University of Oulu

J. Phys. Chem. A 2023, 127, 6, 1395–1401,

Forming bonds while breaking old ones : isomer-dependent formation of H₃O⁺ from aminobenzoic acid during X-ray-induced fragmentation

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Author: Abid, Abdul Rahman1,2; Veteläinen, Onni1; Boudjemia, Nacer1;
Organizations: 1Nano and Molecular Systems Research Unit, University of Oulu, 90570 Oulu, Finland
2Molecular and Condensed Matter Physics, Uppsala University, 75120 Uppsala, Sweden
3MAX IV Laboratory, Lund University, 22100 Lund, Sweden
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.5 MB)
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Language: English
Published: American Chemical Society, 2023
Publish Date: 2023-02-10


Intramolecular hydrogen transfer, a reaction where donor and acceptor sites of a hydrogen atom are part of the same molecule, is a ubiquitous reaction in biochemistry and organic synthesis. In this work, we report hydronium ion (H₃O⁺) production from aminobenzoic acid (ABA) after core-level ionization with soft X-ray synchrotron radiation. The formation of H₃O⁺ during the fragmentation requires that at least two hydrogen atoms migrate to one of the oxygen atoms within the molecule. The comparison of two structural isomers, ortho- and meta-ABA, revealed that the production of H₃O⁺ depends strongly on the structure of the molecule, the ortho-isomer being much more prone to produce H₃O⁺. The isomer-dependency suggests that the amine group acts as a donor in the hydrogen transfer process. In the case of ortho-ABA, detailed H₃O⁺ production pathways were investigated using photoelectron-photoion-photoion coincidence (PEPIPICO) spectroscopy. It was found that H₃O⁺ can result from a direct two-body dissociation but also from sequential fragmentation processes.

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Series: The journal of physical chemistry. A
ISSN: 1089-5639
ISSN-E: 1520-5215
ISSN-L: 1089-5639
Volume: 127
Issue: 6
Pages: 1395 - 1401
DOI: 10.1021/acs.jpca.2c06869
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
116 Chemical sciences
Funding: The research leading to these results has been supported by the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie I4Future (Grant no. 713606). This project was also granted travel funding from CALIPSOPlus from the EU Framework Programme for Research and Innovation Horizon 2020 (Grant no. 730872). A.R.A. acknowledges Väisälä Fund, Finnish Academy of Science & Letters, and M.P., O.V., E.P., and M.H. acknowledge the Academy of Finland for financial support (including The University of Oulu and The Academy of Finland Profi5 - project 326291). E.P. also acknowledges the financial support from the Finnish Cultural Foundation (North Ostrobothnia Regional Fund) and was partially supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences and Biosciences Division under award DEAC02-06CH11357. O.B. acknowledges funding from the Swedish Research Council (VR) for the project VR 2017-04162. We thank Prof. E. Kukk for the help with the coincidence setup, Dr. K. Chernenko for assistance during the experiments, and Mr. K. Rantamaula for assistance with the calculations of meta-ABA. We acknowledge MAX IV Laboratory for time on Beamline FinEstBeAMS under Proposal 20190884. Research conducted at MAX IV, a Swedish national user facility, is supported by the Swedish Research council under contract 2018-07152, the Swedish Governmental Agency for Innovation Systems under contract 2018-04969, and Formas under contract 2019-02496.
EU Grant Number: (713606) I4FUTURE - Novel Imaging and Characterisation Methods in Bio, Medical, and Environmental Research and Technology Innovations
Copyright information: © 2023 The Authors. Published by American Chemical Society. Published under the Creative Commons Attribution 4.0 International (CC BY 4.0) license.