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Wang E, Shan X, Chen L, Pfeifer T, Chen X, Ren X, Dorn A. Ultrafast Proton Transfer Dynamics on the Repulsive Potential of the Ethanol Dication: Roaming-Mediated Isomerization versus Coulomb Explosion. J Phys Chem A 2020; 124:2785-2791. [PMID: 32159968 PMCID: PMC7307916 DOI: 10.1021/acs.jpca.0c02074] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
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If
a molecular dication is produced on a repulsive potential energy
surface (PES), it normally dissociates. Before that, however, ultrafast
nuclear dynamics can change the PES and significantly influence the
fragmentation pathway. Here, we investigate the electron-impact-induced
double ionization and subsequent fragmentation processes of the ethanol
molecule using multiparticle coincident momentum spectroscopy and
ab initio dynamical simulations. For the electronic ground state of
the ethanol dication, we observe several fragmentation channels that
cannot be reached by direct Coulomb explosion (CE) but require preceding
isomerization. Our simulations show that ultrafast hydrogen or proton
transfer (PT) can stabilize the repulsive PES of the dication before
the direct CE and form intermediate H2 or H2O. These neutrals stay in the vicinity of the precursor, and roaming
mechanisms lead to isomerization and finally PT resulting in emission
of H3+ or H3O+. The present
findings can help to understand the complex fragmentation dynamics
of molecular cations.
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Affiliation(s)
- Enliang Wang
- Max Planck Institut für Kernphysik, Saupfercheckweg, 1, 69117 Heidelberg, Germany
| | - Xu Shan
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Lei Chen
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Thomas Pfeifer
- Max Planck Institut für Kernphysik, Saupfercheckweg, 1, 69117 Heidelberg, Germany
| | - Xiangjun Chen
- Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xueguang Ren
- Max Planck Institut für Kernphysik, Saupfercheckweg, 1, 69117 Heidelberg, Germany.,School of Science, Xi'an Jiaotong University, Xianning West Road 28, Xi'an 710049, China
| | - Alexander Dorn
- Max Planck Institut für Kernphysik, Saupfercheckweg, 1, 69117 Heidelberg, Germany
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2
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Martínez Fernández L, Cerezo J, Asha H, Santoro F, Coriani S, Improta R. The Absorption Spectrum of Guanine Based Radicals: a Comparative Computational Analysis. CHEMPHOTOCHEM 2019. [DOI: 10.1002/cptc.201900107] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Lara Martínez Fernández
- Departamento de Química, Facultad de Ciencias, Mòdulo13Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC Cantoblanco 28049 Madrid Spain
| | - Javier Cerezo
- Departamento de Química, Facultad de Ciencias, Mòdulo13Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC Cantoblanco 28049 Madrid Spain
| | - Haritha Asha
- Istituto di Biostrutture e Bioimmagini-CNR Via Mezzocannone 6 I-80134 Napoli
| | - Fabrizio Santoro
- Istituto di Chimica dei Composti Organometallici (ICCOM-CNR)Area della Ricerca del CNR Via Moruzzi 1 I-56124 Pisa
| | - Sonia Coriani
- DTU ChemistryTechnical University of Denmark, Kemitorvet Building 207 DK-2800 Kongens Lyngby Denmark
| | - Roberto Improta
- Istituto di Biostrutture e Bioimmagini-CNR Via Mezzocannone 6 I-80134 Napoli
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3
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Liu X, Wei X, Zhou H, Meng S, Zhao Y, Xue J, Zheng X. UV and Resonance Raman Spectroscopic and Theoretical Studies on the Solvent-Dependent Ground and Excited-State Thione → Thiol Tautomerization of 4,6-Dimethyl-2-mercaptopyrimidine (DMMP). J Phys Chem A 2018; 122:5710-5720. [PMID: 29889517 DOI: 10.1021/acs.jpca.8b04525] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The vibrational spectra of 4,6-dimethyl-2-mercaptopyrimidine (DMMP) in acetonitrile, methanol, and water were assigned by resonance Raman spectroscopy through a combination of Fourier-transform infrared spectroscopy (FT-IR), FT-Raman UV-vis spectroscopy, and density functional theoretical (DFT) calculations. The FT-Raman spectra show that the neat solid DMMP is formed as a dimer due to intermolecular hydrogen bonding. In methanol and water, however, the majority of the Raman spectra were assigned to the vibrational modes of DMMP(solvent) n ( n = 1-4) clusters containing NH···O hydrogen bonds. The intermolecular NH···O hydrogen bond interactions, which are key constituents of the stable DMMP thione structure, revealed significant structural differences in acetonitrile, methanol, and water. In addition, UV-induced hydrogen transfer isomeric reactions between the thione and thiol forms of DMMP were detected in water and acetonitrile. DFT calculations indicate that the observed thione → thiol tautomerization should occur easily in lower excited states in acetonitrile and water.
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4
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Yang Y, Yang W, Su H, Fang W, Chen X. Mechanistic insights into the photogeneration and quenching of guanine radical cation via one-electron oxidation of G-quadruplex DNA. Phys Chem Chem Phys 2018; 20:13598-13606. [DOI: 10.1039/c8cp01718b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Selectivity of activation site for the photogeneration and quenching of guanine radical cation was elucidated by the analysis of the relaxation paths of one-electron oxidation of G-quadruplex DNA.
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Affiliation(s)
- Yumei Yang
- Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education
- Department of Chemistry
- Beijing Normal University
- Beijing 100875
- P. R. China
| | - Wenjing Yang
- College of Material Science & Engineering
- Taiyuan University of Technology
- People's Republic of China
| | - Hongmei Su
- Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education
- Department of Chemistry
- Beijing Normal University
- Beijing 100875
- P. R. China
| | - Weihai Fang
- Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education
- Department of Chemistry
- Beijing Normal University
- Beijing 100875
- P. R. China
| | - Xuebo Chen
- Key Laboratory of Theoretical and Computational Photochemistry of Ministry of Education
- Department of Chemistry
- Beijing Normal University
- Beijing 100875
- P. R. China
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5
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New Members and Foreign Associates of the National Academy of Sciences New Fellows and Foreign Members of the Royal Society. Angew Chem Int Ed Engl 2017; 56:7349-7350. [DOI: 10.1002/anie.201704983] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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6
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Neue Mitglieder der National Academy of Sciences Neue Mitglieder der Royal Society. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201704983] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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7
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Keane PM, Baptista FR, Gurung SP, Devereux SJ, Sazanovich IV, Towrie M, Brazier JA, Cardin CJ, Kelly JM, Quinn SJ. Long-Lived Excited-State Dynamics of i-Motif Structures Probed by Time-Resolved Infrared Spectroscopy. Chemphyschem 2016; 17:1281-7. [PMID: 26879336 DOI: 10.1002/cphc.201501183] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Indexed: 01/22/2023]
Abstract
UV-generated excited states of cytosine (C) nucleobases are precursors to mutagenic photoproduct formation. The i-motif formed from C-rich sequences is known to exhibit high yields of long-lived excited states following UV absorption. Here the excited states of several i-motif structures have been characterized following 267 nm laser excitation using time-resolved infrared spectroscopy (TRIR). All structures possess a long-lived excited state of ∼300 ps and notably in some cases decays greater than 1 ns are observed. These unusually long-lived lifetimes are attributed to the interdigitated DNA structure which prevents direct base stacking overlap.
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Affiliation(s)
- Páraic M Keane
- Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK.
| | | | - Sarah P Gurung
- Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK
- Diamond Light Source, Harwell Science and Innovation campus, Didcot, Oxfordshire, OX11 0QX, UK
| | - Stephen J Devereux
- School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland
| | - Igor V Sazanovich
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation campus, Didcot, Oxfordshire, OX11 0QX, UK
| | - Michael Towrie
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Science and Innovation campus, Didcot, Oxfordshire, OX11 0QX, UK
| | - John A Brazier
- Department of Pharmacy, University of Reading, Whiteknights, Reading, RG6 6AD, UK
| | - Christine J Cardin
- Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK
| | - John M Kelly
- School of Chemistry, Trinity College Dublin, Dublin 2, Ireland
| | - Susan J Quinn
- School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland.
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