer F, von Haeften K, Zappa F, Scheier P. An intense source for cold cluster ions of a specific composition. Rev Sci Instrum 2020; 91:033315. [PMID: 32260000 DOI: 10.1063/1.5133112] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 02/26/2020] [Indexed: 05/18/2023]
Abstract
The demand for nanoscale materials of ultra-high purity and narrow size distribution is addressed. Clusters of Au, C60, H2O, and serine are produced inside helium nanodroplets using a combination of ionization, mass filtering, collisions with atomic or molecular vapor, and electrostatic extraction, in a specific and novel sequence. The helium droplets are produced in an expansion of cold helium gas through a nozzle into vacuum. The droplets are ionized by electron bombardment and subjected to a mass filter. The ionic and mass-selected helium droplets are then guided through a vacuum chamber filled with atomic or molecular vapor where they collide and "pick up" the vapor. The dopants then agglomerate inside the helium droplets around charge centers to singly charged clusters. Evaporation of the helium droplets is induced by collisions in a helium-filled radio frequency (RF)-hexapole, which liberates the cluster ions from the host droplets. The clusters are analyzed with a time-of-flight mass spectrometer. It is demonstrated that using this sequence, the size distribution of the dopant cluster ions is distinctly narrower compared to ionization after pickup. Likewise, the ion cluster beam is more intense. The mass spectra show, as well, that ion clusters of the dopants can be produced with only few helium atoms attached, which will be important for messenger spectroscopy. All these findings are important for the scientific research of clusters and nanoscale materials in general.
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Affiliation(s)
- L Tiefenthaler
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - J Ameixa
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - P Martini
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - S Albertini
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - L Ballauf
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - M Zankl
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - M Goulart
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - F Laimer
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - K von Haeften
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - F Zappa
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - P Scheier
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
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Ameixa J, Arthur-Baidoo E, Meißner R, Makurat S, Kozak W, Butowska K, Ferreira da Silva F, Rak J, Denifl S. Low-energy electron-induced decomposition of 5-trifluoromethanesulfonyl-uracil: A potential radiosensitizer. J Chem Phys 2018; 149:164307. [PMID: 30384761 DOI: 10.1063/1.5050594] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
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 C5-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-C5 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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Affiliation(s)
- J Ameixa
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - E Arthur-Baidoo
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - R Meißner
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
| | - S Makurat
- Laboratory of Biological Sensitizers, Physical Chemistry Department, Faculty of Chemistry, University of Gdańsk, 80-308 Gdańsk, Poland
| | - W Kozak
- Laboratory of Biological Sensitizers, Physical Chemistry Department, Faculty of Chemistry, University of Gdańsk, 80-308 Gdańsk, Poland
| | - K Butowska
- Laboratory of Biophysics, Department of Molecular and Cellular Biology, Intercollegiate Faculty of Biotechnology of the University of Gdańsk and Medical University of Gdańsk, 80-307 Gdańsk, Poland
| | - F Ferreira da Silva
- Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal
| | - J Rak
- Laboratory of Biological Sensitizers, Physical Chemistry Department, Faculty of Chemistry, University of Gdańsk, 80-308 Gdańsk, Poland
| | - S Denifl
- Institut für Ionenphysik und Angewandte Physik and Center for Molecular Biosciences (CMBI), Leopold-Franzens Universität Innsbruck, Technikerstraße 25/3, 6020 Innsbruck, Austria
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