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Ring‐selective fragmentation in the tirapazamine molecule upon low‐energy electron attachment
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Orientador(es)
Resumo(s)
We investigate dissociative electron attachment to tirapazamine through a crossed elec-tron–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 produc-ing heavier ions (90–161 u), we consider the predissociation of an OH radical with possible roaming mechanism, as introduced in our recent letter [Angew Chem Int. Ed., 59, 17177 (2020)], 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.
Descrição
S.D. acknowledges support for Open Access Funding by the Austrian Science Fund as well as the Radiation Biology and Biophysics Doctoral Train-ing Programme (RaBBiT, PD/00193/2012); UIBD/04378/2020 (UCIBIO); and UIBD/00068/2020 (CEFITEC).
Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Palavras-chave
Dissociative electron attachment Low‐energy electron Predissociation Radiosensitizer Roaming Tirapazamine Catalysis Molecular Biology Spectroscopy Computer Science Applications Physical and Theoretical Chemistry Organic Chemistry Inorganic Chemistry